textview: Add a line-spacing property

This exposes a line-spacing property that corresponds
to the PangoLayout property of the same name.

gtk/gtklabel.c

@@ -264,6 +264,7 @@ struct _GtkLabel
 
   float    xalign;
   float    yalign;
+  float    line_spacing;
 
   guint    mnemonics_visible  : 1;
   guint    jtype              : 2;
@@ -391,6 +392,7 @@ enum {
   PROP_XALIGN,
   PROP_YALIGN,
   PROP_EXTRA_MENU,
+  PROP_LINE_SPACING,
   NUM_PROPERTIES
 };
 
@@ -514,6 +516,9 @@ gtk_label_set_property (GObject      *object,
     case PROP_EXTRA_MENU:
       gtk_label_set_extra_menu (self, g_value_get_object (value));
       break;
+    case PROP_LINE_SPACING:
+      gtk_label_set_line_spacing (self, g_value_get_float (value));
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -584,6 +589,9 @@ gtk_label_get_property (GObject     *object,
     case PROP_EXTRA_MENU:
       g_value_set_object (value, gtk_label_get_extra_menu (self));
       break;
+    case PROP_LINE_SPACING:
+      g_value_set_float (value, gtk_label_get_line_spacing (self));
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -600,6 +608,7 @@ gtk_label_init (GtkLabel *self)
 
   self->xalign = 0.5;
   self->yalign = 0.5;
+  self->line_spacing = 0.0;
 
   self->jtype = GTK_JUSTIFY_LEFT;
   self->wrap = FALSE;
@@ -2457,6 +2466,20 @@ gtk_label_class_init (GtkLabelClass *class)
                           G_TYPE_MENU_MODEL,
                           GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY);
 
+  /**
+   * GtkLabel:line-spacing: (attributes org.gtk.Property.get=gtk_label_get_line_spacing org.gtk.Property.set=gtk_label_set_line_spacing)
+   *
+   * The line spacing factor that is applied between consecutive lines.
+   *
+   * Since: 4.4
+   */
+  label_props[PROP_LINE_SPACING] =
+      g_param_spec_float ("line-spacing",
+                          P_("Linespacing"),
+                          P_("The factor for spacing between lines"),
+                          0.0, 10.0, 0.0,
+                          GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY);
+
   g_object_class_install_properties (gobject_class, NUM_PROPERTIES, label_props);
 
   /**
@@ -4005,6 +4028,7 @@ gtk_label_ensure_layout (GtkLabel *self)
   pango_layout_set_alignment (self->layout, align);
   pango_layout_set_ellipsize (self->layout, self->ellipsize);
   pango_layout_set_wrap (self->layout, self->wrap_mode);
+  pango_layout_set_line_spacing (self->layout, self->line_spacing);
   pango_layout_set_single_paragraph_mode (self->layout, self->single_line_mode);
   if (self->lines > 0)
     pango_layout_set_height (self->layout, - self->lines);
@@ -5778,3 +5802,56 @@ gtk_label_get_extra_menu (GtkLabel *self)
 
   return self->extra_menu;
 }
+
+/**
+ * gtk_label_set_line_spacing: (attributes org.gtk.Method.set_property=line-spacing)
+ * @self: a `GtkLabel`
+ * @factor: the new line spacing factor
+ *
+ * Sets a factor for line spacing.
+ *
+ * Typical values are: 0, 1, 1.5, 2. The default values is 0.
+ *
+ * If @factor is non-zero, lines are placed so that
+ *
+ *     baseline2 = baseline1 + factor * height2
+ *
+ * where height2 is the line height of the second line
+ * (as determined by the font(s)).
+ *
+ * If @factor is zero (the default), no spacing is applied.
+ *
+ * Since: 4.4
+ */
+void
+gtk_label_set_line_spacing (GtkLabel *self,
+                            float     factor)
+{
+  g_return_if_fail (GTK_IS_LABEL (self));
+
+  if (self->line_spacing == factor)
+    return;
+
+  self->line_spacing = factor;
+
+  gtk_label_clear_layout (self);
+  gtk_widget_queue_resize (GTK_WIDGET (self));
+
+  g_object_notify_by_pspec (G_OBJECT (self), label_props[PROP_LINE_SPACING]);
+}
+
+/**
+ * gtk_label_get_line_spacing: (attributes org.gtk.Method.get_property=line-spacing)
+ * @self: a `GtkLabel`
+ *
+ * Gets the line spacing factor of @self.
+ *
+ * Since: 4.4
+ */
+float
+gtk_label_get_line_spacing (GtkLabel *self)
+{
+  g_return_val_if_fail (GTK_IS_LABEL (self), 0.0);
+
+  return self->line_spacing;
+}

gtk/gtklabel.h

@@ -172,6 +172,12 @@ void         gtk_label_set_extra_menu (GtkLabel   *self,
 GDK_AVAILABLE_IN_ALL
 GMenuModel * gtk_label_get_extra_menu (GtkLabel   *self);
 
+GDK_AVAILABLE_IN_4_4
+void         gtk_label_set_line_spacing (GtkLabel *self,
+                                         float     factor);
+
+GDK_AVAILABLE_IN_4_4
+float        gtk_label_get_line_spacing (GtkLabel *self);
 
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GtkLabel, g_object_unref)
 

gtk/gtktextattributes.c

@@ -387,6 +387,9 @@ _gtk_text_attributes_fill_from_tags (GtkTextAttributes *dest,
       if (tag->priv->pixels_inside_wrap_set)
         dest->pixels_inside_wrap = vals->pixels_inside_wrap;
 
+      if (tag->priv->line_spacing_set)
+        dest->line_spacing = vals->line_spacing;
+
       if (tag->priv->tabs_set)
         {
           if (dest->tabs)
@@ -457,6 +460,7 @@ _gtk_text_tag_affects_size (GtkTextTag *tag)
     priv->pixels_above_lines_set ||
     priv->pixels_below_lines_set ||
     priv->pixels_inside_wrap_set ||
+    priv->line_spacing_set ||
     priv->tabs_set ||
     priv->underline_set ||
     priv->overline_set ||

gtk/gtktextattributes.h

@@ -147,6 +147,8 @@ struct _GtkTextAttributes
   int pixels_below_lines;
   int pixels_inside_wrap;
 
+  float line_spacing;
+
   int letter_spacing;
 
   guint invisible : 1;

gtk/gtktexttag.c

@@ -107,6 +107,7 @@ enum {
   PROP_PIXELS_ABOVE_LINES,
   PROP_PIXELS_BELOW_LINES,
   PROP_PIXELS_INSIDE_WRAP,
+  PROP_LINE_SPACING,
   PROP_EDITABLE,
   PROP_WRAP_MODE,
   PROP_JUSTIFICATION,
@@ -150,6 +151,7 @@ enum {
   PROP_PIXELS_ABOVE_LINES_SET,
   PROP_PIXELS_BELOW_LINES_SET,
   PROP_PIXELS_INSIDE_WRAP_SET,
+  PROP_LINE_SPACING_SET,
   PROP_EDITABLE_SET,
   PROP_WRAP_MODE_SET,
   PROP_JUSTIFICATION_SET,
@@ -585,6 +587,8 @@ gtk_text_tag_class_init (GtkTextTagClass *klass)
    * GtkTextTag:pixels-inside-wrap:
    *
    * Pixels of blank space between wrapped lines in a paragraph.
+   *
+   * Ignored if line-spacing is set.
    */
   g_object_class_install_property (object_class,
                                    PROP_PIXELS_INSIDE_WRAP,
@@ -596,6 +600,21 @@ gtk_text_tag_class_init (GtkTextTagClass *klass)
                                                      0,
                                                      GTK_PARAM_READWRITE));
 
+  /**
+   * GtkTextag:line-spacing:
+   *
+   * The line spacing factor that is applied between consecutive lines.
+   *
+   * Since: 4.4
+   */
+  g_object_class_install_property (object_class,
+                                   PROP_LINE_SPACING,
+                                   g_param_spec_float ("line-spacing",
+                                                     P_("Linespacing"),
+                                                     P_("The factor for spacing between lines"),
+                                                     0.0, 10.0, 0.0,
+                                                     GTK_PARAM_READWRITE));
+
   /**
    * GtkTextTag:strikethrough:
    *
@@ -936,6 +955,10 @@ gtk_text_tag_class_init (GtkTextTagClass *klass)
                 P_("Pixels inside wrap set"),
                 P_("Whether this tag affects the number of pixels between wrapped lines"));
 
+  ADD_SET_PROP ("line-spacing-set", PROP_LINE_SPACING_SET,
+                P_("Linespacing set"),
+                P_("Whether this tag affects spacing between wrapped lines"));
+
   ADD_SET_PROP ("strikethrough-set", PROP_STRIKETHROUGH_SET,
                 P_("Strikethrough set"),
                 P_("Whether this tag affects strikethrough"));
@@ -1573,6 +1596,13 @@ gtk_text_tag_set_property (GObject      *object,
       size_changed = TRUE;
       break;
 
+    case PROP_LINE_SPACING:
+      priv->line_spacing_set = TRUE;
+      priv->values->line_spacing = g_value_get_float (value);
+      g_object_notify (object, "line-spacing-set");
+      size_changed = TRUE;
+      break;
+
     case PROP_EDITABLE:
       priv->editable_set = TRUE;
       priv->values->editable = g_value_get_boolean (value);

gtk/gtktexttagprivate.h

@@ -71,6 +71,7 @@ struct _GtkTextTagPrivate
   guint pixels_above_lines_set : 1;
   guint pixels_below_lines_set : 1;
   guint pixels_inside_wrap_set : 1;
+  guint line_spacing_set : 1;
   guint tabs_set : 1;
   guint underline_set : 1;
   guint overline_set : 1;

gtk/gtktextview.c

@@ -173,6 +173,8 @@ struct _GtkTextViewPrivate
   GtkWidget *selection_bubble;
   guint selection_bubble_timeout_id;
 
+  float line_spacing;
+
   GtkWidget *magnifier_popover;
   GtkWidget *magnifier;
 
@@ -359,7 +361,8 @@ enum
   PROP_INPUT_PURPOSE,
   PROP_INPUT_HINTS,
   PROP_MONOSPACE,
-  PROP_EXTRA_MENU
+  PROP_EXTRA_MENU,
+  PROP_LINE_SPACING
 };
 
 static GQuark quark_text_selection_data = 0;
@@ -1153,6 +1156,21 @@ gtk_text_view_class_init (GtkTextViewClass *klass)
                                                         G_TYPE_MENU_MODEL,
                                                         GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));
 
+  /**
+   * GtkTextView:line-spacing: (attributes org.gtk.Property.get=gtk_text_view_get_line_spacing org.gtk.Property.set=gtk_text_view_set_line_spacing)
+   *
+   * The line spacing factor that is applied between consecutive lines.
+   *
+   * Since: 4.4
+   */
+  g_object_class_install_property (gobject_class,
+                                   PROP_LINE_SPACING,
+                                   g_param_spec_float ("line-spacing",
+                                                       P_("Linespacing"),
+                                                       P_("The factor for spacing between lines"),
+                                                       0.0, 10.0, 0.0,
+                                                       GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));
+
    /* GtkScrollable interface */
    g_object_class_override_property (gobject_class, PROP_HADJUSTMENT,    "hadjustment");
    g_object_class_override_property (gobject_class, PROP_VADJUSTMENT,    "vadjustment");
@@ -3390,6 +3408,65 @@ gtk_text_view_get_pixels_inside_wrap (GtkTextView *text_view)
   return text_view->priv->pixels_inside_wrap;
 }
 
+/**
+ * gtk_text_view_set_line_spacing: (attributes org.gtk.Method.set_property=line-spacing)
+ * @self: a `GtkTextView`
+ * @factor: the new line spacing factor
+ *
+ * Sets the default factor for line spacing.
+ *
+ * Typical values are: 0, 1, 1.5, 2. The default values is 0.
+ *
+ * If @factor is non-zero, lines are placed so that
+ *
+ *     baseline2 = baseline1 + factor * height2
+ *
+ * where height2 is the line height of the second line
+ * (as determined by the font(s)).
+ *
+ * If @factor is zero (the default), the pixels-inside-wrap value
+ * is used.
+ *
+ * Since: 4.4
+ */
+void
+gtk_text_view_set_line_spacing (GtkTextView *text_view,
+                                float        line_spacing)
+{
+  GtkTextViewPrivate *priv = text_view->priv;
+
+  g_return_if_fail (GTK_IS_TEXT_VIEW (text_view));
+
+  if (priv->line_spacing == line_spacing)
+    return;
+
+  priv->line_spacing = line_spacing;
+
+  if (priv->layout && priv->layout->default_style)
+    {
+      priv->layout->default_style->line_spacing = line_spacing;
+      gtk_text_layout_default_style_changed (priv->layout);
+    }
+
+  g_object_notify (G_OBJECT (text_view), "line-spacing");
+}
+
+/**
+ * gtk_text_view_get_line_spacing: (attributes org.gtk.Method.get_property=line-spacing)
+ * @self: a `GtkTextView`
+ *
+ * Gets the default line spacing factor of @text_view.
+ *
+ * Since: 4.4
+ */
+float
+gtk_text_view_get_line_spacing (GtkTextView *text_view)
+{
+  g_return_val_if_fail (GTK_IS_TEXT_VIEW (text_view), 0.0);
+
+  return text_view->priv->line_spacing;
+}
+
 /**
  * gtk_text_view_set_justification: (attributes org.gtk.Method.set_property=justification)
  * @text_view: a `GtkTextView`
@@ -4105,6 +4182,10 @@ gtk_text_view_set_property (GObject         *object,
       gtk_text_view_set_extra_menu (text_view, g_value_get_object (value));
       break;
 
+    case PROP_LINE_SPACING:
+      gtk_text_view_set_line_spacing (text_view, g_value_get_float (value));
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -4225,6 +4306,10 @@ gtk_text_view_get_property (GObject         *object,
       g_value_set_object (value, gtk_text_view_get_extra_menu (text_view));
       break;
 
+    case PROP_LINE_SPACING:
+      g_value_set_float (value, gtk_text_view_get_line_spacing (text_view));
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;

gtk/gtktextview.h

@@ -432,6 +432,12 @@ PangoContext    *gtk_text_view_get_rtl_context        (GtkTextView      *text_vi
 GDK_AVAILABLE_IN_ALL
 PangoContext    *gtk_text_view_get_ltr_context        (GtkTextView      *text_view);
 
+GDK_AVAILABLE_IN_4_4
+void             gtk_text_view_set_line_spacing       (GtkTextView      *text_view,
+                                                       float             factor);
+GDK_AVAILABLE_IN_4_4
+float            gtk_text_view_get_line_spacing       (GtkTextView      *text_view);
+
 G_END_DECLS
 
 #endif /* __GTK_TEXT_VIEW_H__ */