Support decoding PNG to 565.

src/codec/SkCodec_libpng.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodec_libpng.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 401 matching lines @@
                 break;
             default:
                 // We cannot decode a non-opaque image to opaque (or unknown)
                 return false;
         }
     }
     // Check for supported color types
     switch (dst.colorType()) {
         case kN32_SkColorType:
             return true;
+        case kRGB_565_SkColorType:
+            return src.alphaType() == kOpaque_SkAlphaType;
         default:
             return dst.colorType() == src.colorType();
     }
 }
 
 SkCodec::Result SkPngCodec::initializeSwizzler(const SkImageInfo& requestedInfo,
                                                const Options& options,
                                                SkPMColor ctable[],
                                                int* ctableCount) {
     // FIXME: Could we use the return value of setjmp to specify the type of
@@ skipping 373 matching lines @@
 
     const SkImageInfo& srcInfo = codec->getInfo();
     if (codec->fNumberPasses > 1) {
         // interlaced image
         return SkNEW_ARGS(SkPngInterlacedScanlineDecoder, (srcInfo, codec.detach()));
     }
 
     return SkNEW_ARGS(SkPngScanlineDecoder, (srcInfo, codec.detach()));
 }