Adding png scanline decoding to kIndex8

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
 
@@ skipping 52 matching lines @@
      *  This object is owned by the SkCodec, which will handle its lifetime. The
      *  returned object is only valid until the SkCodec is deleted or the next
      *  call to getScanlineDecoder, whichever comes first.
      *
      *  Calling a second time will rewind and replace the existing one with a
      *  new one. If the stream cannot be rewound, this will delete the existing
      *  one and return NULL.
      *
      *  @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.  This color table will be
+     *      populated if the png has a color palette and we ask to decode in

[scroggo, 2015/04/21 21:43:05]

nit: "we ask to decode in" -> dstInfo.colorType() is

[msarett, 2015/04/22 14:32:52]

Done.

+     *      kIndex8 mode.
+     *  @param ctableCount A pointer to the size of the color table.  Will be
+     *      modified in kIndex8 mode if we have a color palette.

[scroggo, 2015/04/21 21:43:04]

modified to what?

[msarett, 2015/04/22 14:32:52]

Done.

      *  @return New SkScanlineDecoder, or NULL on failure.
      *
      *  NOTE: If any rows were previously decoded, this requires rewinding the
      *  SkStream.
      *
      *  NOTE: The scanline decoder is owned by the SkCodec and will delete it
      *  when the SkCodec is deleted.
      */
-    SkScanlineDecoder* getScanlineDecoder(const SkImageInfo& dstInfo);
+    SkScanlineDecoder* getScanlineDecoder(const SkImageInfo& dstInfo, const Options* options,

[scroggo, 2015/04/21 21:43:05]

Should we have a version that does not take Options or color table stuff, like
getPixels?

[msarett, 2015/04/22 14:32:52]

I have added this version.

+                                          SkPMColor ctable[], int* ctableCount);
 
     /**
      *  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 {
@@ skipping 27 matching lines @@
     virtual SkEncodedFormat onGetEncodedFormat() const = 0;
 
     /**
      *  Override if your codec supports scanline decoding.
      *
      *  As in onGetPixels(), the implementation must call rewindIfNeeded() and
      *  handle as appropriate.
      *
      *  @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.  This color table will be
+     *      populated if the png has a color palette and we ask to decode in

[scroggo, 2015/04/21 21:43:05]

same wording nit.

[msarett, 2015/04/22 14:32:52]

Done.

+     *      kIndex8 mode.
+     *  @param ctableCount A pointer to the size of the color table.  Will be
+     *      modified in kIndex8 mode if we have a color palette.

[scroggo, 2015/04/21 21:43:05]

same question

[msarett, 2015/04/22 14:32:52]

Done.

      *  @return New SkScanlineDecoder on success, NULL otherwise. The SkCodec
      *      will take ownership of the returned scanline decoder.
      */
-    virtual SkScanlineDecoder* onGetScanlineDecoder(const SkImageInfo& dstInfo) {
+    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
     };
@@ skipping 26 matching lines @@
 #ifdef SK_SUPPORT_LEGACY_BOOL_ONGETINFO
     const SkImageInfo                   fInfo;
 #endif  //  SK_SUPPORT_LEGACY_BOOL_ONGETINFO
     SkAutoTDelete<SkStream>             fStream;
     bool                                fNeedsRewind;
     SkAutoTDelete<SkScanlineDecoder>    fScanlineDecoder;
 
     typedef SkImageGenerator INHERITED;
 };
 #endif // SkCodec_DEFINED