[gtk/line-spacing: 2/2] textview: Add a line-spacing property

[Matthias Clasen <matthiasc src gnome org>]

commit 9fedf63c9c41393e7f5b77af1329a731c960fb8b
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Aug 5 22:22:50 2021 -0400

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

 gtk/gtktextattributes.c |  4 +++
 gtk/gtktextattributes.h |  2 ++
 gtk/gtktexttag.c        | 30 +++++++++++++++++
 gtk/gtktexttagprivate.h |  1 +
 gtk/gtktextview.c       | 87 ++++++++++++++++++++++++++++++++++++++++++++++++-
 gtk/gtktextview.h       |  6 ++++
 6 files changed, 129 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtktextattributes.c b/gtk/gtktextattributes.c
index 738caa6bc1..becbad4202 100644
--- a/gtk/gtktextattributes.c
+++ b/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 ||
diff --git a/gtk/gtktextattributes.h b/gtk/gtktextattributes.h
index 05f7750247..479b961b3a 100644
--- a/gtk/gtktextattributes.h
+++ b/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;
diff --git a/gtk/gtktexttag.c b/gtk/gtktexttag.c
index fdf17a6efc..273f8c0c78 100644
--- a/gtk/gtktexttag.c
+++ b/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);
diff --git a/gtk/gtktexttagprivate.h b/gtk/gtktexttagprivate.h
index b0bd079532..f78eba76f0 100644
--- a/gtk/gtktexttagprivate.h
+++ b/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;
diff --git a/gtk/gtktextview.c b/gtk/gtktextview.c
index d6673bed62..768ab2245e 100644
--- a/gtk/gtktextview.c
+++ b/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;
diff --git a/gtk/gtktextview.h b/gtk/gtktextview.h
index 325077a871..496ca09a2b 100644
--- a/gtk/gtktextview.h
+++ b/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__ */