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
diff --git a/tests/CodecTest.cpp b/tests/CodecTest.cpp
index 341433b..3248241 100644
--- a/tests/CodecTest.cpp
+++ b/tests/CodecTest.cpp
@@ -22,6 +22,13 @@
#include "png.h"
+#if PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR < 5
+ // FIXME (scroggo): Google3 needs to be updated to use a newer version of libpng. In
+ // the meantime, we had to break some pieces of SkPngCodec in order to support Google3.
+ // The parts that are broken are likely not used by Google3.
+ #define SK_PNG_DISABLE_TESTS
+#endif
+
static void md5(const SkBitmap& bm, SkMD5::Digest* digest) {
SkAutoLockPixels autoLockPixels(bm);
SkASSERT(bm.getPixels());
@@ -79,6 +86,62 @@
return rect;
}
+static void test_incremental_decode(skiatest::Reporter* r, SkCodec* codec, const SkImageInfo& info,
+ const SkMD5::Digest& goodDigest) {
+ SkBitmap bm;
+ bm.allocPixels(info);
+ SkAutoLockPixels autoLockPixels(bm);
+
+ REPORTER_ASSERT(r, SkCodec::kSuccess == codec->startIncrementalDecode(info, bm.getPixels(),
+ bm.rowBytes()));
+
+ REPORTER_ASSERT(r, SkCodec::kSuccess == codec->incrementalDecode());
+
+ compare_to_good_digest(r, goodDigest, bm);
+}
+
+// Test in stripes, similar to DM's kStripe_Mode
+static void test_in_stripes(skiatest::Reporter* r, SkCodec* codec, const SkImageInfo& info,
+ const SkMD5::Digest& goodDigest) {
+ SkBitmap bm;
+ bm.allocPixels(info);
+ bm.eraseColor(SK_ColorYELLOW);
+
+ const int height = info.height();
+ // Note that if numStripes does not evenly divide height there will be an extra
+ // stripe.
+ const int numStripes = 4;
+
+ if (numStripes > height) {
+ // Image is too small.
+ return;
+ }
+
+ const int stripeHeight = height / numStripes;
+
+ // Iterate through the image twice. Once to decode odd stripes, and once for even.
+ for (int oddEven = 1; oddEven >= 0; oddEven--) {
+ for (int y = oddEven * stripeHeight; y < height; y += 2 * stripeHeight) {
+ SkIRect subset = SkIRect::MakeLTRB(0, y, info.width(),
+ SkTMin(y + stripeHeight, height));
+ SkCodec::Options options;
+ options.fSubset = ⊂
+ if (SkCodec::kSuccess != codec->startIncrementalDecode(info, bm.getAddr(0, y),
+ bm.rowBytes(), &options)) {
+ ERRORF(r, "failed to start incremental decode!\ttop: %i\tbottom%i\n",
+ subset.top(), subset.bottom());
+ return;
+ }
+ if (SkCodec::kSuccess != codec->incrementalDecode()) {
+ ERRORF(r, "failed incremental decode starting from line %i\n", y);
+ return;
+ }
+ }
+ }
+
+ compare_to_good_digest(r, goodDigest, bm);
+}
+
template<typename Codec>
static void test_codec(skiatest::Reporter* r, Codec* codec, SkBitmap& bm, const SkImageInfo& info,
const SkISize& size, SkCodec::Result expectedResult, SkMD5::Digest* digest,
@@ -187,12 +250,14 @@
return false;
}
+// FIXME: Break up this giant function
static void check(skiatest::Reporter* r,
const char path[],
SkISize size,
bool supportsScanlineDecoding,
bool supportsSubsetDecoding,
- bool supportsIncomplete = true) {
+ bool supportsIncomplete,
+ bool supportsNewScanlineDecoding = false) {
SkAutoTDelete<SkStream> stream(GetResourceAsStream(path));
if (!stream) {
@@ -221,12 +286,15 @@
test_codec(r, codec.get(), bm, info, size, expectedResult, &codecDigest, nullptr);
// Scanline decoding follows.
- // Need to call startScanlineDecode() first.
- REPORTER_ASSERT(r, codec->getScanlines(bm.getAddr(0, 0), 1, 0)
- == 0);
- REPORTER_ASSERT(r, codec->skipScanlines(1)
- == 0);
+ if (supportsNewScanlineDecoding && !isIncomplete) {
+ test_incremental_decode(r, codec, info, codecDigest);
+ test_in_stripes(r, codec, info, codecDigest);
+ }
+
+ // Need to call startScanlineDecode() first.
+ REPORTER_ASSERT(r, codec->getScanlines(bm.getAddr(0, 0), 1, 0) == 0);
+ REPORTER_ASSERT(r, !codec->skipScanlines(1));
const SkCodec::Result startResult = codec->startScanlineDecode(info);
if (supportsScanlineDecoding) {
bm.eraseColor(SK_ColorYELLOW);
@@ -321,7 +389,7 @@
}
// SkAndroidCodec tests
- if (supportsScanlineDecoding || supportsSubsetDecoding) {
+ if (supportsScanlineDecoding || supportsSubsetDecoding || supportsNewScanlineDecoding) {
SkAutoTDelete<SkStream> stream(GetResourceAsStream(path));
if (!stream) {
@@ -359,6 +427,7 @@
REPORTER_ASSERT(r, gen->getPixels(info, bm.getPixels(), bm.rowBytes()));
compare_to_good_digest(r, codecDigest, bm);
+#ifndef SK_PNG_DISABLE_TESTS
// Test using SkFrontBufferedStream, as Android does
SkStream* bufferedStream = SkFrontBufferedStream::Create(
new SkMemoryStream(std::move(fullData)), SkCodec::MinBufferedBytesNeeded());
@@ -368,26 +437,28 @@
if (codec) {
test_info(r, codec.get(), info, SkCodec::kSuccess, &codecDigest);
}
+#endif
}
// If we've just tested incomplete decodes, let's run the same test again on full decodes.
if (isIncomplete) {
- check(r, path, size, supportsScanlineDecoding, supportsSubsetDecoding, false);
+ check(r, path, size, supportsScanlineDecoding, supportsSubsetDecoding, false,
+ supportsNewScanlineDecoding);
}
}
DEF_TEST(Codec, r) {
// WBMP
- check(r, "mandrill.wbmp", SkISize::Make(512, 512), true, false);
+ check(r, "mandrill.wbmp", SkISize::Make(512, 512), true, false, true);
// WEBP
- check(r, "baby_tux.webp", SkISize::Make(386, 395), false, true);
- check(r, "color_wheel.webp", SkISize::Make(128, 128), false, true);
- check(r, "yellow_rose.webp", SkISize::Make(400, 301), false, true);
+ check(r, "baby_tux.webp", SkISize::Make(386, 395), false, true, true);
+ check(r, "color_wheel.webp", SkISize::Make(128, 128), false, true, true);
+ check(r, "yellow_rose.webp", SkISize::Make(400, 301), false, true, true);
// BMP
- check(r, "randPixels.bmp", SkISize::Make(8, 8), true, false);
- check(r, "rle.bmp", SkISize::Make(320, 240), true, false);
+ check(r, "randPixels.bmp", SkISize::Make(8, 8), true, false, true);
+ check(r, "rle.bmp", SkISize::Make(320, 240), true, false, true);
// ICO
// FIXME: We are not ready to test incomplete ICOs
@@ -395,7 +466,7 @@
// Decodes an embedded BMP image
check(r, "color_wheel.ico", SkISize::Make(128, 128), true, false, false);
// Decodes an embedded PNG image
- check(r, "google_chrome.ico", SkISize::Make(256, 256), true, false, false);
+ check(r, "google_chrome.ico", SkISize::Make(256, 256), false, false, false, true);
// GIF
// FIXME: We are not ready to test incomplete GIFs
@@ -405,30 +476,30 @@
check(r, "randPixels.gif", SkISize::Make(8, 8), true, false, false);
// JPG
- check(r, "CMYK.jpg", SkISize::Make(642, 516), true, false);
- check(r, "color_wheel.jpg", SkISize::Make(128, 128), true, false);
+ check(r, "CMYK.jpg", SkISize::Make(642, 516), true, false, true);
+ check(r, "color_wheel.jpg", SkISize::Make(128, 128), true, false, true);
// grayscale.jpg is too small to test incomplete
check(r, "grayscale.jpg", SkISize::Make(128, 128), true, false, false);
- check(r, "mandrill_512_q075.jpg", SkISize::Make(512, 512), true, false);
+ check(r, "mandrill_512_q075.jpg", SkISize::Make(512, 512), true, false, true);
// randPixels.jpg is too small to test incomplete
check(r, "randPixels.jpg", SkISize::Make(8, 8), true, false, false);
// PNG
- check(r, "arrow.png", SkISize::Make(187, 312), true, false, false);
- check(r, "baby_tux.png", SkISize::Make(240, 246), true, false, false);
- check(r, "color_wheel.png", SkISize::Make(128, 128), true, false, false);
- check(r, "half-transparent-white-pixel.png", SkISize::Make(1, 1), true, false, false);
- check(r, "mandrill_128.png", SkISize::Make(128, 128), true, false, false);
- check(r, "mandrill_16.png", SkISize::Make(16, 16), true, false, false);
- check(r, "mandrill_256.png", SkISize::Make(256, 256), true, false, false);
- check(r, "mandrill_32.png", SkISize::Make(32, 32), true, false, false);
- check(r, "mandrill_512.png", SkISize::Make(512, 512), true, false, false);
- check(r, "mandrill_64.png", SkISize::Make(64, 64), true, false, false);
- check(r, "plane.png", SkISize::Make(250, 126), true, false, false);
- // FIXME: We are not ready to test incomplete interlaced pngs
- check(r, "plane_interlaced.png", SkISize::Make(250, 126), true, false, false);
- check(r, "randPixels.png", SkISize::Make(8, 8), true, false, false);
- check(r, "yellow_rose.png", SkISize::Make(400, 301), true, false, false);
+ check(r, "arrow.png", SkISize::Make(187, 312), false, false, true, true);
+ check(r, "baby_tux.png", SkISize::Make(240, 246), false, false, true, true);
+ check(r, "color_wheel.png", SkISize::Make(128, 128), false, false, true, true);
+ // half-transparent-white-pixel.png is too small to test incomplete
+ check(r, "half-transparent-white-pixel.png", SkISize::Make(1, 1), false, false, false, true);
+ check(r, "mandrill_128.png", SkISize::Make(128, 128), false, false, true, true);
+ check(r, "mandrill_16.png", SkISize::Make(16, 16), false, false, true, true);
+ check(r, "mandrill_256.png", SkISize::Make(256, 256), false, false, true, true);
+ check(r, "mandrill_32.png", SkISize::Make(32, 32), false, false, true, true);
+ check(r, "mandrill_512.png", SkISize::Make(512, 512), false, false, true, true);
+ check(r, "mandrill_64.png", SkISize::Make(64, 64), false, false, true, true);
+ check(r, "plane.png", SkISize::Make(250, 126), false, false, true, true);
+ check(r, "plane_interlaced.png", SkISize::Make(250, 126), false, false, true, true);
+ check(r, "randPixels.png", SkISize::Make(8, 8), false, false, true, true);
+ check(r, "yellow_rose.png", SkISize::Make(400, 301), false, false, true, true);
// RAW
// Disable RAW tests for Win32.
@@ -439,98 +510,6 @@
#endif
}
-// Test interlaced PNG in stripes, similar to DM's kStripe_Mode
-DEF_TEST(Codec_stripes, r) {
- const char * path = "plane_interlaced.png";
- SkAutoTDelete<SkStream> stream(GetResourceAsStream(path));
- REPORTER_ASSERT(r, stream);
- if (!stream) {
- return;
- }
-
- SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.release()));
- REPORTER_ASSERT(r, codec);
-
- if (!codec) {
- return;
- }
-
- switch (codec->getScanlineOrder()) {
- case SkCodec::kBottomUp_SkScanlineOrder:
- case SkCodec::kOutOfOrder_SkScanlineOrder:
- ERRORF(r, "This scanline order will not match the original.");
- return;
- default:
- break;
- }
-
- // Baseline for what the image should look like, using N32.
- const SkImageInfo info = codec->getInfo().makeColorType(kN32_SkColorType);
-
- SkBitmap bm;
- bm.allocPixels(info);
- SkAutoLockPixels autoLockPixels(bm);
- SkCodec::Result result = codec->getPixels(info, bm.getPixels(), bm.rowBytes());
- REPORTER_ASSERT(r, result == SkCodec::kSuccess);
-
- SkMD5::Digest digest;
- md5(bm, &digest);
-
- // Now decode in stripes
- const int height = info.height();
- const int numStripes = 4;
- int stripeHeight;
- int remainingLines;
- SkTDivMod(height, numStripes, &stripeHeight, &remainingLines);
-
- bm.eraseColor(SK_ColorYELLOW);
-
- result = codec->startScanlineDecode(info);
- REPORTER_ASSERT(r, result == SkCodec::kSuccess);
-
- // Odd stripes
- for (int i = 1; i < numStripes; i += 2) {
- // Skip the even stripes
- bool skipResult = codec->skipScanlines(stripeHeight);
- REPORTER_ASSERT(r, skipResult);
-
- int linesDecoded = codec->getScanlines(bm.getAddr(0, i * stripeHeight), stripeHeight,
- bm.rowBytes());
- REPORTER_ASSERT(r, linesDecoded == stripeHeight);
- }
-
- // Even stripes
- result = codec->startScanlineDecode(info);
- REPORTER_ASSERT(r, result == SkCodec::kSuccess);
-
- for (int i = 0; i < numStripes; i += 2) {
- int linesDecoded = codec->getScanlines(bm.getAddr(0, i * stripeHeight), stripeHeight,
- bm.rowBytes());
- REPORTER_ASSERT(r, linesDecoded == stripeHeight);
-
- // Skip the odd stripes
- if (i + 1 < numStripes) {
- bool skipResult = codec->skipScanlines(stripeHeight);
- REPORTER_ASSERT(r, skipResult);
- }
- }
-
- // Remainder at the end
- if (remainingLines > 0) {
- result = codec->startScanlineDecode(info);
- REPORTER_ASSERT(r, result == SkCodec::kSuccess);
-
- bool skipResult = codec->skipScanlines(height - remainingLines);
- REPORTER_ASSERT(r, skipResult);
-
- int linesDecoded = codec->getScanlines(bm.getAddr(0, height - remainingLines),
- remainingLines, bm.rowBytes());
- REPORTER_ASSERT(r, linesDecoded == remainingLines);
- }
-
- compare_to_good_digest(r, digest, bm);
-}
-
static void test_invalid_stream(skiatest::Reporter* r, const void* stream, size_t len) {
// Neither of these calls should return a codec. Bots should catch us if we leaked anything.
SkCodec* codec = SkCodec::NewFromStream(new SkMemoryStream(stream, len, false));
@@ -670,26 +649,41 @@
return;
}
SkAutoTDelete<SkCodec> decoder(SkCodec::NewFromStream(stream.release()));
+ if (!decoder) {
+ SkDebugf("Missing codec for %s\n", path);
+ return;
+ }
+
+ const SkImageInfo info = decoder->getInfo().makeColorType(kIndex_8_SkColorType);
// This should return kSuccess because kIndex8 is supported.
SkPMColor colorStorage[256];
int colorCount;
- SkCodec::Result result = decoder->startScanlineDecode(
- decoder->getInfo().makeColorType(kIndex_8_SkColorType), nullptr, colorStorage, &colorCount);
- REPORTER_ASSERT(r, SkCodec::kSuccess == result);
- // The rest of the test is uninteresting if kIndex8 is not supported
- if (SkCodec::kSuccess != result) {
+ SkCodec::Result result = decoder->startScanlineDecode(info, nullptr, colorStorage,
+ &colorCount);
+ if (SkCodec::kSuccess == result) {
+ // This should return kInvalidParameters because, in kIndex_8 mode, we must pass in a valid
+ // colorPtr and a valid colorCountPtr.
+ result = decoder->startScanlineDecode(info, nullptr, nullptr, nullptr);
+ REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
+ result = decoder->startScanlineDecode(info);
+ REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
+ } else if (SkCodec::kUnimplemented == result) {
+ // New method should be supported:
+ SkBitmap bm;
+ sk_sp<SkColorTable> colorTable(new SkColorTable(colorStorage, 256));
+ bm.allocPixels(info, nullptr, colorTable.get());
+ result = decoder->startIncrementalDecode(info, bm.getPixels(), bm.rowBytes(), nullptr,
+ colorStorage, &colorCount);
+ REPORTER_ASSERT(r, SkCodec::kSuccess == result);
+ result = decoder->startIncrementalDecode(info, bm.getPixels(), bm.rowBytes());
+ REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
+ } else {
+ // The test is uninteresting if kIndex8 is not supported
+ ERRORF(r, "Should not call test_invalid_parameters for non-Index8 file: %s\n", path);
return;
}
- // This should return kInvalidParameters because, in kIndex_8 mode, we must pass in a valid
- // colorPtr and a valid colorCountPtr.
- result = decoder->startScanlineDecode(
- decoder->getInfo().makeColorType(kIndex_8_SkColorType), nullptr, nullptr, nullptr);
- REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
- result = decoder->startScanlineDecode(
- decoder->getInfo().makeColorType(kIndex_8_SkColorType));
- REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
}
DEF_TEST(Codec_Params, r) {
@@ -697,6 +691,11 @@
test_invalid_parameters(r, "mandrill.wbmp");
}
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+
+#ifndef SK_PNG_DISABLE_TESTS // reading chunks does not work properly with older versions.
+ // It does not appear that anyone in Google3 is reading chunks.
+
static void codex_test_write_fn(png_structp png_ptr, png_bytep data, png_size_t len) {
SkWStream* sk_stream = (SkWStream*)png_get_io_ptr(png_ptr);
if (!sk_stream->write(data, len)) {
@@ -704,7 +703,6 @@
}
}
-#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
DEF_TEST(Codec_pngChunkReader, r) {
// Create a dummy bitmap. Use unpremul RGBA for libpng.
SkBitmap bm;
@@ -850,6 +848,7 @@
REPORTER_ASSERT(r, SkCodec::kSuccess == result);
REPORTER_ASSERT(r, chunkReader.allHaveBeenSeen());
}
+#endif // SK_PNG_DISABLE_TESTS
#endif // PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
// Stream that can only peek up to a limit
@@ -1167,7 +1166,8 @@
}
static void test_conversion_possible(skiatest::Reporter* r, const char* path,
- bool testScanlineDecoder) {
+ bool supportsScanlineDecoder,
+ bool supportsIncrementalDecoder) {
SkAutoTDelete<SkStream> stream(GetResourceAsStream(path));
SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.release()));
SkImageInfo infoF16 = codec->getInfo().makeColorType(kRGBA_F16_SkColorType);
@@ -1176,22 +1176,129 @@
bm.allocPixels(infoF16);
SkCodec::Result result = codec->getPixels(infoF16, bm.getPixels(), bm.rowBytes());
REPORTER_ASSERT(r, SkCodec::kInvalidConversion == result);
- if (testScanlineDecoder) {
- result = codec->startScanlineDecode(infoF16);
+
+ result = codec->startScanlineDecode(infoF16);
+ if (supportsScanlineDecoder) {
REPORTER_ASSERT(r, SkCodec::kInvalidConversion == result);
+ } else {
+ REPORTER_ASSERT(r, SkCodec::kUnimplemented == result);
+ }
+
+ result = codec->startIncrementalDecode(infoF16, bm.getPixels(), bm.rowBytes());
+ if (supportsIncrementalDecoder) {
+ REPORTER_ASSERT(r, SkCodec::kInvalidConversion == result);
+ } else {
+ REPORTER_ASSERT(r, SkCodec::kUnimplemented == result);
}
infoF16 = infoF16.makeColorSpace(infoF16.colorSpace()->makeLinearGamma());
result = codec->getPixels(infoF16, bm.getPixels(), bm.rowBytes());
REPORTER_ASSERT(r, SkCodec::kSuccess == result);
- if (testScanlineDecoder) {
- result = codec->startScanlineDecode(infoF16);
+ result = codec->startScanlineDecode(infoF16);
+ if (supportsScanlineDecoder) {
REPORTER_ASSERT(r, SkCodec::kSuccess == result);
+ } else {
+ REPORTER_ASSERT(r, SkCodec::kUnimplemented == result);
+ }
+
+ result = codec->startIncrementalDecode(infoF16, bm.getPixels(), bm.rowBytes());
+ if (supportsIncrementalDecoder) {
+ REPORTER_ASSERT(r, SkCodec::kSuccess == result);
+ } else {
+ REPORTER_ASSERT(r, SkCodec::kUnimplemented == result);
}
}
DEF_TEST(Codec_F16ConversionPossible, r) {
- test_conversion_possible(r, "color_wheel.webp", false);
- test_conversion_possible(r, "mandrill_512_q075.jpg", true);
- test_conversion_possible(r, "yellow_rose.png", true);
+ test_conversion_possible(r, "color_wheel.webp", false, false);
+ test_conversion_possible(r, "mandrill_512_q075.jpg", true, false);
+ test_conversion_possible(r, "yellow_rose.png", false, true);
+}
+
+// Only rewinds up to a limit.
+class LimitedRewindingStream : public SkStream {
+public:
+ static SkStream* Make(const char path[], size_t limit) {
+ SkStream* stream = GetResourceAsStream(path);
+ if (!stream) {
+ return nullptr;
+ }
+ return new LimitedRewindingStream(stream, limit);
+ }
+
+ size_t read(void* buffer, size_t size) override {
+ const size_t bytes = fStream->read(buffer, size);
+ fPosition += bytes;
+ return bytes;
+ }
+
+ bool isAtEnd() const override {
+ return fStream->isAtEnd();
+ }
+
+ bool rewind() override {
+ if (fPosition <= fLimit && fStream->rewind()) {
+ fPosition = 0;
+ return true;
+ }
+
+ return false;
+ }
+
+private:
+ SkAutoTDelete<SkStream> fStream;
+ const size_t fLimit;
+ size_t fPosition;
+
+ LimitedRewindingStream(SkStream* stream, size_t limit)
+ : fStream(stream)
+ , fLimit(limit)
+ , fPosition(0)
+ {
+ SkASSERT(fStream);
+ }
+};
+
+DEF_TEST(Codec_fallBack, r) {
+ // SkAndroidCodec needs to be able to fall back to scanline decoding
+ // if incremental decoding does not work. Make sure this does not
+ // require a rewind.
+
+ // Formats that currently do not support incremental decoding
+ auto files = {
+ "box.gif",
+ "CMYK.jpg",
+ "color_wheel.ico",
+ "mandrill.wbmp",
+ "randPixels.bmp",
+ };
+ for (auto file : files) {
+ SkStream* stream = LimitedRewindingStream::Make(file, 14);
+ if (!stream) {
+ SkDebugf("Missing resources (%s). Set --resourcePath.\n", file);
+ return;
+ }
+
+ SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream));
+ if (!codec) {
+ ERRORF(r, "Failed to create codec for %s,", file);
+ continue;
+ }
+
+ SkImageInfo info = codec->getInfo().makeColorType(kN32_SkColorType);
+ SkBitmap bm;
+ bm.allocPixels(info);
+
+ if (SkCodec::kUnimplemented != codec->startIncrementalDecode(info, bm.getPixels(),
+ bm.rowBytes())) {
+ ERRORF(r, "Is scanline decoding now implemented for %s?", file);
+ continue;
+ }
+
+ // Scanline decoding should not require a rewind.
+ SkCodec::Result result = codec->startScanlineDecode(info);
+ if (SkCodec::kSuccess != result) {
+ ERRORF(r, "Scanline decoding failed for %s with %i", file, result);
+ }
+ }
}