theme: Add background functions for single buttons

With the existing background functions, single buttons can not be
styled separately - on the left side, the style of the left button
is picked, and the right button's style on the right side.

As theme authors may want to add rounded corners to button groups
as a whole, it makes sense to treat the case of a single button in
a group differently.

https://bugzilla.gnome.org/show_bug.cgi?id=635683

doc/theme-format.txt

@@ -22,6 +22,12 @@ This document has separate sections for each format version. You may
 want to read the document in reverse order, since the base features
 are discussed under version 1.
 
+New Features in Theme Format Version 3.3
+========================================
+
+Add two additional button background functions - left_single_background and
+right_single_background - for button groups with just a single button.
+
 New Features in Theme Format Version 3.2
 ========================================
 

src/ui/theme-parser.c

@@ -38,7 +38,7 @@
  * look out for.
  */
 #define THEME_MAJOR_VERSION 3
-#define THEME_MINOR_VERSION 2
+#define THEME_MINOR_VERSION 3
 #define THEME_VERSION (1000 * THEME_MAJOR_VERSION + THEME_MINOR_VERSION)
 
 #define METACITY_THEME_FILENAME_FORMAT "metacity-theme-%d.xml"

src/ui/theme-private.h

@@ -234,7 +234,7 @@ struct _MetaFrameGeometry
 
   /* used for a memset hack */
 #define ADDRESS_OF_BUTTON_RECTS(fgeom) (((char*)(fgeom)) + G_STRUCT_OFFSET (MetaFrameGeometry, close_rect))
-#define LENGTH_OF_BUTTON_RECTS (G_STRUCT_OFFSET (MetaFrameGeometry, right_right_background) + sizeof (GdkRectangle) - G_STRUCT_OFFSET (MetaFrameGeometry, close_rect))
+#define LENGTH_OF_BUTTON_RECTS (G_STRUCT_OFFSET (MetaFrameGeometry, right_single_background) + sizeof (GdkRectangle) - G_STRUCT_OFFSET (MetaFrameGeometry, close_rect))
   
   /* The button rects (if changed adjust memset hack) */
   MetaButtonSpace close_rect;
@@ -252,9 +252,11 @@ struct _MetaFrameGeometry
   GdkRectangle left_left_background;
   GdkRectangle left_middle_backgrounds[MAX_MIDDLE_BACKGROUNDS];
   GdkRectangle left_right_background;
+  GdkRectangle left_single_background;
   GdkRectangle right_left_background;
   GdkRectangle right_middle_backgrounds[MAX_MIDDLE_BACKGROUNDS];
   GdkRectangle right_right_background;
+  GdkRectangle right_single_background;
   /* End of button rects (if changed adjust memset hack) */
 
   /* Saved button layout */
@@ -647,9 +649,11 @@ typedef enum
   META_BUTTON_TYPE_LEFT_LEFT_BACKGROUND,
   META_BUTTON_TYPE_LEFT_MIDDLE_BACKGROUND,
   META_BUTTON_TYPE_LEFT_RIGHT_BACKGROUND,
+  META_BUTTON_TYPE_LEFT_SINGLE_BACKGROUND,
   META_BUTTON_TYPE_RIGHT_LEFT_BACKGROUND,
   META_BUTTON_TYPE_RIGHT_MIDDLE_BACKGROUND,
   META_BUTTON_TYPE_RIGHT_RIGHT_BACKGROUND,
+  META_BUTTON_TYPE_RIGHT_SINGLE_BACKGROUND,
   META_BUTTON_TYPE_CLOSE,
   META_BUTTON_TYPE_MAXIMIZE,
   META_BUTTON_TYPE_MINIMIZE,

src/ui/theme.c

@@ -734,7 +734,9 @@ meta_frame_layout_calc_geometry (const MetaFrameLayout  *layout,
 
   for (i = 0; i < n_left; i++)
     {
-      if (i == 0) /* prefer left background if only one button */
+      if (n_left == 1)
+        left_bg_rects[i] = &fgeom->left_single_background;
+      else if (i == 0)
         left_bg_rects[i] = &fgeom->left_left_background;
       else if (i == (n_left - 1))
         left_bg_rects[i] = &fgeom->left_right_background;
@@ -744,8 +746,9 @@ meta_frame_layout_calc_geometry (const MetaFrameLayout  *layout,
 
   for (i = 0; i < n_right; i++)
     {
-      /* prefer right background if only one button */
+      if (n_right == 1)
-      if (i == (n_right - 1))
+        right_bg_rects[i] = &fgeom->right_single_background;
+      else if (i == (n_right - 1))
         right_bg_rects[i] = &fgeom->right_right_background;
       else if (i == 0)
         right_bg_rects[i] = &fgeom->right_left_background;
@@ -4260,6 +4263,7 @@ map_button_state (MetaButtonType           button_type,
 
     /* Map position buttons to the corresponding function */
     case META_BUTTON_TYPE_RIGHT_LEFT_BACKGROUND:
+    case META_BUTTON_TYPE_RIGHT_SINGLE_BACKGROUND:
       if (fgeom->n_right_buttons > 0)
         function = fgeom->button_layout.right_buttons[0];
       break;
@@ -4272,6 +4276,7 @@ map_button_state (MetaButtonType           button_type,
         function = fgeom->button_layout.right_buttons[middle_bg_offset + 1];
       break;
     case META_BUTTON_TYPE_LEFT_LEFT_BACKGROUND:
+    case META_BUTTON_TYPE_LEFT_SINGLE_BACKGROUND:
       if (fgeom->n_left_buttons > 0)
         function = fgeom->button_layout.left_buttons[0];
       break;
@@ -4309,10 +4314,19 @@ get_button (MetaFrameStyle *style,
       parent = parent->parent;
     }
 
-  /* We fall back to middle button backgrounds if we don't
+  /* We fall back to the side buttons if we don't have
-   * have the ones on the sides
+   * single button backgrounds, and to middle button
+   * backgrounds if we don't have the ones on the sides
    */
 
+  if (op_list == NULL &&
+      type == META_BUTTON_TYPE_LEFT_SINGLE_BACKGROUND)
+    return get_button (style, META_BUTTON_TYPE_LEFT_LEFT_BACKGROUND, state);
+
+  if (op_list == NULL &&
+      type == META_BUTTON_TYPE_RIGHT_SINGLE_BACKGROUND)
+    return get_button (style, META_BUTTON_TYPE_RIGHT_RIGHT_BACKGROUND, state);
+
   if (op_list == NULL &&
       (type == META_BUTTON_TYPE_LEFT_LEFT_BACKGROUND ||
        type == META_BUTTON_TYPE_LEFT_RIGHT_BACKGROUND))
@@ -4387,6 +4401,10 @@ button_rect (MetaButtonType           type,
     case META_BUTTON_TYPE_LEFT_RIGHT_BACKGROUND:
       *rect = fgeom->left_right_background;
       break;
+
+    case META_BUTTON_TYPE_LEFT_SINGLE_BACKGROUND:
+      *rect = fgeom->left_single_background;
+      break;
       
     case META_BUTTON_TYPE_RIGHT_LEFT_BACKGROUND:
       *rect = fgeom->right_left_background;
@@ -4399,6 +4417,10 @@ button_rect (MetaButtonType           type,
     case META_BUTTON_TYPE_RIGHT_RIGHT_BACKGROUND:
       *rect = fgeom->right_right_background;
       break;
+
+    case META_BUTTON_TYPE_RIGHT_SINGLE_BACKGROUND:
+      *rect = fgeom->right_single_background;
+      break;
       
     case META_BUTTON_TYPE_CLOSE:
       *rect = fgeom->close_rect.visible;
@@ -5873,12 +5895,16 @@ meta_button_type_from_string (const char *str, MetaTheme *theme)
     return META_BUTTON_TYPE_LEFT_MIDDLE_BACKGROUND;
   else if (strcmp ("left_right_background", str) == 0)
     return META_BUTTON_TYPE_LEFT_RIGHT_BACKGROUND;
+  else if (strcmp ("left_single_background", str) == 0)
+    return META_BUTTON_TYPE_LEFT_SINGLE_BACKGROUND;
   else if (strcmp ("right_left_background", str) == 0)
     return META_BUTTON_TYPE_RIGHT_LEFT_BACKGROUND;
   else if (strcmp ("right_middle_background", str) == 0)
     return META_BUTTON_TYPE_RIGHT_MIDDLE_BACKGROUND;
   else if (strcmp ("right_right_background", str) == 0)
     return META_BUTTON_TYPE_RIGHT_RIGHT_BACKGROUND;
+  else if (strcmp ("right_single_background", str) == 0)
+    return META_BUTTON_TYPE_RIGHT_SINGLE_BACKGROUND;
   else
     return META_BUTTON_TYPE_LAST;
 }
@@ -5914,12 +5940,16 @@ meta_button_type_to_string (MetaButtonType type)
       return "left_middle_background";
     case META_BUTTON_TYPE_LEFT_RIGHT_BACKGROUND:
       return "left_right_background";
+    case META_BUTTON_TYPE_LEFT_SINGLE_BACKGROUND:
+      return "left_single_background";
     case META_BUTTON_TYPE_RIGHT_LEFT_BACKGROUND:
       return "right_left_background";
     case META_BUTTON_TYPE_RIGHT_MIDDLE_BACKGROUND:
       return "right_middle_background";
     case META_BUTTON_TYPE_RIGHT_RIGHT_BACKGROUND:
       return "right_right_background";      
+    case META_BUTTON_TYPE_RIGHT_SINGLE_BACKGROUND:
+      return "right_single_background";
     case META_BUTTON_TYPE_LAST:
       break;
     }
@@ -6793,6 +6823,10 @@ meta_theme_earliest_version_with_button (MetaButtonType type)
     case META_BUTTON_TYPE_UNSTICK:
       return 2000;
 
+    case META_BUTTON_TYPE_LEFT_SINGLE_BACKGROUND:
+    case META_BUTTON_TYPE_RIGHT_SINGLE_BACKGROUND:
+      return 3003;
+
     default:
       meta_warning("Unknown button %d\n", type);
       return 1000;