fix SkBitmap::erase to handle RGBA and BGRA

src/core/SkBitmap.cpp

 
 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkBitmap.h"
@@ skipping 821 matching lines @@
     SkASSERT(!area.isEmpty());
     {
         SkIRect total = { 0, 0, this->width(), this->height() };
         SkASSERT(total.contains(area));
     }
 #endif
 
     switch (fInfo.colorType()) {
         case kUnknown_SkColorType:
         case kIndex_8_SkColorType:
-            return; // can't erase
+            return; // can't erase. Should we bzero so the memory is not uninitialized?
         default:
             break;
     }
 
     SkAutoLockPixels alp(*this);
     // perform this check after the lock call
     if (!this->readyToDraw()) {
         return;
     }
 
     int height = area.height();
     const int width = area.width();
     const int rowBytes = fRowBytes;
 
-    // make rgb premultiplied
-    if (255 != a) {
-        r = SkAlphaMul(r, a);
-        g = SkAlphaMul(g, a);
-        b = SkAlphaMul(b, a);
-    }
-
     switch (this->colorType()) {
         case kAlpha_8_SkColorType: {
             uint8_t* p = this->getAddr8(area.fLeft, area.fTop);
             while (--height >= 0) {
                 memset(p, a, width);
                 p += rowBytes;
             }
             break;
         }
         case kARGB_4444_SkColorType:
         case kRGB_565_SkColorType: {
             uint16_t* p = this->getAddr16(area.fLeft, area.fTop);;
             uint16_t v;
 
+            // make rgb premultiplied
+            if (255 != a) {
+                r = SkAlphaMul(r, a);
+                g = SkAlphaMul(g, a);
+                b = SkAlphaMul(b, a);
+            }
+
             if (kARGB_4444_SkColorType == this->colorType()) {
                 v = pack_8888_to_4444(a, r, g, b);
             } else {
                 v = SkPackRGB16(r >> (8 - SK_R16_BITS),
                                 g >> (8 - SK_G16_BITS),
                                 b >> (8 - SK_B16_BITS));
             }
             while (--height >= 0) {
                 sk_memset16(p, v, width);
                 p = (uint16_t*)((char*)p + rowBytes);
             }
             break;
         }
-        case kPMColor_SkColorType: {
-            // what to do about BGRA or RGBA (which ever is != PMColor ?
-            // for now we don't support them.
+        case kBGRA_8888_SkColorType:
+        case kRGBA_8888_SkColorType: {
             uint32_t* p = this->getAddr32(area.fLeft, area.fTop);
-            uint32_t  v = SkPackARGB32(a, r, g, b);
+
+            if (255 != a && kPremul_SkAlphaType == this->alphaType()) {
+                r = SkAlphaMul(r, a);
+                g = SkAlphaMul(g, a);
+                b = SkAlphaMul(b, a);
+            }
+            uint32_t v = kRGBA_8888_SkColorType == this->colorType() ?
+                         SkPackARGB_as_RGBA(a, r, g, b) : SkPackARGB_as_BGRA(a, r, g, b);
 
             while (--height >= 0) {
                 sk_memset32(p, v, width);
                 p = (uint32_t*)((char*)p + rowBytes);
             }
             break;
         }
         default:
             return; // no change, so don't call notifyPixelsChanged()
     }
@@ skipping 816 matching lines @@
 ///////////////////////////////////////////////////////////////////////////////
 
 #ifdef SK_DEBUG
 void SkImageInfo::validate() const {
     SkASSERT(fWidth >= 0);
     SkASSERT(fHeight >= 0);
     SkASSERT(SkColorTypeIsValid(fColorType));
     SkASSERT(SkAlphaTypeIsValid(fAlphaType));
 }
 #endif