Bug 552537. Cache the CGImageRef that we create for a CGBitmapContext so that we can take advantage of Quartz caching optimizations. r=jrmuizel

gfx/cairo/cairo/src/cairo-quartz-private.h

@@ -54,6 +54,14 @@ typedef struct cairo_quartz_surface {
     cairo_surface_t *imageSurfaceEquiv;
 
     cairo_surface_clipper_t clipper;
+
+    /**
+     * If non-null, this is a CGImage representing the contents of the surface.
+     * We clear this out before any painting into the surface, so that we
+     * don't force a copy to be created.
+     */
+    CGImageRef bitmapContextImage;
+
     cairo_rectangle_int_t extents;
 } cairo_quartz_surface_t;
 

gfx/cairo/cairo/src/cairo-quartz-surface.c

@@ -1139,9 +1139,14 @@ _cairo_surface_to_cgimage (cairo_surface_t *target,
 	}
 
 	if (_cairo_quartz_is_cgcontext_bitmap_context (surface->cgContext)) {
-	    *image_out = CGBitmapContextCreateImage (surface->cgContext);
-	    if (*image_out)
-		return CAIRO_STATUS_SUCCESS;
+	    if (!surface->bitmapContextImage) {
+	        surface->bitmapContextImage =
+	            CGBitmapContextCreateImage (surface->cgContext);
+	    }
+	    if (surface->bitmapContextImage) {
+                *image_out = CGImageRetain (surface->bitmapContextImage);
+                return CAIRO_STATUS_SUCCESS;
+            }
 	}
     }
 
@@ -1593,6 +1598,19 @@ _cairo_quartz_setup_radial_source (cairo_quartz_surface_t *surface,
     state->action = DO_SHADING;
 }
 
+/**
+ * Call this before any operation that can modify the contents of a
+ * cairo_quartz_surface_t.
+ */
+static void
+_cairo_quartz_surface_will_change (cairo_quartz_surface_t *surface)
+{
+    if (surface->bitmapContextImage) {
+        CGImageRelease (surface->bitmapContextImage);
+        surface->bitmapContextImage = NULL;
+    }
+}
+
 /**
  * Sets up internal state to be used to draw the source mask, stored in
  * cairo_quartz_state_t. Guarantees to call CGContextSaveGState on
@@ -1614,6 +1632,8 @@ _cairo_quartz_setup_state (cairo_quartz_surface_t *surface,
     state.shading = NULL;
     state.pattern = NULL;
 
+    _cairo_quartz_surface_will_change (surface);
+
     // Save before we change the pattern, colorspace, etc. so that
     // we can restore and make sure that quartz releases our
     // pattern (which may be stack allocated)
@@ -1941,6 +1961,11 @@ _cairo_quartz_surface_finish (void *abstract_surface)
 
     surface->cgContext = NULL;
 
+    if (surface->bitmapContextImage) {
+        CGImageRelease (surface->bitmapContextImage);
+        surface->bitmapContextImage = NULL;
+    }
+
     if (surface->imageSurfaceEquiv) {
 	cairo_surface_destroy (surface->imageSurfaceEquiv);
 	surface->imageSurfaceEquiv = NULL;
@@ -2011,6 +2036,8 @@ _cairo_quartz_surface_acquire_dest_image (void *abstract_surface,
 
     ND((stderr, "%p _cairo_quartz_surface_acquire_dest_image\n", surface));
 
+    _cairo_quartz_surface_will_change (surface);
+
     status = _cairo_quartz_get_image (surface, image_out);
     if (status)
 	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
@@ -2944,6 +2971,7 @@ _cairo_quartz_surface_create_internal (CGContextRef cgContext,
 
     surface->imageData = NULL;
     surface->imageSurfaceEquiv = NULL;
+    surface->bitmapContextImage = NULL;
 
     return surface;
 }