Function imageWritePng

3rdparty/bimg/src/image.cpp:5453–5544

	};

	int32_t imageWritePng(bx::WriterI* _writer, uint32_t _width, uint32_t _height, uint32_t _srcPitch, const void* _src, TextureFormat::Enum _format, bool _yflip, bx::Error* _err)
	{
		BX_ERROR_SCOPE(_err);

		switch (_format)
		{
		case TextureFormat::R8:
		case TextureFormat::RGBA8:
		case TextureFormat::BGRA8:
			break;

		default:
			BX_ERROR_SET(_err, BIMG_ERROR, "PNG: Unsupported texture format.");
			return 0;
		}

		const bool grayscale = TextureFormat::R8    == _format;
		const bool bgra      = TextureFormat::BGRA8 == _format;

		int32_t total = 0;
		total += bx::write(_writer, "\x89PNG\r\n\x1a\n", _err);
		total += bx::write(_writer, bx::toBigEndian<uint32_t>(13), _err);

		HashWriter<bx::HashCrc32> writerC(_writer);
		total += bx::write(&writerC, "IHDR", _err);
		total += bx::write(&writerC, bx::toBigEndian(_width),  _err);
		total += bx::write(&writerC, bx::toBigEndian(_height), _err);
		total += bx::write(&writerC, "\x08\x06", _err);
		total += bx::writeRep(&writerC, 0, 3, _err);
		total += bx::write(_writer, bx::toBigEndian(writerC.end() ), _err);

		const uint32_t bpp    = grayscale ? 8 : 32;
		const uint32_t stride = _width*bpp/8;
		const uint16_t zlen   = bx::toLittleEndian<uint16_t>(uint16_t(stride + 1) );
		const uint16_t zlenC  = bx::toLittleEndian<uint16_t>(~zlen);

		total += bx::write(_writer, bx::toBigEndian<uint32_t>(_height*(stride+6)+6), _err);

		writerC.begin();
		total += bx::write(&writerC, "IDAT", _err);
		total += bx::write(&writerC, "\x78\x9c", _err);

		const uint8_t* data = (const uint8_t*)_src;
		int32_t step = int32_t(_srcPitch);
		if (_yflip)
		{
			data += _srcPitch*_height - _srcPitch;
			step = -step;
		}

		HashWriter<bx::HashAdler32> writerA(&writerC);

		for (uint32_t ii = 0; ii < _height && _err->isOk(); ++ii)
		{
			total += bx::write(&writerC, uint8_t(ii == _height-1 ? 1 : 0), _err);
			total += bx::write(&writerC, zlen,  _err);
			total += bx::write(&writerC, zlenC, _err);