private byte[] Decode(string path)
{
var result = new byte[0];
using (var stream = new System.IO.FileStream(path, System.IO.FileMode.Open))
{
var header = new PngHeader(stream);
var chunks = new List <PngChunk>();
while (stream.Position < stream.Length)
{
var chunk = new PngChunk(stream);
chunks.Add(chunk);
if (chunk.Type == "IEND")
{
break;
}
}
var ihdr = chunks.Where(a => a.Type == "IHDR").FirstOrDefault();
var ihdrData = ihdr.IRDRInfo;
Width = ihdrData.Width;
Height = ihdrData.Height;
var data = new List <byte>();
for (var i = 0; i < chunks.Count; i++)
{
if (chunks[i].Type == "IDAT")
{
data.AddRange(chunks[i].Data);
}
}
var pngData = new List <byte>();
// The first byte 0x78 is called CMF, and the value means CM = 8, CINFO = 7. CM = 8 denotes the "deflate"
// compression method with a window size up to 32K. This is the method used by gzip and PNG. CINFO = 7 indicates a
// 32K window size.
// The 0x9C is called FLG and the value means FLEVEL = 2, CHECK = 28.
// The information in FLEVEL is not needed for decompression; it is there to indicate if recompression might be worthwhile.
// CHECK is set to whatever value is necessary such that CMF*256 + FLG is a multiple of 31
// we'll ignore the 2 bytees
using (var deflate = new System.IO.Compression.DeflateStream(new System.IO.MemoryStream(data.Skip(2).Take(data.Count - 2).ToArray()), System.IO.Compression.CompressionMode.Decompress))
{
var buffer = new byte[32768];
while (deflate.CanRead)
{
int count = deflate.Read(buffer, 0, buffer.Length);
pngData.AddRange(buffer.Take(count));
if (count < 32768)
{
break;
}
}
}
var bytesPerPixel = 3;
_dataStructure = ImageDataStructure.Rgb;
switch (ihdrData.ColorType)
{
case PngChunk.ColorTypeCode.ColorUsedAlphaChannelUsed:
bytesPerPixel = 4;
_dataStructure = ImageDataStructure.Rgba;
break;
}
result = new byte[Width * Height * bytesPerPixel];
var previousScanLine = new byte[Width * bytesPerPixel];
var scanLine = new byte[Width * bytesPerPixel];
var pngArray = pngData.ToArray();
var dataLineWithFilter = Width * bytesPerPixel + 1;
for (var i = 0; i < Height; i++)
{
// first byte of each line specifies the filter
var filter = (PngChunk.FilterTypeCode)pngArray[dataLineWithFilter * i];
// copy the data of the scan line
Array.Copy(pngArray, dataLineWithFilter * i + 1, scanLine, 0, scanLine.Length);
previousScanLine = Defilter(filter, scanLine, previousScanLine, bytesPerPixel);
Array.Copy(previousScanLine, 0, result, scanLine.Length * i, scanLine.Length);
}
}
return(result);
}
public bool Save(string path)
{
try
{
using (var stream = new System.IO.FileStream(path, System.IO.FileMode.Create))
{
var header = new PngHeader();
stream.Write(header.Data, 0, header.Data.Length);
PngChunk.Write(stream, "IHDR", PngChunk.CreateIHDRData(new PngChunk.IHDRData()
{
Width = TransformedWidth,
Height = TransformedHeight,
BitDepth = 8,
ColorType = PngChunk.ColorTypeCode.ColorUsedAlphaChannelUsed,
CompressionMethod = PngChunk.CompressionMethodCode.Deflate,
FilterMethod = PngChunk.FilterTypeCode.None,
InterlaceMethod = PngChunk.InterlaceMethodCode.None
}));
DataStructure = ImageDataStructure.Rgba;
var imageData = new byte[Data.Length + TransformedHeight];
for (int i = 0; i < TransformedHeight; i++)
{
imageData[i * TransformedWidth * 4 + i] = (byte)PngChunk.FilterTypeCode.None;
Array.Copy(Data, i * TransformedWidth * 4, imageData, i * TransformedWidth * 4 + i + 1, TransformedWidth * 4);
}
using (var idatStream = new MemoryStream())
{
idatStream.WriteByte(0x78);
idatStream.WriteByte(0x9C);
using (var deflate = new System.IO.Compression.DeflateStream(idatStream, System.IO.Compression.CompressionMode.Compress))
{
var window = 32768;
var count = 0;
while (count * window < imageData.Length)
{
var buffer = imageData.Skip(count * window).Take(window).ToArray();
deflate.Write(buffer, 0, buffer.Length);
count++;
}
deflate.Dispose();
PngChunk.Write(stream, "IDAT", idatStream.ToArray());
}
}
PngChunk.Write(stream, "IEND", new byte[0]);
}
}
catch (Exception)
{
return(false);
}
return(true);
}
