public Stream Write(Texture2D texture2D)
{
textureData = new Color[texture2D.Width * texture2D.Height];
texture2D.GetData<Color>(textureData);
var outputStream = new MemoryStream();
// write PNG signature
outputStream.Write(HeaderChunk.PngSignature, 0, HeaderChunk.PngSignature.Length);
// write header chunk
var headerChunk = new HeaderChunk();
headerChunk.Width = (uint)texture2D.Width;
headerChunk.Height = (uint)texture2D.Height;
headerChunk.BitDepth = 8;
headerChunk.ColorType = colorType;
headerChunk.CompressionMethod = 0;
headerChunk.FilterMethod = 0;
headerChunk.InterlaceMethod = 0;
var headerChunkBytes = headerChunk.Encode();
outputStream.Write(headerChunkBytes, 0, headerChunkBytes.Length);
// write data chunks
var encodedPixelData = EncodePixelData(texture2D);
var compressedPixelData = new MemoryStream();
try
{
using (var deflateStream = new ZlibStream(new MemoryStream(encodedPixelData), CompressionMode.Compress))
{
deflateStream.CopyTo(compressedPixelData);
}
}
catch (Exception exception)
{
throw new Exception("An error occurred during DEFLATE compression.", exception);
}
var dataChunk = new DataChunk();
dataChunk.Data = compressedPixelData.ToArray();
var dataChunkBytes = dataChunk.Encode();
outputStream.Write(dataChunkBytes, 0, dataChunkBytes.Length);
// write end chunk
var endChunk = new EndChunk();
var endChunkBytes = endChunk.Encode();
outputStream.Write(endChunkBytes, 0, endChunkBytes.Length);
return outputStream;
}
private void ProcessChunk(byte[] chunkBytes)
{
string chunkType = PngChunk.GetChunkTypeString(chunkBytes.Skip(4).Take(4).ToArray());
switch (chunkType)
{
case "IHDR":
var headerChunk = new HeaderChunk();
headerChunk.Decode(chunkBytes);
width = (int)headerChunk.Width;
height = (int)headerChunk.Height;
bitsPerSample = (int)headerChunk.BitDepth;
colorType = headerChunk.ColorType;
chunks.Add(headerChunk);
break;
case "PLTE":
var paletteChunk = new PaletteChunk();
paletteChunk.Decode(chunkBytes);
palette = paletteChunk.Palette;
chunks.Add(paletteChunk);
break;
case "tRNS":
var transparencyChunk = new TransparencyChunk();
transparencyChunk.Decode(chunkBytes);
palette.AddAlphaToColors(transparencyChunk.PaletteTransparencies);
break;
case "IDAT":
var dataChunk = new DataChunk();
dataChunk.Decode(chunkBytes);
dataChunks.Add(dataChunk);
break;
default:
break;
}
}