gecko-dev/gfx/cairo/win32-transparent-surface.patch

diff --git a/gfx/cairo/cairo/src/cairo-win32-surface.c b/gfx/cairo/cairo/src/cairo-win32-surface.c
--- a/gfx/cairo/cairo/src/cairo-win32-surface.c
+++ b/gfx/cairo/cairo/src/cairo-win32-surface.c
@@ -1709,40 +1709,23 @@ _cairo_win32_surface_show_glyphs (void		
     }
 #else
     return CAIRO_INT_STATUS_UNSUPPORTED;
 #endif
 }
 
 #undef STACK_GLYPH_SIZE
 
-/**
- * cairo_win32_surface_create:
- * @hdc: the DC to create a surface for
- *
- * Creates a cairo surface that targets the given DC.  The DC will be
- * queried for its initial clip extents, and this will be used as the
- * size of the cairo surface.  The resulting surface will always be of
- * format %CAIRO_FORMAT_RGB24; should you need another surface format,
- * you will need to create one through
- * cairo_win32_surface_create_with_dib().
- *
- * Return value: the newly created surface
- **/
-cairo_surface_t *
-cairo_win32_surface_create (HDC hdc)
+static cairo_surface_t *
+cairo_win32_surface_create_internal (HDC hdc, cairo_format_t format)
 {
     cairo_win32_surface_t *surface;
 
-    cairo_format_t format;
     RECT rect;
 
-    /* Assume that everything coming in as a HDC is RGB24 */
-    format = CAIRO_FORMAT_RGB24;
-
     surface = malloc (sizeof (cairo_win32_surface_t));
     if (surface == NULL)
 	return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     if (_cairo_win32_save_initial_clip (hdc, surface) != CAIRO_STATUS_SUCCESS) {
 	free (surface);
 	return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
@@ -1765,17 +1748,58 @@ cairo_win32_surface_create (HDC hdc)
     surface->extents.width = rect.right - rect.left;
     surface->extents.height = rect.bottom - rect.top;
 
     surface->flags = _cairo_win32_flags_for_dc (surface->dc);
 
     _cairo_surface_init (&surface->base, &cairo_win32_surface_backend,
 			 _cairo_content_from_format (format));
 
-    return (cairo_surface_t *)surface;
+    return &surface->base;
+}
+
+/**
+ * cairo_win32_surface_create:
+ * @hdc: the DC to create a surface for
+ *
+ * Creates a cairo surface that targets the given DC.  The DC will be
+ * queried for its initial clip extents, and this will be used as the
+ * size of the cairo surface.  The resulting surface will always be of
+ * format %CAIRO_FORMAT_RGB24; should you need another surface format,
+ * you will need to create one through
+ * cairo_win32_surface_create_with_dib() or call
+ * cairo_win32_surface_create_with_alpha.
+ *
+ * Return value: the newly created surface
+ **/
+cairo_surface_t *
+cairo_win32_surface_create (HDC hdc)
+{
+    /* Assume everything comes in as RGB24 */
+    return cairo_win32_surface_create_internal(hdc, CAIRO_FORMAT_RGB24);
+}
+
+/**
+ * cairo_win32_surface_create_with_alpha:
+ * @hdc: the DC to create a surface for
+ *
+ * Creates a cairo surface that targets the given DC.  The DC will be
+ * queried for its initial clip extents, and this will be used as the
+ * size of the cairo surface.  The resulting surface will always be of
+ * format %CAIRO_FORMAT_ARGB32; this format is used when drawing into
+ * transparent windows.
+ *
+ * Return value: the newly created surface
+ *
+ * Since: 1.10
+ **/
+cairo_surface_t *
+cairo_win32_surface_create_with_alpha (HDC hdc)
+{
+    return cairo_win32_surface_create_internal(hdc, CAIRO_FORMAT_ARGB32);
 }
 
 /**
  * cairo_win32_surface_create_with_dib:
  * @format: format of pixels in the surface to create
  * @width: width of the surface, in pixels
  * @height: height of the surface, in pixels
  *
diff --git a/gfx/cairo/cairo/src/cairo-win32.h b/gfx/cairo/cairo/src/cairo-win32.h
--- a/gfx/cairo/cairo/src/cairo-win32.h
+++ b/gfx/cairo/cairo/src/cairo-win32.h
@@ -44,16 +44,19 @@
 #include <windows.h>
 
 CAIRO_BEGIN_DECLS
 
 cairo_public cairo_surface_t *
 cairo_win32_surface_create (HDC hdc);
 
 cairo_public cairo_surface_t *
+cairo_win32_surface_create_with_alpha (HDC hdc);
+
+cairo_public cairo_surface_t *
 cairo_win32_printing_surface_create (HDC hdc);
 
 cairo_public cairo_surface_t *
 cairo_win32_surface_create_with_ddb (HDC hdc,
                                      cairo_format_t format,
                                      int width,
                                      int height);