[gtk+] GtkTextView: Fix regression in GtkSourceView drawing

[Alexander Larsson <alexl src gnome org>]

commit 1ac13435b7c14dd9b97ad7a9d292acd51337d66e
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Oct 2 15:14:56 2013 +0200

    GtkTextView: Fix regression in GtkSourceView drawing
    
    GtkSourceView draws before chaining upo to GtkTextView and assumes
    that this will be visible, but the pixelcache will just overdraw
    that with background.
    
    So, we stop drawing the background to the pixel cache and instead
    make it an CAIRO_CONTENT_COLOR_ALPHA surface to make the previously
    drawn content see through.
    
    This is slower, but more backwards compatible.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=708423

 gtk/gtktextview.c |   19 +++++++------------
 1 files changed, 7 insertions(+), 12 deletions(-)
---
diff --git a/gtk/gtktextview.c b/gtk/gtktextview.c
index e34e2b3..63680bf 100644
--- a/gtk/gtktextview.c
+++ b/gtk/gtktextview.c
@@ -1477,6 +1477,13 @@ gtk_text_view_init (GtkTextView *text_view)
 
   priv->pixel_cache = _gtk_pixel_cache_new ();
 
+  /* Widgets inheriting from GtkTextView (like GtkSourceView) rely on being able to
+     paint before chaining up to GtkTextView.draw() and having that be visible, that
+     doesn't work unless we have alpha in the textview pixelcache. This is slightly
+     suboptimal, as it means drawing the cache is slower (and OVER operation) rather
+     than a pure blit, but is required for backwards compat. */
+  _gtk_pixel_cache_set_content (priv->pixel_cache, CAIRO_CONTENT_COLOR_ALPHA);
+
   /* Set up default style */
   priv->wrap_mode = GTK_WRAP_NONE;
   priv->pixels_above_lines = 0;
@@ -5252,18 +5259,6 @@ draw_text (cairo_t  *cr,
            gpointer  user_data)
 {
   GtkWidget *widget = user_data;
-  GtkStyleContext *context;
-  GdkRectangle bg_rect;
-
-  gdk_cairo_get_clip_rectangle (cr, &bg_rect);
-
-  context = gtk_widget_get_style_context (widget);
-  gtk_style_context_save (context);
-  gtk_style_context_add_class (context, GTK_STYLE_CLASS_VIEW);
-  gtk_render_background (context, cr,
-                         bg_rect.x, bg_rect.y,
-                         bg_rect.width, bg_rect.height);
-  gtk_style_context_restore (context);
 
   gtk_text_view_paint (widget, cr);
 }