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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.
- #include "tools/imagediff/image_diff_png.h"
- #include <stdlib.h>
- #include <string.h>
- #include <ostream>
- #include "base/check.h"
- #include "base/notreached.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(nullptr),
- 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 BUILDFLAG(IS_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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