Merge SkCodec with SkScanlineDecoder

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"
@@ skipping 58 matching lines @@
 }
 
 SkCodec* SkCodec::NewFromData(SkData* data) {
     if (!data) {
         return nullptr;
     }
     return NewFromStream(new SkMemoryStream(data));
 }
 
 SkCodec::SkCodec(const SkImageInfo& info, SkStream* stream)
-    : fInfo(info)
+    : fSrcInfo(info)
     , fStream(stream)
     , fNeedsRewind(false)
+    , fDstInfo()
+    , fOptions()
+    , fCurrScanline(-1)
 {}
 
 SkCodec::~SkCodec() {}
 
 bool SkCodec::rewindIfNeeded() {
     // Store the value of fNeedsRewind so we can update it. Next read will
     // require a rewind.
     const bool needsRewind = fNeedsRewind;
     fNeedsRewind = true;
     if (!needsRewind) {
         return true;
     }
 
+    // startScanlineDecode will need to be called before decoding scanlines.
+    fCurrScanline = -1;
+
     if (!fStream->rewind()) {
         return false;
     }
 
     return this->onRewind();
 }
 
 SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                                    const Options* options, SkPMColor ctable[], int* ctableCount) {
     if (kUnknown_SkColorType == info.colorType()) {
@@ skipping 36 matching lines @@
 
     if ((kIncompleteInput == result || kSuccess == result) && ctableCount) {
         SkASSERT(*ctableCount >= 0 && *ctableCount <= 256);
     }
     return result;
 }
 
 SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes) {
     return this->getPixels(info, pixels, rowBytes, nullptr, nullptr, nullptr);
 }
+
+SkCodec::Result SkCodec::startScanlineDecode(const SkImageInfo& dstInfo,
+        const SkCodec::Options* options, SkPMColor ctable[], int* ctableCount) {
+    // Reset fCurrScanline in case of failure.
+    fCurrScanline = -1;
+    // Ensure that valid color ptrs are passed in for kIndex8 color type
+    if (kIndex_8_SkColorType == dstInfo.colorType()) {
+        if (nullptr == ctable || nullptr == ctableCount) {
+            return SkCodec::kInvalidParameters;
+        }
+    } else {
+        if (ctableCount) {
+            *ctableCount = 0;
+        }
+        ctableCount = nullptr;
+        ctable = nullptr;
+    }
+
+    // Set options.
+    Options optsStorage;
+    if (nullptr == options) {
+        options = &optsStorage;
+    }
+
+    const Result result = this->onStartScanlineDecode(dstInfo, *options, ctable, ctableCount);
+    if (result != SkCodec::kSuccess) {
+        return result;
+    }
+
+    fCurrScanline = 0;
+    fDstInfo = dstInfo;
+    fOptions = *options;
+    return kSuccess;
+}
+
+SkCodec::Result SkCodec::startScanlineDecode(const SkImageInfo& dstInfo) {
+    return this->startScanlineDecode(dstInfo, nullptr, nullptr, nullptr);
+}
+
+SkCodec::Result SkCodec::getScanlines(void* dst, int countLines, size_t rowBytes) {
+    if (fCurrScanline < 0) {
+        return kScanlineDecodingNotStarted;
+    }
+
+    SkASSERT(!fDstInfo.isEmpty());
+    if ((rowBytes < fDstInfo.minRowBytes() && countLines > 1 ) || countLines <= 0
+         || fCurrScanline + countLines > fDstInfo.height()) {
+        return kInvalidParameters;
+    }
+
+    const Result result = this->onGetScanlines(dst, countLines, rowBytes);
+    fCurrScanline += countLines;
+    return result;
+}
+
+SkCodec::Result SkCodec::skipScanlines(int countLines) {
+    if (fCurrScanline < 0) {
+        return kScanlineDecodingNotStarted;
+    }
+
+    SkASSERT(!fDstInfo.isEmpty());
+    if (fCurrScanline + countLines > fDstInfo.height()) {
+        // Arguably, we could just skip the scanlines which are remaining,
+        // and return kSuccess. We choose to return invalid so the client
+        // can catch their bug.
+        return SkCodec::kInvalidParameters;
+    }
+
+    const Result result = this->onSkipScanlines(countLines);
+    fCurrScanline += countLines;
+    return result;
+}