Add bitmap manipulation functions in advance of themes.

skia/ext/image_operations.h

Index: skia/ext/image_operations.h
===================================================================
--- skia/ext/image_operations.h	(revision 13970)
+++ skia/ext/image_operations.h	(working copy)
@@ -7,6 +7,7 @@
 
 #include "base/basictypes.h"
 #include "base/gfx/rect.h"
+#include "SkColor.h"
 
 class SkBitmap;
 
@@ -46,13 +47,46 @@
                          ResizeMethod method,
                          int dest_width, int dest_height);
 
-
   // Create a bitmap that is a blend of two others. The alpha argument
   // specifies the opacity of the second bitmap. The provided bitmaps must
   // use have the kARGB_8888_Config config and be of equal dimensions.
   static SkBitmap CreateBlendedBitmap(const SkBitmap& first,
                                       const SkBitmap& second,
                                       double alpha);
+
+  // Create a bitmap that is the original bitmap masked out by the mask defined
+  // in the alpha bitmap.

[brettw, 2009/04/28 02:49:43]

Can you add in this comment whether the images can be different sizes and what
will happen in this case?

+  static SkBitmap CreateMaskedBitmap(const SkBitmap& first,
+                                     const SkBitmap& alpha);
+
+  // Blur a bitmap using an average-blur algorithm over the rectangle defined
+  // by |blur_amount|. The blur will wrap around image edges.
+  static SkBitmap CreateBlurredBitmap(const SkBitmap& bitmap, int blur_amount);
+
+  // Shift a bitmap's HSL values. The shift values are in the range of 0-1, 
+  // with the option to specify -1 for 'no change'. The shift values are 
+  // defined as:
+  // hsl_shift[0] (hue): The absolute hue value for the image - 0 and 1 map
+  //    to 0 and 360 on the hue color wheel (red).
+  // hsl_shift[1] (saturation): A saturation shift for the image, with the 
+  //    following key values:
+  //    0 = remove all color.
+  //    0.5 = leave unchanged.
+  //    1 = fully saturate the image.
+  // hsl_shift[2] (lightness): A lightness shift for the image, with the 
+  //    following key values:
+  //    0 = remove all lightness (make all pixels black).
+  //    0.5 = leave unchanged.
+  //    1 = full lightness (make all pixels white).
+  static SkBitmap CreateHSLShiftedBitmap(const SkBitmap& bitmap,
+                                         float hsl_shift[3]);
+
+  // Create a bitmap that is cropped from another bitmap. This is special
+  // because it tiles the original bitmap, so your coordinates can extend
+  // outside the bounds of the original image.
+  static SkBitmap CreateTiledBitmap(const SkBitmap& bitmap,
+                                    int src_x, int src_y,
+                                    int dst_w, int dst_h);
  private:
   ImageOperations();  // Class for scoping only.
 };