add optimization table for blitproc functions

git-svn-id: http://skia.googlecode.com/svn/trunk@295 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 22 insertions, 0 deletions

diff --git a/src/core/SkBlitRow.h b/src/core/SkBlitRow.h
index bb6a29b829..473c925b4d 100644
--- a/src/core/SkBlitRow.h
+++ b/src/core/SkBlitRow.h
@@ -7,16 +7,38 @@
 class SkBlitRow {
 public:
     enum {
+        //! If set, the alpha parameter will be != 255
         kGlobalAlpha_Flag   = 0x01,
+        //! If set, the src colors may have alpha != 255
         kSrcPixelAlpha_Flag = 0x02,
+        //! If set, the resulting 16bit colors should be dithered
         kDither_Flag        = 0x04
     };
 
+    /** Function pointer that reads a scanline of src SkPMColors, and writes
+        a corresponding scanline of 16bit colors (specific format based on the
+        config passed to the Factory.
+     
+        The x,y params are useful just for dithering
+     
+        @param alpha A global alpha to be applied to all of the src colors
+        @param x The x coordinate of the beginning of the scanline
+        @param y THe y coordinate of the scanline
+     */
     typedef void (*Proc)(uint16_t* SK_RESTRICT dst,
                          const SkPMColor* SK_RESTRICT src,
                          int count, U8CPU alpha, int x, int y);
 
+    //! Public entry-point to return a blit function ptr
     static Proc Factory(unsigned flags, SkBitmap::Config);
+
+private:
+    /** These global arrays are indexed using the flags parameterr to Factory,
+        and contain either NULL, or a platform-specific function-ptr to be used
+        in place of the system default.
+     */
+    static const Proc gPlatform_565_Procs[];
+    static const Proc gPlatform_4444_Procs[];
 };
 
 #endif