add null-surface

Bug:crbug.com/737726
Change-Id: Iec9094d8d7232943e90fe2d9745fc83bcdf90954
Reviewed-on: https://skia-review.googlesource.com/21190
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/core/SkSurface.h b/include/core/SkSurface.h
index 08e558cac7..f6142c9e3b 100644
--- a/include/core/SkSurface.h
+++ b/include/core/SkSurface.h
@@ -176,6 +176,12 @@ public:
         return MakeRenderTarget(gr, b, info, 0, kBottomLeft_GrSurfaceOrigin, nullptr);
     }
 
+    /**
+     *  Returns a surface that stores no pixels. It can be drawn to via its canvas, but that
+     *  canvas does not draw anything. Calling makeImageSnapshot() will return nullptr.
+     */
+    static sk_sp<SkSurface> MakeNull(int width, int height);
+
     int width() const { return fWidth; }
     int height() const { return fHeight; }