SkISize SkSampledCodec::accountForNativeScaling(int* sampleSizePtr, int* nativeSampleSize) const {
SkISize preSampledSize = this->codec()->getInfo().dimensions();
int sampleSize = *sampleSizePtr;
SkASSERT(sampleSize > 1);
if (nativeSampleSize) {
*nativeSampleSize = 1;
}
// Only JPEG supports native downsampling.
if (this->codec()->getEncodedFormat() == SkEncodedImageFormat::kJPEG) {
// See if libjpeg supports this scale directly
switch (sampleSize) {
case 2:
case 4:
case 8:
// This class does not need to do any sampling.
*sampleSizePtr = 1;
return this->codec()->getScaledDimensions(get_scale_from_sample_size(sampleSize));
default:
break;
}
// Check if sampleSize is a multiple of something libjpeg can support.
int remainder;
const int sampleSizes[] = { 8, 4, 2 };
for (int supportedSampleSize : sampleSizes) {
int actualSampleSize;
SkTDivMod(sampleSize, supportedSampleSize, &actualSampleSize, &remainder);
if (0 == remainder) {
float scale = get_scale_from_sample_size(supportedSampleSize);
// this->codec() will scale to this size.
preSampledSize = this->codec()->getScaledDimensions(scale);
// And then this class will sample it.
*sampleSizePtr = actualSampleSize;
if (nativeSampleSize) {
*nativeSampleSize = supportedSampleSize;
}
break;
}
}
}
return preSampledSize;
}
// 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(resource(path));
if (!stream) {
SkDebugf("Missing resource '%s'\n", path);
}
SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.detach()));
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);
}
