/*
* 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 "SkCodecPriv.h"
#include "SkColorSpaceXform.h"
#include "SkSampler.h"
#include "SkStreamPriv.h"
#include "SkTemplates.h"
#include "SkWebpCodec.h"
// A WebP decoder on top of (subset of) libwebp
// For more information on WebP image format, and libwebp library, see:
// https://code.google.com/speed/webp/
// http://www.webmproject.org/code/#libwebp-webp-image-library
// https://chromium.googlesource.com/webm/libwebp
// If moving libwebp out of skia source tree, path for webp headers must be
// updated accordingly. Here, we enforce using local copy in webp sub-directory.
#include "webp/decode.h"
#include "webp/demux.h"
#include "webp/encode.h"
bool SkWebpCodec::IsWebp(const void* buf, size_t bytesRead) {
// WEBP starts with the following:
// RIFFXXXXWEBPVP
// Where XXXX is unspecified.
const char* bytes = static_cast<const char*>(buf);
return bytesRead >= 14 && !memcmp(bytes, "RIFF", 4) && !memcmp(&bytes[8], "WEBPVP", 6);
}
// Parse headers of RIFF container, and check for valid Webp (VP8) content.
// NOTE: This calls peek instead of read, since onGetPixels will need these
// bytes again.
// Returns an SkWebpCodec on success;
SkCodec* SkWebpCodec::NewFromStream(SkStream* stream) {
std::unique_ptr<SkStream> streamDeleter(stream);
// Webp demux needs a contiguous data buffer.
sk_sp<SkData> data = nullptr;
if (stream->getMemoryBase()) {
// It is safe to make without copy because we'll hold onto the stream.
data = SkData::MakeWithoutCopy(stream->getMemoryBase(), stream->getLength());
} else {
data = SkCopyStreamToData(stream);
// If we are forced to copy the stream to a data, we can go ahead and delete the stream.
streamDeleter.reset(nullptr);
}
// It's a little strange that the |demux| will outlive |webpData|, though it needs the
// pointer in |webpData| to remain valid. This works because the pointer remains valid
// until the SkData is freed.
WebPData webpData = { data->bytes(), data->size() };
SkAutoTCallVProc<WebPDemuxer, WebPDemuxDelete> demux(WebPDemuxPartial(&webpData, nullptr));
if (nullptr == demux) {
return nullptr;
}
const int width = WebPDemuxGetI(demux, WEBP_FF_CANVAS_WIDTH);
const int height = WebPDemuxGetI(demux, WEBP_FF_CANVAS_HEIGHT);
// Sanity check for image size that's about to be decoded.
{
const int64_t size = sk_64_mul(width, height);
if (!sk_64_isS32(size)) {
return nullptr;
}
// now check that if we are 4-bytes per pixel, we also don't overflow
if (sk_64_asS32(size) > (0x7FFFFFFF >> 2)) {
return nullptr;
}
}
WebPChunkIterator chunkIterator;
SkAutoTCallVProc<WebPChunkIterator, WebPDemuxReleaseChunkIterator> autoCI(&chunkIterator);
sk_sp<SkColorSpace> colorSpace = nullptr;
bool unsupportedICC = false;
if (WebPDemuxGetChunk(demux, "ICCP", 1, &chunkIterator)) {
colorSpace = SkColorSpace::MakeICC(chunkIterator.chunk.bytes, chunkIterator.chunk.size);
if (!colorSpace) {
unsupportedICC = true;
}
}
if (!colorSpace) {
colorSpace = SkColorSpace::MakeSRGB();
}
// Get the first frame and its "features" to determine the color and alpha types.
// Since we do not yet support animated webp, this is the only frame that we will
// decode.
WebPIterator frame;
SkAutoTCallVProc<WebPIterator, WebPDemuxReleaseIterator> autoFrame(&frame);
if (!WebPDemuxGetFrame(demux, 1, &frame)) {
return nullptr;
}
WebPBitstreamFeatures features;
VP8StatusCode status = WebPGetFeatures(frame.fragment.bytes, frame.fragment.size, &features);
if (VP8_STATUS_OK != status) {
return nullptr;
}
SkEncodedInfo::Color color;
SkEncodedInfo::Alpha alpha;
switch (features.format) {
case 0:
// This indicates a "mixed" format. We could see this for
// animated webps (multiple fragments).
// I believe that this is a rare case.
// We could also guess kYUV here, but I think it makes more
// sense to guess kBGRA which is likely closer to the final
// output. Otherwise, we might end up converting
// BGRA->YUVA->BGRA.
color = SkEncodedInfo::kBGRA_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
break;
case 1:
// This is the lossy format (YUV).
if (SkToBool(features.has_alpha) || frame.width != width || frame.height != height) {
color = SkEncodedInfo::kYUVA_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
} else {
color = SkEncodedInfo::kYUV_Color;
alpha = SkEncodedInfo::kOpaque_Alpha;
}
break;
case 2:
// This is the lossless format (BGRA).
color = SkEncodedInfo::kBGRA_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
break;
default:
return nullptr;
}
SkEncodedInfo info = SkEncodedInfo::Make(color, alpha, 8);
SkWebpCodec* codecOut = new SkWebpCodec(width, height, info, std::move(colorSpace),
streamDeleter.release(), demux.release(),
std::move(data));
codecOut->setUnsupportedICC(unsupportedICC);
return codecOut;
}
SkISize SkWebpCodec::onGetScaledDimensions(float desiredScale) const {
SkISize dim = this->getInfo().dimensions();
// SkCodec treats zero dimensional images as errors, so the minimum size
// that we will recommend is 1x1.
dim.fWidth = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fWidth));
dim.fHeight = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fHeight));
return dim;
}
bool SkWebpCodec::onDimensionsSupported(const SkISize& dim) {
const SkImageInfo& info = this->getInfo();
return dim.width() >= 1 && dim.width() <= info.width()
&& dim.height() >= 1 && dim.height() <= info.height();
}
static WEBP_CSP_MODE webp_decode_mode(SkColorType ct, bool premultiply) {
switch (ct) {
case kBGRA_8888_SkColorType:
return premultiply ? MODE_bgrA : MODE_BGRA;
case kRGBA_8888_SkColorType:
return premultiply ? MODE_rgbA : MODE_RGBA;
case kRGB_565_SkColorType:
return MODE_RGB_565;
default:
return MODE_LAST;
}
}
bool SkWebpCodec::onGetValidSubset(SkIRect* desiredSubset) const {
if (!desiredSubset) {
return false;
}
SkIRect dimensions = SkIRect::MakeSize(this->getInfo().dimensions());
if (!dimensions.contains(*desiredSubset)) {
return false;
}
// As stated below, libwebp snaps to even left and top. Make sure top and left are even, so we
// decode this exact subset.
// Leave right and bottom unmodified, so we suggest a slightly larger subset than requested.
desiredSubset->fLeft = (desiredSubset->fLeft >> 1) << 1;
desiredSubset->fTop = (desiredSubset->fTop >> 1) << 1;
return true;
}
SkCodec::Result SkWebpCodec::onGetPixels(const SkImageInfo& dstInfo, void* dst, size_t rowBytes,
const Options& options, SkPMColor*, int*,
int* rowsDecodedPtr) {
if (!conversion_possible(dstInfo, this->getInfo()) ||
!this->initializeColorXform(dstInfo, options.fPremulBehavior))
{
return kInvalidConversion;
}
WebPDecoderConfig config;
if (0 == WebPInitDecoderConfig(&config)) {
// ABI mismatch.
// FIXME: New enum for this?
return kInvalidInput;
}
// Free any memory associated with the buffer. Must be called last, so we declare it first.
SkAutoTCallVProc<WebPDecBuffer, WebPFreeDecBuffer> autoFree(&(config.output));
WebPIterator frame;
SkAutoTCallVProc<WebPIterator, WebPDemuxReleaseIterator> autoFrame(&frame);
// If this succeeded in NewFromStream(), it should succeed again here.
SkAssertResult(WebPDemuxGetFrame(fDemux, 1, &frame));
// Get the frameRect. libwebp will have already signaled an error if this is not fully
// contained by the canvas.
auto frameRect = SkIRect::MakeXYWH(frame.x_offset, frame.y_offset, frame.width, frame.height);
SkASSERT(this->getInfo().bounds().contains(frameRect));
bool frameIsSubset = frameRect.size() != this->getInfo().dimensions();
if (frameIsSubset) {
SkSampler::Fill(dstInfo, dst, rowBytes, 0, options.fZeroInitialized);
}
int dstX = frameRect.x();
int dstY = frameRect.y();
int subsetWidth = frameRect.width();
int subsetHeight = frameRect.height();
if (options.fSubset) {
SkIRect subset = *options.fSubset;
SkASSERT(this->getInfo().bounds().contains(subset));
SkASSERT(SkIsAlign2(subset.fLeft) && SkIsAlign2(subset.fTop));
SkASSERT(this->getValidSubset(&subset) && subset == *options.fSubset);
if (!SkIRect::IntersectsNoEmptyCheck(subset, frameRect)) {
return kSuccess;
}
int minXOffset = SkTMin(dstX, subset.x());
int minYOffset = SkTMin(dstY, subset.y());
dstX -= minXOffset;
dstY -= minYOffset;
frameRect.offset(-minXOffset, -minYOffset);
subset.offset(-minXOffset, -minYOffset);
// Just like we require that the requested subset x and y offset are even, libwebp
// guarantees that the frame x and y offset are even (it's actually impossible to specify
// an odd frame offset). So we can still guarantee that the adjusted offsets are even.
SkASSERT(SkIsAlign2(subset.fLeft) && SkIsAlign2(subset.fTop));
SkIRect intersection;
SkAssertResult(intersection.intersect(frameRect, subset));
subsetWidth = intersection.width();
subsetHeight = intersection.height();
config.options.use_cropping = 1;
config.options.crop_left = subset.x();
config.options.crop_top = subset.y();
config.options.crop_width = subsetWidth;
config.options.crop_height = subsetHeight;
}
// Ignore the frame size and offset when determining if scaling is necessary.
int scaledWidth = subsetWidth;
int scaledHeight = subsetHeight;
SkISize srcSize = options.fSubset ? options.fSubset->size() : this->getInfo().dimensions();
if (srcSize != dstInfo.dimensions()) {
config.options.use_scaling = 1;
if (frameIsSubset) {
float scaleX = ((float) dstInfo.width()) / srcSize.width();
float scaleY = ((float) dstInfo.height()) / srcSize.height();
// We need to be conservative here and floor rather than round.
// Otherwise, we may find ourselves decoding off the end of memory.
dstX = scaleX * dstX;
scaledWidth = scaleX * scaledWidth;
dstY = scaleY * dstY;
scaledHeight = scaleY * scaledHeight;
if (0 == scaledWidth || 0 == scaledHeight) {
return kSuccess;
}
} else {
scaledWidth = dstInfo.width();
scaledHeight = dstInfo.height();
}
config.options.scaled_width = scaledWidth;
config.options.scaled_height = scaledHeight;
}
// Swizzling between RGBA and BGRA is zero cost in a color transform. So when we have a
// color transform, we should decode to whatever is easiest for libwebp, and then let the
// color transform swizzle if necessary.
// Lossy webp is encoded as YUV (so RGBA and BGRA are the same cost). Lossless webp is
// encoded as BGRA. This means decoding to BGRA is either faster or the same cost as RGBA.
config.output.colorspace = this->colorXform() ? MODE_BGRA :
webp_decode_mode(dstInfo.colorType(), dstInfo.alphaType() == kPremul_SkAlphaType);
config.output.is_external_memory = 1;
// We will decode the entire image and then perform the color transform. libwebp
// does not provide a row-by-row API. This is a shame particularly when we do not want
// 8888, since we will need to create another image sized buffer.
SkAutoTMalloc<uint32_t> pixels;
bool needsCopy = this->colorXform() && kRGBA_8888_SkColorType != dstInfo.colorType() &&
kBGRA_8888_SkColorType != dstInfo.colorType();
void* webpDst = needsCopy ? pixels.reset(dstInfo.width() * dstInfo.height()) : dst;
size_t webpRowBytes = needsCopy ? dstInfo.width() * sizeof(uint32_t) : rowBytes;
size_t totalBytes = needsCopy ? webpRowBytes * dstInfo.height()
: dstInfo.getSafeSize(webpRowBytes);
size_t dstBpp = SkColorTypeBytesPerPixel(dstInfo.colorType());
size_t webpBpp = needsCopy ? sizeof(uint32_t) : dstBpp;
size_t offset = dstX * webpBpp + dstY * webpRowBytes;
config.output.u.RGBA.rgba = SkTAddOffset<uint8_t>(webpDst, offset);
config.output.u.RGBA.stride = (int) webpRowBytes;
config.output.u.RGBA.size = totalBytes - offset;
SkAutoTCallVProc<WebPIDecoder, WebPIDelete> idec(WebPIDecode(nullptr, 0, &config));
if (!idec) {
return kInvalidInput;
}
int rowsDecoded;
SkCodec::Result result;
switch (WebPIUpdate(idec, frame.fragment.bytes, frame.fragment.size)) {
case VP8_STATUS_OK:
rowsDecoded = scaledHeight;
result = kSuccess;
break;
case VP8_STATUS_SUSPENDED:
WebPIDecGetRGB(idec, &rowsDecoded, nullptr, nullptr, nullptr);
*rowsDecodedPtr = rowsDecoded + dstY;
result = kIncompleteInput;
break;
default:
return kInvalidInput;
}
if (this->colorXform()) {
SkColorSpaceXform::ColorFormat dstColorFormat = select_xform_format(dstInfo.colorType());
SkAlphaType xformAlphaType = select_xform_alpha(dstInfo.alphaType(),
this->getInfo().alphaType());
uint32_t* xformSrc = (uint32_t*) config.output.u.RGBA.rgba;
void* xformDst = SkTAddOffset<void>(dst, dstBpp * dstX + rowBytes * dstY);
size_t srcRowBytes = config.output.u.RGBA.stride;
for (int y = 0; y < rowsDecoded; y++) {
SkAssertResult(this->colorXform()->apply(dstColorFormat, xformDst,
SkColorSpaceXform::kBGRA_8888_ColorFormat, xformSrc, scaledWidth,
xformAlphaType));
xformDst = SkTAddOffset<void>(xformDst, rowBytes);
xformSrc = SkTAddOffset<uint32_t>(xformSrc, srcRowBytes);
}
}
return result;
}
SkWebpCodec::SkWebpCodec(int width, int height, const SkEncodedInfo& info,
sk_sp<SkColorSpace> colorSpace, SkStream* stream, WebPDemuxer* demux,
sk_sp<SkData> data)
: INHERITED(width, height, info, stream, std::move(colorSpace))
, fDemux(demux)
, fData(std::move(data))
{}