Support decoding opaque images to unpremul/premul

src/codec/SkJpegCodec.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.h"
 #include "SkJpegCodec.h"
 #include "SkJpegDecoderMgr.h"
@@ skipping 208 matching lines @@
  * Sets the output color space
  */
 bool SkJpegCodec::setOutputColorSpace(const SkImageInfo& dst) {
     const SkImageInfo& src = this->getInfo();
 
     // Ensure that the profile type is unchanged
     if (dst.profileType() != src.profileType()) {
         return false;
     }
 
-    // Ensure that the alpha type is opaque
-    if (kOpaque_SkAlphaType != dst.alphaType()) {
-        return false;
-    }
-
     // Check if we will decode to CMYK because a conversion to RGBA is not supported
     J_COLOR_SPACE colorSpace = fDecoderMgr->dinfo()->jpeg_color_space;
     bool isCMYK = JCS_CMYK == colorSpace || JCS_YCCK == colorSpace;
 
     // Check for valid color types and set the output color space
     switch (dst.colorType()) {
         case kN32_SkColorType:
             if (isCMYK) {
                 fDecoderMgr->dinfo()->out_color_space = JCS_CMYK;
             } else {
@@ skipping 262 matching lines @@
 SkScanlineDecoder* SkJpegCodec::NewSDFromStream(SkStream* stream) {
     SkAutoTDelete<SkJpegCodec> codec(static_cast<SkJpegCodec*>(SkJpegCodec::NewFromStream(stream)));
     if (!codec) {
         return NULL;
     }
 
     const SkImageInfo& srcInfo = codec->getInfo();
     // Return the new scanline decoder
     return SkNEW_ARGS(SkJpegScanlineDecoder, (srcInfo, codec.detach()));
 }