libmetacity: support margins on titlebar title/buttons in GTK+ theme

GTK+ improved its CSS support, and the default theme started to
make use of it, so we must update our theming code accordingly.
Add support for margins where they make sense.

Adapted from:
https://git.gnome.org/browse/mutter/commit/?id=e0ffef06dd810ff5acb54605f05f95133541151b

2 files changed, 34 insertions, 3 deletions

diff --git a/libmetacity/meta-frame-layout.h b/libmetacity/meta-frame-layout.h
index a03d4aa7..3bff2034 100644
--- a/libmetacity/meta-frame-layout.h
+++ b/libmetacity/meta-frame-layout.h
@@ -66,6 +66,11 @@ struct _MetaFrameLayout
     /** Space between titlebar elements */
     guint titlebar_spacing;
 
+    /** Margin of title */
+    GtkBorder title_margin;
+    /** Margin of titlebar buttons */
+    GtkBorder button_margin;
+
     /** Min size of titlebar region */
     GtkRequisition titlebar_min_size;
     /** Min size of titlebar buttons */
diff --git a/libmetacity/meta-theme-gtk.c b/libmetacity/meta-theme-gtk.c
index fa756ee9..05d5b6a4 100644
--- a/libmetacity/meta-theme-gtk.c
+++ b/libmetacity/meta-theme-gtk.c
@@ -260,11 +260,18 @@ frame_layout_sync_with_style (MetaFrameLayout *layout,
   get_padding_and_border (style, &layout->gtk.titlebar_border);
   scale_border (&layout->gtk.titlebar_border, layout->title_scale);
 
+  style = style_info->styles[META_STYLE_ELEMENT_TITLE];
+  get_margin (style, &layout->gtk.title_margin);
+  scale_border (&layout->gtk.title_margin, layout->title_scale);
+
   style = style_info->styles[META_STYLE_ELEMENT_BUTTON];
   get_min_size (style, &layout->gtk.button_min_size);
   get_padding_and_border (style, &layout->button_border);
   scale_border (&layout->button_border, layout->title_scale);
 
+  get_margin (style, &layout->gtk.button_margin);
+  scale_border (&layout->gtk.button_margin, layout->title_scale);
+
   style = style_info->styles[META_STYLE_ELEMENT_IMAGE];
   get_min_size (style, &requisition);
   get_padding_and_border (style, &border);
@@ -275,6 +282,12 @@ frame_layout_sync_with_style (MetaFrameLayout *layout,
   layout->button_border.top += border.top;
   layout->button_border.bottom += border.bottom;
 
+  get_margin (style, &border);
+  layout->button_border.left += border.left;
+  layout->button_border.right += border.right;
+  layout->button_border.top += border.top;
+  layout->button_border.bottom += border.bottom;
+
   layout->gtk.button_min_size.width = MAX (layout->gtk.button_min_size.width,
                                            requisition.width);
   layout->gtk.button_min_size.height = MAX (layout->gtk.button_min_size.height,
@@ -306,9 +319,14 @@ meta_theme_gtk_get_frame_borders (MetaThemeImpl    *impl,
 
   if (!layout->has_title)
     text_height = 0;
+  else
+    text_height = layout->gtk.title_margin.top +
+                   text_height +
+                  layout->gtk.title_margin.bottom;
 
   buttons_height = MAX ((gint) layout->gtk.icon_size, layout->gtk.button_min_size.height) +
-                   layout->button_border.top + layout->button_border.bottom;
+                   layout->gtk.button_margin.top + layout->button_border.top +
+                   layout->gtk.button_margin.bottom + layout->button_border.bottom;
 
   content_height = MAX (buttons_height, text_height);
   content_height = MAX (content_height, layout->gtk.titlebar_min_size.height) +
@@ -578,11 +596,15 @@ meta_theme_gtk_calc_geometry (MetaThemeImpl          *impl,
 
       space_used_by_buttons = 0;
 
+      space_used_by_buttons += layout->gtk.button_margin.left /** scale*/ * n_left;
       space_used_by_buttons += button_width * n_left;
+      space_used_by_buttons += layout->gtk.button_margin.right /** scale*/ * n_left;
       space_used_by_buttons += (button_width * 0.75) * n_left_spacers;
       space_used_by_buttons += layout->gtk.titlebar_spacing * MAX (n_left - 1, 0);
 
+      space_used_by_buttons += layout->gtk.button_margin.left /** scale*/ * n_right;
       space_used_by_buttons += button_width * n_right;
+      space_used_by_buttons += layout->gtk.button_margin.right /** scale*/ * n_right;
       space_used_by_buttons += (button_width * 0.75) * n_right_spacers;
       space_used_by_buttons += layout->gtk.titlebar_spacing * MAX (n_right - 1, 0);
 
@@ -664,6 +686,8 @@ meta_theme_gtk_calc_geometry (MetaThemeImpl          *impl,
       if (x < 0) /* if we go negative, leave the buttons we don't get to as 0-width */
         break;
 
+      x -= layout->gtk.button_margin.right /** scale*/;
+
       rect = right_func_rects[i];
 
       rect->visible.x = x - button_width;
@@ -689,7 +713,7 @@ meta_theme_gtk_calc_geometry (MetaThemeImpl          *impl,
       else
         g_memmove (&(rect->clickable), &(rect->visible), sizeof(rect->clickable));
 
-      x = rect->visible.x;
+      x = rect->visible.x - layout->gtk.button_margin.left /** scale*/;
 
       if (i > 0)
         x -= layout->gtk.titlebar_spacing;
@@ -708,6 +732,8 @@ meta_theme_gtk_calc_geometry (MetaThemeImpl          *impl,
     {
       MetaButtonSpace *rect;
 
+      x += layout->gtk.button_margin.left /** scale*/;
+
       rect = left_func_rects[i];
 
       rect->visible.x = x;
@@ -725,7 +751,7 @@ meta_theme_gtk_calc_geometry (MetaThemeImpl          *impl,
       else
         g_memmove (&(rect->clickable), &(rect->visible), sizeof(rect->clickable));
 
-      x = rect->visible.x + rect->visible.width;
+      x = rect->visible.x + rect->visible.width + layout->gtk.button_margin.right /** scale*/;
       if (i < n_left - 1)
         x += layout->gtk.titlebar_spacing;
       if (left_buttons_has_spacer[i])