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// Copyright 2016 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include "Common/Image.h"
#include <csetjmp>
#include <cstdlib>
#include <cstring>
#include <memory>
#include <png.h>
#include <vector>
#include "Common/CommonTypes.h"
#include "Common/Logging/Log.h"
namespace Common
{
static int MultiplyAlpha(int alpha, int color)
{
const int temp = (alpha * color) + 0x80;
return ((temp + (temp >> 8)) >> 8);
}
static void PremultiplyData(png_structp png, png_row_infop row_info, png_bytep data)
{
for (png_size_t i = 0; i < row_info->rowbytes; i += 4, data += 4)
{
const png_byte alpha = data[3];
u32 w;
if (alpha == 0)
{
w = 0;
}
else
{
png_byte red = data[0];
png_byte green = data[1];
png_byte blue = data[2];
if (alpha != 0xff)
{
red = MultiplyAlpha(alpha, red);
green = MultiplyAlpha(alpha, green);
blue = MultiplyAlpha(alpha, blue);
}
w = (alpha << 24) | (red << 16) | (green << 8) | (blue << 0);
}
std::memcpy(data, &w, sizeof(w));
}
}
struct ReadProgress
{
const u8* current;
const u8* end;
};
static void ReadCallback(png_structp png, png_bytep data, png_size_t size)
{
ReadProgress* progress = static_cast<ReadProgress*>(png_get_io_ptr(png));
for (size_t i = 0; i < size; ++i)
{
if (progress->current >= progress->end)
png_error(png, "Read beyond end of file"); // This makes us longjmp back to LoadPNG
data[i] = *(progress->current);
++(progress->current);
}
}
static void PNGErrorCallback(png_structp png, png_const_charp error_msg)
{
ERROR_LOG(COMMON, "PNG loading error: %s", error_msg);
longjmp(png_jmpbuf(png), 1);
}
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4611)
// VS shows the following warning even though no C++ objects are destroyed in LoadPNG:
// "warning C4611: interaction between '_setjmp' and C++ object destruction is non-portable"
#endif
bool LoadPNG(const std::vector<u8>& input, std::vector<u8>* data_out, u32* width_out,
u32* height_out)
{
const bool is_png = !png_sig_cmp(input.data(), 0, input.size());
if (!is_png)
return false;
png_struct* png =
png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, PNGErrorCallback, nullptr);
if (!png)
return false;
png_info* info = png_create_info_struct(png);
if (!info)
{
png_destroy_read_struct(&png, &info, nullptr);
return false;
}
// It would've been nice to use std::vector for this, but using setjmp safely
// means that we have to use this manually managed volatile pointer garbage instead.
png_byte** volatile row_pointers_volatile = nullptr;
if (setjmp(png_jmpbuf(png)))
{
free(row_pointers_volatile);
png_destroy_read_struct(&png, &info, nullptr);
return false;
}
ReadProgress read_progress{input.data(), input.data() + input.size()};
png_set_read_fn(png, &read_progress, ReadCallback);
png_read_info(png, info);
png_uint_32 width, height;
int depth, color_type, interlace;
png_get_IHDR(png, info, &width, &height, &depth, &color_type, &interlace, nullptr, nullptr);
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(png);
else if (color_type == PNG_COLOR_TYPE_GRAY)
png_set_expand_gray_1_2_4_to_8(png);
if (png_get_valid(png, info, PNG_INFO_tRNS))
png_set_tRNS_to_alpha(png);
if (depth == 16)
png_set_strip_16(png);
else if (depth < 8)
png_set_packing(png);
if (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png);
if (interlace != PNG_INTERLACE_NONE)
png_set_interlace_handling(png);
png_set_bgr(png);
png_set_filler(png, 0xff, PNG_FILLER_AFTER);
png_set_read_user_transform_fn(png, PremultiplyData);
png_read_update_info(png, info);
png_get_IHDR(png, info, &width, &height, &depth, &color_type, &interlace, nullptr, nullptr);
const size_t stride = width * 4;
data_out->resize(stride * height);
png_byte** row_pointers = static_cast<png_byte**>(malloc(height * sizeof(png_byte*)));
if (!row_pointers)
{
png_destroy_read_struct(&png, &info, nullptr);
return false;
}
for (png_uint_32 i = 0; i < height; i++)
row_pointers[i] = &(*data_out)[i * stride];
row_pointers_volatile = row_pointers;
png_read_image(png, row_pointers);
png_read_end(png, info);
free(row_pointers);
png_destroy_read_struct(&png, &info, nullptr);
*width_out = width;
*height_out = height;
return true;
}
#ifdef _MSC_VER
#pragma warning(pop)
#endif
} // namespace Common
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