Consolidate SkCodec functions for handling rewind

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 171 matching lines @@
     dinfo.global_state = DSTATE_READY;
     dinfo.num_components = 0;
     dinfo.scale_num = num;
     dinfo.scale_denom = denom;
     turbo_jpeg_calc_output_dimensions(&dinfo);
 
     // Return the calculated output dimensions for the given scale
     return SkISize::Make(dinfo.output_width, dinfo.output_height);
 }
 
-/*
- * Handles rewinding the input stream if it is necessary
- */
-bool SkJpegCodec::handleRewind() {
-    switch(this->rewindIfNeeded()) {
-        case kCouldNotRewind_RewindState:
-            return fDecoderMgr->returnFalse("could not rewind");
-        case kRewound_RewindState: {
-            JpegDecoderMgr* decoderMgr = NULL;
-            if (!ReadHeader(this->stream(), NULL, &decoderMgr)) {
-                return fDecoderMgr->returnFalse("could not rewind");
-            }
-            SkASSERT(NULL != decoderMgr);
-            fDecoderMgr.reset(decoderMgr);
-            return true;
-        }
-        case kNoRewindNecessary_RewindState:
-            return true;
-        default:
-            SkASSERT(false);
-            return false;
+bool SkJpegCodec::onRewind() {
+    JpegDecoderMgr* decoderMgr = NULL;
+    if (!ReadHeader(this->stream(), NULL, &decoderMgr)) {
+        return fDecoderMgr->returnFalse("could not rewind");
     }
+    SkASSERT(NULL != decoderMgr);
+    fDecoderMgr.reset(decoderMgr);
+    return true;
 }
 
 /*
  * Checks if the conversion between the input image and the requested output
  * image has been implemented
  * Sets the output color space
  */
 bool SkJpegCodec::setOutputColorSpace(const SkImageInfo& dst) {
     const SkImageInfo& src = this->getInfo();
 
@@ skipping 73 matching lines @@
     return true;
 }
 
 /*
  * Performs the jpeg decode
  */
 SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
                                          void* dst, size_t dstRowBytes,
                                          const Options& options, SkPMColor*, int*) {
     // Rewind the stream if needed
-    if (!this->handleRewind()) {
+    if (!this->rewindIfNeeded()) {
         return fDecoderMgr->returnFailure("could not rewind stream", kCouldNotRewind);
     }
 
     if (options.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
     }
 
     // Get a pointer to the decompress info since we will use it quite frequently
     jpeg_decompress_struct* dinfo = fDecoderMgr->dinfo();
@@ skipping 74 matching lines @@
     SkJpegScanlineDecoder(const SkImageInfo& srcInfo, SkJpegCodec* codec)
         : INHERITED(srcInfo)
         , fCodec(codec)
         , fOpts()
     {}
 
     SkCodec::Result onStart(const SkImageInfo& dstInfo, const SkCodec::Options& options,
                             SkPMColor ctable[], int* ctableCount) override {
 
         // Rewind the stream if needed
-        if (!fCodec->handleRewind()) {
+        if (!fCodec->rewindIfNeeded()) {
             return SkCodec::kCouldNotRewind;
         }
 
         // Set the jump location for libjpeg errors
         if (setjmp(fCodec->fDecoderMgr->getJmpBuf())) {
             SkCodecPrintf("setjmp: Error from libjpeg\n");
             return SkCodec::kInvalidInput;
         }
 
         // Check if we can decode to the requested destination and set the output color space
@@ skipping 93 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()));
 }