diff --git a/engine/src/flutter/BUILD.gn b/engine/src/flutter/BUILD.gn index f40a6ca52e..78f7e135e6 100644 --- a/engine/src/flutter/BUILD.gn +++ b/engine/src/flutter/BUILD.gn @@ -14,6 +14,7 @@ group("sky") { "//sky/engine/wtf:unittests", "//sky/services/inspector", "//sky/tools/debugger", + "//sky/tools/imagediff", "//sky/tools/tester", "//sky/viewer", ] diff --git a/engine/src/flutter/tools/imagediff/BUILD.gn b/engine/src/flutter/tools/imagediff/BUILD.gn new file mode 100644 index 0000000000..887f4123f3 --- /dev/null +++ b/engine/src/flutter/tools/imagediff/BUILD.gn @@ -0,0 +1,20 @@ +# 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", + "//third_party/libpng", + "//third_party/zlib", + ] +} diff --git a/engine/src/flutter/tools/imagediff/image_diff.cc b/engine/src/flutter/tools/imagediff/image_diff.cc new file mode 100644 index 0000000000..e562048ce2 --- /dev/null +++ b/engine/src/flutter/tools/imagediff/image_diff.cc @@ -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 +#include +#include +#include + +#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 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 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(&(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(&data_.front())[(y * w_ + x) * 4]; + *reinterpret_cast(addr) = color; + } + + private: + // pixel dimensions of the image + int w_, h_; + + std::vector 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(actual.w()) * + static_cast(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 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(actual.w()) * + static_cast(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] \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 \n" + " Compares two files on disk, outputs an image that visualizes the\n" + " difference to \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: 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 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(&png_encoding.front()), + base::checked_cast(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; +} diff --git a/engine/src/flutter/tools/imagediff/image_diff_png.cc b/engine/src/flutter/tools/imagediff/image_diff_png.cc new file mode 100644 index 0000000000..e9d98c8c90 --- /dev/null +++ b/engine/src/flutter/tools/imagediff/image_diff_png.cc @@ -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 +#include + +#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. + PngDecoderState(ColorFormat ofmt, std::vector* 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* 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( + 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(w) * static_cast(h); + if (total_size > ((1 << 29) - 1)) + longjmp(png_jmpbuf(png_ptr), 1); + state->width = static_cast(w); + state->height = static_cast(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( + png_get_progressive_ptr(png_ptr)); + + DCHECK(pass == 0); + if (static_cast(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( + 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(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* 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(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* o) : out(o) {} + std::vector* 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(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& 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(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 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& 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(&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& comments, + int compression_level, + std::vector* 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& comments, + std::vector* 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* 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* output) { + return Encode(input, FORMAT_RGBA, + width, height, row_byte_width, false, + std::vector(), 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* output) { + return Encode(input, FORMAT_BGRA, + width, height, row_byte_width, discard_transparency, + std::vector(), output); +} + +} // image_diff_png diff --git a/engine/src/flutter/tools/imagediff/image_diff_png.h b/engine/src/flutter/tools/imagediff/image_diff_png.h new file mode 100644 index 0000000000..c371337f99 --- /dev/null +++ b/engine/src/flutter/tools/imagediff/image_diff_png.h @@ -0,0 +1,35 @@ +// 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 +#include + +namespace image_diff_png { + +// Decode a PNG into an RGBA pixel array. +bool DecodePNG(const unsigned char* input, size_t input_size, + std::vector* 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* 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* output); + +} // namespace image_diff_png + +#endif // TOOLS_IMAGEDIFF_IMAGE_DIFF_PNG_H_