Add an option on SkImageDecoder to skip writing 0s.

src/images/SkImageDecoder.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkImageDecoder.h"
 #include "SkBitmap.h"
@@ skipping 22 matching lines @@
 ///////////////////////////////////////////////////////////////////////////////
 
 SkImageDecoder::SkImageDecoder()
     : fPeeker(NULL)
     , fChooser(NULL)
     , fAllocator(NULL)
     , fSampleSize(1)
     , fDefaultPref(SkBitmap::kNo_Config)
     , fDitherImage(true)
     , fUsePrefTable(false)
+    , fSkipWritingZeroes(false)
     , fPreferQualityOverSpeed(false)
     , fRequireUnpremultipliedColors(false) {
 }
 
 SkImageDecoder::~SkImageDecoder() {
     SkSafeUnref(fPeeker);
     SkSafeUnref(fChooser);
     SkSafeUnref(fAllocator);
 }
 
 void SkImageDecoder::copyFieldsToOther(SkImageDecoder* other) {
     if (NULL == other) {
         return;
     }
     other->setPeeker(fPeeker);
     other->setChooser(fChooser);
     other->setAllocator(fAllocator);
     other->setSampleSize(fSampleSize);
     if (fUsePrefTable) {
         other->setPrefConfigTable(fPrefTable);
     } else {
         other->fDefaultPref = fDefaultPref;
     }
+    other->setDitherImage(fDitherImage);
+    other->setSkipWritingZeroes(fSkipWritingZeroes);
     other->setPreferQualityOverSpeed(fPreferQualityOverSpeed);
     other->setRequireUnpremultipliedColors(fRequireUnpremultipliedColors);
 }
 
 SkImageDecoder::Format SkImageDecoder::getFormat() const {
     return kUnknown_Format;
 }
 
 const char* SkImageDecoder::getFormatName() const {
     return GetFormatName(this->getFormat());
@@ skipping 384 matching lines @@
             if (kUnknown_Format == *format) {
                 if (stream->rewind()) {
                     *format = GetStreamFormat(stream);
                 }
             }
         }
         delete codec;
     }
     return success;
 }