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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/gfx/codec/png_codec.h"
#include <stdint.h>
#include <optional>
#include "base/logging.h"
#include "base/metrics/histogram_macros.h"
#include "base/notreached.h"
#include "base/strings/string_util.h"
#include "skia/buildflags.h"
#include "skia/rusty_png_feature.h"
#include "third_party/skia/include/codec/SkPngDecoder.h"
#include "third_party/skia/include/core/SkAlphaType.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkColorType.h"
#include "third_party/skia/include/core/SkUnPreMultiply.h"
#include "third_party/skia/include/encode/SkPngEncoder.h"
#include "third_party/zlib/zlib.h"
#include "ui/gfx/codec/vector_wstream.h"
#include "ui/gfx/geometry/size.h"
#if BUILDFLAG(SKIA_BUILD_RUST_PNG)
#include "third_party/skia/experimental/rust_png/decoder/SkPngRustDecoder.h"
#endif
namespace gfx {
PNGCodec::DecodeOutput::DecodeOutput() = default;
PNGCodec::DecodeOutput::DecodeOutput(PNGCodec::DecodeOutput&& other) = default;
PNGCodec::DecodeOutput& PNGCodec::DecodeOutput::operator=(
PNGCodec::DecodeOutput&& other) = default;
PNGCodec::DecodeOutput::~DecodeOutput() = default;
// Decoder --------------------------------------------------------------------
namespace {
std::unique_ptr<SkCodec> CreatePngDecoder(std::unique_ptr<SkStream> stream,
SkCodec::Result* result) {
if (skia::IsRustyPngEnabled()) {
#if BUILDFLAG(SKIA_BUILD_RUST_PNG)
return SkPngRustDecoder::Decode(std::move(stream), result);
#else
// The `if` condition guarantees `SKIA_BUILD_RUST_PNG`.
NOTREACHED();
#endif
}
return SkPngDecoder::Decode(std::move(stream), result);
}
struct PreparationOutput {
std::unique_ptr<SkCodec> codec;
SkImageInfo image_info;
};
std::optional<PreparationOutput> PrepareForPNGDecode(
base::span<const uint8_t> input,
PNGCodec::ColorFormat format) {
PreparationOutput output;
// Parse the input stream with the PNG decoder, yielding a SkCodec.
auto stream = std::make_unique<SkMemoryStream>(input.data(), input.size(),
/*copyData=*/false);
SkCodec::Result result;
output.codec = CreatePngDecoder(std::move(stream), &result);
if (!output.codec || result != SkCodec::kSuccess) {
return std::nullopt;
}
// Protect against large PNGs. See http://bugzil.la/251381 for more details.
// The limit of `1000000` has been copied from `blink::PNGImageDecoder` and
// originates all the way back in WebKit.
SkISize size = output.codec->dimensions();
const int32_t kMaxPNGSize = 1000000;
if ((size.width() > kMaxPNGSize) || (size.height() > kMaxPNGSize)) {
return std::nullopt;
}
constexpr int kBytesPerPixel = 4;
if (size.area() >= (INT_MAX / kBytesPerPixel)) {
return std::nullopt;
}
// Create an SkImageInfo matching the PNG's, but with our desired format.
SkImageInfo codec_info = output.codec->getInfo();
SkAlphaType alpha_type = codec_info.alphaType();
SkColorType color_type;
switch (format) {
case PNGCodec::FORMAT_RGBA:
color_type = kRGBA_8888_SkColorType;
break;
case PNGCodec::FORMAT_BGRA:
color_type = kBGRA_8888_SkColorType;
break;
case PNGCodec::FORMAT_SkBitmap:
color_type = kN32_SkColorType;
if (alpha_type == kUnpremul_SkAlphaType) {
alpha_type = kPremul_SkAlphaType;
}
break;
default:
NOTREACHED() << "Invalid color format " << format;
}
output.image_info =
SkImageInfo::Make(codec_info.width(), codec_info.height(), color_type,
alpha_type, codec_info.refColorSpace());
return output;
}
} // namespace
// static
std::optional<PNGCodec::DecodeOutput> PNGCodec::Decode(
base::span<const uint8_t> input,
ColorFormat format) {
SCOPED_UMA_HISTOGRAM_TIMER_MICROS("ImageDecoder.Png.UiGfxIntoVector");
std::optional<PreparationOutput> preparation_output =
PrepareForPNGDecode(input, format);
if (!preparation_output) {
return std::nullopt;
}
DecodeOutput output;
output.width = preparation_output->image_info.width();
output.height = preparation_output->image_info.height();
// Always decode into vanilla sRGB, because the output array is a bag of RGBA
// pixels and doesn't have an associated colorspace.
SkImageInfo info_srgb =
preparation_output->image_info.makeColorSpace(SkColorSpace::MakeSRGB());
// Decode the pixels into the `output` vector.
output.output.resize(info_srgb.computeMinByteSize());
SkCodec::Result result = preparation_output->codec->getPixels(
info_srgb, output.output.data(),
preparation_output->image_info.minRowBytes());
if (result != SkCodec::kSuccess) {
return std::nullopt;
}
return output;
}
SkBitmap PNGCodec::Decode(base::span<const uint8_t> input) {
SCOPED_UMA_HISTOGRAM_TIMER_MICROS("ImageDecoder.Png.UiGfxIntoSkBitmap");
std::optional<PreparationOutput> preparation_output =
PrepareForPNGDecode(input, FORMAT_SkBitmap);
if (!preparation_output) {
return SkBitmap();
}
// The image alpha type is likely to be "unpremultiplied," as this is set by
// the PNG standard. However, Skia prefers premultiplied bitmaps. We update
// the image-info struct to specify premultiplication; the SkCodec will
// automatically fix up the pixels as it runs.
SkAlphaType alpha = preparation_output->image_info.alphaType();
if (alpha == kUnpremul_SkAlphaType) {
preparation_output->image_info =
preparation_output->image_info.makeAlphaType(kPremul_SkAlphaType);
}
// Decode the image pixels directly into the SkBitmap. Alpha premultiplication
// will be performed by `getPixels`. No colorspace conversion will occur,
// because the bitmap uses the same colorspace as the original PNG.
SkBitmap bitmap;
if (!bitmap.tryAllocPixels(preparation_output->image_info)) {
return SkBitmap();
}
SkCodec::Result result =
preparation_output->codec->getPixels(bitmap.pixmap());
if (result == SkCodec::kSuccess) {
return bitmap;
} else {
return SkBitmap();
}
}
// Encoder --------------------------------------------------------------------
namespace {
void AddComments(SkPngEncoder::Options& options,
const std::vector<PNGCodec::Comment>& comments) {
std::vector<const char*> comment_pointers;
std::vector<size_t> comment_sizes;
for (const auto& comment : comments) {
comment_pointers.push_back(comment.key.c_str());
comment_pointers.push_back(comment.text.c_str());
comment_sizes.push_back(comment.key.length() + 1);
comment_sizes.push_back(comment.text.length() + 1);
}
options.fComments = SkDataTable::MakeCopyArrays(
(void const* const*)comment_pointers.data(), comment_sizes.data(),
static_cast<int>(comment_pointers.size()));
}
std::optional<std::vector<uint8_t>> EncodeSkPixmap(
const SkPixmap& src,
const std::vector<PNGCodec::Comment>& comments,
int zlib_level,
bool disable_filters) {
std::vector<uint8_t> output;
VectorWStream dst(&output);
SkPngEncoder::Options options;
AddComments(options, comments);
options.fZLibLevel = zlib_level;
if (disable_filters) {
options.fFilterFlags = SkPngEncoder::FilterFlag::kNone;
}
if (!skia::EncodePng(&dst, src, options)) {
return std::nullopt;
}
return output;
}
std::optional<std::vector<uint8_t>> EncodeSkPixmap(
const SkPixmap& src,
bool discard_transparency,
const std::vector<PNGCodec::Comment>& comments,
int zlib_level,
bool disable_filters) {
if (discard_transparency) {
SkImageInfo opaque_info = src.info().makeAlphaType(kOpaque_SkAlphaType);
SkBitmap copy;
if (!copy.tryAllocPixels(opaque_info)) {
return std::nullopt;
}
SkPixmap opaque_pixmap;
bool success = copy.peekPixels(&opaque_pixmap);
DCHECK(success);
// The following step does the unpremul as we set the dst alpha type to be
// kUnpremul_SkAlphaType. Later, because opaque_pixmap has
// kOpaque_SkAlphaType, we'll discard the transparency as required.
success =
src.readPixels(opaque_info.makeAlphaType(kUnpremul_SkAlphaType),
opaque_pixmap.writable_addr(), opaque_pixmap.rowBytes());
DCHECK(success);
return EncodeSkPixmap(opaque_pixmap, comments, zlib_level, disable_filters);
}
// If the image's pixels are all opaque, encode the PNG as opaque, regardless
// of the pixmap's alphaType.
if (src.info().alphaType() != kOpaque_SkAlphaType && src.computeIsOpaque()) {
SkPixmap opaque_pixmap{src.info().makeAlphaType(kOpaque_SkAlphaType),
src.addr(), src.rowBytes()};
return EncodeSkPixmap(opaque_pixmap, comments, zlib_level, disable_filters);
}
// Encode the PNG without any conversions.
return EncodeSkPixmap(src, comments, zlib_level, disable_filters);
}
std::optional<std::vector<uint8_t>> EncodeSkBitmap(const SkBitmap& input,
bool discard_transparency,
int zlib_level,
bool disable_filters) {
SkPixmap src;
if (!input.peekPixels(&src)) {
return std::nullopt;
}
return EncodeSkPixmap(src, discard_transparency,
std::vector<PNGCodec::Comment>(), zlib_level,
disable_filters);
}
} // namespace
std::optional<std::vector<uint8_t>> PNGCodec::Encode(
const unsigned char* input,
ColorFormat format,
const Size& size,
int row_byte_width,
bool discard_transparency,
const std::vector<Comment>& comments) {
// Initialization required for Windows although the switch covers all cases.
SkColorType colorType = kN32_SkColorType;
switch (format) {
case FORMAT_RGBA:
colorType = kRGBA_8888_SkColorType;
break;
case FORMAT_BGRA:
colorType = kBGRA_8888_SkColorType;
break;
case FORMAT_SkBitmap:
colorType = kN32_SkColorType;
break;
}
auto alphaType =
format == FORMAT_SkBitmap ? kPremul_SkAlphaType : kUnpremul_SkAlphaType;
SkImageInfo info =
SkImageInfo::Make(size.width(), size.height(), colorType, alphaType);
SkPixmap src(info, input, row_byte_width);
return EncodeSkPixmap(src, discard_transparency, comments,
DEFAULT_ZLIB_COMPRESSION, /*disable_filters=*/false);
}
std::optional<std::vector<uint8_t>> PNGCodec::EncodeBGRASkBitmap(
const SkBitmap& input,
bool discard_transparency) {
return EncodeSkBitmap(input, discard_transparency, DEFAULT_ZLIB_COMPRESSION,
/*disable_filters=*/false);
}
std::optional<std::vector<uint8_t>> PNGCodec::FastEncodeBGRASkBitmap(
const SkBitmap& input,
bool discard_transparency) {
return EncodeSkBitmap(input, discard_transparency, Z_BEST_SPEED,
/*disable_filters=*/true);
}
PNGCodec::Comment::Comment(const std::string& k, const std::string& t)
: key(k), text(t) {}
PNGCodec::Comment::~Comment() = default;
} // namespace gfx
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