From 79f5678feeb16910c27ac6c24e93ca0f8b479c8d Mon Sep 17 00:00:00 2001
From: C. Scott Ananian <cscott@cscott.net>
Date: Thu, 10 Nov 2011 23:33:09 +0000
Subject: Fix 'read pixel' operation under GTK3 (now faster in GTK2 as well).

---
diff --git a/TurtleArt/tacanvas.py b/TurtleArt/tacanvas.py
index ac20092..8b294a9 100644
--- a/TurtleArt/tacanvas.py
+++ b/TurtleArt/tacanvas.py
@@ -700,16 +700,12 @@ class TurtleGraphics:
             h = self.tw.turtle_canvas.get_height()
             if x < 0 or x > (w - 1) or y < 0 or y > (h - 1):
                 return(-1, -1, -1, -1)
-            # Map the cairo surface onto a pixmap
-            pixmap = gtk.gdk.Pixmap(None, w, h, 24)
-            cr = pixmap.cairo_create()
-            cr.set_source_surface(self.tw.turtle_canvas, 0, 0)
-            cr.paint()
+            # Map the cairo surface onto a pixbuf
+            pixbuf = Gdk.pixbuf_get_from_surface(self.tw.turtle_canvas,
+                                                 x, y, 1, 1)
             # Read the pixel
-            pixel = pixmap.get_image(x, y, 1, 1).get_pixel(0, 0)
-            return(int((pixel & 0xFF0000) >> 16),
-                   int((pixel & 0x00FF00) >> 8),
-                   int((pixel & 0x0000FF) >> 0), 0)
+            pixels = pixbuf.get_pixels()
+            return (ord(pixels[0]), ord(pixels[1]), ord(pixels[2]), 0)
         else:
             return(-1, -1, -1, -1)
 
diff --git a/util/gtkcompat.py b/util/gtkcompat.py
index c188a13..87622b8 100644
--- a/util/gtkcompat.py
+++ b/util/gtkcompat.py
@@ -29,6 +29,7 @@ except ValueError, ImportError:
   import gconf
   import pango as Pango
   import pangocairo as PangoCairo
+  import cairo
   Gdk = Gtk.gdk
   Rectangle = Gdk.Rectangle
 
@@ -42,6 +43,16 @@ except ValueError, ImportError:
 
   Gdk.cairo_set_source_pixbuf = \
     lambda cr, img, x, y: cr.set_source_pixbuf(img, x, y)
+  def gdk_pixbuf_get_from_surface(surface, x, y, w, h):
+    pixmap = Gdk.Pixmap(None, w, h, 24)
+    cr = pixmap.cairo_create()
+    cr.set_source_surface(surface, -x, -y)
+    cr.rectangle(0,0,w,h);
+    cr.set_operator(cairo.OPERATOR_SOURCE)
+    cr.fill()
+    cmap = Gdk.colormap_get_system()
+    return Gdk.pixbuf_get_from_drawable(None, pixmap, cmap, 0, 0, 0, 0, w, h)
+  Gdk.pixbuf_get_from_surface = gdk_pixbuf_get_from_surface
 
   class GdkEventMask:
     EXPOSURE_MASK = Gdk.EXPOSURE_MASK
--
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