Add gsk_path_get_previous/next_point

These functions let you iterate over the 'significant'
points of a path.

LOG

@@ -0,0 +1,150 @@
+TAP version 13
+# random seed: R02S22611f6aefc1121b0ab2dc5286960449
+# GLib-GIO-DEBUG: _g_io_module_get_default: Found default implementation dconf (DConfSettingsBackend) for ‘gsettings-backend’
+# GLib-GIO-DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
+# GLib-GIO-DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
+1..1
+# Start of ops tests
+# testcase 0 op 0
+collecting# 
+    Cubic 0: # M 100.000000 100.000000 C 150.000000 100.000000 200.000000 100.000000 250.000000 100.000000 
+    Cubic 1: # M 250.000000 100.000000 C 300.000000 100.000000 350.000000 100.000000 400.000000 100.000000 
+    Line 2: # M 400 100 L 200 300 
+    Line 3: # M 200 300 L 100 100 
+    Cubic 4: # M 200.000000 100.000000 C 250.000000 100.000000 300.000000 100.000000 350.000000 100.000000 
+    Cubic 5: # M 350.000000 100.000000 C 400.000000 100.000000 450.000000 100.000000 500.000000 100.000000 
+    Line 6: # M 500 100 L 300 300 
+    Line 7: # M 300 300 L 200 100 
+splitting# 
+1 intersections between Cubic 0 and Cubic 1# 
+1 intersections between Cubic 0 and Line 3# 
+9 intersections between Cubic 0 and Cubic 4# 
+# split Cubic 0.0 from Cubic 0 at 0.666666: M 100.000000 100.000000 C 133.333298 100.000000 166.666595 100.000000 199.999893 100.000000
+split Cubic 0.1 from Cubic 0 at 0.666666: M 199.999893 100.000000 C 216.666595 100.000000 233.333298 100.000000 250.000000 100.000000split Cubic 0.4 from Cubic 0 at 0.00600814: M 200.300323 100.000000 C 216.866882 100.000000 233.433441 100.000000 250.000000 100.000000split Cubic 0.7 from Cubic 0 at 0.00604445: M 200.600708 100.000000 C 217.067139 100.000000 233.533569 100.000000 250.000000 100.000000# split Cubic 4.9 from Cubic 4 at 0.00533867: M 200.800812 100.000000 C 250.533875 100.000000 300.266937 100.000000 350.000000 100.000000
+1 intersections between Cubic 0.1 and Line 7# 
+1 intersections between Cubic 1 and Line 2# 
+9 intersections between Cubic 1 and Cubic 4.9# 
+split Cubic 1.9 from Cubic 1 at 0.00534248: M 250.801361 100.000000 C 300.534241 100.000000 350.267120 100.000000 400.000000 100.000000# split Cubic 4.9.0 from Cubic 4.9 at 0.329756: M 200.800812 100.000000 C 217.200577 100.000000 233.600342 100.000000 250.000122 100.000000
+# split Cubic 4.9.1 from Cubic 4.9 at 0.329756: M 250.000122 100.000000 C 283.333435 100.000000 316.666718 100.000000 350.000000 100.000000
+# split Cubic 4.9.6 from Cubic 4.9 at 0.00500283: M 250.500412 100.000000 C 283.666931 100.000000 316.833466 100.000000 350.000000 100.000000
+9 intersections between Cubic 1.9 and Cubic 5# 
+# split Cubic 1.9.0 from Cubic 1.9 at 0.664877: M 250.801361 100.000000 C 283.867615 100.000000 316.933868 100.000000 350.000122 100.000000
+split Cubic 1.9.1 from Cubic 1.9 at 0.664877: M 350.000122 100.000000 C 366.666748 100.000000 383.333374 100.000000 400.000000 100.000000split Cubic 1.9.4 from Cubic 1.9 at 0.00601021: M 350.300598 100.000000 C 366.867065 100.000000 383.433533 100.000000 400.000000 100.000000split Cubic 1.9.7 from Cubic 1.9 at 0.00604655: M 350.601074 100.000000 C 367.067383 100.000000 383.533691 100.000000 400.000000 100.000000# split Cubic 5.9 from Cubic 5 at 0.00534248: M 350.801361 100.000000 C 400.534241 100.000000 450.267120 100.000000 500.000000 100.000000
+1 intersections between Line 2 and Line 3# 
+1 intersections between Line 2 and Line 7# 
+# split Line 2.0 from Line 2 at 0.666667: M 400 100 L 266.667 233.333
+split Line 2.1 from Line 2 at 0.666667: M 266.667 233.333 L 200 300# split Line 7.0 from Line 7 at 0.333333: M 300 300 L 266.667 233.333
+# split Line 7.1 from Line 7 at 0.333333: M 266.667 233.333 L 200 100
+1 intersections between Cubic 4 and Cubic 4.9.0# 
+1 intersections between Cubic 4 and Line 7.1# 
+1 intersections between Cubic 4.9.0 and Cubic 4.9.1# 
+1 intersections between Cubic 4.9.1 and Cubic 4.9.6# 
+1 intersections between Cubic 4.9.6 and Cubic 5# 
+1 intersections between Cubic 5 and Cubic 5.9# 
+1 intersections between Cubic 5.9 and Line 6# 
+1 intersections between Line 6 and Line 7.0# 
+    Cubic 0.0: # M 100.000000 100.000000 C 133.333298 100.000000 166.666595 100.000000 199.999893 100.000000 
+    Cubic 0.1: # M 199.999893 100.000000 C 200.100037 100.000000 200.200180 100.000000 200.300323 100.000000 
+    Cubic 0.4: # M 200.300323 100.000000 C 200.400452 100.000000 200.500580 100.000000 200.600708 100.000000 
+    Cubic 0.7: # M 200.600708 100.000000 C 217.067139 100.000000 233.533569 100.000000 250.000000 100.000000 
+    Cubic 1: # M 250.000000 100.000000 C 250.267120 100.000000 250.534241 100.000000 250.801361 100.000000 
+    Cubic 1.9.0: # M 250.801361 100.000000 C 283.867615 100.000000 316.933868 100.000000 350.000122 100.000000 
+    Cubic 1.9.1: # M 350.000122 100.000000 C 350.100281 100.000000 350.200439 100.000000 350.300598 100.000000 
+    Cubic 1.9.4: # M 350.300598 100.000000 C 350.400757 100.000000 350.500916 100.000000 350.601074 100.000000 
+    Cubic 1.9.7: # M 350.601074 100.000000 C 367.067383 100.000000 383.533691 100.000000 400.000000 100.000000 
+    Line 2.0: # M 400 100 L 266.667 233.333 
+    Line 2.1: # M 266.667 233.333 L 200 300 
+    Line 3: # M 200 300 L 100 100 
+    Cubic 4: # M 200.000000 100.000000 C 200.266937 100.000000 200.533875 100.000000 200.800812 100.000000 
+    Cubic 4.9.0: # M 200.800812 100.000000 C 217.200577 100.000000 233.600342 100.000000 250.000122 100.000000 
+    Cubic 4.9.1: # M 250.000122 100.000000 C 250.166885 100.000000 250.333649 100.000000 250.500412 100.000000 
+    Cubic 4.9.6: # M 250.500412 100.000000 C 283.666931 100.000000 316.833466 100.000000 350.000000 100.000000 
+    Cubic 5: # M 350.000000 100.000000 C 350.267120 100.000000 350.534241 100.000000 350.801361 100.000000 
+    Cubic 5.9: # M 350.801361 100.000000 C 400.534241 100.000000 450.267120 100.000000 500.000000 100.000000 
+    Line 6: # M 500 100 L 300 300 
+    Line 7.0: # M 300 300 L 266.667 233.333 
+    Line 7.1: # M 266.667 233.333 L 200 100 
+classifying# 
+ 01 Cubic 0.0: # M 100.000000 100.000000 C 133.333298 100.000000 166.666595 100.000000 199.999893 100.000000 
+[11 Cubic 0.7: # M 200.600708 100.000000 C 217.067139 100.000000 233.533569 100.000000 250.000000 100.000000 ]
+[11 Cubic 1.9.0: # M 250.801361 100.000000 C 283.867615 100.000000 316.933868 100.000000 350.000122 100.000000 ]
+[11 Cubic 1.9.7: # M 350.601074 100.000000 C 367.067383 100.000000 383.533691 100.000000 400.000000 100.000000 ]
+[11 Line 2.0: # M 400 100 L 266.667 233.333 ]
+ 01 Line 2.1: # M 266.667 233.333 L 200 300 
+ 01 Line 3: # M 200 300 L 100 100 
+[11 Cubic 4: # M 200.000000 100.000000 C 200.266937 100.000000 200.533875 100.000000 200.800812 100.000000 ]
+[11 Cubic 4.9.0: # M 200.800812 100.000000 C 217.200577 100.000000 233.600342 100.000000 250.000122 100.000000 ]
+[11 Cubic 4.9.6: # M 250.500412 100.000000 C 283.666931 100.000000 316.833466 100.000000 350.000000 100.000000 ]
+[11 Cubic 5: # M 350.000000 100.000000 C 350.267120 100.000000 350.534241 100.000000 350.801361 100.000000 ]
+ 01 Cubic 5.9: # M 350.801361 100.000000 C 400.534241 100.000000 450.267120 100.000000 500.000000 100.000000 
+ 01 Line 6: # M 500 100 L 300 300 
+ 01 Line 7.0: # M 300 300 L 266.667 233.333 
+[11 Line 7.1: # M 266.667 233.333 L 200 100 ]
+fixups# 
+# found 3 bad nodes
+# split Cubic 0/Cubic 4 BAD 200.600723 100.000000
+# 	[11 Line 7.1 ] 116.565
+# 	[11 Cubic 0.7 ] 180
+# 	[11 Cubic 4 ] 180
+# 	[11 Cubic 4 ] 180
+# 	[11 Cubic 4.9.0 ] 180
+# 	>01 Cubic 0.0  360
+# split Cubic 1/Cubic 4.9 BAD 250.801376 100.000000
+# 	[11 Cubic 1.9.0 ] 180
+# 	[11 Cubic 4.9.6 ] 180
+# 	[11 Cubic 0.7 ] 360
+# 	[11 Cubic 4.9.0 ] 360
+# split Cubic 1.9/Cubic 5 BAD 350.601105 100.000000
+# 	[11 Cubic 1.9.7 ] 180
+# 	[11 Cubic 5 ] 180
+# 	[11 Cubic 5 ] 180
+# 	<01 Cubic 5.9  180
+# 	[11 Cubic 1.9.0 ] 360
+# 	[11 Cubic 4.9.6 ] 360
+reassembling# 
+start new contour Cubic 0.0# 
+# Cubic 0.0 ends at: 
+# start 0 100.000000 100.000000
+# 	>01 Line 3  116.565
+# 	(10 Cubic 0.0 ) 180
+picking cw# 
+append Line 3# 
+# Line 3 ends at: 
+# end 2 200.000000 300.000000
+# 	>01 Line 2.1  225
+# 	(10 Line 3 ) 296.565
+picking cw# 
+append Line 2.1# 
+# Line 2.1 ends at: 
+# split Line 2/Line 7 266.666656 233.333344
+# 	(10 Line 2.1 ) 45
+# 	>01 Line 7.0  116.565
+# 	[11 Line 2.0 ] 225
+# 	[11 Line 7.1 ] 296.565
+picking cw# 
+append Line 7.0# 
+# Line 7.0 ends at: 
+# end 6 300.000000 300.000000
+# 	>01 Line 6  225
+# 	(10 Line 7.0 ) 296.565
+picking cw# 
+append Line 6# 
+# Line 6 ends at: 
+# end 5 500.000000 100.000000
+# 	(10 Line 6 ) 45
+# 	>01 Cubic 5.9  360
+picking cw# 
+append Cubic 5.9# 
+# Cubic 5.9 ends at: 
+# split Cubic 1.9/Cubic 5 BAD 350.601105 100.000000
+# 	[11 Cubic 1.9.7 ] 180
+# 	[11 Cubic 5 ] 180
+# 	[11 Cubic 5 ] 180
+# 	(10 Cubic 5.9 ) 180
+# 	[11 Cubic 1.9.0 ] 360
+# 	[11 Cubic 4.9.6 ] 360
+picking cw# 
+**
+ERROR:../testsuite/gsk/path-ops.c:359:test_ops_simple: assertion failed (s == tests[i].out): ("M 354.60110473632812 100 A 4 4 0 0 0 346.60110473632812 100 A 4 4 0 0 0 354.60110473632812 100 z M 252.80137634277344 100 A 2 2 0 0 0 248.80137634277344 100 A 2 2 0 0 0 252.80137634277344 100 z M 204.60072326660156 100 A 4 4 0 0 0 196.60072326660156 100 A 4 4 0 0 0 204.60072326660156 100 z" == "M 100 100 z")
+not ok /ops/simple - ERROR:../testsuite/gsk/path-ops.c:359:test_ops_simple: assertion failed (s == tests[i].out): ("M 354.60110473632812 100 A 4 4 0 0 0 346.60110473632812 100 A 4 4 0 0 0 354.60110473632812 100 z M 252.80137634277344 100 A 2 2 0 0 0 248.80137634277344 100 A 2 2 0 0 0 252.80137634277344 100 z M 204.60072326660156 100 A 4 4 0 0 0 196.60072326660156 100 A 4 4 0 0 0 204.60072326660156 100 z" == "M 100 100 z")
+Bail out!

demos/gtk-demo/demo.gresource.xml

@@ -336,6 +336,7 @@
     <file>panes.c</file>
     <file>password_entry.c</file>
     <file>path_fill.c</file>
+    <file>path_text.c</file>
     <file>peg_solitaire.c</file>
     <file>pickers.c</file>
     <file>printing.c</file>
@@ -421,6 +422,9 @@
   <gresource prefix="/fontrendering">
     <file>fontrendering.ui</file>
   </gresource>
+  <gresource prefix="/path_text">
+    <file>path_text.ui</file>
+  </gresource>
   <gresource prefix="/org/gtk/Demo4">
     <file>icons/16x16/actions/application-exit.png</file>
     <file>icons/16x16/actions/document-new.png</file>

demos/gtk-demo/meson.build

@@ -73,6 +73,7 @@ demos = files([
   'panes.c',
   'password_entry.c',
   'path_fill.c',
+  'path_text.c',
   'peg_solitaire.c',
   'pickers.c',
   'printing.c',

demos/gtk-demo/path_text.c

@@ -0,0 +1,604 @@
+/* Path/Text
+ *
+ * This demo shows how to use GskPath to animate a path along another path.
+ */
+
+#include <glib/gi18n.h>
+#include <gtk/gtk.h>
+
+#define GTK_TYPE_PATH_WIDGET (gtk_path_widget_get_type ())
+G_DECLARE_FINAL_TYPE (GtkPathWidget, gtk_path_widget, GTK, PATH_WIDGET, GtkWidget)
+
+#define POINT_SIZE 8
+
+enum {
+  PROP_0,
+  PROP_TEXT,
+  PROP_EDITABLE,
+  N_PROPS
+};
+
+struct _GtkPathWidget
+{
+  GtkWidget parent_instance;
+
+  char *text;
+  gboolean editable;
+
+  graphene_point_t points[4];
+
+  guint active_point;
+  float line_closest;
+
+  GskPath *line_path;
+  GskPathMeasure *line_measure;
+  GskPath *text_path;
+
+  GdkPaintable *background;
+};
+
+struct _GtkPathWidgetClass
+{
+  GtkWidgetClass parent_class;
+};
+
+static GParamSpec *properties[N_PROPS] = { NULL, };
+
+G_DEFINE_TYPE (GtkPathWidget, gtk_path_widget, GTK_TYPE_WIDGET)
+
+static GskPath *
+create_path_from_text (GtkWidget  *widget,
+                       const char *text,
+                       graphene_point_t *out_offset)
+{
+  PangoLayout *layout;
+  PangoFontDescription *desc;
+  GskPathBuilder *builder;
+  GskPath *result;
+
+  layout = gtk_widget_create_pango_layout (widget, text);
+  desc = pango_font_description_from_string ("sans bold 36");
+  pango_layout_set_font_description (layout, desc);
+  pango_font_description_free (desc);
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_layout (builder, layout);
+  result = gsk_path_builder_free_to_path (builder);
+
+  if (out_offset)
+    graphene_point_init (out_offset, 0, - pango_layout_get_baseline (layout) / (double) PANGO_SCALE);
+  g_object_unref (layout);
+
+  return result;
+}
+
+typedef struct
+{
+  GskPathMeasure *measure;
+  GskPathBuilder *builder;
+  graphene_point_t offset;
+  double scale;
+} GtkPathTransform;
+
+static void
+gtk_path_transform_point (GskPathMeasure         *measure,
+                          const graphene_point_t *pt,
+                          const graphene_point_t *offset,
+                          float                   scale,
+                          graphene_point_t       *res)
+{
+  graphene_vec2_t tangent;
+  GskPathPoint point;
+
+  if (gsk_path_measure_get_point (measure, (pt->x + offset->x) * scale, &point))
+    {
+      GskPath *path = gsk_path_measure_get_path (measure);
+
+      gsk_path_point_get_position (path, &point, res);
+      gsk_path_point_get_tangent (path, &point, GSK_PATH_END, &tangent);
+
+      res->x -= (pt->y + offset->y) * scale * graphene_vec2_get_y (&tangent);
+      res->y += (pt->y + offset->y) * scale * graphene_vec2_get_x (&tangent);
+    }
+}
+
+static gboolean
+gtk_path_transform_op (GskPathOperation        op,
+                       const graphene_point_t *pts,
+                       gsize                   n_pts,
+                       gpointer                data)
+{
+  GtkPathTransform *transform = data;
+
+  switch (op)
+  {
+    case GSK_PATH_MOVE:
+      {
+        graphene_point_t res;
+        gtk_path_transform_point (transform->measure, &pts[0], &transform->offset, transform->scale, &res);
+        gsk_path_builder_move_to (transform->builder, res.x, res.y);
+      }
+      break;
+
+    case GSK_PATH_LINE:
+      {
+        graphene_point_t res;
+        gtk_path_transform_point (transform->measure, &pts[1], &transform->offset, transform->scale, &res);
+        gsk_path_builder_line_to (transform->builder, res.x, res.y);
+      }
+      break;
+
+    case GSK_PATH_QUAD:
+      {
+        graphene_point_t res[2];
+        gtk_path_transform_point (transform->measure, &pts[1], &transform->offset, transform->scale, &res[0]);
+        gtk_path_transform_point (transform->measure, &pts[2], &transform->offset, transform->scale, &res[1]);
+        gsk_path_builder_quad_to (transform->builder, res[0].x, res[0].y, res[1].x, res[1].y);
+      }
+      break;
+
+    case GSK_PATH_CUBIC:
+      {
+        graphene_point_t res[3];
+        gtk_path_transform_point (transform->measure, &pts[1], &transform->offset, transform->scale, &res[0]);
+        gtk_path_transform_point (transform->measure, &pts[2], &transform->offset, transform->scale, &res[1]);
+        gtk_path_transform_point (transform->measure, &pts[3], &transform->offset, transform->scale, &res[2]);
+        gsk_path_builder_cubic_to (transform->builder, res[0].x, res[0].y, res[1].x, res[1].y, res[2].x, res[2].y);
+      }
+      break;
+
+    case GSK_PATH_CLOSE:
+      gsk_path_builder_close (transform->builder);
+      break;
+
+    default:
+      g_assert_not_reached();
+      return FALSE;
+  }
+
+  return TRUE;
+}
+
+static GskPath *
+gtk_path_transform (GskPathMeasure         *measure,
+                    GskPath                *path,
+                    const graphene_point_t *offset)
+{
+  GtkPathTransform transform = { measure, gsk_path_builder_new (), *offset };
+  graphene_rect_t bounds;
+
+  gsk_path_get_bounds (path, &bounds);
+  if (bounds.origin.x + bounds.size.width > 0)
+    transform.scale = gsk_path_measure_get_length (measure) / (bounds.origin.x + bounds.size.width);
+  else
+    transform.scale = 1.0f;
+
+  gsk_path_foreach (path, -1, gtk_path_transform_op, &transform);
+
+  return gsk_path_builder_free_to_path (transform.builder);
+}
+
+static void
+gtk_path_widget_clear_text_path (GtkPathWidget *self)
+{
+  g_clear_pointer (&self->text_path, gsk_path_unref);
+}
+
+static void
+gtk_path_widget_clear_paths (GtkPathWidget *self)
+{
+  gtk_path_widget_clear_text_path (self);
+
+  g_clear_pointer (&self->line_path, gsk_path_unref);
+  g_clear_pointer (&self->line_measure, gsk_path_measure_unref);
+}
+
+static void
+gtk_path_widget_create_text_path (GtkPathWidget *self)
+{
+  GskPath *path;
+  graphene_point_t offset;
+
+  gtk_path_widget_clear_text_path (self);
+
+  if (self->line_measure == NULL)
+    return;
+
+  path = create_path_from_text (GTK_WIDGET (self), self->text, &offset);
+  self->text_path = gtk_path_transform (self->line_measure, path, &offset);
+
+  gsk_path_unref (path);
+}
+
+static void
+gtk_path_widget_create_paths (GtkPathWidget *self)
+{
+  double width = gtk_widget_get_width (GTK_WIDGET (self));
+  double height = gtk_widget_get_height (GTK_WIDGET (self));
+  GskPathBuilder *builder;
+
+  gtk_path_widget_clear_paths (self);
+
+  if (width <= 0 || height <= 0)
+    return;
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_move_to (builder,
+                            self->points[0].x * width, self->points[0].y * height);
+  gsk_path_builder_cubic_to (builder,
+                             self->points[1].x * width, self->points[1].y * height,
+                             self->points[2].x * width, self->points[2].y * height,
+                             self->points[3].x * width, self->points[3].y * height);
+  self->line_path = gsk_path_builder_free_to_path (builder);
+
+  self->line_measure = gsk_path_measure_new (self->line_path);
+
+  gtk_path_widget_create_text_path (self);
+}
+
+static void
+gtk_path_widget_allocate (GtkWidget *widget,
+                          int        width,
+                          int        height,
+                          int        baseline)
+{
+  GtkPathWidget *self = GTK_PATH_WIDGET (widget);
+
+  GTK_WIDGET_CLASS (gtk_path_widget_parent_class)->size_allocate (widget, width, height, baseline);
+
+  gtk_path_widget_create_paths (self);
+}
+
+static void
+gtk_path_widget_snapshot (GtkWidget   *widget,
+                          GtkSnapshot *snapshot)
+{
+  GtkPathWidget *self = GTK_PATH_WIDGET (widget);
+  double width = gtk_widget_get_width (widget);
+  double height = gtk_widget_get_height (widget);
+  GskPath *path;
+  GskStroke *stroke;
+  gsize i;
+
+  /* frosted glass the background */
+  gtk_snapshot_push_blur (snapshot, 100);
+  gdk_paintable_snapshot (self->background, snapshot, width, height);
+  gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 1, 1, 1, 0.6 }, &GRAPHENE_RECT_INIT (0, 0, width, height));
+  gtk_snapshot_pop (snapshot);
+
+  /* draw the text */
+  if (self->text_path)
+    {
+      gtk_snapshot_push_fill (snapshot, self->text_path, GSK_FILL_RULE_WINDING);
+      gdk_paintable_snapshot (self->background, snapshot, width, height);
+
+      /* ... with an emboss effect */
+      stroke = gsk_stroke_new (2.0);
+      gtk_snapshot_translate (snapshot, &GRAPHENE_POINT_INIT(1, 1));
+      gtk_snapshot_push_stroke (snapshot, self->text_path, stroke);
+      gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 0, 0, 0, 0.2 }, &GRAPHENE_RECT_INIT (0, 0, width, height));
+      gsk_stroke_free (stroke);
+      gtk_snapshot_pop (snapshot);
+
+      gtk_snapshot_pop (snapshot);
+    }
+
+  if (self->editable && self->line_path)
+    {
+      GskPathBuilder *builder;
+
+      /* draw the control line */
+      stroke = gsk_stroke_new (1.0);
+      gtk_snapshot_push_stroke (snapshot, self->line_path, stroke);
+      gsk_stroke_free (stroke);
+      gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 0, 0, 0, 1 }, &GRAPHENE_RECT_INIT (0, 0, width, height));
+      gtk_snapshot_pop (snapshot);
+
+      /* draw the points */
+      builder = gsk_path_builder_new ();
+      for (i = 0; i < 4; i++)
+        {
+          gsk_path_builder_add_circle (builder, &GRAPHENE_POINT_INIT (self->points[i].x * width, self->points[i].y * height), POINT_SIZE);
+        }
+      path = gsk_path_builder_free_to_path (builder);
+
+      gtk_snapshot_push_fill (snapshot, path, GSK_FILL_RULE_WINDING);
+      gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 1, 1, 1, 1 }, &GRAPHENE_RECT_INIT (0, 0, width, height));
+      gtk_snapshot_pop (snapshot);
+
+      stroke = gsk_stroke_new (1.0);
+      gtk_snapshot_push_stroke (snapshot, path, stroke);
+      gsk_stroke_free (stroke);
+      gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 0, 0, 0, 1 }, &GRAPHENE_RECT_INIT (0, 0, width, height));
+      gtk_snapshot_pop (snapshot);
+
+      gsk_path_unref (path);
+    }
+
+  if (self->line_closest >= 0)
+    {
+      GskPathBuilder *builder;
+      GskPathPoint point;
+      graphene_point_t closest;
+
+      builder = gsk_path_builder_new ();
+      if (gsk_path_measure_get_point (self->line_measure, self->line_closest, &point))
+        {
+          gsk_path_point_get_position (self->line_path, &point, &closest);
+          gsk_path_builder_add_circle (builder, &closest, POINT_SIZE);
+          path = gsk_path_builder_free_to_path (builder);
+
+          gtk_snapshot_push_fill (snapshot, path, GSK_FILL_RULE_WINDING);
+          gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 0, 0, 1, 1 }, &GRAPHENE_RECT_INIT (0, 0, width, height));
+          gtk_snapshot_pop (snapshot);
+
+          gsk_path_unref (path);
+        }
+    }
+}
+
+static void
+gtk_path_widget_set_text (GtkPathWidget *self,
+                          const char    *text)
+{
+  if (g_strcmp0 (self->text, text) == 0)
+    return;
+
+  g_free (self->text);
+  self->text = g_strdup (text);
+
+  gtk_path_widget_create_paths (self);
+
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_TEXT]);
+}
+
+static void
+gtk_path_widget_set_editable (GtkPathWidget *self,
+                              gboolean       editable)
+{
+  if (self->editable == editable)
+    return;
+
+  self->editable = editable;
+
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_EDITABLE]);
+}
+
+static void
+gtk_path_widget_set_property (GObject      *object,
+                              guint         prop_id,
+                              const GValue *value,
+                              GParamSpec   *pspec)
+
+{
+  GtkPathWidget *self = GTK_PATH_WIDGET (object);
+
+  switch (prop_id)
+    {
+    case PROP_TEXT:
+      gtk_path_widget_set_text (self, g_value_get_string (value));
+      break;
+
+    case PROP_EDITABLE:
+      gtk_path_widget_set_editable (self, g_value_get_boolean (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_path_widget_get_property (GObject    *object,
+                              guint       prop_id,
+                              GValue     *value,
+                              GParamSpec *pspec)
+{
+  GtkPathWidget *self = GTK_PATH_WIDGET (object);
+
+  switch (prop_id)
+    {
+    case PROP_TEXT:
+      g_value_set_string (value, self->text);
+      break;
+
+    case PROP_EDITABLE:
+      g_value_set_boolean (value, self->editable);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_path_widget_dispose (GObject *object)
+{
+  GtkPathWidget *self = GTK_PATH_WIDGET (object);
+
+  gtk_path_widget_clear_paths (self);
+
+  G_OBJECT_CLASS (gtk_path_widget_parent_class)->dispose (object);
+}
+
+static void
+gtk_path_widget_class_init (GtkPathWidgetClass *klass)
+{
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = gtk_path_widget_dispose;
+  object_class->set_property = gtk_path_widget_set_property;
+  object_class->get_property = gtk_path_widget_get_property;
+
+  widget_class->size_allocate = gtk_path_widget_allocate;
+  widget_class->snapshot = gtk_path_widget_snapshot;
+
+  properties[PROP_TEXT] =
+    g_param_spec_string ("text",
+                         "text",
+                         "Text transformed along a path",
+                         NULL,
+                         G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  properties[PROP_EDITABLE] =
+    g_param_spec_boolean ("editable",
+                          "editable",
+                          "If the path can be edited by the user",
+                          FALSE,
+                          G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (object_class, N_PROPS, properties);
+}
+
+static void
+drag_begin (GtkGestureDrag *gesture,
+            double          x,
+            double          y,
+            GtkPathWidget  *self)
+{
+  graphene_point_t mouse = GRAPHENE_POINT_INIT (x, y);
+  double width = gtk_widget_get_width (GTK_WIDGET (self));
+  double height = gtk_widget_get_height (GTK_WIDGET (self));
+  gsize i;
+
+  for (i = 0; i < 4; i++)
+    {
+      if (graphene_point_distance (&GRAPHENE_POINT_INIT (self->points[i].x * width, self->points[i].y * height), &mouse, NULL, NULL) <= POINT_SIZE)
+        {
+          self->active_point = i;
+          break;
+        }
+    }
+  if (i == 4)
+    {
+      gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_DENIED);
+      return;
+    }
+
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+}
+
+static void
+drag_update (GtkGestureDrag *drag,
+             double          offset_x,
+             double          offset_y,
+             GtkPathWidget  *self)
+{
+  double width = gtk_widget_get_width (GTK_WIDGET (self));
+  double height = gtk_widget_get_height (GTK_WIDGET (self));
+  double start_x, start_y;
+
+  gtk_gesture_drag_get_start_point (drag, &start_x, &start_y);
+
+  self->points[self->active_point] = GRAPHENE_POINT_INIT ((start_x + offset_x) / width,
+                                                          (start_y + offset_y) / height);
+  self->points[self->active_point].x = CLAMP (self->points[self->active_point].x, 0, 1);
+  self->points[self->active_point].y = CLAMP (self->points[self->active_point].y, 0, 1);
+
+  gtk_path_widget_create_paths (self);
+
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+}
+
+static void
+pointer_motion (GtkEventControllerMotion *controller,
+                double                    x,
+                double                    y,
+                GtkPathWidget            *self)
+{
+  GskPathPoint point;
+  graphene_point_t pos;
+
+  if (gsk_path_get_closest_point (gsk_path_measure_get_path (self->line_measure),
+                                  &GRAPHENE_POINT_INIT (x, y),
+                                  INFINITY,
+                                  &point))
+    {
+      gsk_path_point_get_position (self->line_path, &point, &pos);
+      self->line_closest = graphene_point_distance (&pos, &GRAPHENE_POINT_INIT (x, y), NULL, NULL);
+    
+      gtk_widget_queue_draw (GTK_WIDGET (self));
+    }
+}
+
+static void
+pointer_leave (GtkEventControllerMotion *controller,
+               GtkPathWidget            *self)
+{
+  self->line_closest = -1;
+
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+}
+
+static void
+gtk_path_widget_init (GtkPathWidget *self)
+{
+  GtkEventController *controller;
+
+  controller = GTK_EVENT_CONTROLLER (gtk_gesture_drag_new ());
+  g_signal_connect (controller, "drag-begin", G_CALLBACK (drag_begin), self);
+  g_signal_connect (controller, "drag-update", G_CALLBACK (drag_update), self);
+  g_signal_connect (controller, "drag-end", G_CALLBACK (drag_update), self);
+  gtk_widget_add_controller (GTK_WIDGET (self), controller);
+
+  controller = GTK_EVENT_CONTROLLER (gtk_event_controller_motion_new ());
+  g_signal_connect (controller, "enter", G_CALLBACK (pointer_motion), self);
+  g_signal_connect (controller, "motion", G_CALLBACK (pointer_motion), self);
+  g_signal_connect (controller, "leave", G_CALLBACK (pointer_leave), self);
+  gtk_widget_add_controller (GTK_WIDGET (self), controller);
+
+  self->line_closest = -1;
+
+  self->points[0] = GRAPHENE_POINT_INIT (0.1, 0.9);
+  self->points[1] = GRAPHENE_POINT_INIT (0.3, 0.1);
+  self->points[2] = GRAPHENE_POINT_INIT (0.7, 0.1);
+  self->points[3] = GRAPHENE_POINT_INIT (0.9, 0.9);
+
+  self->background = GDK_PAINTABLE (gdk_texture_new_from_resource ("/sliding_puzzle/portland-rose.jpg"));
+
+  gtk_path_widget_set_text (self, "It's almost working");
+}
+
+GtkWidget *
+gtk_path_widget_new (void)
+{
+  GtkPathWidget *self;
+
+  self = g_object_new (GTK_TYPE_PATH_WIDGET, NULL);
+
+  return GTK_WIDGET (self);
+}
+
+GtkWidget *
+do_path_text (GtkWidget *do_widget)
+{
+  static GtkWidget *window = NULL;
+
+  if (!window)
+    {
+      GtkBuilder *builder;
+
+      g_type_ensure (GTK_TYPE_PATH_WIDGET);
+
+      builder = gtk_builder_new_from_resource ("/path_text/path_text.ui");
+      window = GTK_WIDGET (gtk_builder_get_object (builder, "window"));
+      gtk_window_set_display (GTK_WINDOW (window),
+                              gtk_widget_get_display (do_widget));
+      g_object_add_weak_pointer (G_OBJECT (window), (gpointer *) &window);
+      g_object_unref (builder);
+    }
+
+  if (!gtk_widget_get_visible (window))
+    gtk_window_present (GTK_WINDOW (window));
+  else
+    gtk_window_destroy (GTK_WINDOW (window));
+
+  return window;
+}

demos/gtk-demo/path_text.ui

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkWindow" id="window">
+    <property name="title" translatable="yes">Text along a Path</property>
+    <child type="titlebar">
+      <object class="GtkHeaderBar">
+        <child type="end">
+          <object class="GtkToggleButton" id="edit-toggle">
+            <property name="icon-name">document-edit-symbolic</property>
+          </object>
+        </child>
+      </object>
+    </child>
+    <child>
+      <object class="GtkBox">
+        <property name="orientation">vertical</property>
+        <child>
+          <object class="GtkRevealer">
+            <property name="reveal-child" bind-source="edit-toggle" bind-property="active" bind-flags="sync-create"></property>
+            <child>
+              <object class="GtkEntry" id="text">
+                <property name="text">Through the looking glass</property>
+              </object>
+            </child>
+          </object>
+        </child>
+        <child>
+          <object class="GtkPathWidget" id="view">
+            <property name="editable" bind-source="edit-toggle" bind-property="active" bind-flags="sync-create"></property>
+            <property name="text" bind-source="text" bind-property="text" bind-flags="sync-create"></property>
+            <property name="hexpand">true</property>
+            <property name="vexpand">true</property>
+          </object>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>

gsk/gsk.h

@@ -22,6 +22,7 @@
 #include <gsk/gskenums.h>
 #include <gsk/gskpath.h>
 #include <gsk/gskpathbuilder.h>
+#include <gsk/gskpathmeasure.h>
 #include <gsk/gskpathpoint.h>
 #include <gsk/gskrenderer.h>
 #include <gsk/gskrendernode.h>

gsk/gskcontour.c

@@ -66,6 +66,16 @@ struct _GskContourClass
                                                  float                   threshold,
                                                  GskRealPathPoint       *result,
                                                  float                  *out_dist);
+  void                  (* get_start_point)     (const GskContour       *contour,
+                                                 GskRealPathPoint       *result);
+  void                  (* get_end_point)       (const GskContour       *contour,
+                                                 GskRealPathPoint       *result);
+  gboolean              (* get_previous_point)  (const GskContour       *contour,
+                                                 GskRealPathPoint       *point,
+                                                 GskRealPathPoint       *result);
+  gboolean              (* get_next_point)      (const GskContour       *contour,
+                                                 GskRealPathPoint       *point,
+                                                 GskRealPathPoint       *result);
   void                  (* get_position)        (const GskContour       *contour,
                                                  GskRealPathPoint       *point,
                                                  graphene_point_t       *position);
@@ -76,6 +86,26 @@ struct _GskContourClass
   float                 (* get_curvature)       (const GskContour       *contour,
                                                  GskRealPathPoint       *point,
                                                  graphene_point_t       *center);
+  gpointer              (* init_measure)        (const GskContour       *contour,
+                                                 float                   tolerance,
+                                                 float                  *out_length);
+  void                  (* free_measure)        (const GskContour       *contour,
+                                                 gpointer                measure_data);
+  int                   (* point_compare)       (const GskContour       *contour,
+                                                 GskRealPathPoint       *p1,
+                                                 GskRealPathPoint       *p2);
+  void                  (* add_segment)         (const GskContour       *contour,
+                                                 GskPathBuilder         *builder,
+                                                 gboolean                emit_move_to,
+                                                 GskRealPathPoint       *start,
+                                                 GskRealPathPoint       *end);
+  void                  (* get_point)           (const GskContour       *contour,
+                                                 gpointer                measure_data,
+                                                 float                   offset,
+                                                 GskRealPathPoint       *result);
+  float                 (* get_distance)        (const GskContour       *contour,
+                                                 GskRealPathPoint       *point,
+                                                 gpointer                measure_data);
 };
 
 /* {{{ Utilities */
@@ -367,6 +397,211 @@ gsk_standard_contour_get_start_end (const GskContour *contour,
     *end = self->points[self->n_points - 1];
 }
 
+typedef struct
+{
+  float start;
+  float end;
+  float start_progress;
+  float end_progress;
+  GskCurveLineReason reason;
+  graphene_point_t start_point;
+  graphene_point_t end_point;
+  gsize op;
+} GskStandardContourMeasure;
+
+typedef struct
+{
+  GArray *array;
+  GskStandardContourMeasure measure;
+} LengthDecompose;
+
+static gboolean
+gsk_standard_contour_measure_add_point (const graphene_point_t *from,
+                                        const graphene_point_t *to,
+                                        float                   from_progress,
+                                        float                   to_progress,
+                                        GskCurveLineReason      reason,
+                                        gpointer                user_data)
+{
+  LengthDecompose *decomp = user_data;
+  float seg_length;
+
+  seg_length = graphene_point_distance (from, to, NULL, NULL);
+  decomp->measure.end += seg_length;
+
+  if (decomp->measure.start >= decomp->measure.end)
+    return TRUE;
+
+  decomp->measure.start_progress = from_progress;
+  decomp->measure.end_progress = to_progress;
+  decomp->measure.start_point = *from;
+  decomp->measure.end_point = *to;
+  decomp->measure.reason = reason;
+
+  g_array_append_val (decomp->array, decomp->measure);
+
+  decomp->measure.start += seg_length;
+
+  return TRUE;
+}
+
+static gpointer
+gsk_standard_contour_init_measure (const GskContour *contour,
+                                   float             tolerance,
+                                   float            *out_length)
+{
+  const GskStandardContour *self = (const GskStandardContour *) contour;
+  gsize i;
+  float length;
+  GArray *array;
+
+  array = g_array_new (FALSE, FALSE, sizeof (GskStandardContourMeasure));
+  length = 0;
+
+  for (i = 1; i < self->n_ops; i ++)
+    {
+      GskCurve curve;
+      LengthDecompose decomp = { array, { length, length, 0, 0, GSK_CURVE_LINE_REASON_SHORT, { 0, 0 }, { 0, 0 }, i } };
+
+      gsk_curve_init (&curve, self->ops[i]);
+      gsk_curve_decompose (&curve, tolerance, gsk_standard_contour_measure_add_point, &decomp);
+      length = decomp.measure.start;
+    }
+
+  *out_length = length;
+
+  return array;
+}
+
+static void
+gsk_standard_contour_free_measure (const GskContour *contour,
+                                   gpointer          data)
+{
+  g_array_free (data, TRUE);
+}
+
+static int
+gsk_standard_contour_find_measure (gconstpointer m,
+                                   gconstpointer l)
+{
+  const GskStandardContourMeasure *measure = m;
+  float length = *(const float *) l;
+
+  if (measure->start > length)
+    return 1;
+  else if (measure->end <= length)
+    return -1;
+  else
+    return 0;
+}
+
+static int
+gsk_standard_contour_point_compare (const GskContour *contour,
+                                    GskRealPathPoint *p1,
+                                    GskRealPathPoint *p2)
+{
+  if (p1->data.std.idx < p2->data.std.idx)
+    return -1;
+  else if (p1->data.std.idx > p2->data.std.idx)
+    return 1;
+  else if (p1->data.std.t < p2->data.std.t)
+    return -1;
+  else if (p1->data.std.t > p2->data.std.t)
+    return 1;
+  else
+    return 0;
+}
+
+static void
+add_curve (GskCurve       *curve,
+           GskPathBuilder *builder,
+           gboolean       *emit_move_to)
+{
+  if (*emit_move_to)
+    {
+      const graphene_point_t *s;
+
+      s = gsk_curve_get_start_point (curve);
+      gsk_path_builder_move_to (builder, s->x, s->y);
+      *emit_move_to = FALSE;
+    }
+  gsk_curve_builder_to (curve, builder);
+}
+
+static void
+gsk_standard_contour_add_segment (const GskContour *contour,
+                                  GskPathBuilder   *builder,
+                                  gboolean          emit_move_to,
+                                  GskRealPathPoint *start,
+                                  GskRealPathPoint *end)
+{
+  GskStandardContour *self = (GskStandardContour *) contour;
+  gsize first, last;
+  float first_t, last_t;
+  GskCurve c, c1, c2;
+
+  if (start)
+    {
+      first = start->data.std.idx;
+      first_t = start->data.std.t;
+    }
+  else
+    {
+      first = 1;
+      first_t = 0;
+    }
+
+  if (end)
+    {
+      last = end->data.std.idx;
+      last_t = end->data.std.t;
+    }
+  else
+    {
+      last = self->n_ops - 1;
+      last_t = 1;
+    }
+
+  gsk_curve_init (&c, self->ops[first]);
+
+  if (first == last)
+    {
+      gsk_curve_segment (&c, first_t, last_t, &c1);
+      add_curve (&c1, builder, &emit_move_to);
+      return;
+    }
+
+  if (first_t == 0)
+    {
+      add_curve (&c, builder, &emit_move_to);
+    }
+  else if (first_t < 1)
+    {
+      gsk_curve_split (&c, first_t, &c1, &c2);
+      add_curve (&c2, builder, &emit_move_to);
+    }
+
+  for (gsize i = first + 1; i < last; i++)
+    {
+      gsk_curve_init (&c, self->ops[i]);
+      add_curve (&c, builder, &emit_move_to);
+    }
+
+  gsk_curve_init (&c, self->ops[last]);
+  if (c.op == GSK_PATH_CLOSE)
+    c.op = GSK_PATH_LINE;
+
+  if (last_t == 1)
+    {
+      add_curve (&c, builder, &emit_move_to);
+    }
+  else if (last_t > 0)
+    {
+      gsk_curve_split (&c, last_t, &c1, &c2);
+      add_curve (&c, builder, &emit_move_to);
+    }
+}
+
 static int
 gsk_standard_contour_get_winding (const GskContour       *contour,
                                   const graphene_point_t *point)
@@ -437,7 +672,8 @@ gsk_standard_contour_get_closest_point (const GskContour       *contour,
         continue;
 
       gsk_curve_init (&c, self->ops[i]);
-      if (gsk_curve_get_closest_point (&c, point, threshold, &distance, &t))
+      if (gsk_curve_get_closest_point (&c, point, threshold, &distance, &t) &&
+          distance < threshold)
         {
           best_idx = i;
           best_t = t;
@@ -456,6 +692,100 @@ gsk_standard_contour_get_closest_point (const GskContour       *contour,
   return FALSE;
 }
 
+static void
+gsk_standard_contour_get_start_point (const GskContour *contour,
+                                      GskRealPathPoint *result)
+{
+  result->data.std.idx = 1;
+  result->data.std.t = 0;
+}
+
+static void
+gsk_standard_contour_get_end_point (const GskContour *contour,
+                                    GskRealPathPoint *result)
+{
+  GskStandardContour *self = (GskStandardContour *) contour;
+
+  result->data.std.idx = self->n_ops - 1;
+  result->data.std.t = 1;
+}
+
+static gboolean
+gsk_standard_contour_get_previous_point (const GskContour *contour,
+                                         GskRealPathPoint *point,
+                                         GskRealPathPoint *result)
+{
+  if (point->data.std.t > 0)
+    {
+      result->data.std.idx = point->data.std.idx;
+      result->data.std.t = 0;
+      return TRUE;
+    }
+  else if (point->data.std.idx > 1)
+    {
+      result->data.std.idx = point->data.std.idx - 1;
+      result->data.std.t = 0;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+gsk_standard_contour_get_next_point (const GskContour *contour,
+                                     GskRealPathPoint *point,
+                                     GskRealPathPoint *result)
+{
+  GskStandardContour *self = (GskStandardContour *) contour;
+
+  if (point->data.std.t < 1)
+    {
+      result->data.std.idx = point->data.std.idx;
+      result->data.std.t = 1;
+      return TRUE;
+    }
+  else if (point->data.std.idx + 1 < self->n_ops - 1)
+    {
+      result->data.std.idx = point->data.std.idx + 1;
+      result->data.std.t = 1;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static void
+gsk_standard_contour_get_point (const GskContour *contour,
+                                gpointer          measure_data,
+                                float             distance,
+                                GskRealPathPoint *result)
+{
+  GArray *array = measure_data;
+  unsigned int idx;
+  GskStandardContourMeasure *measure;
+  float fraction, t;
+
+  if (array->len == 0)
+    {
+      result->data.std.idx = 0;
+      result->data.std.t = 0;
+      return;
+    }
+
+  if (!g_array_binary_search (array, &distance, gsk_standard_contour_find_measure, &idx))
+    idx = array->len - 1;
+
+  measure = &g_array_index (array, GskStandardContourMeasure, idx);
+
+  fraction = (distance - measure->start) / (measure->end - measure->start);
+  t = measure->start_progress + fraction * (measure->end_progress - measure->start_progress);
+
+  g_assert (t >= 0 && t <= 1);
+
+  result->data.std.idx = measure->op;
+  result->data.std.t = t;
+}
+
 static void
 gsk_standard_contour_get_position (const GskContour *contour,
                                    GskRealPathPoint *point,
@@ -496,8 +826,8 @@ gsk_standard_contour_get_tangent (const GskContour *contour,
 
   if (t == 0 && direction == GSK_PATH_START)
     {
-      /* Look at the previous segment */
-      if (idx > 0)
+      /* Look at the previous segment (0 is always a move, so skip it) */
+      if (idx > 1)
         {
           idx--;
           t = 1;
@@ -518,7 +848,8 @@ gsk_standard_contour_get_tangent (const GskContour *contour,
         }
       else if (self->flags & GSK_PATH_CLOSED)
         {
-          idx = 0;
+          /* segment 0 is always a move */
+          idx = 1;
           t = 0;
         }
     }
@@ -542,6 +873,37 @@ gsk_standard_contour_get_curvature (const GskContour *contour,
   return gsk_curve_get_curvature (&curve, point->data.std.t, center);
 }
 
+static float
+gsk_standard_contour_get_distance (const GskContour *contour,
+                                   GskRealPathPoint *point,
+                                   gpointer          measure_data)
+{
+  GArray *array = measure_data;
+
+  if (G_UNLIKELY (point->data.std.idx == 0))
+    return 0;
+
+  for (unsigned int i = 0; i < array->len; i++)
+    {
+      GskStandardContourMeasure *measure = &g_array_index (array, GskStandardContourMeasure, i);
+      float fraction;
+
+      if (measure->op != point->data.std.idx)
+        continue;
+
+      if (measure->end_progress < point->data.std.t)
+        continue;
+
+      g_assert (measure->op == point->data.std.idx);
+      g_assert (measure->start_progress <= point->data.std.t && point->data.std.t <= measure->end_progress);
+
+      fraction = (point->data.std.t - measure->start_progress) / (measure->end_progress - measure->start_progress);
+      return measure->start + fraction * (measure->end - measure->start);
+    }
+
+  return 0;
+}
+
 static const GskContourClass GSK_STANDARD_CONTOUR_CLASS =
 {
   sizeof (GskStandardContour),
@@ -557,9 +919,19 @@ static const GskContourClass GSK_STANDARD_CONTOUR_CLASS =
   gsk_standard_contour_reverse,
   gsk_standard_contour_get_winding,
   gsk_standard_contour_get_closest_point,
+  gsk_standard_contour_get_start_point,
+  gsk_standard_contour_get_end_point,
+  gsk_standard_contour_get_previous_point,
+  gsk_standard_contour_get_next_point,
   gsk_standard_contour_get_position,
   gsk_standard_contour_get_tangent,
   gsk_standard_contour_get_curvature,
+  gsk_standard_contour_init_measure,
+  gsk_standard_contour_free_measure,
+  gsk_standard_contour_point_compare,
+  gsk_standard_contour_add_segment,
+  gsk_standard_contour_get_point,
+  gsk_standard_contour_get_distance,
 };
 
 /* You must ensure the contour has enough size allocated,
@@ -681,6 +1053,21 @@ gsk_contour_foreach (const GskContour   *self,
   return self->klass->foreach (self, tolerance, func, user_data);
 }
 
+gpointer
+gsk_contour_init_measure (const GskContour *self,
+                          float             tolerance,
+                          float            *out_length)
+{
+  return self->klass->init_measure (self, tolerance, out_length);
+}
+
+void
+gsk_contour_free_measure (const GskContour *self,
+                          gpointer          data)
+{
+  self->klass->free_measure (self, data);
+}
+
 void
 gsk_contour_get_start_end (const GskContour *self,
                            graphene_point_t *start,
@@ -689,6 +1076,24 @@ gsk_contour_get_start_end (const GskContour *self,
   self->klass->get_start_end (self, start, end);
 }
 
+int
+gsk_contour_point_compare (const GskContour *self,
+                           GskRealPathPoint *p1,
+                           GskRealPathPoint *p2)
+{
+  return self->klass->point_compare (self, p1, p2);
+}
+
+void
+gsk_contour_add_segment (const GskContour *self,
+                         GskPathBuilder   *builder,
+                         gboolean          emit_move_to,
+                         GskRealPathPoint *start,
+                         GskRealPathPoint *end)
+{
+  self->klass->add_segment (self, builder, emit_move_to, start, end);
+}
+
 int
 gsk_contour_get_winding (const GskContour       *self,
                          const graphene_point_t *point)
@@ -706,6 +1111,45 @@ gsk_contour_get_closest_point (const GskContour       *self,
   return self->klass->get_closest_point (self, point, threshold, result, out_dist);
 }
 
+void
+gsk_contour_get_start_point (const GskContour *self,
+                             GskRealPathPoint *result)
+{
+  self->klass->get_start_point (self, result);
+}
+
+void
+gsk_contour_get_end_point (const GskContour *self,
+                           GskRealPathPoint *result)
+{
+  self->klass->get_end_point (self, result);
+}
+
+gboolean
+gsk_contour_get_previous_point (const GskContour *self,
+                                GskRealPathPoint *point,
+                                GskRealPathPoint *result)
+{
+  return self->klass->get_previous_point (self, point, result);
+}
+
+gboolean
+gsk_contour_get_next_point (const GskContour *self,
+                            GskRealPathPoint *point,
+                            GskRealPathPoint *result)
+{
+  return self->klass->get_next_point (self, point, result);
+}
+
+void
+gsk_contour_get_point (const GskContour *self,
+                       gpointer          measure_data,
+                       float             offset,
+                       GskRealPathPoint *result)
+{
+  self->klass->get_point (self, measure_data, offset, result);
+}
+
 void
 gsk_contour_get_position (const GskContour *self,
                           GskRealPathPoint *point,
@@ -731,6 +1175,14 @@ gsk_contour_get_curvature (const GskContour *self,
   return self->klass->get_curvature (self, point, center);
 }
 
+float
+gsk_contour_get_distance (const GskContour *self,
+                          GskRealPathPoint *point,
+                          gpointer          measure_data)
+{
+  return self->klass->get_distance (self, point, measure_data);
+}
+
 /* }}} */
 
 /* vim:set foldmethod=marker expandtab: */

gsk/gskcontourprivate.h

@@ -57,14 +57,17 @@ void                    gsk_contour_get_start_end               (const GskContou
                                                                  graphene_point_t       *end);
 int                     gsk_contour_get_winding                 (const GskContour       *self,
                                                                  const graphene_point_t *point);
+
 gboolean                gsk_contour_get_closest_point           (const GskContour       *self,
                                                                  const graphene_point_t *point,
                                                                  float                   threshold,
                                                                  GskRealPathPoint       *result,
                                                                  float                  *out_dist);
+
 void                    gsk_contour_get_position                (const GskContour       *self,
                                                                  GskRealPathPoint       *point,
                                                                  graphene_point_t       *pos);
+
 void                    gsk_contour_get_tangent                 (const GskContour       *self,
                                                                  GskRealPathPoint       *point,
                                                                  GskPathDirection        direction,
@@ -72,5 +75,37 @@ void                    gsk_contour_get_tangent                 (const GskContou
 float                   gsk_contour_get_curvature               (const GskContour       *self,
                                                                  GskRealPathPoint       *point,
                                                                  graphene_point_t       *center);
+gpointer                gsk_contour_init_measure                (const GskContour       *self,
+                                                                 float                   tolerance,
+                                                                 float                  *out_length);
+void                    gsk_contour_free_measure                (const GskContour       *self,
+                                                                 gpointer                data);
+int                     gsk_contour_point_compare               (const GskContour       *self,
+                                                                 GskRealPathPoint       *p1,
+                                                                 GskRealPathPoint       *p2);
+
+void                    gsk_contour_add_segment                 (const GskContour       *self,
+                                                                 GskPathBuilder         *builder,
+                                                                 gboolean                emit_move_to,
+                                                                 GskRealPathPoint       *start,
+                                                                 GskRealPathPoint       *end);
+
+void                    gsk_contour_get_point                   (const GskContour       *self,
+                                                                 gpointer                measure_data,
+                                                                 float                   offset,
+                                                                 GskRealPathPoint       *result);
+void                    gsk_contour_get_start_point             (const GskContour       *self,
+                                                                 GskRealPathPoint       *result);
+void                    gsk_contour_get_end_point               (const GskContour       *self,
+                                                                 GskRealPathPoint       *result);
+gboolean                gsk_contour_get_previous_point          (const GskContour       *self,
+                                                                 GskRealPathPoint       *point,
+                                                                 GskRealPathPoint       *result);
+gboolean                gsk_contour_get_next_point              (const GskContour       *self,
+                                                                 GskRealPathPoint       *point,
+                                                                 GskRealPathPoint       *result);
+float                   gsk_contour_get_distance                (const GskContour       *self,
+                                                                 GskRealPathPoint       *point,
+                                                                 gpointer                measure_data);
 
 G_END_DECLS

gsk/gskpath.c

@@ -540,6 +540,74 @@ gsk_path_get_closest_point (GskPath                *self,
   return found;
 }
 
+/**
+ * gsk_path_get_start_point:
+ * @self: a `GskPath`
+ * @result: (out caller-allocates): return location for point
+ *
+ * Gets the start point of the path.
+ *
+ * An empty path has no points, so `FALSE`
+ * is returned in this case.
+ *
+ * Returns: `TRUE` if @result was filled
+ *
+ * Since: 4.14
+ */
+gboolean
+gsk_path_get_start_point (GskPath      *self,
+                          GskPathPoint *result)
+{
+  GskRealPathPoint *res = (GskRealPathPoint *) result;
+
+  g_return_val_if_fail (self != NULL, FALSE);
+  g_return_val_if_fail (result != NULL, FALSE);
+
+  if (self->n_contours == 0)
+    return FALSE;
+
+  gsk_contour_get_start_point (self->contours[0], res);
+
+  res->path = self;
+  res->contour = 0;
+
+  return TRUE;
+}
+
+/**
+ * gsk_path_get_end_point:
+ * @self: a `GskPath`
+ * @result: (out caller-allocates): return location for point
+ *
+ * Gets the end point of the path.
+ *
+ * An empty path has no points, so `FALSE`
+ * is returned in this case.
+ *
+ * Returns: `TRUE` if @result was filled
+ *
+ * Since: 4.14
+ */
+gboolean
+gsk_path_get_end_point (GskPath      *self,
+                        GskPathPoint *result)
+{
+  GskRealPathPoint *res = (GskRealPathPoint *) result;
+
+  g_return_val_if_fail (self != NULL, FALSE);
+  g_return_val_if_fail (result!= NULL, FALSE);
+
+  if (self->n_contours == 0)
+    return FALSE;
+
+  gsk_contour_get_end_point (self->contours[self->n_contours - 1], res);
+
+  res->path = self;
+  res->contour = self->n_contours - 1;
+
+  return TRUE;
+}
+
 /**
  * gsk_path_foreach:
  * @self: a `GskPath`
@@ -1323,3 +1391,174 @@ error:
 
   return NULL;
 }
+
+/**
+ * gsk_path_builder_add_segment:
+ * @self: a `GskPathBuilder`
+ * @path: the `GskPath` to take the segment to
+ * @start: the point on @path to start at
+ * @end: the point on @path to end at
+ *
+ * Adds to @self the segment of @path from @start to @end.
+ *
+ * If @start is after @end, the path will first add the segment
+ * from @start to the end of the path, and then add the segment from
+ * the beginning to @end. If the path is closed, these segments will
+ * be connected.
+ *
+ * Since: 4.14
+ */
+void
+gsk_path_builder_add_segment (GskPathBuilder     *self,
+                              GskPath            *path,
+                              const GskPathPoint *start,
+                              const GskPathPoint *end)
+{
+  GskRealPathPoint *s = (GskRealPathPoint *) start;
+  GskRealPathPoint *e = (GskRealPathPoint *) end;
+  const GskContour *contour;
+
+  g_return_if_fail (self != NULL);
+  g_return_if_fail (path != NULL);
+  g_return_if_fail (path == s->path);
+  g_return_if_fail (path == e->path);
+
+  contour = gsk_path_get_contour (path, s->contour);
+
+  if (s->contour == e->contour)
+    {
+      if (gsk_contour_point_compare (contour, s, e) < 0)
+        {
+          gsk_contour_add_segment (contour, self, TRUE, s, e);
+          return;
+        }
+      else if (path->n_contours == 1)
+        {
+          gsk_contour_add_segment (contour, self, TRUE, s, NULL);
+          gsk_contour_add_segment (contour, self, FALSE, NULL, e);
+          return;
+        }
+    }
+
+  gsk_contour_add_segment (contour, self, TRUE, s, NULL);
+
+  for (gsize i = (s->contour + 1) % path->n_contours; i != e->contour; i = (i + 1) % path->n_contours)
+    gsk_path_builder_add_contour (self, gsk_contour_dup (gsk_path_get_contour (path, i)));
+
+  contour = gsk_path_get_contour (path, e->contour);
+  gsk_contour_add_segment (contour, self, FALSE, NULL, e);
+}
+
+/**
+ * gsk_path_get_previous_point:
+ * @self: a `GskPath`
+ * @point: a point on @self
+ * @result: (out caller-allocates): Return location for the result
+ *
+ * Gets the previous 'significant' point on @self before @point.
+ *
+ * The 'significant' points of a path are typically the
+ * on-curve points that have been specified when the
+ * path was created.
+ *
+ * For example, in a path with 3 Bézier segments, the
+ * significant points are the start of the first segment,
+ * the start point of the second segment (which coincides
+ * with the end point of the first segment), the start
+ * point of the third segment, and the end point of the
+ * last segment.
+ *
+ * If @point is the start point of the path, there is no
+ * prior point, and this function returns `FALSE`.
+ *
+ * Returns: `TRUE` if @result has been set to a point
+ */
+gboolean
+gsk_path_get_previous_point (GskPath            *self,
+                             const GskPathPoint *point,
+                             GskPathPoint       *result)
+{
+  GskRealPathPoint *p = (GskRealPathPoint *) point;
+  GskRealPathPoint *res = (GskRealPathPoint *) result;
+  const GskContour *contour;
+
+  g_return_val_if_fail (self != NULL, FALSE);
+  g_return_val_if_fail (self == p->path, FALSE);
+
+  contour = gsk_path_get_contour (self, p->contour);
+
+  if (gsk_contour_get_previous_point (contour, p, res))
+    {
+      res->path  = self;
+      res->contour = p->contour;
+      return TRUE;
+    }
+
+  if (p->contour > 0)
+    {
+      contour = gsk_path_get_contour (self, p->contour - 1);
+      gsk_contour_get_end_point (contour, res);
+      res->path = self;
+      res->contour = p->contour - 1;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+/**
+ * gsk_path_get_next_point:
+ * @self: a `GskPath`
+ * @point: a point on @self
+ * @result: (out caller-allocates): Return location for the result
+ *
+ * Gets the next 'significant' point on @self after @point.
+ *
+ * The 'significant' points of a path are typically the
+ * on-curve points that have been specified when the
+ * path was created.
+ *
+ * For example, in a path with 3 Bézier segments, the
+ * significant points are the start of the first segment,
+ * the start point of the second segment (which coincides
+ * with the end point of the first segment), the start
+ * point of the third segment, and the end point of the
+ * last segment.
+ *
+ * If @point is the end point of the path, there is no
+ * next point, and this function returns `FALSE`.
+ *
+ * Returns: `TRUE` if @result has been set to a point
+ */
+gboolean
+gsk_path_get_next_point (GskPath            *self,
+                         const GskPathPoint *point,
+                         GskPathPoint       *result)
+{
+  GskRealPathPoint *p = (GskRealPathPoint *) point;
+  GskRealPathPoint *res = (GskRealPathPoint *) result;
+  const GskContour *contour;
+
+  g_return_val_if_fail (self != NULL, FALSE);
+  g_return_val_if_fail (self == p->path, FALSE);
+
+  contour = gsk_path_get_contour (self, p->contour);
+
+  if (gsk_contour_get_next_point (contour, p, res))
+    {
+      res->path  = self;
+      res->contour = p->contour;
+      return TRUE;
+    }
+
+  if (p->contour < self->n_contours - 1)
+    {
+      contour = gsk_path_get_contour (self, p->contour + 1);
+      gsk_contour_get_start_point (contour, res);
+      res->path = self;
+      res->contour = p->contour + 1;
+      return TRUE;
+    }
+
+  return FALSE;
+}

gsk/gskpath.h

@@ -116,6 +116,23 @@ gboolean                gsk_path_get_closest_point              (GskPath
                                                                  float                   threshold,
                                                                  GskPathPoint           *result);
 
+GDK_AVAILABLE_IN_4_14
+gboolean                gsk_path_get_previous_point             (GskPath                *self,
+                                                                 const GskPathPoint     *point,
+                                                                 GskPathPoint           *result);
+
+GDK_AVAILABLE_IN_4_14
+gboolean                gsk_path_get_next_point                 (GskPath                *self,
+                                                                 const GskPathPoint     *point,
+                                                                 GskPathPoint           *result);
+
+GDK_AVAILABLE_IN_4_14
+gboolean                gsk_path_get_start_point                (GskPath                *self,
+                                                                 GskPathPoint           *result);
+GDK_AVAILABLE_IN_4_14
+gboolean                gsk_path_get_end_point                  (GskPath                *self,
+                                                                 GskPathPoint           *result);
+
 GDK_AVAILABLE_IN_4_14
 gboolean                gsk_path_foreach                        (GskPath                *self,
                                                                  GskPathForeachFlags     flags,

gsk/gskpathbuilder.h

@@ -68,7 +68,11 @@ GDK_AVAILABLE_IN_4_14
 void                    gsk_path_builder_add_circle             (GskPathBuilder         *self,
                                                                  const graphene_point_t *center,
                                                                  float                   radius);
-
+GDK_AVAILABLE_IN_4_14
+void                    gsk_path_builder_add_segment            (GskPathBuilder         *self,
+                                                                 GskPath                *path,
+                                                                 const GskPathPoint     *start,
+                                                                 const GskPathPoint     *end);
 GDK_AVAILABLE_IN_4_14
 void                    gsk_path_builder_move_to                (GskPathBuilder         *self,
                                                                  float                   x,

gsk/gskpathmeasure.c

@@ -0,0 +1,328 @@
+/*
+ * Copyright © 2020 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#include "config.h"
+
+#include "gskpathmeasure.h"
+
+#include "gskpathbuilder.h"
+#include "gskpathpointprivate.h"
+#include "gskpathprivate.h"
+
+/**
+ * GskPathMeasure:
+ *
+ * `GskPathMeasure` is an object that allows measurements
+ * on `GskPath`s such as determining the length of the path.
+ *
+ * Many measuring operations require approximating the path
+ * with simpler shapes. Therefore, a `GskPathMeasure` has
+ * a tolerance that determines what precision is required
+ * for such approximations.
+ *
+ * A `GskPathMeasure` struct is a reference counted struct
+ * and should be treated as opaque.
+ */
+
+typedef struct _GskContourMeasure GskContourMeasure;
+
+struct _GskContourMeasure
+{
+  float length;
+  gpointer contour_data;
+};
+
+struct _GskPathMeasure
+{
+  /*< private >*/
+  guint ref_count;
+
+  GskPath *path;
+  float tolerance;
+
+  float length;
+  gsize n_contours;
+  GskContourMeasure measures[];
+};
+
+G_DEFINE_BOXED_TYPE (GskPathMeasure, gsk_path_measure,
+                     gsk_path_measure_ref,
+                     gsk_path_measure_unref)
+
+/**
+ * gsk_path_measure_new:
+ * @path: the path to measure
+ *
+ * Creates a measure object for the given @path.
+ *
+ * Returns: a new `GskPathMeasure` representing @path
+ *
+ * Since: 4.14
+ */
+GskPathMeasure *
+gsk_path_measure_new (GskPath *path)
+{
+  return gsk_path_measure_new_with_tolerance (path, GSK_PATH_TOLERANCE_DEFAULT);
+}
+
+/**
+ * gsk_path_measure_new_with_tolerance:
+ * @path: the path to measure
+ * @tolerance: the tolerance for measuring operations
+ *
+ * Creates a measure object for the given @path and @tolerance.
+ *
+ * Returns: a new `GskPathMeasure` representing @path
+ *
+ * Since: 4.14
+ */
+GskPathMeasure *
+gsk_path_measure_new_with_tolerance (GskPath *path,
+                                     float    tolerance)
+{
+  GskPathMeasure *self;
+  gsize i, n_contours;
+
+  g_return_val_if_fail (path != NULL, NULL);
+  g_return_val_if_fail (tolerance > 0, NULL);
+
+  n_contours = gsk_path_get_n_contours (path);
+
+  self = g_malloc0 (sizeof (GskPathMeasure) + n_contours * sizeof (GskContourMeasure));
+
+  self->ref_count = 1;
+  self->path = gsk_path_ref (path);
+  self->tolerance = tolerance;
+  self->n_contours = n_contours;
+
+  for (i = 0; i < n_contours; i++)
+    {
+      self->measures[i].contour_data = gsk_contour_init_measure (gsk_path_get_contour (path, i),
+                                                                 self->tolerance,
+                                                                 &self->measures[i].length);
+      self->length += self->measures[i].length;
+    }
+
+  return self;
+}
+
+/**
+ * gsk_path_measure_ref:
+ * @self: a `GskPathMeasure`
+ *
+ * Increases the reference count of a `GskPathMeasure` by one.
+ *
+ * Returns: the passed in `GskPathMeasure`.
+ *
+ * Since: 4.14
+ */
+GskPathMeasure *
+gsk_path_measure_ref (GskPathMeasure *self)
+{
+  g_return_val_if_fail (self != NULL, NULL);
+
+  self->ref_count++;
+
+  return self;
+}
+
+/**
+ * gsk_path_measure_unref:
+ * @self: a `GskPathMeasure`
+ *
+ * Decreases the reference count of a `GskPathMeasure` by one.
+ *
+ * If the resulting reference count is zero, frees the object.
+ *
+ * Since: 4.14
+ */
+void
+gsk_path_measure_unref (GskPathMeasure *self)
+{
+  gsize i;
+
+  g_return_if_fail (self != NULL);
+  g_return_if_fail (self->ref_count > 0);
+
+  self->ref_count--;
+  if (self->ref_count > 0)
+    return;
+
+  for (i = 0; i < self->n_contours; i++)
+    {
+      gsk_contour_free_measure (gsk_path_get_contour (self->path, i),
+                                self->measures[i].contour_data);
+    }
+
+  gsk_path_unref (self->path);
+  g_free (self);
+}
+
+/**
+ * gsk_path_measure_get_path:
+ * @self: a `GskPathMeasure`
+ *
+ * Returns the path that the measure was created for.
+ *
+ * Returns: (transfer none): the path of @self
+ *
+ * Since: 4.14
+ */
+GskPath *
+gsk_path_measure_get_path (GskPathMeasure *self)
+{
+  return self->path;
+}
+
+/**
+ * gsk_path_measure_get_tolerance:
+ * @self: a `GskPathMeasure`
+ *
+ * Returns the tolerance that the measure was created with.
+ *
+ * Returns: the tolerance of @self
+ *
+ * Since: 4.14
+ */
+float
+gsk_path_measure_get_tolerance (GskPathMeasure *self)
+{
+  return self->tolerance;
+}
+
+/**
+ * gsk_path_measure_get_length:
+ * @self: a `GskPathMeasure`
+ *
+ * Gets the length of the path being measured.
+ *
+ * The length is cached, so this function does not do any work.
+ *
+ * Returns: The length of the path measured by @self
+ *
+ * Since: 4.14
+ */
+float
+gsk_path_measure_get_length (GskPathMeasure *self)
+{
+  g_return_val_if_fail (self != NULL, 0);
+
+  return self->length;
+}
+
+static float
+gsk_path_measure_clamp_distance (GskPathMeasure *self,
+                                 float           distance)
+{
+  if (isnan (distance))
+    return 0;
+
+  return CLAMP (distance, 0, self->length);
+}
+
+/**
+ * gsk_path_measure_get_point:
+ * @self: a `GskPathMeasure`
+ * @distance: the distance
+ * @result: (out caller-allocates): return location for the result
+ *
+ * Sets @result to the point at the given distance into the path.
+ *
+ * An empty path has no points, so `FALSE` is returned in that case.
+ *
+ * Returns: `TRUE` if @result was set
+ *
+ * Since: 4.14
+ */
+gboolean
+gsk_path_measure_get_point (GskPathMeasure *self,
+                            float           distance,
+                            GskPathPoint   *result)
+{
+  GskRealPathPoint *res = (GskRealPathPoint *) result;
+  gsize i;
+  float offset;
+  const GskContour *contour;
+
+  g_return_val_if_fail (self != NULL, FALSE);
+  g_return_val_if_fail (result != NULL, FALSE);
+
+  if (self->n_contours == 0)
+    return FALSE;
+
+  offset = gsk_path_measure_clamp_distance (self, distance);
+
+  for (i = 0; i < self->n_contours - 1; i++)
+    {
+      if (offset < self->measures[i].length)
+        break;
+
+      offset -= self->measures[i].length;
+    }
+
+  g_assert (0 <= i && i < self->n_contours);
+
+  offset = CLAMP (offset, 0, self->measures[i].length);
+
+  contour = gsk_path_get_contour (self->path, i);
+
+  gsk_contour_get_point (contour, self->measures[i].contour_data, offset, res);
+
+  res->path = self->path;
+  res->contour = i;
+
+  return TRUE;
+}
+
+/**
+ * gsk_path_point_get_distance:
+ * @measure: a `GskPathMeasure`
+ * @point: a `GskPathPoint on the path of @self
+ *
+ * Returns the distance from the beginning of the path
+ * to @point.
+ *
+ * Returns: the distance of @point
+ *
+ * Since: 4.14
+ */
+float
+gsk_path_point_get_distance (GskPathMeasure     *measure,
+                             const GskPathPoint *point)
+{
+  GskRealPathPoint *p = (GskRealPathPoint *)point;
+  const GskContour *contour = gsk_path_get_contour (measure->path, p->contour);
+  float contour_offset = 0;
+
+  g_return_val_if_fail (measure != NULL, 0);
+  g_return_val_if_fail (measure->path == p->path, 0);
+  g_return_val_if_fail (contour != NULL, 0);
+
+  for (gsize i = 0; i < measure->n_contours; i++)
+    {
+      if (contour == gsk_path_get_contour (measure->path, i))
+        return contour_offset + gsk_contour_get_distance (contour,
+                                                          p,
+                                                          measure->measures[i].contour_data);
+
+      contour_offset += measure->measures[i].length;
+    }
+
+  g_return_val_if_reached (0);
+}

gsk/gskpathmeasure.h

@@ -0,0 +1,66 @@
+/*
+ * Copyright © 2020 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#pragma once
+
+#if !defined (__GSK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gsk/gsk.h> can be included directly."
+#endif
+
+
+#include <gsk/gskpath.h>
+#include <gsk/gskpathpoint.h>
+
+G_BEGIN_DECLS
+
+#define GSK_TYPE_PATH_MEASURE (gsk_path_measure_get_type ())
+
+GDK_AVAILABLE_IN_4_14
+GType                   gsk_path_measure_get_type               (void) G_GNUC_CONST;
+GDK_AVAILABLE_IN_4_14
+GskPathMeasure *        gsk_path_measure_new                    (GskPath                *path);
+GDK_AVAILABLE_IN_4_14
+GskPathMeasure *        gsk_path_measure_new_with_tolerance     (GskPath                *path,
+                                                                 float                   tolerance);
+
+GDK_AVAILABLE_IN_4_14
+GskPathMeasure *        gsk_path_measure_ref                    (GskPathMeasure         *self);
+GDK_AVAILABLE_IN_4_14
+void                    gsk_path_measure_unref                  (GskPathMeasure         *self);
+
+GDK_AVAILABLE_IN_4_14
+GskPath *               gsk_path_measure_get_path               (GskPathMeasure         *self) G_GNUC_PURE;
+GDK_AVAILABLE_IN_4_14
+float                   gsk_path_measure_get_tolerance          (GskPathMeasure         *self) G_GNUC_PURE;
+
+GDK_AVAILABLE_IN_4_14
+float                   gsk_path_measure_get_length             (GskPathMeasure         *self);
+
+GDK_AVAILABLE_IN_4_14
+gboolean                gsk_path_measure_get_point              (GskPathMeasure         *self,
+                                                                 float                   distance,
+                                                                 GskPathPoint           *result);
+
+GDK_AVAILABLE_IN_4_14
+float                   gsk_path_measure_get_distance           (GskPathMeasure         *self,
+                                                                 const GskPathPoint     *point);
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GskPathMeasure, gsk_path_measure_unref)
+
+G_END_DECLS

gsk/gskpathpoint.c

@@ -22,6 +22,7 @@
 #include "gskpathpointprivate.h"
 
 #include "gskcontourprivate.h"
+#include "gskpathmeasure.h"
 
 #include "gdk/gdkprivate.h"
 
@@ -33,7 +34,8 @@
  * It can be queried for properties of the path at that point, such as its
  * tangent or its curvature.
  *
- * To obtain a `GskPathPoint`, use [method@Gsk.Path.get_closest_point].
+ * To obtain a `GskPathPoint`, use [method@Gsk.Path.get_closest_point]
+ * or [method@Gsk.PathMeasure.get_point].
  *
  * Note that `GskPathPoint` structs are meant to be stack-allocated, and
  * don't a reference to the path object they are obtained from. It is the

gsk/gskpathpoint.h

@@ -64,4 +64,8 @@ float                   gsk_path_point_get_curvature   (GskPath            *path
                                                         const GskPathPoint *point,
                                                         graphene_point_t   *center);
 
+GDK_AVAILABLE_IN_4_14
+float                   gsk_path_point_get_distance    (GskPathMeasure     *measure,
+                                                        const GskPathPoint *point);
+
 G_END_DECLS

gsk/gsktypes.h

@@ -27,6 +27,7 @@
 
 typedef struct _GskPath                 GskPath;
 typedef struct _GskPathBuilder          GskPathBuilder;
+typedef struct _GskPathMeasure          GskPathMeasure;
 typedef struct _GskPathPoint            GskPathPoint;
 typedef struct _GskRenderer             GskRenderer;
 typedef struct _GskStroke               GskStroke;

gsk/meson.build

@@ -28,6 +28,7 @@ gsk_public_sources = files([
   'gskglshader.c',
   'gskpath.c',
   'gskpathbuilder.c',
+  'gskpathmeasure.c',
   'gskpathpoint.c',
   'gskrenderer.c',
   'gskrendernode.c',
@@ -75,6 +76,7 @@ gsk_public_headers = files([
   'gskglshader.h',
   'gskpath.h',
   'gskpathbuilder.h',
+  'gskpathmeasure.h',
   'gskpathpoint.h',
   'gskrenderer.h',
   'gskrendernode.h',

testsuite/gsk/measure-special-cases.c

@@ -0,0 +1,268 @@
+/*
+ * Copyright © 2020 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#include <gtk/gtk.h>
+
+
+static void
+test_bad_split (void)
+{
+  GskPath *path, *path1;
+  GskPathMeasure *measure, *measure1;
+  GskPathBuilder *builder;
+  float split, length, epsilon;
+  GskPathPoint point0, point1;
+
+  /* An example that was isolated from the /path/segment test path.c
+   * It shows how uneven parametrization of cubics can lead to bad
+   * lengths reported by the measure.
+   */
+
+  path = gsk_path_parse ("M 0 0 C 2 0 4 0 4 0");
+
+  measure = gsk_path_measure_new (path);
+  split = 2.962588;
+  gsk_path_measure_get_point (measure, 0, &point0);
+  gsk_path_measure_get_point (measure, split, &point1);
+  length = gsk_path_measure_get_length (measure);
+  epsilon = MAX (length / 256, 1.f / 1024);
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_segment (builder, path, &point0, &point1);;
+  path1 = gsk_path_builder_free_to_path (builder);
+  measure1 = gsk_path_measure_new (path1);
+
+  g_assert_cmpfloat_with_epsilon (split, gsk_path_measure_get_length (measure1), epsilon);
+
+  gsk_path_measure_unref (measure1);
+  gsk_path_unref (path1);
+  gsk_path_measure_unref (measure);
+  gsk_path_unref (path);
+}
+
+static void
+test_bad_in_fill (void)
+{
+  GskPath *path;
+  gboolean inside;
+
+  /* A fat Cantarell W */
+  path = gsk_path_parse ("M -2 694 M 206.1748046875 704 L 390.9371337890625 704 L 551.1888427734375 99.5035400390625 L 473.0489501953125 99.5035400390625 L 649.1048583984375 704 L 828.965087890625 704 L 1028.3077392578125 10 L 857.8111572265625 10 L 710.0489501953125 621.251708984375 L 775.9720458984375 598.426513671875 L 614.5245361328125 14.0489501953125 L 430.2237548828125 14.0489501953125 L 278.6783447265625 602.230712890625 L 330.0909423828125 602.230712890625 L 195.88818359375 10 L 5.7342529296875 10 L 206.1748046875 704 Z");
+
+  /* The midpoint of the right foot of a fat Cantarell X */
+  inside = gsk_path_in_fill (path, &GRAPHENE_POINT_INIT (552.360107, 704.000000), GSK_FILL_RULE_WINDING);
+
+  g_assert_false (inside);
+
+  gsk_path_unref (path);
+}
+
+/* Test that path_in_fill implicitly closes contours. I think this is wrong,
+ * but it is what "everybody" does.
+ */
+static void
+test_unclosed_in_fill (void)
+{
+  GskPath *path;
+
+  path = gsk_path_parse ("M 0 0 L 0 100 L 100 100 L 100 0 Z");
+  g_assert_true (gsk_path_in_fill (path, &GRAPHENE_POINT_INIT (50, 50), GSK_FILL_RULE_WINDING));
+  gsk_path_unref (path);
+
+  path = gsk_path_parse ("M 0 0 L 0 100 L 100 100 L 100 0");
+  g_assert_true (gsk_path_in_fill (path, &GRAPHENE_POINT_INIT (50, 50), GSK_FILL_RULE_WINDING));
+  gsk_path_unref (path);
+}
+
+static void
+test_rect (void)
+{
+  GskPathBuilder *builder;
+  GskPath *path;
+  GskPathMeasure *measure;
+  GskPathPoint point;
+  graphene_point_t p;
+  graphene_vec2_t tangent, expected_tangent;
+  float length;
+  gboolean ret;
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_rect (builder, &GRAPHENE_RECT_INIT (0, 0, 100, 50));
+  path = gsk_path_builder_free_to_path (builder);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+
+  g_assert_true (length == 300);
+
+#define TEST_POS_AT(distance, X, Y) \
+  ret = gsk_path_measure_get_point (measure, distance, &point); \
+  g_assert_true (ret); \
+  gsk_path_point_get_position (path, &point, &p); \
+  g_assert_true (graphene_point_near (&p, &GRAPHENE_POINT_INIT (X, Y), 0.01)); \
+  ret = gsk_path_get_closest_point (path, &GRAPHENE_POINT_INIT (X, Y), INFINITY, &point); \
+  g_assert_true (ret); \
+  if (distance < length) \
+    g_assert_true (fabs (gsk_path_point_get_distance (measure, &point) - distance) < 0.01); \
+  else \
+    g_assert_true (fabs (gsk_path_point_get_distance (measure, &point)) < 0.01); \
+  gsk_path_point_get_position (path, &point, &p); \
+  g_assert_true (graphene_point_near (&p, &GRAPHENE_POINT_INIT (X, Y), 0.01)); \
+
+#define TEST_TANGENT_AT(distance, x1, y1, x2, y2) \
+  ret = gsk_path_measure_get_point (measure, distance, &point); \
+  g_assert_true (ret); \
+  gsk_path_point_get_tangent (path, &point, GSK_PATH_START, &tangent); \
+  g_assert_true (graphene_vec2_near (&tangent, graphene_vec2_init (&expected_tangent, x1, y1), 0.01)); \
+  gsk_path_point_get_tangent (path, &point, GSK_PATH_END, &tangent); \
+  g_assert_true (graphene_vec2_near (&tangent, graphene_vec2_init (&expected_tangent, x2, y2), 0.01)); \
+
+#define TEST_POS_AT2(distance, X, Y, expected_distance) \
+  ret = gsk_path_measure_get_point (measure, distance, &point); \
+  g_assert_true (ret); \
+  gsk_path_point_get_position (path, &point, &p); \
+  g_assert_true (graphene_point_near (&p, &GRAPHENE_POINT_INIT (X, Y), 0.01)); \
+  ret = gsk_path_get_closest_point (path, &GRAPHENE_POINT_INIT (X, Y), INFINITY, &point); \
+  g_assert_true (ret); \
+  g_assert_true (fabs (gsk_path_point_get_distance (measure, &point) - expected_distance) < 0.01); \
+  gsk_path_point_get_position (path, &point, &p); \
+  g_assert_true (graphene_point_near (&p, &GRAPHENE_POINT_INIT (X, Y), 0.01)); \
+
+  TEST_POS_AT (0, 0, 0)
+  TEST_POS_AT (25, 25, 0)
+  TEST_POS_AT (100, 100, 0)
+  TEST_POS_AT (110, 100, 10)
+  TEST_POS_AT (150, 100, 50)
+  TEST_POS_AT (175, 75, 50)
+  TEST_POS_AT (250, 0, 50)
+  TEST_POS_AT (260, 0, 40)
+  TEST_POS_AT2 (300, 0, 0, 0)
+
+  TEST_TANGENT_AT (0, 0, -1, 1, 0)
+  TEST_TANGENT_AT (50, 1, 0, 1, 0)
+  TEST_TANGENT_AT (100, 1, 0, 0, 1)
+  TEST_TANGENT_AT (125, 0, 1, 0, 1)
+  TEST_TANGENT_AT (150, 0, 1, -1, 0)
+  TEST_TANGENT_AT (200, -1, 0, -1, 0)
+  TEST_TANGENT_AT (250, -1, 0, 0, -1)
+  TEST_TANGENT_AT (275, 0, -1, 0, -1)
+
+  gsk_path_measure_unref (measure);
+  gsk_path_unref (path);
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_rect (builder, &GRAPHENE_RECT_INIT (100, 50, -100, -50));
+  path = gsk_path_builder_free_to_path (builder);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+
+  g_assert_true (length == 300);
+
+  TEST_POS_AT (0, 100, 50)
+  TEST_POS_AT (25, 75, 50)
+  TEST_POS_AT (100, 0, 50)
+  TEST_POS_AT (110, 0, 40)
+  TEST_POS_AT (150, 0, 0)
+  TEST_POS_AT (175, 25, 0)
+  TEST_POS_AT (250, 100, 0)
+  TEST_POS_AT (260, 100, 10)
+  TEST_POS_AT (300, 100, 50)
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_rect (builder, &GRAPHENE_RECT_INIT (100, 0, -100, 50));
+  path = gsk_path_builder_free_to_path (builder);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+
+  g_assert_true (length == 300);
+
+  TEST_POS_AT (0, 100, 0)
+  TEST_POS_AT (25, 75, 0)
+  TEST_POS_AT (100, 0, 0)
+  TEST_POS_AT (110, 0, 10)
+  TEST_POS_AT (150, 0, 50)
+  TEST_POS_AT (175, 25, 50)
+  TEST_POS_AT (250, 100, 50)
+  TEST_POS_AT (260, 100, 40)
+  TEST_POS_AT (300, 100, 0)
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_rect (builder, &GRAPHENE_RECT_INIT (0, 0, 100, 0));
+  path = gsk_path_builder_free_to_path (builder);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+
+  g_assert_true (length == 200);
+
+  TEST_POS_AT2 (0, 0, 0, 0)
+  TEST_POS_AT2 (25, 25, 0, 25)
+  TEST_POS_AT2 (100, 100, 0, 100)
+  TEST_POS_AT2 (110, 90, 0, 90)
+  TEST_POS_AT2 (200, 0, 0, 0)
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_rect (builder, &GRAPHENE_RECT_INIT (100, 0, -100, 0));
+  path = gsk_path_builder_free_to_path (builder);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+
+  g_assert_true (length == 200);
+
+  /* These cases are ambiguous */
+  TEST_POS_AT2 (0, 100, 0, 0)
+  TEST_POS_AT2 (25, 75, 0, 25)
+  TEST_POS_AT2 (100, 0, 0, 100)
+  TEST_POS_AT2 (110, 10, 0, 110)
+  TEST_POS_AT2 (200, 100, 0, 0)
+
+  builder = gsk_path_builder_new ();
+  gsk_path_builder_add_rect (builder, &GRAPHENE_RECT_INIT (0, 100, 0, -100));
+  path = gsk_path_builder_free_to_path (builder);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+
+  g_assert_true (length == 200);
+
+  /* These cases are ambiguous */
+  TEST_POS_AT2 (0, 0, 100, 0)
+  TEST_POS_AT2 (25, 0, 75, 25)
+  TEST_POS_AT2 (100, 0, 0, 100)
+  TEST_POS_AT2 (110, 0, 10, 110)
+  TEST_POS_AT2 (200, 0, 100, 0)
+
+#undef TEST_POS_AT
+#undef TEST_POS_AT2
+#undef TEST_TANGENT_AT
+
+  gsk_path_measure_unref (measure);
+  gsk_path_unref (path);
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  gtk_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/measure/bad-split", test_bad_split);
+  g_test_add_func ("/measure/bad-in-fill", test_bad_in_fill);
+  g_test_add_func ("/measure/unclosed-in-fill", test_unclosed_in_fill);
+  g_test_add_func ("/measure/rect", test_rect);
+
+  return g_test_run ();
+}

testsuite/gsk/measure.c

@@ -0,0 +1,887 @@
+/*
+ * Copyright © 2020 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#include <gtk/gtk.h>
+
+static GskPath *
+create_random_degenerate_path (guint max_contours)
+{
+#define N_DEGENERATE_PATHS 14
+  GskPathBuilder *builder;
+  guint i;
+
+  builder = gsk_path_builder_new ();
+
+  switch (g_test_rand_int_range (0, N_DEGENERATE_PATHS))
+  {
+    case 0:
+      /* empty path */
+      break;
+
+    case 1:
+      /* a single point */
+      gsk_path_builder_move_to (builder, 
+                                g_test_rand_double_range (-1000, 1000),
+                                g_test_rand_double_range (-1000, 1000));
+      break;
+
+    case 2:
+      /* N points */
+      for (i = 0; i < MIN (10, max_contours); i++)
+        {
+          gsk_path_builder_move_to (builder, 
+                                    g_test_rand_double_range (-1000, 1000),
+                                    g_test_rand_double_range (-1000, 1000));
+        }
+      break;
+
+    case 3:
+      /* 1 closed point */
+      gsk_path_builder_move_to (builder, 
+                                g_test_rand_double_range (-1000, 1000),
+                                g_test_rand_double_range (-1000, 1000));
+      gsk_path_builder_close (builder);
+      break;
+
+    case 4:
+      /* the same point closed N times */
+      gsk_path_builder_move_to (builder, 
+                                g_test_rand_double_range (-1000, 1000),
+                                g_test_rand_double_range (-1000, 1000));
+      for (i = 0; i < MIN (10, max_contours); i++)
+        {
+          gsk_path_builder_close (builder);
+        }
+      break;
+
+    case 5:
+      /* a zero-width and zero-height rect */
+      gsk_path_builder_add_rect (builder,
+                                 &GRAPHENE_RECT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      0, 0));
+      break;
+
+    case 6:
+      /* a zero-width rect */
+      gsk_path_builder_add_rect (builder,
+                                 &GRAPHENE_RECT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      0,
+                                                      g_test_rand_double_range (-1000, 1000)));
+      break;
+
+    case 7:
+      /* a zero-height rect */
+      gsk_path_builder_add_rect (builder,
+                                 &GRAPHENE_RECT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      0));
+      break;
+
+    case 8:
+      /* a negative-size rect */
+      gsk_path_builder_add_rect (builder,
+                                 &GRAPHENE_RECT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 0),
+                                                      g_test_rand_double_range (-1000, 0)));
+      break;
+
+    case 9:
+      /* an absolutely random rect */
+      gsk_path_builder_add_rect (builder,
+                                 &GRAPHENE_RECT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000)));
+      break;
+
+    case 10:
+      /* an absolutely random rect */
+      gsk_path_builder_add_rect (builder,
+                                 &GRAPHENE_RECT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000)));
+      break;
+
+    case 11:
+      /* an absolutely random circle */
+      gsk_path_builder_add_circle (builder,
+                                   &GRAPHENE_POINT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                         g_test_rand_double_range (-1000, 1000)),
+                                   g_test_rand_double_range (1, 1000));
+      break;
+
+    case 12:
+      /* a zero-length line */
+      {
+        graphene_point_t point = GRAPHENE_POINT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000));
+        gsk_path_builder_move_to (builder, point.x, point.y);
+        gsk_path_builder_line_to (builder, point.x, point.y);
+      }
+      break;
+
+    case 13:
+      /* a curve with start == end */
+      {
+        graphene_point_t point = GRAPHENE_POINT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000));
+        gsk_path_builder_move_to (builder, point.x, point.y);
+        gsk_path_builder_cubic_to (builder,
+                                   g_test_rand_double_range (-1000, 1000),
+                                   g_test_rand_double_range (-1000, 1000),
+                                   g_test_rand_double_range (-1000, 1000),
+                                   g_test_rand_double_range (-1000, 1000),
+                                   point.x, point.y);
+      }
+      break;
+
+    case N_DEGENERATE_PATHS:
+    default:
+      g_assert_not_reached ();
+  }
+
+  return gsk_path_builder_free_to_path (builder);
+}
+
+static GskPath *
+create_random_path (guint max_contours);
+
+static void
+add_shape_contour (GskPathBuilder *builder)
+{
+#define N_SHAPE_CONTOURS 3
+  switch (g_test_rand_int_range (0, N_SHAPE_CONTOURS))
+  {
+    case 0:
+      gsk_path_builder_add_rect (builder,
+                                 &GRAPHENE_RECT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (-1000, 1000),
+                                                      g_test_rand_double_range (1, 1000),
+                                                      g_test_rand_double_range (1, 1000)));
+      break;
+
+    case 1:
+      gsk_path_builder_add_circle (builder,
+                                   &GRAPHENE_POINT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                         g_test_rand_double_range (-1000, 1000)),
+                                   g_test_rand_double_range (1, 1000));
+      break;
+
+    case 2:
+      {
+        GskPath *path = create_random_path (1);
+        gsk_path_builder_add_path (builder, path);
+        gsk_path_unref (path);
+      }
+      break;
+
+    case N_SHAPE_CONTOURS:
+    default:
+      g_assert_not_reached ();
+      break;
+  }
+}
+
+static void
+add_standard_contour (GskPathBuilder *builder)
+{
+  guint i, n;
+
+  if (g_test_rand_bit ())
+    {
+      if (g_test_rand_bit ())
+        gsk_path_builder_move_to (builder,
+                                  g_test_rand_double_range (-1000, 1000),
+                                  g_test_rand_double_range (-1000, 1000));
+      else
+        gsk_path_builder_rel_move_to (builder,
+                                      g_test_rand_double_range (-1000, 1000),
+                                      g_test_rand_double_range (-1000, 1000));
+    }
+
+  /* that 20 is random, but should be enough to get some
+   * crazy self-intersecting shapes */
+  n = g_test_rand_int_range (1, 20);
+  for (i = 0; i < n; i++)
+    {
+      switch (g_test_rand_int_range (0, 6))
+      {
+        case 0:
+          gsk_path_builder_line_to (builder,
+                                    g_test_rand_double_range (-1000, 1000),
+                                    g_test_rand_double_range (-1000, 1000));
+          break;
+
+        case 1:
+          gsk_path_builder_rel_line_to (builder,
+                                        g_test_rand_double_range (-1000, 1000),
+                                        g_test_rand_double_range (-1000, 1000));
+          break;
+
+        case 2:
+          gsk_path_builder_quad_to (builder,
+                                    g_test_rand_double_range (-1000, 1000),
+                                    g_test_rand_double_range (-1000, 1000),
+                                    g_test_rand_double_range (-1000, 1000),
+                                    g_test_rand_double_range (-1000, 1000));
+          break;
+
+        case 3:
+          gsk_path_builder_rel_quad_to (builder,
+                                        g_test_rand_double_range (-1000, 1000),
+                                        g_test_rand_double_range (-1000, 1000),
+                                        g_test_rand_double_range (-1000, 1000),
+                                        g_test_rand_double_range (-1000, 1000));
+          break;
+
+        case 4:
+          gsk_path_builder_cubic_to (builder,
+                                     g_test_rand_double_range (-1000, 1000),
+                                     g_test_rand_double_range (-1000, 1000),
+                                     g_test_rand_double_range (-1000, 1000),
+                                     g_test_rand_double_range (-1000, 1000),
+                                     g_test_rand_double_range (-1000, 1000),
+                                     g_test_rand_double_range (-1000, 1000));
+          break;
+
+        case 5:
+          gsk_path_builder_rel_cubic_to (builder,
+                                         g_test_rand_double_range (-1000, 1000),
+                                         g_test_rand_double_range (-1000, 1000),
+                                         g_test_rand_double_range (-1000, 1000),
+                                         g_test_rand_double_range (-1000, 1000),
+                                         g_test_rand_double_range (-1000, 1000),
+                                         g_test_rand_double_range (-1000, 1000));
+          break;
+
+        default:
+          g_assert_not_reached();
+          break;
+      }
+    }
+
+  if (g_test_rand_bit ())
+    gsk_path_builder_close (builder);
+}
+
+static GskPath *
+create_random_path (guint max_contours)
+{
+  GskPathBuilder *builder;
+  guint i, n;
+
+  /* 5% chance for a weird shape */
+  if (!g_test_rand_int_range (0, 20))
+    return create_random_degenerate_path (max_contours);
+
+  builder = gsk_path_builder_new ();
+  n = g_test_rand_int_range (1, 10);
+  n = MIN (n, max_contours);
+
+  for (i = 0; i < n; i++)
+    {
+      /* 2/3 of shapes are standard contours */
+      if (g_test_rand_int_range (0, 3))
+        add_standard_contour (builder);
+      else
+        add_shape_contour (builder);
+    }
+
+  return gsk_path_builder_free_to_path (builder);
+}
+
+typedef struct {
+  GskPathOperation op;
+  graphene_point_t pts[4];
+  float weight;
+} PathOperation;
+
+static void
+test_segment_start (void)
+{
+  GskPath *path, *path1;
+  GskPathMeasure *measure, *measure1;
+  GskPathBuilder *builder;
+  float epsilon, length;
+  guint i;
+  GskPathPoint point0, point1;
+
+  path = create_random_path (G_MAXUINT);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+  epsilon = MAX (length / 1024, G_MINFLOAT);
+  gsk_path_measure_get_point (measure, 0, &point0);
+
+  for (i = 0; i < 100; i++)
+    {
+      float seg_length = length * i / 100.0f;
+
+      gsk_path_measure_get_point (measure, seg_length, &point1);
+
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &point0, &point1);
+      path1 = gsk_path_builder_free_to_path (builder);
+      measure1 = gsk_path_measure_new (path1);
+
+      if (seg_length == 0)
+        g_assert_cmpfloat_with_epsilon (gsk_path_measure_get_length (measure), gsk_path_measure_get_length (measure1), epsilon);
+      else
+        g_assert_cmpfloat_with_epsilon (seg_length, gsk_path_measure_get_length (measure1), epsilon);
+
+      gsk_path_measure_unref (measure1);
+      gsk_path_unref (path1);
+    }
+
+  gsk_path_measure_unref (measure);
+  gsk_path_unref (path);
+}
+
+static void
+test_segment_end (void)
+{
+  GskPath *path, *path1;
+  GskPathMeasure *measure, *measure1;
+  GskPathBuilder *builder;
+  float epsilon, length;
+  guint i;
+  GskPathPoint point0, point1;
+
+  path = create_random_path (G_MAXUINT);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+  epsilon = MAX (length / 1024, G_MINFLOAT);
+
+  for (i = 0; i < 100; i++)
+    {
+      float seg_length = length * i / 100.0f;
+
+      gsk_path_measure_get_point (measure, length - seg_length, &point0);
+      gsk_path_measure_get_point (measure, length, &point1);
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &point0, &point1);
+      path1 = gsk_path_builder_free_to_path (builder);
+      measure1 = gsk_path_measure_new (path1);
+
+      if (seg_length == 0)
+        g_assert_cmpfloat_with_epsilon (gsk_path_measure_get_length (measure), gsk_path_measure_get_length (measure1), epsilon);
+      else
+        g_assert_cmpfloat_with_epsilon (seg_length, gsk_path_measure_get_length (measure1), epsilon);
+
+      gsk_path_measure_unref (measure1);
+      gsk_path_unref (path1);
+    }
+
+  gsk_path_measure_unref (measure);
+  gsk_path_unref (path);
+}
+
+static void
+test_segment_chunk (void)
+{
+  GskPath *path, *path1, *path2;
+  GskPathMeasure *measure, *measure1, *measure2;
+  GskPathBuilder *builder;
+  float epsilon, length;
+  guint i;
+  GskPathPoint point0, point1;
+
+  path = create_random_path (G_MAXUINT);
+  measure = gsk_path_measure_new (path);
+  length = gsk_path_measure_get_length (measure);
+  epsilon = MAX (length / 1024, G_MINFLOAT);
+
+  for (i = 0; i <= 100; i++)
+    {
+      float seg_start = length * i / 200.0f;
+
+      gsk_path_measure_get_point (measure, seg_start, &point0);
+      gsk_path_measure_get_point (measure, seg_start + length / 2, &point1);
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &point0, &point1);
+      path1 = gsk_path_builder_free_to_path (builder);
+      measure1 = gsk_path_measure_new (path1);
+
+      g_assert_cmpfloat_with_epsilon (length / 2, gsk_path_measure_get_length (measure1), epsilon);
+
+      gsk_path_measure_get_point (measure, seg_start + length / 2, &point0);
+      gsk_path_measure_get_point (measure, seg_start, &point1);
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &point0, &point1);
+      path2 = gsk_path_builder_free_to_path (builder);
+      measure2 = gsk_path_measure_new (path2);
+
+      g_assert_cmpfloat_with_epsilon (length / 2, gsk_path_measure_get_length (measure2), epsilon);
+
+      gsk_path_measure_unref (measure2);
+      gsk_path_unref (path2);
+      gsk_path_measure_unref (measure1);
+      gsk_path_unref (path1);
+    }
+
+  gsk_path_measure_unref (measure);
+  gsk_path_unref (path);
+}
+
+static void
+test_segment (void)
+{
+  GskPath *path, *path1, *path2, *path3;
+  GskPathMeasure *measure, *measure1, *measure2, *measure3;
+  GskPathBuilder *builder;
+  guint i;
+  float split1, split2, epsilon, length;
+  GskPathPoint point0, point1, point2, point3;
+
+  for (i = 0; i < 1000; i++)
+    {
+      path = create_random_path (G_MAXUINT);
+      measure = gsk_path_measure_new (path);
+      length = gsk_path_measure_get_length (measure);
+      /* chosen high enough to stop the testsuite from failing */
+      epsilon = MAX (length / 64, 1.f / 1024);
+
+      split1 = g_test_rand_double_range (0, length);
+      split2 = g_test_rand_double_range (split1, length);
+
+      gsk_path_measure_get_point (measure, 0, &point0);
+      gsk_path_measure_get_point (measure, split1, &point1);
+      gsk_path_measure_get_point (measure, split2, &point2);
+      gsk_path_measure_get_point (measure, length, &point3);
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &point0, &point1);
+      path1 = gsk_path_builder_free_to_path (builder);
+      measure1 = gsk_path_measure_new (path1);
+
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &point1, &point2);
+      path2 = gsk_path_builder_free_to_path (builder);
+      measure2 = gsk_path_measure_new (path2);
+
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &point2, &point3);
+      path3 = gsk_path_builder_free_to_path (builder);
+      measure3 = gsk_path_measure_new (path3);
+
+      g_assert_cmpfloat_with_epsilon (split1, gsk_path_measure_get_length (measure1), epsilon);
+      g_assert_cmpfloat_with_epsilon (split2 - split1, gsk_path_measure_get_length (measure2), epsilon);
+      g_assert_cmpfloat_with_epsilon (length - split2, gsk_path_measure_get_length (measure3), epsilon);
+
+      gsk_path_measure_unref (measure2);
+      gsk_path_measure_unref (measure1);
+      gsk_path_measure_unref (measure);
+      gsk_path_unref (path2);
+      gsk_path_unref (path1);
+      gsk_path_unref (path);
+    }
+}
+
+static void
+test_get_point (void)
+{
+  static const guint max_contours = 5;
+  static const float tolerance = 1.0;
+  GskPath *path;
+  GskPathMeasure *measure;
+  GskPathPoint point;
+  guint n_discontinuities;
+  float length, offset, last_offset;
+  graphene_point_t p, last_point;
+  guint i, j;
+  gboolean ret;
+
+  for (i = 0; i < 10; i++)
+    {
+      path = create_random_path (max_contours);
+      measure = gsk_path_measure_new_with_tolerance (path, tolerance);
+      length = gsk_path_measure_get_length (measure);
+      n_discontinuities = 0;
+
+      ret = gsk_path_measure_get_point (measure, 0, &point);
+      if (!ret)
+        {
+          g_assert_true (gsk_path_is_empty (path));
+          continue;
+        }
+      gsk_path_point_get_position (path, &point, &last_point);
+
+      /* FIXME: anything we can test with tangents here? */
+      last_offset = 0;
+
+      for (j = 1; j <= 1024; j++)
+        {
+          offset = length * j / 1024;
+          ret = gsk_path_measure_get_point (measure, offset, &point);
+          g_assert_true (ret);
+          gsk_path_point_get_position (path, &point, &p);
+
+          if (graphene_point_distance (&last_point, &p, NULL, NULL) > 2 * (offset - last_offset))
+            {
+              n_discontinuities++;
+              g_assert_cmpint (n_discontinuities, <, max_contours);
+            }
+
+          last_offset = offset;
+          last_point = p;
+        }
+
+      gsk_path_measure_unref (measure);
+      gsk_path_unref (path);
+    }
+}
+
+static void
+test_closest_point (void)
+{
+  static const float tolerance = 0.5;
+  GskPath *path, *path1, *path2;
+  GskPathMeasure *measure, *measure1, *measure2;
+  GskPathBuilder *builder;
+  GskPathPoint point;
+  guint i, j;
+  gboolean ret;
+
+  if (!g_test_slow ())
+    {
+      g_test_skip ("Skipping slow test");
+      return;
+    }
+
+  for (i = 0; i < 10; i++)
+    {
+      path1 = create_random_path (G_MAXUINT);
+      measure1 = gsk_path_measure_new_with_tolerance (path1, tolerance);
+      path2 = create_random_path (G_MAXUINT);
+      measure2 = gsk_path_measure_new_with_tolerance (path2, tolerance);
+
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_path (builder, path1);
+      gsk_path_builder_add_path (builder, path2);
+      path = gsk_path_builder_free_to_path (builder);
+      measure = gsk_path_measure_new_with_tolerance (path, tolerance);
+
+      for (j = 0; j < 100; j++)
+        {
+          graphene_point_t test = GRAPHENE_POINT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                       g_test_rand_double_range (-1000, 1000));
+          graphene_point_t p1, p2, p;
+          graphene_vec2_t t1, t2, t;
+          float offset1, offset2, offset;
+          float distance1, distance2, distance;
+
+          offset1 = offset2 = offset = 0;
+          distance1 = distance2 = distance = 0;
+          ret = gsk_path_get_closest_point (path1, &test, INFINITY, &point);
+          g_assert_true (ret);
+
+          gsk_path_point_get_position (path1, &point, &p1);
+          gsk_path_point_get_tangent (path1, &point, GSK_PATH_END, &t1);
+          offset1 = gsk_path_point_get_distance (measure1, &point);
+          distance1 = graphene_point_distance (&p1, &test, NULL, NULL);
+
+          ret = gsk_path_get_closest_point (path2, &test, INFINITY, &point);
+          g_assert_true (ret);
+
+          gsk_path_point_get_position (path2, &point, &p2);
+          gsk_path_point_get_tangent (path2, &point, GSK_PATH_END, &t2);
+          offset2 = gsk_path_point_get_distance (measure2, &point);
+          distance2 = graphene_point_distance (&p2, &test, NULL, NULL);
+
+          ret = gsk_path_get_closest_point (path, &test, INFINITY, &point);
+          g_assert_true (ret);
+
+          gsk_path_point_get_position (path, &point, &p);
+          gsk_path_point_get_tangent (path, &point, GSK_PATH_END, &t);
+          offset = gsk_path_point_get_distance (measure, &point);
+          distance = graphene_point_distance (&p, &test, NULL, NULL);
+
+          if (distance1 == distance)
+            {
+              g_assert_cmpfloat (distance1, ==, distance);
+              g_assert_cmpfloat (p1.x, ==, p.x);
+              g_assert_cmpfloat (p1.y, ==, p.y);
+              g_assert_cmpfloat (offset1, ==, offset);
+              g_assert_true (graphene_vec2_equal (&t1, &t));
+            }
+          else
+            {
+              g_assert_cmpfloat (distance2, ==, distance);
+              g_assert_cmpfloat (p2.x, ==, p.x);
+              g_assert_cmpfloat (p2.y, ==, p.y);
+              g_assert_cmpfloat_with_epsilon (offset2 + gsk_path_measure_get_length (measure1), offset, MAX (G_MINFLOAT, offset / 1024));
+              g_assert_true (graphene_vec2_equal (&t2, &t));
+            }
+        }
+
+      gsk_path_measure_unref (measure2);
+      gsk_path_measure_unref (measure1);
+      gsk_path_measure_unref (measure);
+      gsk_path_unref (path2);
+      gsk_path_unref (path1);
+      gsk_path_unref (path);
+    }
+}
+
+static void
+test_closest_point_for_point (void)
+{
+  static const float tolerance = 0.5;
+  GskPath *path;
+  GskPathMeasure *measure;
+  GskPathPoint point;
+  float length, offset, distance;
+  graphene_point_t p, closest_point;
+  guint i, j;
+  gboolean ret;
+
+  if (!g_test_slow ())
+    {
+      g_test_skip ("Skipping slow test");
+      return;
+    }
+
+  for (i = 0; i < 100; i++)
+    {
+      path = create_random_path (G_MAXUINT);
+      if (gsk_path_is_empty (path))
+        {
+          /* empty paths have no closest point to anything */
+          gsk_path_unref (path);
+          continue;
+        }
+
+      measure = gsk_path_measure_new_with_tolerance (path, tolerance);
+      length = gsk_path_measure_get_length (measure);
+
+      for (j = 0; j < 100; j++)
+        {
+          offset = g_test_rand_double_range (0, length);
+          ret = gsk_path_measure_get_point (measure, offset, &point);
+          g_assert_true (ret);
+          gsk_path_point_get_position (path, &point, &p);
+          ret = gsk_path_get_closest_point (path, &p, 2 * tolerance, &point);
+          g_assert_true (ret);
+          gsk_path_point_get_position (path, &point, &closest_point);
+          //closest_offset = gsk_path_point_get_distance (measure, &point);
+          distance = graphene_point_distance (&p, &closest_point, NULL, NULL);
+
+          /* should be given due to the TRUE return above, but who knows... */
+          g_assert_cmpfloat (distance, <=, 2 * tolerance);
+          g_assert_cmpfloat (graphene_point_distance (&p, &closest_point, NULL, NULL), <=, 2 * tolerance);
+          /* we can't check offsets here, since we might hit self-intersections
+          g_assert_cmpfloat_with_epsilon (closest_offset, offset, 2 * tolerance);
+          */
+        }
+
+      gsk_path_measure_unref (measure);
+      gsk_path_unref (path);
+    }
+}
+
+#define N_PATHS 3
+static void
+test_in_fill_union (void)
+{
+  GskPath *path;
+  GskPathMeasure *measure, *measures[N_PATHS];
+  GskPathBuilder *builder;
+  guint i, j, k;
+
+  for (i = 0; i < 100; i++)
+    {
+      builder = gsk_path_builder_new ();
+      for (k = 0; k < N_PATHS; k++)
+        {
+          path = create_random_path (G_MAXUINT);
+          measures[k] = gsk_path_measure_new (path);
+          gsk_path_builder_add_path (builder, path);
+          gsk_path_unref (path);
+        }
+      path = gsk_path_builder_free_to_path (builder);
+      measure = gsk_path_measure_new (path);
+      gsk_path_unref (path);
+
+      for (j = 0; j < 100; j++)
+        {
+          graphene_point_t test = GRAPHENE_POINT_INIT (g_test_rand_double_range (-1000, 1000),
+                                                       g_test_rand_double_range (-1000, 1000));
+          GskFillRule fill_rule;
+
+          for (fill_rule = GSK_FILL_RULE_WINDING; fill_rule <= GSK_FILL_RULE_EVEN_ODD; fill_rule++)
+            {
+              guint n_in_fill = 0;
+              gboolean in_fill;
+
+              for (k = 0; k < N_PATHS; k++)
+                {
+                  if (gsk_path_in_fill (gsk_path_measure_get_path (measures[k]), &test, GSK_FILL_RULE_EVEN_ODD))
+                    n_in_fill++;
+                }
+
+              in_fill = gsk_path_in_fill (gsk_path_measure_get_path (measure), &test, GSK_FILL_RULE_EVEN_ODD);
+
+              switch (fill_rule)
+              {
+                case GSK_FILL_RULE_WINDING:
+                  if (n_in_fill == 0)
+                    g_assert_false (in_fill);
+                  else if (n_in_fill == 1)
+                    g_assert_true (in_fill);
+                  /* else we can't say anything because the winding rule doesn't give enough info */
+                  break;
+
+                case GSK_FILL_RULE_EVEN_ODD:
+                  g_assert_cmpint (in_fill, ==, n_in_fill & 1);
+                  break;
+
+                default:
+                  g_assert_not_reached ();
+                  break;
+              }
+            }
+        }
+
+      gsk_path_measure_unref (measure);
+      for (k = 0; k < N_PATHS; k++)
+        {
+          gsk_path_measure_unref (measures[k]);
+        }
+    }
+}
+#undef N_PATHS
+
+/* This is somewhat sucky because using foreach breaks up the contours
+ * (like rects and circles) and replaces everything with the standard
+ * contour.
+ * But at least it extensively tests the standard contour.
+ */
+static gboolean
+rotate_path_cb (GskPathOperation        op,
+                const graphene_point_t *pts,
+                gsize                   n_pts,
+                gpointer                user_data)
+{
+  GskPathBuilder **builders = user_data;
+
+  switch (op)
+  {
+    case GSK_PATH_MOVE:
+      gsk_path_builder_move_to (builders[0], pts[0].x, pts[0].y);
+      gsk_path_builder_move_to (builders[1], pts[0].y, -pts[0].x);
+      break;
+
+    case GSK_PATH_CLOSE:
+      gsk_path_builder_close (builders[0]);
+      gsk_path_builder_close (builders[1]);
+      break;
+
+    case GSK_PATH_LINE:
+      gsk_path_builder_line_to (builders[0], pts[1].x, pts[1].y);
+      gsk_path_builder_line_to (builders[1], pts[1].y, -pts[1].x);
+      break;
+
+    case GSK_PATH_QUAD:
+      gsk_path_builder_quad_to (builders[0], pts[1].x, pts[1].y, pts[2].x, pts[2].y);
+      gsk_path_builder_quad_to (builders[1], pts[1].y, -pts[1].x, pts[2].y, -pts[2].x);
+      break;
+
+    case GSK_PATH_CUBIC:
+      gsk_path_builder_cubic_to (builders[0], pts[1].x, pts[1].y, pts[2].x, pts[2].y, pts[3].x, pts[3].y);
+      gsk_path_builder_cubic_to (builders[1], pts[1].y, -pts[1].x, pts[2].y, -pts[2].x, pts[3].y, -pts[3].x);
+      break;
+
+    default:
+      g_assert_not_reached ();
+      return FALSE;
+  }
+
+  return TRUE;
+}
+
+static void
+test_in_fill_rotated (void)
+{
+  GskPath *path;
+  GskPathBuilder *builders[2];
+  GskPathMeasure *measures[2];
+  guint i, j;
+
+#define N_FILL_RULES 2
+  /* if this triggers, you added a new enum value to GskFillRule, so the define above needs
+   * an update */
+  g_assert_null (g_enum_get_value (g_type_class_ref (GSK_TYPE_FILL_RULE), N_FILL_RULES));
+
+  for (i = 0; i < 100; i++)
+    {
+      path = create_random_path (G_MAXUINT);
+      builders[0] = gsk_path_builder_new ();
+      builders[1] = gsk_path_builder_new ();
+      /* Use -1 here because we want all the flags, even future additions */
+      gsk_path_foreach (path, -1, rotate_path_cb, builders);
+      gsk_path_unref (path);
+
+      path = gsk_path_builder_free_to_path (builders[0]);
+      measures[0] = gsk_path_measure_new (path);
+      gsk_path_unref (path);
+      path = gsk_path_builder_free_to_path (builders[1]);
+      measures[1] = gsk_path_measure_new (path);
+      gsk_path_unref (path);
+
+      for (j = 0; j < 100; j++)
+        {
+          GskFillRule fill_rule = g_random_int_range (0, N_FILL_RULES);
+          float x = g_test_rand_double_range (-1000, 1000);
+          float y = g_test_rand_double_range (-1000, 1000);
+  
+          g_assert_cmpint (gsk_path_in_fill (gsk_path_measure_get_path (measures[0]), &GRAPHENE_POINT_INIT (x, y), fill_rule),
+                           ==,
+                           gsk_path_in_fill (gsk_path_measure_get_path (measures[1]), &GRAPHENE_POINT_INIT (y, -x), fill_rule));
+          g_assert_cmpint (gsk_path_in_fill (gsk_path_measure_get_path (measures[0]), &GRAPHENE_POINT_INIT (y, x), fill_rule),
+                           ==,
+                           gsk_path_in_fill (gsk_path_measure_get_path (measures[1]), &GRAPHENE_POINT_INIT (x, -y), fill_rule));
+        }
+
+      gsk_path_measure_unref (measures[0]);
+      gsk_path_measure_unref (measures[1]);
+    }
+#undef N_FILL_RULES
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  gtk_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/measure/segment_start", test_segment_start);
+  g_test_add_func ("/measure/segment_end", test_segment_end);
+  g_test_add_func ("/measure/segment_chunk", test_segment_chunk);
+  g_test_add_func ("/measure/segment", test_segment);
+  g_test_add_func ("/measure/get_point", test_get_point);
+  g_test_add_func ("/measure/closest_point", test_closest_point);
+  g_test_add_func ("/measure/closest_point_for_point", test_closest_point_for_point);
+  g_test_add_func ("/measure/in-fill-union", test_in_fill_union);
+  g_test_add_func ("/measure/in-fill-rotated", test_in_fill_rotated);
+
+  return g_test_run ();
+}

testsuite/gsk/meson.build

@@ -371,6 +371,8 @@ tests = [
   ['shader'],
   ['path'],
   ['path-special-cases'],
+  ['measure'],
+  ['measure-special-cases'],
 ]
 
 test_cargs = []

testsuite/gsk/path-special-cases.c

@@ -443,7 +443,6 @@ test_path_point (void)
   gsk_path_point_get_tangent (path, &point, GSK_PATH_END, &t2);
   curvature = gsk_path_point_get_curvature (path, &point, &center);
 
-  g_print ("%g %g\n", graphene_vec2_get_x (&t1), graphene_vec2_get_y (&t1));
   g_assert_true (graphene_point_equal (&pos, &GRAPHENE_POINT_INIT (100, 100)));
   g_assert_true (graphene_vec2_equal (&t1, graphene_vec2_y_axis ()));
   graphene_vec2_negate (graphene_vec2_x_axis (), &mx);
@@ -453,6 +452,66 @@ test_path_point (void)
   gsk_path_unref (path);
 }
 
+/* Test that gsk_path_builder_add_segment yields the expected results */
+static void
+test_path_segments (void)
+{
+  struct {
+    const char *path;
+    graphene_point_t p1;
+    graphene_point_t p2;
+    const char *result;
+  } tests[] = {
+    {
+      "M 0 0 L 100 0 L 50 50 Z",
+      { 100, 0 },
+      { 50, 50 },
+      "M 100 0 L 50 50"
+    },
+    {
+      "M 0 0 L 100 0 L 50 50 Z",
+      { 50, 0 },
+      { 70, 0 },
+      "M 50 0 L 70 0"
+    },
+    {
+      "M 0 0 L 100 0 L 50 50 Z",
+      { 70, 0 },
+      { 50, 0 },
+      "M 70 0 L 100 0 L 50 50 L 0 0 L 50 0"
+    },
+    {
+      "M 0 0 L 100 0 L 50 50 Z",
+      { 50, 0 },
+      { 50, 50 },
+      "M 50 0 L 100 0 L 50 50"
+    }
+  };
+
+  for (unsigned int i = 0; i < G_N_ELEMENTS (tests); i++)
+    {
+      GskPath *path;
+      GskPathPoint p1, p2;
+      GskPathBuilder *builder;
+      GskPath *result;
+      char *str;
+
+      path = gsk_path_parse (tests[i].path);
+      g_assert_true (gsk_path_get_closest_point (path, &tests[i].p1, INFINITY, &p1));
+      g_assert_true (gsk_path_get_closest_point (path, &tests[i].p2, INFINITY, &p2));
+
+      builder = gsk_path_builder_new ();
+      gsk_path_builder_add_segment (builder, path, &p1, &p2);
+      result = gsk_path_builder_free_to_path (builder);
+      str = gsk_path_to_string (result);
+
+      g_assert_cmpstr (str, ==, tests[i].result);
+
+      g_free (str);
+      gsk_path_unref (path);
+    }
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -463,6 +522,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/path/rect", test_rect_path);
   g_test_add_func ("/path/foreach", test_foreach);
   g_test_add_func ("/path/point", test_path_point);
+  g_test_add_func ("/path/segments", test_path_segments);
 
   return g_test_run ();
 }