Add SkCanvas::writePixels that takes info+pixels directly

add corresponding methods to device (w/ diff name to avoid colliding with exising virtuals)

BUG=skia:
R=bsalomon@google.com, robertphillips@google.com, junov@google.com, junov@chromium.org

Author: reed@google.com

Review URL: https://codereview.chromium.org/180113010

git-svn-id: http://skia.googlecode.com/svn/trunk@13697 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/sk_tool_utils.h b/tools/sk_tool_utils.h
new file mode 100644
index 0000000..7747a12
--- /dev/null
+++ b/tools/sk_tool_utils.h
@@ -0,0 +1,28 @@
+/*
+ * 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