Make SkPngCodec decode progressively.

This is a step towards using SkCodec in Chromium, where progressive
decoding is necessary.

Switch from using png_read_row (which expects all the data to be
available) to png_process_data, which uses callbacks when rows are
available.

Create a new API for SkCodec, which supports progressive decoding and
scanline decoding. Future changes will switch the other clients off of
startScanlineDecode and get/skip-Scanlines to the new API.

Remove SkCodec::kNone_ScanlineOrder, which was only used for interlaced
PNG images. In the new API, interlaced PNG fits kTopDown. Also remove
updateCurrScanline(), which was only used by the old implementation for
interlaced PNG.

DMSrcSink:
- In CodecSrc::kScanline_Mode, use the new method for scanline decoding
for the supported formats (just PNG and PNG-in-ICO for now).

fuzz.cpp:
- Remove reference to kNone_ScanlineOrder

SkCodec:
- Add new APIs:
    - startIncrementalDecode
    - incrementalDecode
- Remove kNone_SkScanlineOrder and updateCurrScanline()
- Set fDstInfo and fOptions in getPixels(). This may not be necessary
  for all implementations, but it simplifies things for SkPngCodec.

SkPngCodec:
- Implement new APIs
- Switch from sk_read_fn/png_read_row etc to png_process_data
- Expand AutoCleanPng's role to decode the header and create the
  SkPngCodec
- Make the interlaced PNG decoder report how many lines were
  initialized during an incomplete decode

SkIcoCodec:
- Implement the new APIs; supported for PNG in ICO

SkSampledCodec:
- Call the new method for decoding scanlines, and fall back to the old
  method if the new version is unimplemented
- Remove references to kNone_SkScanlineOrder

tests/CodecPartial:
- Add a test which decodes part of an image, then finishes the decode,
  and compares it to the straightforward method

tests/CodecTest:
- Add a test which decodes all scanlines using the new method
- Repurpose the Codec_stripes test to decode using the new method in
  sections rather than all at once
- In the method check(), add a parameter for whether the image supports
  the new method of scanline decoding, and be explicit about whether an
  image supports incomplete
- Test incomplete PNG decodes. We should have been doing it anyway for
  non-interlaced (except for an image that is too small - one row), but
  the new method supports interlaced incomplete as well
- Make test_invalid_parameters test the new method
- Add a test to ensure that it's safe to fall back to scanline decoding without
  rewinding

BUG=skia:4211

The new version was generally faster than the old version (but not significantly so).

Some raw performance differences can be found at https://docs.google.com/a/google.com/spreadsheets/d/1Gis3aRCEa72qBNDRMgGDg3jD-pMgO-FXldlNF9ejo4o/

Design doc can be found at https://docs.google.com/a/google.com/document/d/11Mn8-ePDKwVEMCjs3nWwSjxcSpJ_Cu8DF57KNtUmgLM/

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1997703003

Review-Url: https://codereview.chromium.org/1997703003

1 files changed, 99 insertions, 33 deletions

diff --git a/src/codec/SkCodec.cpp b/src/codec/SkCodec.cpp
index 6f298700b7..84afc2bdee 100644
--- a/src/codec/SkCodec.cpp
+++ b/src/codec/SkCodec.cpp
@@ -158,6 +158,8 @@ bool SkCodec::rewindIfNeeded() {
 
     // startScanlineDecode will need to be called before decoding scanlines.
     fCurrScanline = -1;
+    // startIncrementalDecode will need to be called before incrementalDecode.
+    fStartedIncrementalDecode = false;
 
     if (!fStream->rewind()) {
         return false;
@@ -166,6 +168,20 @@ bool SkCodec::rewindIfNeeded() {
     return this->onRewind();
 }
 
+#define CHECK_COLOR_TABLE                                   \
+    if (kIndex_8_SkColorType == info.colorType()) {         \
+        if (nullptr == ctable || nullptr == ctableCount) {  \
+            return SkCodec::kInvalidParameters;             \
+        }                                                   \
+    } else {                                                \
+        if (ctableCount) {                                  \
+            *ctableCount = 0;                               \
+        }                                                   \
+        ctableCount = nullptr;                              \
+        ctable = nullptr;                                   \
+    }
+
+
 SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                                    const Options* options, SkPMColor ctable[], int* ctableCount) {
     if (kUnknown_SkColorType == info.colorType()) {
@@ -178,17 +194,7 @@ SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t
         return kInvalidParameters;
     }
 
-    if (kIndex_8_SkColorType == info.colorType()) {
-        if (nullptr == ctable || nullptr == ctableCount) {
-            return kInvalidParameters;
-        }
-    } else {
-        if (ctableCount) {
-            *ctableCount = 0;
-        }
-        ctableCount = nullptr;
-        ctable = nullptr;
-    }
+    CHECK_COLOR_TABLE;
 
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
@@ -213,6 +219,11 @@ SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t
         return kInvalidScale;
     }
 
+    fDstInfo = info;
+    // FIXME: fOptions should be updated to options here, since fillIncompleteImage (called below
+    // in this method) accesses it. Without updating, it uses the old value.
+    //fOptions = *options;
+
     // On an incomplete decode, the subclass will specify the number of scanlines that it decoded
     // successfully.
     int rowsDecoded = 0;
@@ -240,23 +251,78 @@ SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t
     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;
+SkCodec::Result SkCodec::startIncrementalDecode(const SkImageInfo& info, void* pixels,
+        size_t rowBytes, const SkCodec::Options* options, SkPMColor* ctable, int* ctableCount) {
+    fStartedIncrementalDecode = false;
+
+    if (kUnknown_SkColorType == info.colorType()) {
+        return kInvalidConversion;
+    }
+    if (nullptr == pixels) {
+        return kInvalidParameters;
+    }
+
     // 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;
+    CHECK_COLOR_TABLE;
+
+    // FIXME: If the rows come after the rows of a previous incremental decode,
+    // we might be able to skip the rewind, but only the implementation knows
+    // that. (e.g. PNG will always need to rewind, since we called longjmp, but
+    // a bottom-up BMP could skip rewinding if the new rows are above the old
+    // rows.)
+    if (!this->rewindIfNeeded()) {
+        return kCouldNotRewind;
+    }
+
+    // Set options.
+    Options optsStorage;
+    if (nullptr == options) {
+        options = &optsStorage;
+    } else if (options->fSubset) {
+        SkIRect size = SkIRect::MakeSize(info.dimensions());
+        if (!size.contains(*options->fSubset)) {
+            return kInvalidParameters;
         }
-    } else {
-        if (ctableCount) {
-            *ctableCount = 0;
+
+        const int top = options->fSubset->top();
+        const int bottom = options->fSubset->bottom();
+        if (top < 0 || top >= info.height() || top >= bottom || bottom > info.height()) {
+            return kInvalidParameters;
         }
-        ctableCount = nullptr;
-        ctable = nullptr;
     }
 
+    if (!this->dimensionsSupported(info.dimensions())) {
+        return kInvalidScale;
+    }
+
+    fDstInfo = info;
+    fOptions = *options;
+
+    const Result result = this->onStartIncrementalDecode(info, pixels, rowBytes,
+            fOptions, ctable, ctableCount);
+    if (kSuccess == result) {
+        fStartedIncrementalDecode = true;
+    } else if (kUnimplemented == result) {
+        // FIXME: This is temporarily necessary, until we transition SkCodec
+        // implementations from scanline decoding to incremental decoding.
+        // SkAndroidCodec will first attempt to use incremental decoding, but
+        // will fall back to scanline decoding if incremental returns
+        // kUnimplemented. rewindIfNeeded(), above, set fNeedsRewind to true
+        // (after potentially rewinding), but we do not want the next call to
+        // startScanlineDecode() to do a rewind.
+        fNeedsRewind = false;
+    }
+    return result;
+}
+
+
+SkCodec::Result SkCodec::startScanlineDecode(const SkImageInfo& info,
+        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
+    CHECK_COLOR_TABLE;
+
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
@@ -266,36 +332,38 @@ SkCodec::Result SkCodec::startScanlineDecode(const SkImageInfo& dstInfo,
     if (nullptr == options) {
         options = &optsStorage;
     } else if (options->fSubset) {
-        SkIRect size = SkIRect::MakeSize(dstInfo.dimensions());
+        SkIRect size = SkIRect::MakeSize(info.dimensions());
         if (!size.contains(*options->fSubset)) {
             return kInvalidInput;
         }
 
         // We only support subsetting in the x-dimension for scanline decoder.
         // Subsetting in the y-dimension can be accomplished using skipScanlines().
-        if (options->fSubset->top() != 0 || options->fSubset->height() != dstInfo.height()) {
+        if (options->fSubset->top() != 0 || options->fSubset->height() != info.height()) {
             return kInvalidInput;
         }
     }
 
     // FIXME: Support subsets somehow?
-    if (!this->dimensionsSupported(dstInfo.dimensions())) {
+    if (!this->dimensionsSupported(info.dimensions())) {
         return kInvalidScale;
     }
 
-    const Result result = this->onStartScanlineDecode(dstInfo, *options, ctable, ctableCount);
+    const Result result = this->onStartScanlineDecode(info, *options, ctable, ctableCount);
     if (result != SkCodec::kSuccess) {
         return result;
     }
 
     fCurrScanline = 0;
-    fDstInfo = dstInfo;
+    fDstInfo = info;
     fOptions = *options;
     return kSuccess;
 }
 
-SkCodec::Result SkCodec::startScanlineDecode(const SkImageInfo& dstInfo) {
-    return this->startScanlineDecode(dstInfo, nullptr, nullptr, nullptr);
+#undef CHECK_COLOR_TABLE
+
+SkCodec::Result SkCodec::startScanlineDecode(const SkImageInfo& info) {
+    return this->startScanlineDecode(info, nullptr, nullptr, nullptr);
 }
 
 int SkCodec::getScanlines(void* dst, int countLines, size_t rowBytes) {
@@ -343,7 +411,6 @@ int SkCodec::outputScanline(int inputScanline) const {
 int SkCodec::onOutputScanline(int inputScanline) const {
     switch (this->getScanlineOrder()) {
         case kTopDown_SkScanlineOrder:
-        case kNone_SkScanlineOrder:
             return inputScanline;
         case kBottomUp_SkScanlineOrder:
             return this->getInfo().height() - inputScanline - 1;
@@ -393,8 +460,7 @@ void SkCodec::fillIncompleteImage(const SkImageInfo& info, void* dst, size_t row
     }
 
     switch (this->getScanlineOrder()) {
-        case kTopDown_SkScanlineOrder:
-        case kNone_SkScanlineOrder: {
+        case kTopDown_SkScanlineOrder: {
             const SkImageInfo fillInfo = info.makeWH(fillWidth, linesRemaining);
             fillDst = SkTAddOffset<void>(dst, linesDecoded * rowBytes);
             fill_proc(fillInfo, fillDst, rowBytes, fillValue, zeroInit, sampler);