Allow creating multiple scanline decoders.

src/codec/SkCodec.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 "SkData.h"
 #include "SkCodec_libbmp.h"
 #include "SkCodec_libgif.h"
 #include "SkCodec_libico.h"
 #include "SkCodec_libpng.h"
 #include "SkCodec_wbmp.h"
 #include "SkCodecPriv.h"
 #ifndef SK_BUILD_FOR_ANDROID_FRAMEWORK
 #include "SkJpegCodec.h"
 #endif
-#include "SkScanlineDecoder.h"
 #include "SkStream.h"
 #include "SkWebpCodec.h"
 
 struct DecoderProc {
     bool (*IsFormat)(SkStream*);
     SkCodec* (*NewFromStream)(SkStream*);
 };
 
 static const DecoderProc gDecoderProcs[] = {
     { SkPngCodec::IsPng, SkPngCodec::NewFromStream },
@@ skipping 43 matching lines @@
     if (!data) {
         return NULL;
     }
     return NewFromStream(SkNEW_ARGS(SkMemoryStream, (data)));
 }
 
 SkCodec::SkCodec(const SkImageInfo& info, SkStream* stream)
     : fInfo(info)
     , fStream(stream)
     , fNeedsRewind(false)
-    , fScanlineDecoder(NULL)
 {}
 
-SkCodec::~SkCodec() {
-    SkDELETE(fScanlineDecoder);
-}
+SkCodec::~SkCodec() {}
 
 SkCodec::RewindState SkCodec::rewindIfNeeded() {
     // Store the value of fNeedsRewind so we can update it. Next read will
     // require a rewind.
     const bool needsRewind = fNeedsRewind;
     fNeedsRewind = true;
     if (!needsRewind) {
         return kNoRewindNecessary_RewindState;
     }
     return fStream->rewind() ? kRewound_RewindState
@@ skipping 47 matching lines @@
 
 SkScanlineDecoder* SkCodec::getScanlineDecoder(const SkImageInfo& dstInfo, const Options* options,
         SkPMColor ctable[], int* ctableCount) {
 
     // Set options.
     Options optsStorage;
     if (NULL == options) {
         options = &optsStorage;
     }
 
-    SkDELETE(fScanlineDecoder);
-    fScanlineDecoder = this->onGetScanlineDecoder(dstInfo, *options, ctable, ctableCount);
-    return fScanlineDecoder;
+    return this->onGetScanlineDecoder(dstInfo, *options, ctable, ctableCount);
 }
 
 SkScanlineDecoder* SkCodec::getScanlineDecoder(const SkImageInfo& dstInfo) {
     SkASSERT(kIndex_8_SkColorType != dstInfo.colorType());
     if (kIndex_8_SkColorType == dstInfo.colorType()) {
         return NULL;
     }
     return this->getScanlineDecoder(dstInfo, NULL, NULL, NULL);
 }