Function WrapJPEGDecompress

common/Image.cpp:410–476

template <typename T>
static bool WrapJPEGDecompress(RGBA8Image* image, T setup_func)
{
	std::vector<u8> scanline;
	jpeg_decompress_struct info = {};

	// NOTE: Be **very** careful not to allocate memory after calling this function.
	// It won't get freed, because fastjmp does not unwind the stack.
	JPEGErrorHandler errhandler;
	if (fastjmp_set(&errhandler.jbuf) != 0)
	{
		jpeg_destroy_decompress(&info);
		return false;
	}
	info.err = &errhandler.err;
	jpeg_create_decompress(&info);
	setup_func(info);

	const int herr = jpeg_read_header(&info, TRUE);
	if (herr != JPEG_HEADER_OK)
	{
		Console.ErrorFmt("jpeg_read_header() returned {}", herr);
		return false;
	}

	if (info.image_width == 0 || info.image_height == 0 || info.num_components < 3)
	{
		Console.ErrorFmt("Invalid image dimensions: {}x{}x{}", info.image_width, info.image_height, info.num_components);
		return false;
	}

	info.out_color_space = JCS_RGB;
	info.out_color_components = 3;

	if (!jpeg_start_decompress(&info))
	{
		Console.ErrorFmt("jpeg_start_decompress() returned failure");
		return false;
	}

	image->SetSize(info.image_width, info.image_height);
	scanline.resize(info.image_width * 3);

	u8* scanline_buffer[1] = {scanline.data()};
	bool result = true;
	for (u32 y = 0; y < info.image_height; y++)
	{
		if (jpeg_read_scanlines(&info, scanline_buffer, 1) != 1)
		{
			Console.ErrorFmt("jpeg_read_scanlines() failed at row {}", y);
			result = false;
			break;
		}

		// RGB -> RGBA
		const u8* src_ptr = scanline.data();
		u32* dst_ptr = image->GetRowPixels(y);
		for (u32 x = 0; x < info.image_width; x++)
		{