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Diffstat (limited to 'samples/image_diff_png.cc')
| -rw-r--r-- | samples/image_diff_png.cc | 644 |
1 files changed, 644 insertions, 0 deletions
diff --git a/samples/image_diff_png.cc b/samples/image_diff_png.cc new file mode 100644 index 0000000000..2ccc3e5c91 --- /dev/null +++ b/samples/image_diff_png.cc @@ -0,0 +1,644 @@ +// 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. + +// This is a duplicate of chromium's src/tools/imagediff/image_diff_png.cc +// that has been modified to build in a pdfium environment, which itself +// was duplicated as follows: + +// 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. + +#include "image_diff_png.h" + +#include <stdlib.h> +#include <string.h> + +#include <string> + +#include "../third_party/base/logging.h" +#include "../core/src/fxcodec/fx_lpng/include/fx_png.h" +#include "../core/src/fxcodec/fx_zlib/include/fx_zlib.h" + +namespace image_diff_png { + +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, +}; + +// 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(); + 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(); + break; + } + } else { + NOTREACHED(); + 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)); + + if (static_cast<int>(row_num) > state->height) { + NOTREACHED(); + 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)); + 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. + if (comment.key.length() > 79) + return; + 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(); + return false; + } + + // Row stride should be at least as long as the length of the data. + if (input_color_components * width < row_byte_width) + return false; + + 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 |