Add SkPngChunkReader.

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 "SkBmpCodec.h"
 #include "SkCodec.h"
 #include "SkData.h"
 #include "SkCodec_libgif.h"
 #include "SkCodec_libico.h"
 #include "SkCodec_libpng.h"
 #include "SkCodec_wbmp.h"
 #include "SkCodecPriv.h"
 #if !defined(GOOGLE3)
 #include "SkJpegCodec.h"
 #endif
 #include "SkStream.h"
 #include "SkWebpCodec.h"
 
 struct DecoderProc {
     bool (*IsFormat)(SkStream*);
     SkCodec* (*NewFromStream)(SkStream*);
 };
 
 static const DecoderProc gDecoderProcs[] = {
-    { SkPngCodec::IsPng, SkPngCodec::NewFromStream },
 #if !defined(GOOGLE3)
     { SkJpegCodec::IsJpeg, SkJpegCodec::NewFromStream },
 #endif
     { SkWebpCodec::IsWebp, SkWebpCodec::NewFromStream },
     { SkGifCodec::IsGif, SkGifCodec::NewFromStream },
     { SkIcoCodec::IsIco, SkIcoCodec::NewFromStream },
     { SkBmpCodec::IsBmp, SkBmpCodec::NewFromStream },
     { SkWbmpCodec::IsWbmp, SkWbmpCodec::NewFromStream }
 };
 
-SkCodec* SkCodec::NewFromStream(SkStream* stream) {
+SkCodec* SkCodec::NewFromStream(SkStream* stream,
+                                SkPngChunkReader* chunkReader) {
     if (!stream) {
         return nullptr;
     }
 
     SkAutoTDelete<SkStream> streamDeleter(stream);
     
     SkAutoTDelete<SkCodec> codec(nullptr);
-    for (uint32_t i = 0; i < SK_ARRAY_COUNT(gDecoderProcs); i++) {
-        DecoderProc proc = gDecoderProcs[i];
-        const bool correctFormat = proc.IsFormat(stream);
-        if (!stream->rewind()) {
-            return nullptr;
-        }
-        if (correctFormat) {
-            codec.reset(proc.NewFromStream(streamDeleter.detach()));
-            break;
+    // PNG is special, since we want to be able to supply an SkPngChunkReader.
+    // But this code follows the same pattern as the loop.
+    const bool isPng = SkPngCodec::IsPng(stream);
+    if (!stream->rewind()) {
+        return NULL;
+    }
+    if (isPng) {
+        codec.reset(SkPngCodec::NewFromStream(streamDeleter.detach(), chunkReader));
+    } else {
+        for (DecoderProc proc : gDecoderProcs) {
+            const bool correctFormat = proc.IsFormat(stream);
+            if (!stream->rewind()) {
+                return nullptr;
+            }
+            if (correctFormat) {
+                codec.reset(proc.NewFromStream(streamDeleter.detach()));
+                break;
+            }
         }
     }
 
     // Set the max size at 128 megapixels (512 MB for kN32).
     // This is about 4x smaller than a test image that takes a few minutes for
     // dm to decode and draw.
     const int32_t maxSize = 1 << 27;
     if (codec && codec->getInfo().width() * codec->getInfo().height() > maxSize) {
         SkCodecPrintf("Error: Image size too large, cannot decode.\n");
         return nullptr;
     } else {
         return codec.detach();
     }
 }
 
-SkCodec* SkCodec::NewFromData(SkData* data) {
+SkCodec* SkCodec::NewFromData(SkData* data, SkPngChunkReader* reader) {
     if (!data) {
         return nullptr;
     }
-    return NewFromStream(new SkMemoryStream(data));
+    return NewFromStream(new SkMemoryStream(data), reader);
 }
 
 SkCodec::SkCodec(const SkImageInfo& info, SkStream* stream)
     : fSrcInfo(info)
     , fStream(stream)
     , fNeedsRewind(false)
     , fDstInfo()
     , fOptions()
     , fCurrScanline(-1)
 {}
@@ skipping 257 matching lines @@
             SkASSERT(1 == linesRequested || this->getInfo().height() == linesRequested);
             const SkImageInfo fillInfo = info.makeWH(info.width(), 1);
             for (int srcY = linesDecoded; srcY < linesRequested; srcY++) {
                 fillDst = SkTAddOffset<void>(dst, this->outputScanline(srcY) * rowBytes);
                 fill_proc(fillInfo, fillDst, rowBytes, fillValue, zeroInit, sampler);
             }
             break;
         }
     }
 }