dolphin/Source/Core/Common/Image.cpp

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// Copyright 2016 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include "Common/Image.h"
#include <string>
#include <vector>
#include <png.h>
#include "Common/CommonTypes.h"
#include "Common/File.h"
namespace Common
{
bool LoadPNG(const std::vector<u8>& input, std::vector<u8>* data_out, u32* width_out,
u32* height_out)
{
// Using the 'Simplified API' of libpng; see section V in the libpng manual.
// Read header
png_image png = {};
png.version = PNG_IMAGE_VERSION;
if (!png_image_begin_read_from_memory(&png, input.data(), input.size()))
return false;
// Prepare output vector
png.format = PNG_FORMAT_RGBA;
size_t png_size = PNG_IMAGE_SIZE(png);
data_out->resize(png_size);
// Convert to RGBA and write into output vector
if (!png_image_finish_read(&png, nullptr, data_out->data(), 0, nullptr))
return false;
*width_out = png.width;
*height_out = png.height;
return true;
}
bool SavePNG(const std::string& path, const u8* input, ImageByteFormat format, u32 width,
u32 height, int stride)
{
png_image png = {};
png.version = PNG_IMAGE_VERSION;
png.width = width;
png.height = height;
size_t byte_per_pixel;
switch (format)
{
case ImageByteFormat::RGB:
png.format = PNG_FORMAT_RGB;
byte_per_pixel = 3;
break;
case ImageByteFormat::RGBA:
png.format = PNG_FORMAT_RGBA;
byte_per_pixel = 4;
break;
default:
return false;
}
// libpng doesn't handle non-ASCII characters in path, so write in two steps:
// first to memory, then to file
std::vector<u8> buffer(byte_per_pixel * width * height);
png_alloc_size_t size = buffer.size();
int success = png_image_write_to_memory(&png, buffer.data(), &size, 0, input, stride, nullptr);
if (!success && size > buffer.size())
{
// initial buffer size guess was too small, set to the now-known size and retry
buffer.resize(size);
png.warning_or_error = 0;
success = png_image_write_to_memory(&png, buffer.data(), &size, 0, input, stride, nullptr);
}
if (!success || (png.warning_or_error & PNG_IMAGE_ERROR) != 0)
return false;
File::IOFile outfile(path, "wb");
if (!outfile)
return false;
return outfile.WriteBytes(buffer.data(), size);
}
bool ConvertRGBAToRGBAndSavePNG(const std::string& path, const u8* input, u32 width, u32 height,
int stride)
{
const std::vector<u8> data = RGBAToRGB(input, width, height, stride);
return SavePNG(path, data.data(), ImageByteFormat::RGB, width, height);
}
std::vector<u8> RGBAToRGB(const u8* input, u32 width, u32 height, int row_stride)
{
std::vector<u8> buffer;
buffer.reserve(width * height * 3);
for (u32 y = 0; y < height; ++y)
{
const u8* pos = input + y * row_stride;
for (u32 x = 0; x < width; ++x)
{
buffer.push_back(pos[x * 4]);
buffer.push_back(pos[x * 4 + 1]);
buffer.push_back(pos[x * 4 + 2]);
}
}
return buffer;
}
} // namespace Common