Neuter some tests that assume special contours

This is a function like gsk_path_foreach, but
it provides a dashed version of the path instead
of the original.

demos/gtk-demo/demo.gresource.xml

@@ -337,7 +337,6 @@
     <file>password_entry.c</file>
     <file>path_fill.c</file>
     <file>path_text.c</file>
-    <file>path_walk.c</file>
     <file>peg_solitaire.c</file>
     <file>pickers.c</file>
     <file>printing.c</file>
@@ -426,10 +425,6 @@
   <gresource prefix="/path_text">
     <file>path_text.ui</file>
   </gresource>
-  <gresource prefix="/path_walk">
-    <file>path_walk.ui</file>
-    <file>path_world.c</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

@@ -74,7 +74,6 @@ demos = files([
   'password_entry.c',
   'path_fill.c',
   'path_text.c',
-  'path_walk.c',
   'peg_solitaire.c',
   'pickers.c',
   'printing.c',

demos/gtk-demo/path_walk.c

@@ -1,346 +0,0 @@
-/* Path/Walk
- *
- * This demo shows how to animate objects along a GskPath
- */
-
-#include <glib/gi18n.h>
-#include <gtk/gtk.h>
-
-#include "path_world.c"
-
-#define GTK_TYPE_PATH_WALK (gtk_path_walk_get_type ())
-G_DECLARE_FINAL_TYPE (GtkPathWalk, gtk_path_walk, GTK, PATH_WALK, GtkWidget)
-
-#define POINT_SIZE 8
-
-enum {
-  PROP_0,
-  PROP_N_POINTS,
-  PROP_PATH,
-  N_PROPS
-};
-
-struct _GtkPathWalk
-{
-  GtkWidget parent_instance;
-
-  GskPath *path;
-  GskPathMeasure *measure;
-  GskPath *arrow_path;
-  guint n_points;
-};
-
-struct _GtkPathWalkClass
-{
-  GtkWidgetClass parent_class;
-};
-
-static GParamSpec *properties[N_PROPS] = { NULL, };
-
-G_DEFINE_TYPE (GtkPathWalk, gtk_path_walk, GTK_TYPE_WIDGET)
-
-static void
-rgba_init_from_hsla (GdkRGBA *rgba,
-                     float    hue,
-                     float    saturation,
-                     float    lightness,
-                     float    alpha)
-{
-  float m1, m2;
-
-  if (lightness <= 0.5)
-    m2 = lightness * (1 + saturation);
-  else
-    m2 = lightness + saturation - lightness * saturation;
-  m1 = 2 * lightness - m2;
-
-  rgba->alpha = alpha;
-
-  if (saturation == 0)
-    {
-      rgba->red = lightness;
-      rgba->green = lightness;
-      rgba->blue = lightness;
-    }
-  else
-    {
-      hue = hue + 120;
-      while (hue > 360)
-        hue -= 360;
-      while (hue < 0)
-        hue += 360;
-
-      if (hue < 60)
-        rgba->red = m1 + (m2 - m1) * hue / 60;
-      else if (hue < 180)
-        rgba->red = m2;
-      else if (hue < 240)
-        rgba->red = m1 + (m2 - m1) * (240 - hue) / 60;
-      else
-        rgba->red = m1;
-
-      hue -= 120;
-      if (hue < 0)
-        hue += 360;
-
-      if (hue < 60)
-        rgba->green = m1 + (m2 - m1) * hue / 60;
-      else if (hue < 180)
-        rgba->green = m2;
-      else if (hue < 240)
-        rgba->green = m1 + (m2 - m1) * (240 - hue) / 60;
-      else
-        rgba->green = m1;
-
-      hue -= 120;
-      if (hue < 0)
-        hue += 360;
-
-      if (hue < 60)
-        rgba->blue = m1 + (m2 - m1) * hue / 60;
-      else if (hue < 180)
-        rgba->blue = m2;
-      else if (hue < 240)
-        rgba->blue = m1 + (m2 - m1) * (240 - hue) / 60;
-      else
-        rgba->blue = m1;
-    }
-}
-
-static void
-gtk_path_walk_snapshot (GtkWidget   *widget,
-                        GtkSnapshot *snapshot)
-{
-  GtkPathWalk *self = GTK_PATH_WALK (widget);
-  double width = gtk_widget_get_width (widget);
-  double height = gtk_widget_get_height (widget);
-  float length, progress;
-  GskStroke *stroke;
-  guint i;
-
-  if (self->path == NULL)
-    return;
-
-  gtk_snapshot_save (snapshot);
-
-  stroke = gsk_stroke_new (2.0);
-  gtk_snapshot_push_stroke (snapshot, self->path, stroke);
-  gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 0, 0, 0, 1 }, &GRAPHENE_RECT_INIT (0, 0, width, height));
-  gtk_snapshot_pop (snapshot);
-  gsk_stroke_free (stroke);
-
-  length = gsk_path_measure_get_length (self->measure);
-  progress = 25.f * gdk_frame_clock_get_frame_time (gtk_widget_get_frame_clock (widget)) / G_USEC_PER_SEC;
-
-  stroke = gsk_stroke_new (1.0);
-  for (i = 0; i < self->n_points; i++)
-    {
-      GskPathPoint point;
-      graphene_point_t position;
-      graphene_vec2_t tangent;
-      GdkRGBA color;
-      float distance;
-
-      distance = i * length / self->n_points;
-      distance = fmod (distance + progress, length);
-
-      gsk_path_measure_get_point (self->measure, distance, &point);
-      gsk_path_point_get_position (self->path, &point, &position);
-      gsk_path_point_get_tangent (self->path, &point, GSK_PATH_START, &tangent);
-      rgba_init_from_hsla (&color, 360.f * i / self->n_points, 1, 0.5, 1);
-
-      gtk_snapshot_save (snapshot);
-      gtk_snapshot_translate (snapshot, &position);
-      gtk_snapshot_rotate (snapshot, 180 / G_PI * atan2 (graphene_vec2_get_y (&tangent), graphene_vec2_get_x (&tangent)));
-      gtk_snapshot_push_fill (snapshot, self->arrow_path, GSK_FILL_RULE_EVEN_ODD);
-      gtk_snapshot_append_color (snapshot, &color, &GRAPHENE_RECT_INIT (-1000, -1000, 2000, 2000));
-      gtk_snapshot_pop (snapshot);
-      gtk_snapshot_push_stroke (snapshot, self->arrow_path, stroke);
-      gtk_snapshot_append_color (snapshot, &(GdkRGBA) { 0, 0, 0, 1 }, &GRAPHENE_RECT_INIT (-1000, -1000, 2000, 2000));
-      gtk_snapshot_pop (snapshot);
-      gtk_snapshot_restore (snapshot);
-    }
-
-  gsk_stroke_free (stroke);
-  gtk_snapshot_restore (snapshot);
-}
-
-static void
-gtk_path_walk_set_n_points (GtkPathWalk *self,
-                            gsize        n_points)
-{
-  if (self->n_points == n_points)
-    return;
-
-  self->n_points = n_points;
-
-  gtk_widget_queue_draw (GTK_WIDGET (self));
-
-  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_N_POINTS]);
-}
-
-static void
-gtk_path_walk_set_path (GtkPathWalk *self,
-                        GskPath     *path)
-{
-  if (self->path == path)
-    return;
-
-  g_clear_pointer (&self->path, gsk_path_unref);
-  g_clear_pointer (&self->measure, gsk_path_measure_unref);
-  if (path)
-    {
-      self->path = gsk_path_ref (path);
-      self->measure = gsk_path_measure_new (self->path);
-    }
-
-  gtk_widget_queue_draw (GTK_WIDGET (self));
-
-  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_PATH]);
-}
-
-static void
-gtk_path_walk_set_property (GObject      *object,
-                            guint         prop_id,
-                            const GValue *value,
-                            GParamSpec   *pspec)
-
-{
-  GtkPathWalk *self = GTK_PATH_WALK (object);
-
-  switch (prop_id)
-    {
-    case PROP_N_POINTS:
-      gtk_path_walk_set_n_points (self, g_value_get_uint (value));
-      break;
-
-    case PROP_PATH:
-      gtk_path_walk_set_path (self, g_value_get_boxed (value));
-      break;
-
-    default:
-      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
-      break;
-    }
-}
-
-static void
-gtk_path_walk_get_property (GObject    *object,
-                            guint       prop_id,
-                            GValue     *value,
-                            GParamSpec *pspec)
-{
-  GtkPathWalk *self = GTK_PATH_WALK (object);
-
-  switch (prop_id)
-    {
-    case PROP_N_POINTS:
-      g_value_set_uint (value, self->n_points);
-      break;
-
-    case PROP_PATH:
-      g_value_set_boxed (value, self->path);
-      break;
-
-    default:
-      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
-      break;
-    }
-}
-
-static void
-gtk_path_walk_dispose (GObject *object)
-{
-  GtkPathWalk *self = GTK_PATH_WALK (object);
-
-  g_clear_pointer (&self->path, gsk_path_unref);
-  g_clear_pointer (&self->measure, gsk_path_measure_unref);
-  g_clear_pointer (&self->arrow_path, gsk_path_unref);
-
-  G_OBJECT_CLASS (gtk_path_walk_parent_class)->dispose (object);
-}
-
-static void
-gtk_path_walk_class_init (GtkPathWalkClass *klass)
-{
-  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
-  GObjectClass *object_class = G_OBJECT_CLASS (klass);
-
-  object_class->dispose = gtk_path_walk_dispose;
-  object_class->set_property = gtk_path_walk_set_property;
-  object_class->get_property = gtk_path_walk_get_property;
-
-  widget_class->snapshot = gtk_path_walk_snapshot;
-
-  properties[PROP_N_POINTS] =
-    g_param_spec_uint ("n-points",
-                       NULL, NULL,
-                       1, G_MAXUINT,
-                       500,
-                       G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
-
-  properties[PROP_PATH] =
-    g_param_spec_boxed ("path",
-                        NULL, NULL,
-                        GSK_TYPE_PATH,
-                        G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
-
-  g_object_class_install_properties (object_class, N_PROPS, properties);
-}
-
-static gboolean
-tick_tick_tick (GtkWidget     *self,
-                GdkFrameClock *frame_clock,
-                gpointer       unused)
-{
-  gtk_widget_queue_draw (GTK_WIDGET (self));
-
-  return G_SOURCE_CONTINUE;
-}
-
-static void
-gtk_path_walk_init (GtkPathWalk *self)
-{
-  self->path = gsk_path_parse (path_world);
-  self->measure = gsk_path_measure_new (self->path);
-  self->arrow_path = gsk_path_parse ("M 5 0 L 0 -5. 0 -2, -5 -2, -5 2, 0 2, 0 5 Z");
-  self->n_points = 500;
-  gtk_widget_add_tick_callback (GTK_WIDGET (self), tick_tick_tick, NULL, NULL);
-}
-
-GtkWidget *
-gtk_path_walk_new (void)
-{
-  GtkPathWalk *self;
-
-  self = g_object_new (GTK_TYPE_PATH_WALK, NULL);
-
-  return GTK_WIDGET (self);
-}
-
-GtkWidget *
-do_path_walk (GtkWidget *do_widget)
-{
-  static GtkWidget *window = NULL;
-
-  if (!window)
-    {
-      GtkBuilder *builder;
-
-      g_type_ensure (GTK_TYPE_PATH_WALK);
-
-      builder = gtk_builder_new_from_resource ("/path_walk/path_walk.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_walk.ui

@@ -1,36 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<interface>
-  <object class="GtkWindow" id="window">
-    <property name="title" translatable="yes">Animation 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="GtkPathWalk" id="view">
-            <property name="hexpand">true</property>
-            <property name="vexpand">true</property>
-          </object>
-        </child>
-      </object>
-    </child>
-  </object>
-</interface>

gsk/gskcontourprivate.h

@@ -95,5 +95,10 @@ void                    gsk_contour_get_point                   (const GskContou
 float                   gsk_contour_get_distance                (const GskContour       *self,
                                                                  GskRealPathPoint       *point,
                                                                  gpointer                measure_data);
+gboolean                gsk_contour_dash                        (const GskContour       *contour,
+                                                                 GskStroke              *stroke,
+                                                                 float                   tolerance,
+                                                                 GskPathForeachFunc      func,
+                                                                 gpointer                user_data);
 
 G_END_DECLS

gsk/gskpath.h

@@ -131,6 +131,13 @@ gboolean                gsk_path_foreach                        (GskPath
                                                                  GskPathForeachFunc      func,
                                                                  gpointer                user_data);
 
+GDK_AVAILABLE_IN_4_14
+gboolean                gsk_path_dash                           (GskPath                *self,
+                                                                 GskStroke              *stroke,
+                                                                 float                   tolerance,
+                                                                 GskPathForeachFunc      func,
+                                                                 gpointer                user_data);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GskPath, gsk_path_unref)
 
 G_END_DECLS

gsk/gskpathdash.c

@@ -0,0 +1,304 @@
+/*
+ * 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 "gskcontourprivate.h"
+#include "gskcurveprivate.h"
+#include "gskpathprivate.h"
+#include "gskstrokeprivate.h"
+
+typedef struct
+{
+  float offset;                 /* how much of the current dash we've spent */
+  gsize dash_index;             /* goes from 0 to n_dash * 2, so we don't have to care about on/off
+                                   for uneven dashes */
+  gboolean on;                  /* If we're currently dashing or not */
+  gboolean may_close;           /* TRUE if we haven't turned the dash off in this contour */
+  gboolean needs_move_to;       /* If we have emitted the initial move_to() yet */
+  enum {
+    NORMAL, /* no special behavior required */
+    SKIP,   /* skip the next dash */
+    ONLY,   /* only do the first dash */
+    DONE    /* done with the first dash */
+  } first_dash_behavior;        /* How to handle the first dash in the loop. We loop closed contours
+                                   twice to make sure the first dash and the last dash can get joined */
+
+  GskCurve curve;               /* Curve we are currently processing */
+
+  float collect_start;          /* We're collecting multiple line segments when decomposing. */
+  float collect_length;         /* No need to emit a curve for every line segment when the dash is long enough. */
+
+  /* from the stroke */
+  float *dash;
+  gsize n_dash;
+  float dash_length;
+  float dash_offset;
+
+  float tolerance;
+  GskPathForeachFunc func;
+  gpointer user_data;
+} GskPathDash;
+
+static void
+gsk_path_dash_setup (GskPathDash *self)
+{
+  self->offset = fmodf (self->dash_offset, 2 * self->dash_length);
+
+  self->dash_index = 0;
+  self->on = TRUE;
+  self->may_close = TRUE;
+  while (self->offset > self->dash[self->dash_index % self->n_dash])
+    {
+      self->offset -= self->dash[self->dash_index % self->n_dash];
+      self->dash_index++;
+      self->on = !self->on;
+    }
+  if (self->first_dash_behavior != ONLY)
+    self->needs_move_to = TRUE;
+}
+
+static gboolean
+gsk_path_dash_ensure_move_to (GskPathDash            *self,
+                              const graphene_point_t *pt)
+{
+  if (!self->needs_move_to)
+    return TRUE;
+
+  if (!self->func (GSK_PATH_MOVE, pt, 1, self->user_data))
+    return FALSE;
+
+  self->needs_move_to = FALSE;
+  return TRUE;
+}
+
+static gboolean
+gsk_path_dash_add_line_segment (const graphene_point_t *start,
+                                const graphene_point_t *end,
+                                float                   t_start,
+                                float                   t_end,
+                                GskCurveLineReason      reason,
+                                gpointer                user_data)
+{
+  GskPathDash *self = user_data;
+  float remaining, length, t_step;
+
+  length = graphene_point_distance (start, end, NULL, NULL);
+  if (self->collect_length)
+    {
+      t_start = self->collect_start;
+      length += self->collect_length;
+      self->collect_length = 0;
+    }
+
+  t_step = t_end - t_start;
+  remaining = length;
+
+  while (remaining)
+    {
+      float piece;
+
+      if (self->offset + remaining <= self->dash[self->dash_index % self->n_dash])
+        {
+          /* try collecting multiple line segments */
+          if (t_end < 1.0)
+            {
+              self->collect_start = t_start + t_step * (length - remaining) / length;
+              self->collect_length = remaining;
+              return TRUE;
+            }
+
+          piece = remaining;
+        }
+      else
+        piece = self->dash[self->dash_index % self->n_dash] - self->offset;
+
+      if (self->on)
+        {
+          if (self->first_dash_behavior != SKIP)
+            {
+              GskCurve segment;
+
+              if (piece)
+                {
+                  gsk_curve_segment (&self->curve,
+                                     t_start + t_step * (length - remaining) / length,
+                                     t_start + t_step * (length - (remaining - piece)) / length,
+                                     &segment);
+                  if (!gsk_path_dash_ensure_move_to (self, gsk_curve_get_start_point (&segment)))
+                    return FALSE;
+
+                  if (!gsk_pathop_foreach (gsk_curve_pathop (&segment), self->func, self->user_data))
+                    return FALSE;
+                }
+              else
+                {
+                  graphene_point_t p;
+
+                  gsk_curve_get_point (&self->curve, t_start + t_step * (length - remaining) / length, &p);
+                  if (!gsk_path_dash_ensure_move_to (self, &p))
+                    return FALSE;
+                }
+            }
+        }
+      else
+        {
+          self->may_close = FALSE;
+          if (self->first_dash_behavior == ONLY)
+            {
+              self->first_dash_behavior = DONE;
+              return FALSE;
+            }
+          self->first_dash_behavior = NORMAL;
+        }
+
+      if (self->offset + remaining <= self->dash[self->dash_index % self->n_dash])
+        {
+          self->offset += remaining;
+          remaining = 0;
+        }
+      else
+        {
+          remaining -= piece;
+          self->offset = 0;
+          self->dash_index++;
+          self->dash_index %= 2 * self->n_dash;
+          self->on = !self->on;
+          self->needs_move_to = TRUE;
+        }
+    }
+
+  return TRUE;
+}
+
+static gboolean
+gsk_path_dash_foreach (GskPathOperation        op,
+                       const graphene_point_t *pts,
+                       gsize                   n_pts,
+                       gpointer                user_data)
+{
+  GskPathDash *self = user_data;
+
+  switch (op)
+  {
+    case GSK_PATH_MOVE:
+      gsk_path_dash_setup (self);
+      break;
+
+    case GSK_PATH_CLOSE:
+      if (self->may_close)
+        {
+          if (graphene_point_equal (&pts[0], &pts[1]))
+            return self->func (GSK_PATH_CLOSE, pts, 2, self->user_data);
+        }
+      else
+        op = GSK_PATH_LINE;
+      G_GNUC_FALLTHROUGH;
+
+    case GSK_PATH_LINE:
+    case GSK_PATH_QUAD:
+    case GSK_PATH_CUBIC:
+      gsk_curve_init_foreach (&self->curve, op, pts, n_pts);
+      if (!gsk_curve_decompose (&self->curve, self->tolerance, gsk_path_dash_add_line_segment, self))
+        return FALSE;
+      break;
+
+    default:
+      g_assert_not_reached ();
+      break;
+  }
+
+  return TRUE;
+}
+
+gboolean
+gsk_contour_dash (const GskContour   *contour,
+                  GskStroke          *stroke,
+                  float               tolerance,
+                  GskPathForeachFunc  func,
+                  gpointer            user_data)
+{
+  GskPathDash self = {
+    .offset = 0,
+    .dash = stroke->dash,
+    .n_dash = stroke->n_dash,
+    .dash_length = stroke->dash_length,
+    .dash_offset = stroke->dash_offset,
+    .tolerance = tolerance,
+    .func = func,
+    .user_data = user_data
+  };
+  gboolean is_closed = gsk_contour_get_flags (contour) & GSK_PATH_CLOSED ? TRUE : FALSE;
+
+  self.first_dash_behavior = is_closed ? SKIP : NORMAL;
+  if (!gsk_contour_foreach (contour, tolerance, gsk_path_dash_foreach, &self))
+    return FALSE;
+
+  if (is_closed)
+    {
+      if (self.first_dash_behavior == NORMAL)
+        self.first_dash_behavior = ONLY;
+      else
+        self.first_dash_behavior = NORMAL;
+      self.needs_move_to = !self.on;
+      if (!gsk_contour_foreach (contour, tolerance, gsk_path_dash_foreach, &self) &&
+          self.first_dash_behavior != DONE)
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+/**
+ * gsk_path_dash:
+ * @self: the `GskPath` to dash
+ * @stroke: the stroke containing the dash parameters
+ * @tolerance: tolerance to use while dashing
+ * @func: (scope call) (closure user_data): the function to call for operations
+ * @user_data: (nullable): user data passed to @func
+ *
+ * Calls @func for every operation of the path that is the result
+ * of dashing @self with the dash pattern from @stroke.
+ *
+ * Returns: `FALSE` if @func returned FALSE`, `TRUE` otherwise.
+ *
+ * Since: 4.14
+ */
+gboolean
+gsk_path_dash (GskPath            *self,
+               GskStroke          *stroke,
+               float               tolerance,
+               GskPathForeachFunc  func,
+               gpointer            user_data)
+{
+  gsize i;
+
+  /* Dashing disabled, no need to do any work */
+  if (stroke->dash_length <= 0)
+    return gsk_path_foreach (self, -1, func, user_data);
+
+  for (i = 0; i < gsk_path_get_n_contours (self); i++)
+    {
+      if (!gsk_contour_dash (gsk_path_get_contour (self, i), stroke, tolerance, func, user_data))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+

gsk/meson.build

@@ -27,6 +27,7 @@ gsk_public_sources = files([
   'gskdiff.c',
   'gskglshader.c',
   'gskpath.c',
+  'gskpathdash.c',
   'gskpathbuilder.c',
   'gskpathmeasure.c',
   'gskpathpoint.c',

testsuite/gsk/dash.c

@@ -0,0 +1,186 @@
+/*
+ * 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 gboolean
+build_path (GskPathOperation        op,
+            const graphene_point_t *pts,
+            gsize                   n_pts,
+            gpointer                user_data)
+{
+  GskPathBuilder *builder = user_data;
+
+  switch (op)
+  {
+    case GSK_PATH_MOVE:
+      gsk_path_builder_move_to (builder, pts[0].x, pts[0].y);
+      break;
+
+    case GSK_PATH_CLOSE:
+      gsk_path_builder_close (builder);
+      break;
+
+    case GSK_PATH_LINE:
+      gsk_path_builder_line_to (builder, pts[1].x, pts[1].y);
+      break;
+
+    case GSK_PATH_QUAD:
+      gsk_path_builder_quad_to (builder, pts[1].x, pts[1].y, pts[2].x, pts[2].y);
+      break;
+
+    case GSK_PATH_CUBIC:
+      gsk_path_builder_cubic_to (builder, pts[1].x, pts[1].y, pts[2].x, pts[2].y, pts[3].x, pts[3].y);
+      break;
+
+    default:
+      g_assert_not_reached ();
+      break;
+  }
+
+  return TRUE;
+}
+
+static void
+test_simple (void)
+{
+  const struct {
+    const char *test;
+    float dash[4];
+    gsize n_dash;
+    float dash_offset;
+    const char *result;
+  } tests[] = {
+    /* a line with a dash of a quarter its size, very simple test */
+    {
+      "M 0 0 L 20 0",
+      { 5, }, 1, 0.f,
+      "M 0 0 L 5 0 M 10 0 L 15 0",
+    },
+    /* a square with a dash of half its size, another simple test */
+    {
+      "M 0 0 h 10 v 10 h -10 z",
+      { 5, }, 1, 0.f,
+      "M 10 0 L 10 5 M 10 10 L 5 10 M 0 10 L 0 5 M 0 0 L 5 0"
+    },
+    /* a square smaller than the dash, make sure it closes */
+    {
+      "M 0 0 h 10 v 10 h -10 z",
+      { 50, }, 1, 0.f,
+      "M 0 0 L 10 0 L 10 10 L 0 10 Z"
+    },
+    /* a square exactly the dash's size, make sure it still closes */
+    {
+      "M 0 0 h 10 v 10 h -10 z",
+      { 40, }, 1, 0.f,
+      "M 0 0 L 10 0 L 10 10 L 0 10 Z"
+    },
+    /* a dash with offset */
+    {
+      "M 0 0 h 10 v 10 h -10 z",
+      { 5, }, 1, 2.5f,
+      "M 7.5 0 L 10 0 L 10 2.5 M 10 7.5 L 10 10 L 7.5 10 M 2.5 10 L 0 10 L 0 7.5 M 0 2.5 L 0 0 L 2.5 0"
+    },
+    /* a dash with offset, but this time the rect isn't closed */
+    {
+      "M 0 0 L 10 0 L 10 10 L 0 10 L 0 0",
+      { 5, }, 1, 2.5f,
+      "M 0 0 L 2.5 0 M 7.5 0 L 10 0 L 10 2.5 M 10 7.5 L 10 10 L 7.5 10 M 2.5 10 L 0 10 L 0 7.5 M 0 2.5 L 0 0"
+    },
+    /* a dash with offset into an empty dash */
+    {
+      "M 0 0 h 10 v 10 h -10 z",
+      { 5, }, 1, 7.5f,
+      "M 2.5 0 L 7.5 0 M 10 2.5 L 10 7.5 M 7.5 10 L 2.5 10 M 0 7.5 L 0 2.5"
+    },
+    /* a dash with offset where the whole rectangle fits into one element - make sure it closes */
+    {
+      "M 0 0 h 10 v 10 h -10 z",
+      { 1, 1, 100 }, 3, 3.f,
+      "M 0 0 L 10 0 L 10 10 L 0 10 Z"
+    },
+    /* a dash with 0-length elements, aka dotting */
+    {
+      "M 0 0 h 10 v 10 h -10 z",
+      { 0, 5 }, 2, 0.f,
+      "M 5 0 M 10 0 M 10 5 M 10 10 M 5 10 M 0 10 M 0 5 M 0 0"
+    },
+#if 0
+    /* a dash of a circle */
+    {
+      "M 10 5 O 10 10, 5 10, 0.70710676908493042 O 0 10, 0 5, 0.70710676908493042 O 0 0, 5 0, 0.70710676908493042 O 10 0, 10 5, 0.70710676908493042 Z",
+      { 32, }, 1, 0.f,
+      "M 10 5 O 10 10, 5 10, 0.70710676908493042 O 0 10, 0 5, 0.70710676908493042 O 0 0, 5 0, 0.70710676908493042 O 10 0, 10 5, 0.70710676908493042 Z",
+    },
+#endif
+    /* a dash with offset and 2 contours */
+    {
+      "M 10 10 h 10 v 10 h -10 z M 20 20 h 10 v 10 h -10 z",
+      { 5, }, 1, 2.5f,
+      "M 17.5 10 L 20 10 L 20 12.5 M 20 17.5 L 20 20 L 17.5 20 M 12.5 20 L 10 20 L 10 17.5 M 10 12.5 L 10 10 L 12.5 10 "
+      "M 27.5 20 L 30 20 L 30 22.5 M 30 27.5 L 30 30 L 27.5 30 M 22.5 30 L 20 30 L 20 27.5 M 20 22.5 L 20 20 L 22.5 20"
+    },
+  };
+  GskPath *path, *result;
+  GskPathBuilder *builder;
+  GskStroke *stroke;
+  char *s;
+
+  for (gsize i = 0; i < G_N_ELEMENTS(tests); i++)
+    {
+      if (g_test_verbose ())
+        g_test_message ("%lu: %s", i, tests[i].test);
+
+      stroke = gsk_stroke_new (1);
+      gsk_stroke_set_dash (stroke, tests[i].dash, tests[i].n_dash);
+      gsk_stroke_set_dash_offset (stroke, tests[i].dash_offset);
+
+      path = gsk_path_parse (tests[i].test);
+      g_assert_nonnull (path);
+#if 0
+      /* This assumes that we have rectangle contours */
+      s = gsk_path_to_string (path);
+      g_assert_cmpstr (s, ==, tests[i].test);
+      g_free (s);
+#endif
+
+      builder = gsk_path_builder_new ();
+      gsk_path_dash (path, stroke, 0.5, build_path, builder);
+      result = gsk_path_builder_free_to_path (builder);
+
+      s = gsk_path_to_string (result);
+      g_assert_cmpstr (s, ==, tests[i].result);
+      g_free (s);
+
+      gsk_path_unref (result);
+      gsk_stroke_free (stroke);
+      gsk_path_unref (path);
+    }
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  gtk_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/dash/simple", test_simple);
+
+  return g_test_run ();
+}

testsuite/gsk/meson.build

@@ -373,6 +373,7 @@ tests = [
   ['path-special-cases'],
   ['measure'],
   ['measure-special-cases'],
+  ['dash'],
 ]
 
 test_cargs = []