| // Copyright (c) 2006-2008 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 "base/basictypes.h" |
| #include "base/gfx/png_encoder.h" |
| #include "base/logging.h" |
| #include "base/scoped_ptr.h" |
| #include "third_party/skia/include/core/SkBitmap.h" |
| |
| extern "C" { |
| #include "third_party/libpng/png.h" |
| } |
| |
| namespace { |
| |
| // Converts BGRA->RGBA and RGBA->BGRA. |
| void ConvertBetweenBGRAandRGBA(const unsigned char* input, int pixel_width, |
| unsigned char* output) { |
| 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) { |
| 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 |
| |
| // 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 { |
| 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 ConvertBGRAtoRGB(const unsigned char* bgra, int pixel_width, |
| unsigned char* rgb) { |
| 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]; |
| } |
| } |
| |
| // Automatically destroys the given write structs on destruction to make |
| // cleanup and error handling code cleaner. |
| class PngWriteStructDestroyer { |
| public: |
| PngWriteStructDestroyer(png_struct** ps, png_info** pi) : ps_(ps), pi_(pi) { |
| } |
| ~PngWriteStructDestroyer() { |
| png_destroy_write_struct(ps_, pi_); |
| } |
| private: |
| png_struct** ps_; |
| png_info** pi_; |
| |
| DISALLOW_EVIL_CONSTRUCTORS(PngWriteStructDestroyer); |
| }; |
| |
| } // namespace |
| |
| // static |
| bool PNGEncoder::Encode(const unsigned char* input, ColorFormat format, |
| int w, int h, int row_byte_width, |
| bool discard_transparency, |
| std::vector<unsigned char>* output) { |
| // Run to convert an input row into the output row format, NULL means no |
| // conversion is necessary. |
| void (*converter)(const unsigned char* in, int w, unsigned char* out) = 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 * w <= row_byte_width); |
| |
| png_struct* png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, |
| png_voidp_NULL, |
| png_error_ptr_NULL, |
| png_error_ptr_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; |
| } |
| PngWriteStructDestroyer 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; |
| } |
| |
| // Set our callback for libpng to give us the data. |
| PngEncoderState state(output); |
| png_set_write_fn(png_ptr, &state, EncoderWriteCallback, NULL); |
| |
| png_set_IHDR(png_ptr, info_ptr, w, h, 8, png_output_color_type, |
| PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, |
| PNG_FILTER_TYPE_DEFAULT); |
| png_write_info(png_ptr, info_ptr); |
| |
| if (!converter) { |
| // No conversion needed, give the data directly to libpng. |
| for (int y = 0; y < h; y ++) |
| png_write_row(png_ptr, |
| const_cast<unsigned char*>(&input[y * row_byte_width])); |
| } else { |
| // Needs conversion using a separate buffer. |
| unsigned char* row = new unsigned char[w * output_color_components]; |
| for (int y = 0; y < h; y ++) { |
| converter(&input[y * row_byte_width], w, row); |
| png_write_row(png_ptr, row); |
| } |
| delete[] row; |
| } |
| |
| png_write_end(png_ptr, info_ptr); |
| return true; |
| } |
| |
| // static |
| bool PNGEncoder::EncodeBGRASkBitmap(const SkBitmap& input, |
| bool discard_transparency, |
| std::vector<unsigned char>* output) { |
| static const int bbp = 4; |
| |
| SkAutoLockPixels lock_input(input); |
| DCHECK(input.empty() || input.bytesPerPixel() == bbp); |
| |
| // SkBitmaps are premultiplied, we need to unpremultiply them. |
| scoped_array<unsigned char> divided( |
| new unsigned char[input.width() * input.height() * bbp]); |
| |
| int i = 0; |
| for (int y = 0; y < input.height(); y++) { |
| for (int x = 0; x < input.width(); x++) { |
| uint32 pixel = input.getAddr32(0, y)[x]; |
| |
| int alpha = SkColorGetA(pixel); |
| if (alpha != 0 && alpha != 255) { |
| divided[i + 0] = (SkColorGetR(pixel) << 8) / alpha; |
| divided[i + 1] = (SkColorGetG(pixel) << 8) / alpha; |
| divided[i + 2] = (SkColorGetB(pixel) << 8) / alpha; |
| divided[i + 3] = alpha; |
| } else { |
| divided[i + 0] = SkColorGetR(pixel); |
| divided[i + 1] = SkColorGetG(pixel); |
| divided[i + 2] = SkColorGetB(pixel); |
| divided[i + 3] = alpha; |
| } |
| i += bbp; |
| } |
| } |
| |
| return Encode(divided.get(), |
| PNGEncoder::FORMAT_RGBA, input.width(), input.height(), |
| input.width() * bbp, discard_transparency, output); |
| } |