C++ FileReader::ReadUint32BE方法代码示例

OPENMPT_NAMESPACE_BEGIN


PNG::Bitmap *PNG::ReadPNG(FileReader &file)
//-----------------------------------------
{
	file.Rewind();
	if(!file.ReadMagic("\211PNG\r\n\032\n"))
	{
		return nullptr;
	}

	uint32_t width = 0;
	uint32_t height = 0;
	uint8_t bitDepth;
	uint8_t colorType;
	uint8_t compressionMethod;
	uint8_t filterMethod;
	uint8_t interlaceMethod;

	std::vector<uint8_t> dataIn;
	std::vector<Pixel> palette;

	while(file.AreBytesLeft())
	{
		uint32_t chunkLength = file.ReadUint32BE();
		char magic[4];
		file.ReadArray(magic);
		FileReader chunk = file.ReadChunk(chunkLength);
		file.Skip(4);	// CRC32
		if(!memcmp(magic, "IHDR", 4))
		{
			// Image header
			width = chunk.ReadUint32BE();
			height = chunk.ReadUint32BE();
			bitDepth = chunk.ReadUint8();
			colorType = chunk.ReadUint8();
			compressionMethod = chunk.ReadUint8();
			filterMethod = chunk.ReadUint8();
			interlaceMethod = chunk.ReadUint8();
			ASSERT(!filterMethod && !interlaceMethod);
		} else if(!memcmp(magic, "IDAT", 4))
		{
			// Data block(s)
			z_stream strm;
			strm.zalloc = Z_NULL;
			strm.zfree = Z_NULL;
			strm.opaque = Z_NULL;
			strm.avail_in = static_cast<uInt>(chunk.GetLength());
			strm.next_in = (Bytef *)(chunk.GetRawData());
			if(inflateInit2(&strm, 15) != Z_OK)
			{
				break;
			}
			int retVal;
			do
			{
				dataIn.resize(dataIn.size() + 4096);
				strm.avail_out = 4096;
				strm.next_out = (Bytef *)&dataIn[dataIn.size() - 4096];
				retVal = inflate(&strm, Z_NO_FLUSH);
			} while(retVal == Z_OK);
			inflateEnd(&strm);
		} else if(!memcmp(magic, "PLTE", 4))
		{
			// Palette for <= 8-bit images
			palette.resize(256);
			size_t numEntries = std::min<size_t>(256u, chunk.GetLength() / 3u);
			for(size_t i = 0; i < numEntries; i++)
			{
				uint8_t p[3];
				chunk.ReadArray(p);
				palette[i] = Pixel(p[0], p[1], p[2], 255);
			}
		}
	}

	// LUT for translating the color type into a number of color samples
	const uint32_t sampleTable[] =
	{
		1,	// 0: Grayscale
		0,
		3,	// 2: RGB
		1,	// 3: Palette bitmap
		2,	// 4: Grayscale + Alpha
		0,
		4	// 6: RGBA
	};
	const uint32_t bitsPerPixel = colorType < CountOf(sampleTable) ? sampleTable[colorType] * bitDepth : 0;

	if(!width || !height || !bitsPerPixel
		|| (colorType != 2  && colorType != 3 && colorType != 6) || bitDepth != 8	// Only RGB(A) and 8-bit palette PNGs for now.
		|| compressionMethod || interlaceMethod
		|| (colorType == 3 && palette.empty())
		|| dataIn.size() < (bitsPerPixel * width * height) / 8 + height)			// Enough data present?
	{
		return nullptr;
	}

	Bitmap *bitmap = new (std::nothrow) Bitmap(width, height);
//.........这里部分代码省略.........

VSTPresets::ErrorCode VSTPresets::LoadFile(FileReader &file, CVstPlugin &plugin)
//------------------------------------------------------------------------------
{
	const bool firstChunk = file.GetPosition() == 0;
	ChunkHeader header;
	if(!file.ReadConvertEndianness(header) || header.chunkMagic != cMagic)
	{
		return invalidFile;
	}
	if(header.fxID != plugin.GetUID())
	{
		return wrongPlugin;
	}

	if(header.fxMagic == fMagic || header.fxMagic == chunkPresetMagic)
	{
		// Program
		PlugParamIndex numParams = file.ReadUint32BE();

		VstPatchChunkInfo info;
		info.version = 1;
		info.pluginUniqueID = header.fxID;
		info.pluginVersion = header.fxVersion;
		info.numElements = numParams;
		MemsetZero(info.future);
		plugin.Dispatch(effBeginLoadProgram, 0, 0, &info, 0.0f);
		plugin.Dispatch(effBeginSetProgram, 0, 0, nullptr, 0.0f);

		char prgName[28];
		file.ReadString<mpt::String::maybeNullTerminated>(prgName, 28);
		plugin.Dispatch(effSetProgramName, 0, 0, prgName, 0.0f);

		if(header.fxMagic == fMagic)
		{
			if(plugin.GetNumParameters() != numParams)
			{
				return wrongParameters;
			}
			for(PlugParamIndex p = 0; p < numParams; p++)
			{
				plugin.SetParameter(p, file.ReadFloatBE());
			}
		} else
		{
			FileReader chunk = file.ReadChunk(file.ReadUint32BE());
			plugin.Dispatch(effSetChunk, 1, chunk.GetLength(), const_cast<char *>(chunk.GetRawData()), 0);
		}
		plugin.Dispatch(effEndSetProgram, 0, 0, nullptr, 0.0f);
	} else if((header.fxMagic == bankMagic || header.fxMagic == chunkBankMagic) && firstChunk)
	{
		// Bank - only read if it's the first chunk in the file, not if it's a sub chunk.
		uint32 numProgs = file.ReadUint32BE();
		uint32 currentProgram = file.ReadUint32BE();
		file.Skip(124);

		VstPatchChunkInfo info;
		info.version = 1;
		info.pluginUniqueID = header.fxID;
		info.pluginVersion = header.fxVersion;
		info.numElements = numProgs;
		MemsetZero(info.future);
		plugin.Dispatch(effBeginLoadBank, 0, 0, &info, 0.0f);

		if(header.fxMagic == bankMagic)
		{
			VstInt32 oldCurrentProgram = plugin.GetCurrentProgram();
			for(uint32 p = 0; p < numProgs; p++)
			{
				plugin.Dispatch(effBeginSetProgram, 0, 0, nullptr, 0.0f);
				plugin.Dispatch(effSetProgram, 0, 0, nullptr, 0.0f);
				ErrorCode retVal = LoadFile(file, plugin);
				if(retVal != noError)
				{
					return retVal;
				}
				plugin.Dispatch(effEndSetProgram, 0, 0, nullptr, 0.0f);
			}
			plugin.SetCurrentProgram(oldCurrentProgram);
		} else
		{
			FileReader chunk = file.ReadChunk(file.ReadUint32BE());
			plugin.Dispatch(effSetChunk, 0, chunk.GetLength(), const_cast<char *>(chunk.GetRawData()), 0);
		}
		if(header.version >= 2)
		{
			plugin.SetCurrentProgram(currentProgram);
		}
	}

	return noError;
}