Support more swizzles to 565 in SkCodec

src/codec/SkCodec_libgif.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_libgif.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 192 matching lines @@
     }
     return NULL;
 }
 
 SkGifCodec::SkGifCodec(const SkImageInfo& srcInfo, SkStream* stream,
                        GifFileType* gif)
     : INHERITED(srcInfo, stream)
     , fGif(gif)
 {}
 
-/*
- * Checks if the conversion between the input image and the requested output
- * image has been implemented
- */
-static bool conversion_possible(const SkImageInfo& dst,
-                                const SkImageInfo& src) {
-    // Ensure that the profile type is unchanged
-    if (dst.profileType() != src.profileType()) {
-        return false;
-    }
-
-    // Check for supported color and alpha types
-    switch (dst.colorType()) {
-        case kN32_SkColorType:
-            return kPremul_SkAlphaType == dst.alphaType() ||
-                    kUnpremul_SkAlphaType == dst.alphaType();
-        case kIndex_8_SkColorType:
-            return kPremul_SkAlphaType == dst.alphaType() ||
-                    kUnpremul_SkAlphaType == dst.alphaType();
-        default:
-            return false;
-    }
-}
-
 bool SkGifCodec::onRewind() {
     GifFileType* gifOut = NULL;
     if (!ReadHeader(this->stream(), NULL, &gifOut)) {
         return false;
     }
 
     SkASSERT(NULL != gifOut);
     fGif.reset(gifOut);
     return true;
 }
@@ skipping 327 matching lines @@
                 // giflib returns an error code if the record type is not known.
                 // We should catch this error immediately.
                 SkASSERT(false);
                 break;
         }
     } while (TERMINATE_RECORD_TYPE != recordType);
 
     return gif_error("Could not find any images to decode in gif file.\n",
             kInvalidInput);
 }