dolphin/Source/Core/Common/ImageC.c

// Copyright 2021 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "Common/ImageC.h"

// Since libpng requires use of setjmp, and setjmp interacts poorly with destructors and other C++
// features, this is in a separate C file.

// The main purpose of this function is to allow specifying the compression level, which
// png_image_write_to_memory does not allow.  row_pointers is not modified by libpng, but also isn't
// const for some reason.
bool SavePNG0(png_structp png_ptr, png_infop info_ptr, int color_type, png_uint_32 width,
              png_uint_32 height, int level, png_voidp io_ptr, png_rw_ptr write_fn,
              png_bytepp row_pointers)
{
  if (setjmp(png_jmpbuf(png_ptr)) != 0)
    return false;

  png_set_compression_level(png_ptr, level);
  png_set_IHDR(png_ptr, info_ptr, width, height, 8, color_type, PNG_INTERLACE_NONE,
               PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
  png_set_rows(png_ptr, info_ptr, row_pointers);
  png_set_write_fn(png_ptr, io_ptr, write_fn, NULL);
  png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);

  return true;
}

// pngerror.c says: "Note that the error function MUST NOT return to the calling routine or serious
// problems will occur.  The return method used in the default routine calls
// longjmp(png_ptr->jmp_buf_ptr, 1)"
void PngError(png_structp png_ptr, png_const_charp msg)
{
  struct ErrorHandler* error_logger = (struct ErrorHandler*)png_get_error_ptr(png_ptr);
  error_logger->StoreError(error_logger, msg);
  png_longjmp(png_ptr, 1);
}

void PngWarning(png_structp png_ptr, png_const_charp msg)
{
  struct ErrorHandler* error_logger = (struct ErrorHandler*)png_get_error_ptr(png_ptr);
  error_logger->StoreWarning(error_logger, msg);
}