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Revert "Revert "Add image_diff from the chromium repo.""

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This reverts commit 79d76b3da8f72ca3affaaaf2821b1d0bb212f522.

The BUILD.gn file needed a dep to //build/config/sanitizers:deps
in order to link under the asan build.

TBR=blundell@chromium.org

Review URL: https://codereview.chromium.org/804563002
This commit is contained in:
Ojan Vafai 2014-12-12 09:48:46 -08:00
parent 64795a309f
commit 325687d810
5 changed files with 1149 additions and 0 deletions
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1
engine/src/flutter/BUILD.gn
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@ -14,6 +14,7 @@ group("sky") {
"//sky/engine/wtf:unittests",
"//sky/services/inspector",
"//sky/tools/debugger",
"//sky/tools/imagediff",
"//sky/tools/tester",
"//sky/viewer",
]

21
engine/src/flutter/tools/imagediff/BUILD.gn Normal file
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@ -0,0 +1,21 @@
# Copyright 2014 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.
executable("imagediff") {
output_name = "image_diff" # Different than dir nam for historical reasons.
sources = [
"image_diff.cc",
"image_diff_png.h",
"image_diff_png.cc",
]
configs += [ "//build/config/compiler:wexit_time_destructors" ]
deps = [
"//base",
"//build/config/sanitizers:deps",
"//third_party/libpng",
"//third_party/zlib",
]
}

449
engine/src/flutter/tools/imagediff/image_diff.cc Normal file
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@ -0,0 +1,449 @@
// Copyright (c) 2011 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.
// This file input format is based loosely on
// Tools/DumpRenderTree/ImageDiff.m
// The exact format of this tool's output to stdout is important, to match
// what the run-webkit-tests script expects.
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include "base/basictypes.h"
#include "base/command_line.h"
#include "base/containers/hash_tables.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/numerics/safe_conversions.h"
#include "base/process/memory.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "sky/tools/imagediff/image_diff_png.h"
#if defined(OS_WIN)
#include "windows.h"
#endif
// Causes the app to remain open, waiting for pairs of filenames on stdin.
// The caller is then responsible for terminating this app.
static const char kOptionPollStdin[] = "use-stdin";
// Causes the app to additionally calculate a diff of the color histograms
// (which is resistant to shifts in layout).
static const char kOptionCompareHistograms[] = "histogram";
// Causes the app to output an image that visualizes the difference.
static const char kOptionGenerateDiff[] = "diff";
// Return codes used by this utility.
static const int kStatusSame = 0;
static const int kStatusDifferent = 1;
static const int kStatusError = 2;
// Color codes.
static const uint32 RGBA_RED = 0x000000ff;
static const uint32 RGBA_ALPHA = 0xff000000;
class Image {
public:
Image() : w_(0), h_(0) {
}
Image(const Image& image)
: w_(image.w_),
h_(image.h_),
data_(image.data_) {
}
bool has_image() const {
return w_ > 0 && h_ > 0;
}
int w() const {
return w_;
}
int h() const {
return h_;
}
const unsigned char* data() const {
return &data_.front();
}
// Creates the image from stdin with the given data length. On success, it
// will return true. On failure, no other methods should be accessed.
bool CreateFromStdin(size_t byte_length) {
if (byte_length == 0)
return false;
scoped_ptr<unsigned char[]> source(new unsigned char[byte_length]);
if (fread(source.get(), 1, byte_length, stdin) != byte_length)
return false;
if (!image_diff_png::DecodePNG(source.get(), byte_length,
&data_, &w_, &h_)) {
Clear();
return false;
}
return true;
}
// Creates the image from the given filename on disk, and returns true on
// success.
bool CreateFromFilename(const base::FilePath& path) {
FILE* f = base::OpenFile(path, "rb");
if (!f)
return false;
std::vector<unsigned char> compressed;
const int buf_size = 1024;
unsigned char buf[buf_size];
size_t num_read = 0;
while ((num_read = fread(buf, 1, buf_size, f)) > 0) {
compressed.insert(compressed.end(), buf, buf + num_read);
}
base::CloseFile(f);
if (!image_diff_png::DecodePNG(&compressed[0], compressed.size(),
&data_, &w_, &h_)) {
Clear();
return false;
}
return true;
}
void Clear() {
w_ = h_ = 0;
data_.clear();
}
// Returns the RGBA value of the pixel at the given location
uint32 pixel_at(int x, int y) const {
DCHECK(x >= 0 && x < w_);
DCHECK(y >= 0 && y < h_);
return *reinterpret_cast<const uint32*>(&(data_[(y * w_ + x) * 4]));
}
void set_pixel_at(int x, int y, uint32 color) const {
DCHECK(x >= 0 && x < w_);
DCHECK(y >= 0 && y < h_);
void* addr = &const_cast<unsigned char*>(&data_.front())[(y * w_ + x) * 4];
*reinterpret_cast<uint32*>(addr) = color;
}
private:
// pixel dimensions of the image
int w_, h_;
std::vector<unsigned char> data_;
};
float PercentageDifferent(const Image& baseline, const Image& actual) {
int w = std::min(baseline.w(), actual.w());
int h = std::min(baseline.h(), actual.h());
// Compute pixels different in the overlap.
int pixels_different = 0;
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
if (baseline.pixel_at(x, y) != actual.pixel_at(x, y))
pixels_different++;
}
}
// Count pixels that are a difference in size as also being different.
int max_w = std::max(baseline.w(), actual.w());
int max_h = std::max(baseline.h(), actual.h());
// These pixels are off the right side, not including the lower right corner.
pixels_different += (max_w - w) * h;
// These pixels are along the bottom, including the lower right corner.
pixels_different += (max_h - h) * max_w;
// Like the WebKit ImageDiff tool, we define percentage different in terms
// of the size of the 'actual' bitmap.
float total_pixels = static_cast<float>(actual.w()) *
static_cast<float>(actual.h());
if (total_pixels == 0) {
// When the bitmap is empty, they are 100% different.
return 100.0f;
}
return 100.0f * pixels_different / total_pixels;
}
typedef base::hash_map<uint32, int32> RgbaToCountMap;
float HistogramPercentageDifferent(const Image& baseline, const Image& actual) {
// TODO(johnme): Consider using a joint histogram instead, as described in
// "Comparing Images Using Joint Histograms" by Pass & Zabih
// http://www.cs.cornell.edu/~rdz/papers/pz-jms99.pdf
int w = std::min(baseline.w(), actual.w());
int h = std::min(baseline.h(), actual.h());
// Count occurences of each RGBA pixel value of baseline in the overlap.
RgbaToCountMap baseline_histogram;
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
// hash_map operator[] inserts a 0 (default constructor) if key not found.
baseline_histogram[baseline.pixel_at(x, y)]++;
}
}
// Compute pixels different in the histogram of the overlap.
int pixels_different = 0;
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
uint32 actual_rgba = actual.pixel_at(x, y);
RgbaToCountMap::iterator it = baseline_histogram.find(actual_rgba);
if (it != baseline_histogram.end() && it->second > 0)
it->second--;
else
pixels_different++;
}
}
// Count pixels that are a difference in size as also being different.
int max_w = std::max(baseline.w(), actual.w());
int max_h = std::max(baseline.h(), actual.h());
// These pixels are off the right side, not including the lower right corner.
pixels_different += (max_w - w) * h;
// These pixels are along the bottom, including the lower right corner.
pixels_different += (max_h - h) * max_w;
// Like the WebKit ImageDiff tool, we define percentage different in terms
// of the size of the 'actual' bitmap.
float total_pixels = static_cast<float>(actual.w()) *
static_cast<float>(actual.h());
if (total_pixels == 0) {
// When the bitmap is empty, they are 100% different.
return 100.0f;
}
return 100.0f * pixels_different / total_pixels;
}
void PrintHelp() {
fprintf(stderr,
"Usage:\n"
" image_diff [--histogram] <compare file> <reference file>\n"
" Compares two files on disk, returning 0 when they are the same;\n"
" passing \"--histogram\" additionally calculates a diff of the\n"
" RGBA value histograms (which is resistant to shifts in layout)\n"
" image_diff --use-stdin\n"
" Stays open reading pairs of filenames from stdin, comparing them,\n"
" and sending 0 to stdout when they are the same\n"
" image_diff --diff <compare file> <reference file> <output file>\n"
" Compares two files on disk, outputs an image that visualizes the\n"
" difference to <output file>\n");
/* For unfinished webkit-like-mode (see below)
"\n"
" image_diff -s\n"
" Reads stream input from stdin, should be EXACTLY of the format\n"
" \"Content-length: <byte length> <data>Content-length: ...\n"
" it will take as many file pairs as given, and will compare them as\n"
" (cmp_file, reference_file) pairs\n");
*/
}
int CompareImages(const base::FilePath& file1,
const base::FilePath& file2,
bool compare_histograms) {
Image actual_image;
Image baseline_image;
if (!actual_image.CreateFromFilename(file1)) {
fprintf(stderr, "image_diff: Unable to open file \"%" PRFilePath "\"\n",
file1.value().c_str());
return kStatusError;
}
if (!baseline_image.CreateFromFilename(file2)) {
fprintf(stderr, "image_diff: Unable to open file \"%" PRFilePath "\"\n",
file2.value().c_str());
return kStatusError;
}
if (compare_histograms) {
float percent = HistogramPercentageDifferent(actual_image, baseline_image);
const char* passed = percent > 0.0 ? "failed" : "passed";
printf("histogram diff: %01.2f%% %s\n", percent, passed);
}
const char* diff_name = compare_histograms ? "exact diff" : "diff";
float percent = PercentageDifferent(actual_image, baseline_image);
const char* passed = percent > 0.0 ? "failed" : "passed";
printf("%s: %01.2f%% %s\n", diff_name, percent, passed);
if (percent > 0.0) {
// failure: The WebKit version also writes the difference image to
// stdout, which seems excessive for our needs.
return kStatusDifferent;
}
// success
return kStatusSame;
/* Untested mode that acts like WebKit's image comparator. I wrote this but
decided it's too complicated. We may use it in the future if it looks useful
char buffer[2048];
while (fgets(buffer, sizeof(buffer), stdin)) {
if (strncmp("Content-length: ", buffer, 16) == 0) {
char* context;
strtok_s(buffer, " ", &context);
int image_size = strtol(strtok_s(NULL, " ", &context), NULL, 10);
bool success = false;
if (image_size > 0 && actual_image.has_image() == 0) {
if (!actual_image.CreateFromStdin(image_size)) {
fputs("Error, input image can't be decoded.\n", stderr);
return 1;
}
} else if (image_size > 0 && baseline_image.has_image() == 0) {
if (!baseline_image.CreateFromStdin(image_size)) {
fputs("Error, baseline image can't be decoded.\n", stderr);
return 1;
}
} else {
fputs("Error, image size must be specified.\n", stderr);
return 1;
}
}
if (actual_image.has_image() && baseline_image.has_image()) {
float percent = PercentageDifferent(actual_image, baseline_image);
if (percent > 0.0) {
// failure: The WebKit version also writes the difference image to
// stdout, which seems excessive for our needs.
printf("diff: %01.2f%% failed\n", percent);
} else {
// success
printf("diff: %01.2f%% passed\n", percent);
}
actual_image.Clear();
baseline_image.Clear();
}
fflush(stdout);
}
*/
}
bool CreateImageDiff(const Image& image1, const Image& image2, Image* out) {
int w = std::min(image1.w(), image2.w());
int h = std::min(image1.h(), image2.h());
*out = Image(image1);
bool same = (image1.w() == image2.w()) && (image1.h() == image2.h());
// TODO(estade): do something with the extra pixels if the image sizes
// are different.
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
uint32 base_pixel = image1.pixel_at(x, y);
if (base_pixel != image2.pixel_at(x, y)) {
// Set differing pixels red.
out->set_pixel_at(x, y, RGBA_RED | RGBA_ALPHA);
same = false;
} else {
// Set same pixels as faded.
uint32 alpha = base_pixel & RGBA_ALPHA;
uint32 new_pixel = base_pixel - ((alpha / 2) & RGBA_ALPHA);
out->set_pixel_at(x, y, new_pixel);
}
}
}
return same;
}
int DiffImages(const base::FilePath& file1, const base::FilePath& file2,
const base::FilePath& out_file) {
Image actual_image;
Image baseline_image;
if (!actual_image.CreateFromFilename(file1)) {
fprintf(stderr, "image_diff: Unable to open file \"%" PRFilePath "\"\n",
file1.value().c_str());
return kStatusError;
}
if (!baseline_image.CreateFromFilename(file2)) {
fprintf(stderr, "image_diff: Unable to open file \"%" PRFilePath "\"\n",
file2.value().c_str());
return kStatusError;
}
Image diff_image;
bool same = CreateImageDiff(baseline_image, actual_image, &diff_image);
if (same)
return kStatusSame;
std::vector<unsigned char> png_encoding;
image_diff_png::EncodeRGBAPNG(
diff_image.data(), diff_image.w(), diff_image.h(),
diff_image.w() * 4, &png_encoding);
if (base::WriteFile(out_file,
reinterpret_cast<char*>(&png_encoding.front()),
base::checked_cast<int>(png_encoding.size())) < 0)
return kStatusError;
return kStatusDifferent;
}
// It isn't strictly correct to only support ASCII paths, but this
// program reads paths on stdin and the program that spawns it outputs
// paths as non-wide strings anyway.
base::FilePath FilePathFromASCII(const std::string& str) {
#if defined(OS_WIN)
return base::FilePath(base::ASCIIToUTF16(str));
#else
return base::FilePath(str);
#endif
}
int main(int argc, const char* argv[]) {
base::EnableTerminationOnHeapCorruption();
CommandLine::Init(argc, argv);
const CommandLine& parsed_command_line = *CommandLine::ForCurrentProcess();
bool histograms = parsed_command_line.HasSwitch(kOptionCompareHistograms);
if (parsed_command_line.HasSwitch(kOptionPollStdin)) {
// Watch stdin for filenames.
std::string stdin_buffer;
base::FilePath filename1;
while (std::getline(std::cin, stdin_buffer)) {
if (stdin_buffer.empty())
continue;
if (!filename1.empty()) {
// CompareImages writes results to stdout unless an error occurred.
base::FilePath filename2 = FilePathFromASCII(stdin_buffer);
if (CompareImages(filename1, filename2, histograms) == kStatusError)
printf("error\n");
fflush(stdout);
filename1 = base::FilePath();
} else {
// Save the first filename in another buffer and wait for the second
// filename to arrive via stdin.
filename1 = FilePathFromASCII(stdin_buffer);
}
}
return 0;
}
const CommandLine::StringVector& args = parsed_command_line.GetArgs();
if (parsed_command_line.HasSwitch(kOptionGenerateDiff)) {
if (args.size() == 3) {
return DiffImages(base::FilePath(args[0]),
base::FilePath(args[1]),
base::FilePath(args[2]));
}
} else if (args.size() == 2) {
return CompareImages(
base::FilePath(args[0]), base::FilePath(args[1]), histograms);
}
PrintHelp();
return kStatusError;
}

643
engine/src/flutter/tools/imagediff/image_diff_png.cc Normal file
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@ -0,0 +1,643 @@
// Copyright 2013 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 "sky/tools/imagediff/image_diff_png.h"
#include <stdlib.h>
#include <string.h>
#include "base/logging.h"
#include "build/build_config.h"
#include "third_party/libpng/png.h"
#include "third_party/zlib/zlib.h"
namespace image_diff_png {
// This is a duplicate of ui/gfx/codec/png_codec.cc, after removing code related
// to Skia, that we can use when running layout tests with minimal dependencies.
namespace {
enum ColorFormat {
// 3 bytes per pixel (packed), in RGB order regardless of endianness.
// This is the native JPEG format.
FORMAT_RGB,
// 4 bytes per pixel, in RGBA order in memory regardless of endianness.
FORMAT_RGBA,
// 4 bytes per pixel, in BGRA order in memory regardless of endianness.
// This is the default Windows DIB order.
FORMAT_BGRA,
// 4 bytes per pixel, in pre-multiplied kARGB_8888_Config format. For use
// with directly writing to a skia bitmap.
FORMAT_SkBitmap
};
// Represents a comment in the tEXt ancillary chunk of the png.
struct Comment {
std::string key;
std::string text;
};
// Converts BGRA->RGBA and RGBA->BGRA.
void ConvertBetweenBGRAandRGBA(const unsigned char* input, int pixel_width,
unsigned char* output, bool* is_opaque) {
for (int x = 0; x < pixel_width; x++) {
const unsigned char* pixel_in = &input[x * 4];
unsigned char* pixel_out = &output[x * 4];
pixel_out[0] = pixel_in[2];
pixel_out[1] = pixel_in[1];
pixel_out[2] = pixel_in[0];
pixel_out[3] = pixel_in[3];
}
}
void ConvertRGBAtoRGB(const unsigned char* rgba, int pixel_width,
unsigned char* rgb, bool* is_opaque) {
for (int x = 0; x < pixel_width; x++) {
const unsigned char* pixel_in = &rgba[x * 4];
unsigned char* pixel_out = &rgb[x * 3];
pixel_out[0] = pixel_in[0];
pixel_out[1] = pixel_in[1];
pixel_out[2] = pixel_in[2];
}
}
} // namespace
// 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(ColorFormat ofmt, std::vector<unsigned char>* o)
: output_format(ofmt),
output_channels(0),
is_opaque(true),
output(o),
row_converter(NULL),
width(0),
height(0),
done(false) {
}
ColorFormat output_format;
int output_channels;
// 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;
// An intermediary buffer for decode output.
std::vector<unsigned char>* output;
// Called to convert a row from the library to the correct output format.
// When NULL, no conversion is necessary.
void (*row_converter)(const unsigned char* in, int w, unsigned char* out,
bool* is_opaque);
// 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;
};
void ConvertRGBtoRGBA(const unsigned char* rgb, int pixel_width,
unsigned char* rgba, bool* is_opaque) {
for (int x = 0; x < pixel_width; x++) {
const unsigned char* pixel_in = &rgb[x * 3];
unsigned char* pixel_out = &rgba[x * 4];
pixel_out[0] = pixel_in[0];
pixel_out[1] = pixel_in[1];
pixel_out[2] = pixel_in[2];
pixel_out[3] = 0xff;
}
}
void ConvertRGBtoBGRA(const unsigned char* rgb, int pixel_width,
unsigned char* bgra, bool* is_opaque) {
for (int x = 0; x < pixel_width; x++) {
const unsigned char* pixel_in = &rgb[x * 3];
unsigned char* pixel_out = &bgra[x * 4];
pixel_out[0] = pixel_in[2];
pixel_out[1] = pixel_in[1];
pixel_out[2] = pixel_in[0];
pixel_out[3] = 0xff;
}
}
// 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, channels;
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);
// 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);
// Transparency for paletted images.
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
png_set_expand(png_ptr);
// Convert 16-bit to 8-bit.
if (bit_depth == 16)
png_set_strip_16(png_ptr);
// 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);
}
// Tell libpng to send us rows for interlaced pngs.
if (interlace_type == PNG_INTERLACE_ADAM7)
png_set_interlace_handling(png_ptr);
// Update our info now
png_read_update_info(png_ptr, info_ptr);
channels = png_get_channels(png_ptr, info_ptr);
// Pick our row format converter necessary for this data.
if (channels == 3) {
switch (state->output_format) {
case FORMAT_RGB:
state->row_converter = NULL; // no conversion necessary
state->output_channels = 3;
break;
case FORMAT_RGBA:
state->row_converter = &ConvertRGBtoRGBA;
state->output_channels = 4;
break;
case FORMAT_BGRA:
state->row_converter = &ConvertRGBtoBGRA;
state->output_channels = 4;
break;
default:
NOTREACHED() << "Unknown output format";
break;
}
} else if (channels == 4) {
switch (state->output_format) {
case FORMAT_RGB:
state->row_converter = &ConvertRGBAtoRGB;
state->output_channels = 3;
break;
case FORMAT_RGBA:
state->row_converter = NULL; // no conversion necessary
state->output_channels = 4;
break;
case FORMAT_BGRA:
state->row_converter = &ConvertBetweenBGRAandRGBA;
state->output_channels = 4;
break;
default:
NOTREACHED() << "Unknown output format";
break;
}
} else {
NOTREACHED() << "Unknown input channels";
longjmp(png_jmpbuf(png_ptr), 1);
}
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) {
PngDecoderState* state = static_cast<PngDecoderState*>(
png_get_progressive_ptr(png_ptr));
DCHECK(pass == 0);
if (static_cast<int>(row_num) > state->height) {
NOTREACHED() << "Invalid row";
return;
}
unsigned char* base = NULL;
base = &state->output->front();
unsigned char* dest = &base[state->width * state->output_channels * row_num];
if (state->row_converter)
state->row_converter(new_row, state->width, dest, &state->is_opaque);
else
memcpy(dest, new_row, state->width * state->output_channels);
}
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;
}
// Automatically destroys the given read structs on destruction to make
// cleanup and error handling code cleaner.
class PngReadStructDestroyer {
public:
PngReadStructDestroyer(png_struct** ps, png_info** pi) : ps_(ps), pi_(pi) {
}
~PngReadStructDestroyer() {
png_destroy_read_struct(ps_, pi_, NULL);
}
private:
png_struct** ps_;
png_info** pi_;
};
bool BuildPNGStruct(const unsigned char* input, size_t input_size,
png_struct** png_ptr, png_info** info_ptr) {
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) {
png_destroy_read_struct(png_ptr, NULL, NULL);
return false;
}
return true;
}
} // namespace
// static
bool Decode(const unsigned char* input, size_t input_size,
ColorFormat format, std::vector<unsigned char>* output,
int* w, int* h) {
png_struct* png_ptr = NULL;
png_info* info_ptr = NULL;
if (!BuildPNGStruct(input, input_size, &png_ptr, &info_ptr))
return false;
PngReadStructDestroyer destroyer(&png_ptr, &info_ptr);
if (setjmp(png_jmpbuf(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_progressive_read_fn(png_ptr, &state, &DecodeInfoCallback,
&DecodeRowCallback, &DecodeEndCallback);
png_process_data(png_ptr,
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;
}
// Encoder --------------------------------------------------------------------
//
// This section of the code is based on nsPNGEncoder.cpp in Mozilla
// (Copyright 2005 Google Inc.)
namespace {
// Passed around as the io_ptr in the png structs so our callbacks know where
// to write data.
struct PngEncoderState {
explicit PngEncoderState(std::vector<unsigned char>* o) : out(o) {}
std::vector<unsigned char>* out;
};
// Called by libpng to flush its internal buffer to ours.
void EncoderWriteCallback(png_structp png, png_bytep data, png_size_t size) {
PngEncoderState* state = static_cast<PngEncoderState*>(png_get_io_ptr(png));
DCHECK(state->out);
size_t old_size = state->out->size();
state->out->resize(old_size + size);
memcpy(&(*state->out)[old_size], data, size);
}
void FakeFlushCallback(png_structp png) {
// We don't need to perform any flushing since we aren't doing real IO, but
// we're required to provide this function by libpng.
}
void ConvertBGRAtoRGB(const unsigned char* bgra, int pixel_width,
unsigned char* rgb, bool* is_opaque) {
for (int x = 0; x < pixel_width; x++) {
const unsigned char* pixel_in = &bgra[x * 4];
unsigned char* pixel_out = &rgb[x * 3];
pixel_out[0] = pixel_in[2];
pixel_out[1] = pixel_in[1];
pixel_out[2] = pixel_in[0];
}
}
#ifdef PNG_TEXT_SUPPORTED
inline char* strdup(const char* str) {
#if defined(OS_WIN)
return _strdup(str);
#else
return ::strdup(str);
#endif
}
class CommentWriter {
public:
explicit CommentWriter(const std::vector<Comment>& comments)
: comments_(comments),
png_text_(new png_text[comments.size()]) {
for (size_t i = 0; i < comments.size(); ++i)
AddComment(i, comments[i]);
}
~CommentWriter() {
for (size_t i = 0; i < comments_.size(); ++i) {
free(png_text_[i].key);
free(png_text_[i].text);
}
delete [] png_text_;
}
bool HasComments() {
return !comments_.empty();
}
png_text* get_png_text() {
return png_text_;
}
int size() {
return static_cast<int>(comments_.size());
}
private:
void AddComment(size_t pos, const Comment& comment) {
png_text_[pos].compression = PNG_TEXT_COMPRESSION_NONE;
// A PNG comment's key can only be 79 characters long.
DCHECK(comment.key.length() < 79);
png_text_[pos].key = strdup(comment.key.substr(0, 78).c_str());
png_text_[pos].text = strdup(comment.text.c_str());
png_text_[pos].text_length = comment.text.length();
#ifdef PNG_iTXt_SUPPORTED
png_text_[pos].itxt_length = 0;
png_text_[pos].lang = 0;
png_text_[pos].lang_key = 0;
#endif
}
const std::vector<Comment> comments_;
png_text* png_text_;
};
#endif // PNG_TEXT_SUPPORTED
// The type of functions usable for converting between pixel formats.
typedef void (*FormatConverter)(const unsigned char* in, int w,
unsigned char* out, bool* is_opaque);
// libpng uses a wacky setjmp-based API, which makes the compiler nervous.
// We constrain all of the calls we make to libpng where the setjmp() is in
// place to this function.
// Returns true on success.
bool DoLibpngWrite(png_struct* png_ptr, png_info* info_ptr,
PngEncoderState* state,
int width, int height, int row_byte_width,
const unsigned char* input, int compression_level,
int png_output_color_type, int output_color_components,
FormatConverter converter,
const std::vector<Comment>& comments) {
#ifdef PNG_TEXT_SUPPORTED
CommentWriter comment_writer(comments);
#endif
unsigned char* row_buffer = NULL;
// Make sure to not declare any locals here -- locals in the presence
// of setjmp() in C++ code makes gcc complain.
if (setjmp(png_jmpbuf(png_ptr))) {
delete[] row_buffer;
return false;
}
png_set_compression_level(png_ptr, compression_level);
// Set our callback for libpng to give us the data.
png_set_write_fn(png_ptr, state, EncoderWriteCallback, FakeFlushCallback);
png_set_IHDR(png_ptr, info_ptr, width, height, 8, png_output_color_type,
PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
#ifdef PNG_TEXT_SUPPORTED
if (comment_writer.HasComments()) {
png_set_text(png_ptr, info_ptr, comment_writer.get_png_text(),
comment_writer.size());
}
#endif
png_write_info(png_ptr, info_ptr);
if (!converter) {
// No conversion needed, give the data directly to libpng.
for (int y = 0; y < height; y ++) {
png_write_row(png_ptr,
const_cast<unsigned char*>(&input[y * row_byte_width]));
}
} else {
// Needs conversion using a separate buffer.
row_buffer = new unsigned char[width * output_color_components];
for (int y = 0; y < height; y ++) {
converter(&input[y * row_byte_width], width, row_buffer, NULL);
png_write_row(png_ptr, row_buffer);
}
delete[] row_buffer;
}
png_write_end(png_ptr, info_ptr);
return true;
}
} // namespace
// static
bool EncodeWithCompressionLevel(const unsigned char* input, ColorFormat format,
const int width, const int height,
int row_byte_width,
bool discard_transparency,
const std::vector<Comment>& comments,
int compression_level,
std::vector<unsigned char>* output) {
// Run to convert an input row into the output row format, NULL means no
// conversion is necessary.
FormatConverter converter = NULL;
int input_color_components, output_color_components;
int png_output_color_type;
switch (format) {
case FORMAT_RGB:
input_color_components = 3;
output_color_components = 3;
png_output_color_type = PNG_COLOR_TYPE_RGB;
discard_transparency = false;
break;
case FORMAT_RGBA:
input_color_components = 4;
if (discard_transparency) {
output_color_components = 3;
png_output_color_type = PNG_COLOR_TYPE_RGB;
converter = ConvertRGBAtoRGB;
} else {
output_color_components = 4;
png_output_color_type = PNG_COLOR_TYPE_RGB_ALPHA;
converter = NULL;
}
break;
case FORMAT_BGRA:
input_color_components = 4;
if (discard_transparency) {
output_color_components = 3;
png_output_color_type = PNG_COLOR_TYPE_RGB;
converter = ConvertBGRAtoRGB;
} else {
output_color_components = 4;
png_output_color_type = PNG_COLOR_TYPE_RGB_ALPHA;
converter = ConvertBetweenBGRAandRGBA;
}
break;
default:
NOTREACHED() << "Unknown pixel format";
return false;
}
// Row stride should be at least as long as the length of the data.
DCHECK(input_color_components * width <= row_byte_width);
png_struct* png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
NULL, NULL, NULL);
if (!png_ptr)
return false;
png_info* info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
png_destroy_write_struct(&png_ptr, NULL);
return false;
}
PngEncoderState state(output);
bool success = DoLibpngWrite(png_ptr, info_ptr, &state,
width, height, row_byte_width,
input, compression_level, png_output_color_type,
output_color_components, converter, comments);
png_destroy_write_struct(&png_ptr, &info_ptr);
return success;
}
// static
bool Encode(const unsigned char* input, ColorFormat format,
const int width, const int height, int row_byte_width,
bool discard_transparency,
const std::vector<Comment>& comments,
std::vector<unsigned char>* output) {
return EncodeWithCompressionLevel(input, format, width, height,
row_byte_width,
discard_transparency,
comments, Z_DEFAULT_COMPRESSION,
output);
}
// Decode a PNG into an RGBA pixel array.
bool DecodePNG(const unsigned char* input, size_t input_size,
std::vector<unsigned char>* output,
int* width, int* height) {
return Decode(input, input_size, FORMAT_RGBA, output, width, height);
}
// Encode an RGBA pixel array into a PNG.
bool EncodeRGBAPNG(const unsigned char* input,
int width,
int height,
int row_byte_width,
std::vector<unsigned char>* output) {
return Encode(input, FORMAT_RGBA,
width, height, row_byte_width, false,
std::vector<Comment>(), output);
}
// Encode an BGRA pixel array into a PNG.
bool EncodeBGRAPNG(const unsigned char* input,
int width,
int height,
int row_byte_width,
bool discard_transparency,
std::vector<unsigned char>* output) {
return Encode(input, FORMAT_BGRA,
width, height, row_byte_width, discard_transparency,
std::vector<Comment>(), output);
}
} // image_diff_png

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engine/src/flutter/tools/imagediff/image_diff_png.h Normal file
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// Copyright 2013 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.
#ifndef TOOLS_IMAGEDIFF_IMAGE_DIFF_PNG_H_
#define TOOLS_IMAGEDIFF_IMAGE_DIFF_PNG_H_
#include <string>
#include <vector>
namespace image_diff_png {
// Decode a PNG into an RGBA pixel array.
bool DecodePNG(const unsigned char* input, size_t input_size,
std::vector<unsigned char>* output,
int* width, int* height);
// Encode an RGBA pixel array into a PNG.
bool EncodeRGBAPNG(const unsigned char* input,
int width,
int height,
int row_byte_width,
std::vector<unsigned char>* output);
// Encode an BGRA pixel array into a PNG.
bool EncodeBGRAPNG(const unsigned char* input,
int width,
int height,
int row_byte_width,
bool discard_transparency,
std::vector<unsigned char>* output);
} // namespace image_diff_png
#endif // TOOLS_IMAGEDIFF_IMAGE_DIFF_PNG_H_