Create a scanline decoder without creating a codec

include/codec/SkCodec.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCodec_DEFINED
 #define SkCodec_DEFINED
 
 #include "SkColor.h"
 #include "SkEncodedFormat.h"
 #include "SkImageInfo.h"
 #include "SkSize.h"
 #include "SkStream.h"
 #include "SkTemplates.h"
 #include "SkTypes.h"
 
 class SkData;
-class SkScanlineDecoder;
 
 /**
  *  Abstraction layer directly on top of an image codec.
  */
 class SkCodec : SkNoncopyable {
 public:
     /**
      *  If this stream represents an encoded image that we know how to decode,
      *  return an SkCodec that can decode it. Otherwise return NULL.
      *
@@ skipping 164 matching lines @@
     Result getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, const Options*,
                      SkPMColor ctable[], int* ctableCount);
 
     /**
      *  Simplified version of getPixels() that asserts that info is NOT kIndex8_SkColorType and
      *  uses the default Options.
      */
     Result getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes);
 
     /**
-     *  Create a new object which can be used to decode individual scanlines.
-     *
-     *  The returned object has its own state, independent of the SkCodec, or any
-     *  previously spawned SkScanlineDecoders. At creation, it will be ready to
-     *  return the first scanline.
-     *
-     *  @param dstInfo Info of the destination. If the dimensions do not match
-     *      those of getInfo, this implies a scale.
-     *  @param options Contains decoding options, including if memory is zero
-     *      initialized.
-     *  @param ctable A pointer to a color table.  When dstInfo.colorType() is
-     *      kIndex8, this should be non-NULL and have enough storage for 256
-     *      colors.  The color table will be populated after decoding the palette.
-     *  @param ctableCount A pointer to the size of the color table.  When
-     *      dstInfo.colorType() is kIndex8, this should be non-NULL.  It will
-     *      be modified to the true size of the color table (<= 256) after
-     *      decoding the palette.
-     *  @return New SkScanlineDecoder, or NULL on failure.
-     *
-     *  NOTE: This requires duplicating the SkStream.
-     */
-    SkScanlineDecoder* getScanlineDecoder(const SkImageInfo& dstInfo, const Options* options,
-                                          SkPMColor ctable[], int* ctableCount);
-
-    /**
-     *  Simplified version of getScanlineDecoder() that asserts that info is NOT
-     *  kIndex8_SkColorType and uses the default Options.
-     */
-    SkScanlineDecoder* getScanlineDecoder(const SkImageInfo& dstInfo);
-
-    /**
      *  Some images may initially report that they have alpha due to the format
      *  of the encoded data, but then never use any colors which have alpha
      *  less than 100%. This function can be called *after* decoding to
      *  determine if such an image truly had alpha. Calling it before decoding
      *  is undefined.
      *  FIXME: see skbug.com/3582.
      */
     bool reallyHasAlpha() const {
         return this->onReallyHasAlpha();
     }
@@ skipping 10 matching lines @@
 
     virtual Result onGetPixels(const SkImageInfo& info,
                                void* pixels, size_t rowBytes, const Options&,
                                SkPMColor ctable[], int* ctableCount) = 0;
 
     virtual bool onGetValidSubset(SkIRect* /* desiredSubset */) const {
         // By default, subsets are not supported.
         return false;
     }
 
-    /**
-     *  Override if your codec supports scanline decoding.
-     *
-     *  @param dstInfo Info of the destination. If the dimensions do not match
-     *      those of getInfo, this implies a scale.
-     *  @param options Contains decoding options, including if memory is zero
-     *      initialized.
-     *  @param ctable A pointer to a color table.  When dstInfo.colorType() is
-     *      kIndex8, this should be non-NULL and have enough storage for 256
-     *      colors.  The color table will be populated after decoding the palette.
-     *  @param ctableCount A pointer to the size of the color table.  When
-     *      dstInfo.colorType() is kIndex8, this should be non-NULL.  It will
-     *      be modified to the true size of the color table (<= 256) after
-     *      decoding the palette.
-     *  @return New SkScanlineDecoder on success, NULL otherwise. The caller is
-     *      responsible for deleting the returned object.
-     */
-    virtual SkScanlineDecoder* onGetScanlineDecoder(const SkImageInfo& dstInfo,
-                                                    const Options& options,
-                                                    SkPMColor ctable[],
-                                                    int* ctableCount) {
-        return NULL;
-    }
-
     virtual bool onReallyHasAlpha() const { return false; }
 
     enum RewindState {
         kRewound_RewindState,
         kNoRewindNecessary_RewindState,
         kCouldNotRewind_RewindState
     };
     /**
      *  If the stream was previously read, attempt to rewind.
      *  @returns:
@@ skipping 16 matching lines @@
     SkStream* stream() {
         return fStream.get();
     }
 
 private:
     const SkImageInfo       fInfo;
     SkAutoTDelete<SkStream> fStream;
     bool                    fNeedsRewind;
 };
 #endif // SkCodec_DEFINED