Do not convert non gray PNG to A8.

src/images/SkImageDecoder_libpng.cpp

 
 /*
  * Copyright 2006 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 "SkImageDecoder.h"
@@ skipping 517 matching lines @@
             //SkASSERT(!*hasAlphap);
         }
 
         *configp = this->getPrefConfig(srcDepth, *hasAlphap);
         // now match the request against our capabilities
         if (*hasAlphap) {
             if (*configp != SkBitmap::kARGB_4444_Config) {
                 *configp = SkBitmap::kARGB_8888_Config;
             }
         } else {
-            if (*configp != SkBitmap::kRGB_565_Config &&
-                *configp != SkBitmap::kARGB_4444_Config &&
-                *configp != SkBitmap::kA8_Config) {
+            if (SkBitmap::kA8_Config == *configp) {
+                if (k8BitGray_SrcDepth != srcDepth) {
+                    // Converting a non grayscale image to A8 is not currently supported.
+                    *configp = SkBitmap::kARGB_8888_Config;
+                }
+            } else if (*configp != SkBitmap::kRGB_565_Config &&
+                       *configp != SkBitmap::kARGB_4444_Config) {
                 *configp = SkBitmap::kARGB_8888_Config;
             }
         }
     }
 
     // sanity check for size
     {
         Sk64 size;
         size.setMul(origWidth, origHeight);
         if (size.isNeg() || !size.is32()) {
@@ skipping 646 matching lines @@
     return SkImageDecoder::kUnknown_Format;
 }
 
 SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kPNG_Type == t) ? SkNEW(SkPNGImageEncoder) : NULL;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libpng_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_png);
 static SkImageEncoder_EncodeReg gEReg(sk_libpng_efactory);