Improve Color32A_D565 quality at the expense of speed.

src/core/SkBlitRow_D16.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlitRow.h"
 #include "SkColorPriv.h"
 #include "SkDither.h"
@@ skipping 186 matching lines @@
                 *dst = SkPackRGB16(dr, dg, db);
             }
             dst += 1;
             DITHER_INC_X(x);
         } while (--count != 0);
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
-static uint32_t pmcolor_to_expand16(SkPMColor c) {
-    unsigned r = SkGetPackedR32(c);
-    unsigned g = SkGetPackedG32(c);
-    unsigned b = SkGetPackedB32(c);
-    return (g << 24) | (r << 13) | (b << 2);
+static void Color32A_D565(uint16_t dst[], SkPMColor src, int count, int x, int y) {
+    for (int i = 0; i < count; i++) {
+        dst[i] = SkSrcOver32To16(src, dst[i]);
+    }
 }
 
-static void Color32A_D565(uint16_t dst[], SkPMColor src, int count, int x, int y) {
-    SkASSERT(count > 0);
-    uint32_t src_expand = pmcolor_to_expand16(src);
-    unsigned scale = SkAlpha255To256(0xFF - SkGetPackedA32(src)) >> 3;
-    do {
-        uint32_t dst_expand = SkExpand_rgb_16(*dst) * scale;
-        *dst = SkCompact_rgb_16((src_expand + dst_expand) >> 5);
-        dst += 1;
-    } while (--count != 0);
-}
-
-///////////////////////////////////////////////////////////////////////////////
-///////////////////////////////////////////////////////////////////////////////
-
 static const SkBlitRow::Proc16 gDefault_565_Procs[] = {
     // no dither
     S32_D565_Opaque,
     S32_D565_Blend,
 
     S32A_D565_Opaque,
     S32A_D565_Blend,
 
     // dither
     S32_D565_Opaque_Dither,
@@ skipping 38 matching lines @@
     flags >>= 1;
 
     SkASSERT(flags < SK_ARRAY_COUNT(gDefault_565_ColorProcs));
 
     SkBlitRow::ColorProc16 proc = PlatformColorFactory565(flags);
     if (NULL == proc) {
         proc = gDefault_565_ColorProcs[flags];
     }
     return proc;
 }