blob: 078294531c4cd21c2afbb4ea0445ea13d2caaeed [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// 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 "base/logging.h"
#include "base/macros.h"
#include "base/notreached.h"
#include "base/strings/string_util.h"
#include "third_party/libpng/png.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkColorPriv.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"
namespace gfx {
// Decoder --------------------------------------------------------------------
//
// This code is based on WebKit libpng interface (PNGImageDecoder), which is
// in turn based on the Mozilla png decoder.
namespace {
// Gamma constants: We assume we're on Windows which uses a gamma of 2.2.
const double kMaxGamma = 21474.83; // Maximum gamma accepted by png library.
const double kDefaultGamma = 2.2;
const double kInverseGamma = 1.0 / kDefaultGamma;
class PngDecoderState {
public:
// Output is a vector<unsigned char>.
PngDecoderState(PNGCodec::ColorFormat ofmt, std::vector<unsigned char>* o)
: output_format(ofmt),
output_channels(0),
bitmap(nullptr),
is_opaque(true),
output(o),
width(0),
height(0),
done(false) {}
// Output is an SkBitmap.
explicit PngDecoderState(SkBitmap* skbitmap)
: output_format(PNGCodec::FORMAT_SkBitmap),
output_channels(0),
bitmap(skbitmap),
is_opaque(true),
output(nullptr),
width(0),
height(0),
done(false) {}
PngDecoderState(const PngDecoderState&) = delete;
PngDecoderState& operator=(const PngDecoderState&) = delete;
PNGCodec::ColorFormat output_format;
int output_channels;
// An incoming SkBitmap to write to. If NULL, we write to output instead.
SkBitmap* bitmap;
// Used during the reading of an SkBitmap. Defaults to true until we see a
// pixel with anything other than an alpha of 255.
bool is_opaque;
// The other way to decode output, where we write into an intermediary buffer
// instead of directly to an SkBitmap.
std::vector<unsigned char>* output;
// Size of the image, set in the info callback.
int width;
int height;
// Set to true when we've found the end of the data.
bool done;
};
// User transform (passed to libpng) which converts a row decoded by libpng to
// Skia format. Expects the row to have 4 channels, otherwise there won't be
// enough room in |data|.
void ConvertRGBARowToSkia(png_structp png_ptr,
png_row_infop row_info,
png_bytep data) {
const int channels = row_info->channels;
DCHECK_EQ(channels, 4);
PngDecoderState* state =
static_cast<PngDecoderState*>(png_get_user_transform_ptr(png_ptr));
DCHECK(state) << "LibPNG user transform pointer is NULL";
unsigned char* const end = data + row_info->rowbytes;
for (unsigned char* p = data; p < end; p += channels) {
uint32_t* sk_pixel = reinterpret_cast<uint32_t*>(p);
const unsigned char alpha = p[channels - 1];
if (alpha != 255) {
state->is_opaque = false;
*sk_pixel = SkPreMultiplyARGB(alpha, p[0], p[1], p[2]);
} else {
*sk_pixel = SkPackARGB32(alpha, p[0], p[1], p[2]);
}
}
}
// Called when the png header has been read. This code is based on the WebKit
// PNGImageDecoder
void DecodeInfoCallback(png_struct* png_ptr, png_info* info_ptr) {
PngDecoderState* state = static_cast<PngDecoderState*>(
png_get_progressive_ptr(png_ptr));
int bit_depth, color_type, interlace_type, compression_type;
int filter_type;
png_uint_32 w, h;
png_get_IHDR(png_ptr, info_ptr, &w, &h, &bit_depth, &color_type,
&interlace_type, &compression_type, &filter_type);
// Bounds check. When the image is unreasonably big, we'll error out and
// end up back at the setjmp call when we set up decoding. "Unreasonably big"
// means "big enough that w * h * 32bpp might overflow an int"; we choose this
// threshold to match WebKit and because a number of places in code assume
// that an image's size (in bytes) fits in a (signed) int.
unsigned long long total_size =
static_cast<unsigned long long>(w) * static_cast<unsigned long long>(h);
if (total_size > ((1 << 29) - 1))
longjmp(png_jmpbuf(png_ptr), 1);
state->width = static_cast<int>(w);
state->height = static_cast<int>(h);
// The following png_set_* calls have to be done in the order dictated by
// the libpng docs. Please take care if you have to move any of them. This
// is also why certain things are done outside of the switch, even though
// they look like they belong there.
// Expand to ensure we use 24-bit for RGB and 32-bit for RGBA.
if (color_type == PNG_COLOR_TYPE_PALETTE ||
(color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8))
png_set_expand(png_ptr);
// The '!= 0' is for silencing a Windows compiler warning.
bool input_has_alpha = ((color_type & PNG_COLOR_MASK_ALPHA) != 0);
// Transparency for paletted images.
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
png_set_expand(png_ptr);
input_has_alpha = true;
}
// Convert 16-bit to 8-bit.
if (bit_depth == 16)
png_set_strip_16(png_ptr);
// Pick our row format converter necessary for this data.
if (!input_has_alpha) {
switch (state->output_format) {
case PNGCodec::FORMAT_RGBA:
state->output_channels = 4;
png_set_add_alpha(png_ptr, 0xFF, PNG_FILLER_AFTER);
break;
case PNGCodec::FORMAT_BGRA:
state->output_channels = 4;
png_set_bgr(png_ptr);
png_set_add_alpha(png_ptr, 0xFF, PNG_FILLER_AFTER);
break;
case PNGCodec::FORMAT_SkBitmap:
state->output_channels = 4;
png_set_add_alpha(png_ptr, 0xFF, PNG_FILLER_AFTER);
break;
}
} else {
switch (state->output_format) {
case PNGCodec::FORMAT_RGBA:
state->output_channels = 4;
break;
case PNGCodec::FORMAT_BGRA:
state->output_channels = 4;
png_set_bgr(png_ptr);
break;
case PNGCodec::FORMAT_SkBitmap:
state->output_channels = 4;
break;
}
}
// Expand grayscale to RGB.
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
// Deal with gamma and keep it under our control.
double gamma;
if (png_get_gAMA(png_ptr, info_ptr, &gamma)) {
if (gamma <= 0.0 || gamma > kMaxGamma) {
gamma = kInverseGamma;
png_set_gAMA(png_ptr, info_ptr, gamma);
}
png_set_gamma(png_ptr, kDefaultGamma, gamma);
} else {
png_set_gamma(png_ptr, kDefaultGamma, kInverseGamma);
}
// Setting the user transforms here (as opposed to inside the switch above)
// because all png_set_* calls need to be done in the specific order
// mandated by libpng.
if (state->output_format == PNGCodec::FORMAT_SkBitmap) {
png_set_read_user_transform_fn(png_ptr, ConvertRGBARowToSkia);
png_set_user_transform_info(png_ptr, state, 0, 0);
}
// Tell libpng to send us rows for interlaced pngs.
if (interlace_type == PNG_INTERLACE_ADAM7)
png_set_interlace_handling(png_ptr);
png_read_update_info(png_ptr, info_ptr);
if (state->bitmap) {
state->bitmap->allocN32Pixels(state->width, state->height);
} else if (state->output) {
state->output->resize(
state->width * state->output_channels * state->height);
}
}
void DecodeRowCallback(png_struct* png_ptr, png_byte* new_row,
png_uint_32 row_num, int pass) {
if (!new_row)
return; // Interlaced image; row didn't change this pass.
PngDecoderState* state = static_cast<PngDecoderState*>(
png_get_progressive_ptr(png_ptr));
if (static_cast<int>(row_num) > state->height) {
NOTREACHED() << "Invalid row";
return;
}
unsigned char* base = NULL;
if (state->bitmap)
base = reinterpret_cast<unsigned char*>(state->bitmap->getAddr32(0, 0));
else if (state->output)
base = &state->output->front();
unsigned char* dest = &base[state->width * state->output_channels * row_num];
png_progressive_combine_row(png_ptr, dest, new_row);
}
void DecodeEndCallback(png_struct* png_ptr, png_info* info) {
PngDecoderState* state = static_cast<PngDecoderState*>(
png_get_progressive_ptr(png_ptr));
// Mark the image as complete, this will tell the Decode function that we
// have successfully found the end of the data.
state->done = true;
}
// Holds png struct and info ensuring the proper destruction.
class PngReadStructInfo {
public:
PngReadStructInfo(): png_ptr_(nullptr), info_ptr_(nullptr) {
}
PngReadStructInfo(const PngReadStructInfo&) = delete;
PngReadStructInfo& operator=(const PngReadStructInfo&) = delete;
~PngReadStructInfo() {
png_destroy_read_struct(&png_ptr_, &info_ptr_, NULL);
}
bool Build(const unsigned char* input, size_t input_size) {
if (input_size < 8)
return false; // Input data too small to be a png
// Have libpng check the signature, it likes the first 8 bytes.
if (png_sig_cmp(const_cast<unsigned char*>(input), 0, 8) != 0)
return false;
png_ptr_ = png_create_read_struct(
PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr_)
return false;
info_ptr_ = png_create_info_struct(png_ptr_);
if (!info_ptr_) {
return false;
}
return true;
}
png_struct* png_ptr_;
png_info* info_ptr_;
};
// Holds png struct and info ensuring the proper destruction.
class PngWriteStructInfo {
public:
PngWriteStructInfo() : png_ptr_(nullptr), info_ptr_(nullptr) {
}
PngWriteStructInfo(const PngWriteStructInfo&) = delete;
PngWriteStructInfo& operator=(const PngWriteStructInfo&) = delete;
~PngWriteStructInfo() {
png_destroy_write_struct(&png_ptr_, &info_ptr_);
}
png_struct* png_ptr_;
png_info* info_ptr_;
};
// Libpng user error and warning functions which allows us to print libpng
// errors and warnings using Chrome's logging facilities instead of stderr.
void LogLibPNGDecodeError(png_structp png_ptr, png_const_charp error_msg) {
DLOG(ERROR) << "libpng decode error: " << error_msg;
longjmp(png_jmpbuf(png_ptr), 1);
}
void LogLibPNGDecodeWarning(png_structp png_ptr, png_const_charp warning_msg) {
DLOG(ERROR) << "libpng decode warning: " << warning_msg;
}
} // namespace
// static
bool PNGCodec::Decode(const unsigned char* input, size_t input_size,
ColorFormat format, std::vector<unsigned char>* output,
int* w, int* h) {
PngReadStructInfo si;
if (!si.Build(input, input_size))
return false;
if (setjmp(png_jmpbuf(si.png_ptr_))) {
// The destroyer will ensure that the structures are cleaned up in this
// case, even though we may get here as a jump from random parts of the
// PNG library called below.
return false;
}
PngDecoderState state(format, output);
png_set_error_fn(si.png_ptr_, NULL,
LogLibPNGDecodeError, LogLibPNGDecodeWarning);
png_set_progressive_read_fn(si.png_ptr_, &state, &DecodeInfoCallback,
&DecodeRowCallback, &DecodeEndCallback);
png_process_data(si.png_ptr_,
si.info_ptr_,
const_cast<unsigned char*>(input),
input_size);
if (!state.done) {
// Fed it all the data but the library didn't think we got all the data, so
// this file must be truncated.
output->clear();
return false;
}
*w = state.width;
*h = state.height;
return true;
}
// static
bool PNGCodec::Decode(const unsigned char* input, size_t input_size,
SkBitmap* bitmap) {
DCHECK(bitmap);
PngReadStructInfo si;
if (!si.Build(input, input_size))
return false;
if (setjmp(png_jmpbuf(si.png_ptr_))) {
// The destroyer will ensure that the structures are cleaned up in this
// case, even though we may get here as a jump from random parts of the
// PNG library called below.
return false;
}
PngDecoderState state(bitmap);
png_set_progressive_read_fn(si.png_ptr_, &state, &DecodeInfoCallback,
&DecodeRowCallback, &DecodeEndCallback);
png_process_data(si.png_ptr_,
si.info_ptr_,
const_cast<unsigned char*>(input),
input_size);
if (!state.done) {
return false;
}
// Set the bitmap's opaqueness based on what we saw.
bitmap->setAlphaType(state.is_opaque ?
kOpaque_SkAlphaType : kPremul_SkAlphaType);
return true;
}
// Encoder --------------------------------------------------------------------
namespace {
static 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()));
}
} // namespace
static bool EncodeSkPixmap(const SkPixmap& src,
const std::vector<PNGCodec::Comment>& comments,
std::vector<unsigned char>* output,
int zlib_level) {
output->clear();
VectorWStream dst(output);
SkPngEncoder::Options options;
AddComments(options, comments);
options.fZLibLevel = zlib_level;
return SkPngEncoder::Encode(&dst, src, options);
}
static bool EncodeSkPixmap(const SkPixmap& src,
bool discard_transparency,
const std::vector<PNGCodec::Comment>& comments,
std::vector<unsigned char>* output,
int zlib_level) {
if (discard_transparency) {
SkImageInfo opaque_info = src.info().makeAlphaType(kOpaque_SkAlphaType);
SkBitmap copy;
if (!copy.tryAllocPixels(opaque_info)) {
return false;
}
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, output, zlib_level);
}
return EncodeSkPixmap(src, comments, output, zlib_level);
}
// static
bool PNGCodec::Encode(const unsigned char* input,
ColorFormat format,
const Size& size,
int row_byte_width,
bool discard_transparency,
const std::vector<Comment>& comments,
std::vector<unsigned char>* output) {
// 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, output,
DEFAULT_ZLIB_COMPRESSION);
}
static bool EncodeSkBitmap(const SkBitmap& input,
bool discard_transparency,
std::vector<unsigned char>* output,
int zlib_level) {
SkPixmap src;
if (!input.peekPixels(&src)) {
return false;
}
return EncodeSkPixmap(src, discard_transparency,
std::vector<PNGCodec::Comment>(), output, zlib_level);
}
// static
bool PNGCodec::EncodeBGRASkBitmap(const SkBitmap& input,
bool discard_transparency,
std::vector<unsigned char>* output) {
return EncodeSkBitmap(input, discard_transparency, output,
DEFAULT_ZLIB_COMPRESSION);
}
// static
bool PNGCodec::EncodeA8SkBitmap(const SkBitmap& input,
std::vector<unsigned char>* output) {
DCHECK_EQ(input.colorType(), kAlpha_8_SkColorType);
auto info = input.info()
.makeColorType(kGray_8_SkColorType)
.makeAlphaType(kOpaque_SkAlphaType);
SkPixmap src(info, input.getAddr(0, 0), input.rowBytes());
return EncodeSkPixmap(src, std::vector<PNGCodec::Comment>(), output,
DEFAULT_ZLIB_COMPRESSION);
}
// static
bool PNGCodec::FastEncodeBGRASkBitmap(const SkBitmap& input,
bool discard_transparency,
std::vector<unsigned char>* output) {
return EncodeSkBitmap(input, discard_transparency, output, Z_BEST_SPEED);
}
PNGCodec::Comment::Comment(const std::string& k, const std::string& t)
: key(k), text(t) {
}
PNGCodec::Comment::~Comment() {
}
} // namespace gfx