4 files changed, 17 insertions, 0 deletions
diff --git a/skia/ext/platform_canvas_mac.cc b/skia/ext/platform_canvas_mac.cc
index 4acbaa6..380a78b 100755
--- a/skia/ext/platform_canvas_mac.cc
+++ b/skia/ext/platform_canvas_mac.cc
@@ -76,4 +76,9 @@ SkDevice* PlatformCanvasMac::setBitmapDevice(const SkBitmap&) {
   return NULL;
 }
 
+// static
+size_t PlatformCanvasMac::StrideForWidth(unsigned width) {
+  return 4 * width;
+}
+
 }  // namespace skia
diff --git a/skia/ext/platform_canvas_mac.h b/skia/ext/platform_canvas_mac.h
index 4f7f524..da745f8 100755
--- a/skia/ext/platform_canvas_mac.h
+++ b/skia/ext/platform_canvas_mac.h
@@ -57,6 +57,11 @@ class PlatformCanvasMac : public SkCanvas {
   // override of a virtual one.
   using SkCanvas::clipRect;
 
+  // Return the stride (length of a line in bytes) for the given width. Because
+  // we use 32-bits per pixel, this will be roughly 4*width. However, for
+  // alignment reasons we may wish to increase that.
+  static size_t StrideForWidth(unsigned width);
+
  protected:
   // Creates a device store for use by the canvas. We override this so that
   // the device is always our own so we know that we can use GDI operations
diff --git a/skia/ext/platform_canvas_win.cc b/skia/ext/platform_canvas_win.cc
index ed0d6d7..a7d878f 100644
--- a/skia/ext/platform_canvas_win.cc
+++ b/skia/ext/platform_canvas_win.cc
@@ -118,4 +118,9 @@ SkDevice* PlatformCanvasWin::setBitmapDevice(const SkBitmap&) {
   return NULL;
 }
 
+// static
+size_t PlatformCanvasWin::StrideForWidth(unsigned width) {
+  return 4 * width;
+}
+
 }  // namespace skia
diff --git a/skia/ext/platform_canvas_win.h b/skia/ext/platform_canvas_win.h
index 88f9cea..7a8c31e 100644
--- a/skia/ext/platform_canvas_win.h
+++ b/skia/ext/platform_canvas_win.h
@@ -57,6 +57,8 @@ class PlatformCanvasWin : public SkCanvas {
   // by the next call to save() or restore().
   PlatformDeviceWin& getTopPlatformDevice() const;
 
+  static size_t StrideForWidth(unsigned width);
+
  protected:
   // Creates a device store for use by the canvas. We override this so that
   // the device is always our own so we know that we can use GDI operations