[pango/pango2: 96/201] layout: Add spacing back

[Matthias Clasen <matthiasc src gnome org>]

commit 3566ba2ca9a5f7d7e7ab8b8f79d7bc5b8e5da2f2
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jan 23 23:06:05 2022 -0500

    layout: Add spacing back
    
    Implement the PangoLayout:spacing property by
    translating it into a line-spacing attribute.

 pango/pango-attributes.c |  4 +--
 pango/pango-layout.c     | 81 +++++++++++++++++++++++++++++++++++++++++++++++-
 pango/pango-layout.h     |  7 +++++
 pango/serializer.c       |  3 ++
 4 files changed, 92 insertions(+), 3 deletions(-)
---
diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index 055c3948..a8d20697 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -1557,8 +1557,8 @@ pango_attr_line_height_new_absolute (int height)
  * if not overridden by line spacing attributes.
  *
  * This affects the values returned by
- * [method@Pango.LayoutLine.get_extents],
- * [method@Pango.LayoutIter.get_line_extents].
+ * [method Pango Line.get_extents],
+ * [method@Pango.LineIter.get_line_extents].
  */
 PangoAttribute *
 pango_attr_line_spacing_new (int spacing)
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index 05247339..6dacf398 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -68,6 +68,7 @@ struct _PangoLayout
   PangoAttrList *attrs;
   PangoFontDescription *font_desc;
   float line_height;
+  int spacing;
   int width;
   int height;
   PangoTabArray *tabs;
@@ -95,6 +96,7 @@ enum
   PROP_ATTRIBUTES,
   PROP_FONT_DESCRIPTION,
   PROP_LINE_HEIGHT,
+  PROP_SPACING,
   PROP_WIDTH,
   PROP_HEIGHT,
   PROP_TABS,
@@ -123,6 +125,7 @@ pango_layout_init (PangoLayout *layout)
   layout->alignment = PANGO_ALIGN_NATURAL;
   layout->ellipsize = PANGO_ELLIPSIZE_NONE;
   layout->line_height = 0.0;
+  layout->spacing = 0;
   layout->auto_dir = TRUE;
   layout->text = g_strdup ("");
   layout->length = 0;
@@ -174,6 +177,10 @@ pango_layout_set_property (GObject      *object,
       pango_layout_set_line_height (layout, g_value_get_float (value));
       break;
 
+    case PROP_SPACING:
+      pango_layout_set_spacing (layout, g_value_get_int (value));
+      break;
+
     case PROP_WIDTH:
       pango_layout_set_width (layout, g_value_get_int (value));
       break;
@@ -246,6 +253,10 @@ pango_layout_get_property (GObject      *object,
       g_value_set_float (value, layout->line_height);
       break;
 
+    case PROP_SPACING:
+      g_value_set_int (value, layout->spacing);
+      break;
+
     case PROP_WIDTH:
       g_value_set_int (value, layout->width);
       break;
@@ -353,6 +364,19 @@ pango_layout_class_init (PangoLayoutClass *class)
                                                 0., G_MAXFLOAT, 0.,
                                                 G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
 
+  /**
+   * PangoLayout:spacing: (attributes org.gtk.Property.get=pango_layout_get_spacing 
org.gtk.Property.set=pango_layout_set_spacing)
+   *
+   * Spacing to add between the lines of the `PangoLayout`.
+   *
+   * The spacing is specified in Pango units.
+   *
+   * The default value is 0.
+   */
+  props[PROP_SPACING] = g_param_spec_int ("spacing", "spacing", "spacing",
+                                        0, G_MAXINT, 0,
+                                        G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
   /**
    * PangoLayout:width: (attributes org.gtk.Property.get=pango_layout_get_width 
org.gtk.Property.set=pango_layout_set_width)
    *
@@ -561,6 +585,13 @@ get_effective_attributes (PangoLayout *layout)
                                      pango_attr_line_height_new (layout->line_height));
     }
 
+  if (layout->spacing != 0)
+    {
+      attrs = ensure_attrs (layout, attrs);
+      pango_attr_list_insert_before (attrs,
+                                     pango_attr_line_spacing_new (layout->spacing));
+    }
+
   if (layout->single_paragraph)
     {
       attrs = ensure_attrs (layout, attrs);
@@ -803,6 +834,7 @@ pango_layout_copy (PangoLayout *layout)
   if (layout->font_desc)
     copy->font_desc = pango_font_description_copy (layout->font_desc);
   copy->line_height = layout->line_height;
+  copy->spacing = layout->spacing;
   copy->width = layout->width;
   copy->height = layout->height;
   if (layout->tabs)
@@ -1067,11 +1099,58 @@ pango_layout_get_line_height (PangoLayout *layout)
   return layout->line_height;
 }
 
+/**
+ * pango_layout_set_spacing:
+ * @layout: a `PangoLayout`
+ * @spacing: the amount of spacing, in Pango units
+ *
+ * Sets the amount of spacing between the lines of the layout.
+ *
+ * When placing lines with spacing, Pango arranges things so that
+ *
+ *     line2.top = line1.bottom + spacing
+ *
+ * The default value is 0.
+ *
+ * Spacing only takes effect if the line height is not
+ * overridden via [method@Pango.Layout.set_line_height].
+ */
+void
+pango_layout_set_spacing (PangoLayout *layout,
+                          int          spacing)
+{
+  g_return_if_fail (PANGO_IS_LAYOUT (layout));
+
+  if (layout->spacing == spacing)
+    return;
+
+  layout->spacing = spacing;
+
+  g_object_notify_by_pspec (G_OBJECT (layout), props[PROP_SPACING]);
+  layout_changed (layout);
+}
+
+/**
+ * pango_layout_get_spacing:
+ * @layout: a `PangoLayout`
+ *
+ * Gets the amount of spacing between the lines of the layout.
+ *
+ * Return value: the spacing in Pango units
+ */
+int
+pango_layout_get_spacing (PangoLayout *layout)
+{
+  g_return_val_if_fail (PANGO_IS_LAYOUT (layout), 0);
+
+  return layout->spacing;
+}
+
 /**
  * pango_layout_set_width:
  * @layout: a `PangoLayout`.
  * @width: the desired width in Pango units, or -1 to indicate that no
- *   wrapping or ellipsization should be performed.
+ *   wrapping or ellipsization should be performed
  *
  * Sets the width to which the lines of the layout should
  * be wrapped or ellipsized.
diff --git a/pango/pango-layout.h b/pango/pango-layout.h
index 1a30b68c..95a2f302 100644
--- a/pango/pango-layout.h
+++ b/pango/pango-layout.h
@@ -70,6 +70,13 @@ PANGO_AVAILABLE_IN_ALL
 float                   pango_layout_get_line_height
                                                     (PangoLayout                  *layout);
 
+PANGO_AVAILABLE_IN_ALL
+void                    pango_layout_set_spacing    (PangoLayout                  *layout,
+                                                     int                           spacing);
+
+PANGO_AVAILABLE_IN_ALL
+int                     pango_layout_get_spacing    (PangoLayout                  *layout);
+
 PANGO_AVAILABLE_IN_ALL
 void                    pango_layout_set_width      (PangoLayout                  *layout,
                                                      int                           width);
diff --git a/pango/serializer.c b/pango/serializer.c
index ba387d5d..92b05063 100644
--- a/pango/serializer.c
+++ b/pango/serializer.c
@@ -828,6 +828,9 @@ layout_to_json (GtkJsonPrinter            *printer,
   if (pango_layout_get_line_height (layout) != 0.)
     gtk_json_printer_add_number (printer, "line-height", pango_layout_get_line_height (layout));
 
+  if (pango_layout_get_spacing (layout) != 0)
+    gtk_json_printer_add_integer (printer, "spacing", pango_layout_get_spacing (layout));
+
   if (flags & PANGO_LAYOUT_SERIALIZE_OUTPUT)
     {
       const PangoLogAttr *log_attrs;