Support more swizzles to 565 in SkCodec

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 373 matching lines @@
         png_destroy_read_struct(&fPng_ptr, &fInfo_ptr, png_infopp_NULL);
         fPng_ptr = NULL;
         fInfo_ptr = NULL;
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Getting the pixels
 ///////////////////////////////////////////////////////////////////////////////
 
-static bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
-    // TODO: Support other conversions
-    if (dst.profileType() != src.profileType()) {
-        return false;
-    }
-
-    // Ensure the alpha type is valid
-    if (!valid_alpha(dst.alphaType(), src.alphaType())) {
-        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
     // error?
     if (setjmp(png_jmpbuf(fPng_ptr))) {
         SkCodecPrintf("setjmp long jump!\n");
         return kInvalidInput;
     }
@@ skipping 359 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()));
 }