[gtk+] dnd: Fix some issues with drag icons

[Matthias Clasen <matthiasc src gnome org>]

commit 1d35f273d6ae7f145e7cf8102d423fd7451f57f5
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Apr 26 22:02:34 2016 -0400

    dnd: Fix some issues with drag icons
    
    In non-composited environments, we were ending up with all-black
    drag icons, because nothing was drawing the background of our new
    toplevel. Fix this by drawing background when we are not composited.
    We don't do this when composited, since we want to allow transparent
    icons.

 gtk/gtkdnd.c |   85 +++++++++++++++++++++++----------------------------------
 1 files changed, 34 insertions(+), 51 deletions(-)
---
diff --git a/gtk/gtkdnd.c b/gtk/gtkdnd.c
index d0b391c..9a5dd11 100644
--- a/gtk/gtkdnd.c
+++ b/gtk/gtkdnd.c
@@ -2056,9 +2056,11 @@ gtk_drag_set_icon_widget_internal (GdkDragContext *context,
     {
       GdkScreen *screen;
       GdkVisual *visual;
+      gboolean has_rgba;
 
       screen = gdk_window_get_screen (gdk_drag_context_get_source_window (context));
       visual = gdk_screen_get_rgba_visual (screen);
+      has_rgba = visual != NULL && gdk_screen_is_composited (screen);
 
       info->icon_window = gtk_window_new (GTK_WINDOW_POPUP);
       gtk_window_set_type_hint (GTK_WINDOW (info->icon_window), GDK_WINDOW_TYPE_HINT_DND);
@@ -2067,7 +2069,10 @@ gtk_drag_set_icon_widget_internal (GdkDragContext *context,
       if (visual)
         gtk_widget_set_visual (info->icon_window, visual);
       gtk_widget_set_events (info->icon_window, GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
-      gtk_widget_set_app_paintable (info->icon_window, TRUE);
+
+      if (has_rgba)
+        gtk_widget_set_app_paintable (info->icon_window, TRUE);
+
       gtk_window_set_hardcoded_window (GTK_WINDOW (info->icon_window),
                                        gdk_drag_context_get_drag_window (context));
       gtk_widget_show (info->icon_window);
@@ -2124,6 +2129,25 @@ gtk_drag_draw_icon_pattern (GtkWidget *window,
 }
 
 static void
+gtk_drag_draw_icon_pattern_and_background (GtkWidget *window,
+                                           cairo_t   *cr,
+                                           gpointer   pattern)
+{
+  GtkStyleContext *context;
+  int width, height;
+
+  context = gtk_widget_get_style_context (window);
+  width = gtk_widget_get_allocated_width (window);
+  height = gtk_widget_get_allocated_height (window);
+
+  gtk_render_background (context, cr, 0, 0, width, height);
+  gtk_render_frame (context, cr, 0, 0, width, height);
+
+  cairo_set_source (cr, pattern);
+  cairo_paint (cr);
+}
+
+static void
 set_icon_helper (GdkDragContext     *context,
                  GtkImageDefinition *def,
                  gint                hot_x,
@@ -2260,7 +2284,7 @@ _gtk_cairo_surface_extents (cairo_surface_t *surface,
  * cursor will be positioned at the (0,0) coordinate of the
  * surface.
  */
-void 
+void
 gtk_drag_set_icon_surface (GdkDragContext  *context,
                            cairo_surface_t *surface)
 {
@@ -2270,20 +2294,18 @@ gtk_drag_set_icon_surface (GdkDragContext  *context,
   cairo_pattern_t *pattern;
   GdkVisual *rgba_visual;
   gboolean has_rgba;
-      
+  cairo_matrix_t matrix;
+
   g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));
   g_return_if_fail (surface != NULL);
 
   _gtk_cairo_surface_extents (surface, &extents);
 
-
   screen = gdk_window_get_screen (gdk_drag_context_get_source_window (context));
   rgba_visual = gdk_screen_get_rgba_visual (screen);
 
   window = gtk_window_new (GTK_WINDOW_POPUP);
-  has_rgba =
-    rgba_visual != NULL &&
-    gdk_screen_is_composited (screen);
+  has_rgba = rgba_visual != NULL && gdk_screen_is_composited (screen);
 
   gtk_window_set_screen (GTK_WINDOW (window), screen);
 
@@ -2298,53 +2320,14 @@ gtk_drag_set_icon_surface (GdkDragContext  *context,
   gtk_widget_set_size_request (window, extents.width, extents.height);
   gtk_widget_realize (window);
 
-  if (cairo_surface_get_content (surface) != CAIRO_CONTENT_COLOR &&
-      !has_rgba)
-    {
-      cairo_surface_t *saturated;
-      cairo_region_t *region;
-      cairo_t *cr;
-
-      region = gdk_cairo_region_create_from_surface (surface);
-      cairo_region_translate (region, -extents.x, -extents.y);
-
-      gtk_widget_shape_combine_region (window, region);
-      cairo_region_destroy (region);
-
-      /* Need to saturate the colors, so it doesn't look like semi-transparent
-       * pixels were painted on black.
-       */
-      saturated = gdk_window_create_similar_surface (gtk_widget_get_window (window),
-                                                     CAIRO_CONTENT_COLOR,
-                                                     extents.width,
-                                                     extents.height);
-      
-      cr = cairo_create (saturated);
-      cairo_push_group_with_content (cr, CAIRO_CONTENT_COLOR_ALPHA);
-      cairo_set_source_surface (cr, surface, -extents.x, -extents.y);
-      cairo_paint (cr);
-      cairo_set_operator (cr, CAIRO_OPERATOR_SATURATE);
-      cairo_paint (cr);
-      cairo_pop_group_to_source (cr);
-      cairo_paint (cr);
-      cairo_destroy (cr);
-    
-      pattern = cairo_pattern_create_for_surface (saturated);
-
-      cairo_surface_destroy (saturated);
-    }
-  else
-    {
-      cairo_matrix_t matrix;
-
-      pattern = cairo_pattern_create_for_surface (surface);
-      cairo_matrix_init_translate (&matrix, extents.x, extents.y);
-      cairo_pattern_set_matrix (pattern, &matrix);
-    }
+  pattern = cairo_pattern_create_for_surface (surface);
+  cairo_matrix_init_translate (&matrix, extents.x, extents.y);
+  cairo_pattern_set_matrix (pattern, &matrix);
 
   g_signal_connect_data (window,
                          "draw",
-                         G_CALLBACK (gtk_drag_draw_icon_pattern),
+                         has_rgba ? G_CALLBACK (gtk_drag_draw_icon_pattern)
+                                  : G_CALLBACK (gtk_drag_draw_icon_pattern_and_background),
                          pattern,
                          (GClosureNotify) cairo_pattern_destroy,
                          G_CONNECT_AFTER);