Add SkCanvas::writePixels that takes info+pixels directly

tools/sk_tool_utils.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef sk_tool_utils_DEFINED
+#define sk_tool_utils_DEFINED
+
+#include "SkCanvas.h"
+#include "SkBitmap.h"
+
+namespace sk_tool_utils {
+
+    /**
+     *  Return the colorType and alphaType that correspond to the specified Config8888
+     */
+    void config8888_to_imagetypes(SkCanvas::Config8888, SkColorType*, SkAlphaType*);
+
+    /**
+     *  Call canvas->writePixels() by using the pixels from bitmap, but with an info that claims
+     *  the pixels are colorType + alphaType
+     */
+    void write_pixels(SkCanvas*, const SkBitmap&, int x, int y, SkColorType, SkAlphaType);
+}
+
+#endif