From 455b4de1fc6be05f985b43c2f8f83eeed2b2a191 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 27 Apr 2012 11:41:41 +0100
Subject: [PATCH] image: Allow a snapshot to steal the original memory upon
 finish

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 src/cairo-image-surface.c   | 18 ++++++++++++++++++
 src/cairo-surface-private.h |  1 +
 src/cairo-surface.c         |  3 +++
 3 files changed, 22 insertions(+)

diff --git a/src/cairo-image-surface.c b/src/cairo-image-surface.c
index 8bbea0020..56914b06b 100644
--- a/src/cairo-image-surface.c
+++ b/src/cairo-image-surface.c
@@ -753,6 +753,24 @@ _cairo_image_surface_snapshot (void *abstract_surface)
     cairo_image_surface_t *image = abstract_surface;
     cairo_image_surface_t *clone;
 
+    /* If we own the image, we can simply steal the memory for the snapshot */
+    if (image->owns_data && image->base._finishing) {
+	clone = (cairo_image_surface_t *)
+	    _cairo_image_surface_create_for_pixman_image (image->pixman_image,
+							  image->pixman_format);
+	if (unlikely (clone->base.status))
+	    return &clone->base;
+
+	image->pixman_image = NULL;
+	image->owns_data = FALSE;
+
+	clone->transparency = image->transparency;
+	clone->color = image->color;
+
+	clone->owns_data = FALSE;
+	return &clone->base;
+    }
+
     clone = (cairo_image_surface_t *)
 	_cairo_image_surface_create_with_pixman_format (NULL,
 							image->pixman_format,
diff --git a/src/cairo-surface-private.h b/src/cairo-surface-private.h
index c4d5de2dc..d23fc0530 100644
--- a/src/cairo-surface-private.h
+++ b/src/cairo-surface-private.h
@@ -65,6 +65,7 @@ struct _cairo_surface {
     unsigned int serial;
     cairo_damage_t *damage;
 
+    unsigned _finishing : 1;
     unsigned finished : 1;
     unsigned is_clear : 1;
     unsigned has_font_options : 1;
diff --git a/src/cairo-surface.c b/src/cairo-surface.c
index 457b3f00a..58db7be75 100644
--- a/src/cairo-surface.c
+++ b/src/cairo-surface.c
@@ -108,6 +108,7 @@ const cairo_surface_t name = {					\
     0,					/* unique id */		\
     0,					/* serial */		\
     NULL,				/* damage */		\
+    FALSE,				/* _finishing */	\
     FALSE,				/* finished */		\
     TRUE,				/* is_clear */		\
     FALSE,				/* has_font_options */	\
@@ -905,6 +906,8 @@ _cairo_surface_finish (cairo_surface_t *surface)
     cairo_surface_flush (surface);
 
     /* update the snapshots *before* we declare the surface as finished */
+    surface->_finishing = TRUE;
+
     _cairo_surface_detach_snapshots (surface);
     if (surface->snapshot_of != NULL)
 	_cairo_surface_detach_snapshot (surface);