private int CalculateScanlineStep(PngColorTypeInformation colorTypeInformation)
{
int scanlineStep = 1;
if (_header.BitDepth >= 8)
{
scanlineStep = (colorTypeInformation.ChannelsPerColor * _header.BitDepth) / 8;
}
return(scanlineStep);
}
private int CalculateScanlineLength(PngColorTypeInformation colorTypeInformation)
{
int scanlineLength = (_header.Width * _header.BitDepth * colorTypeInformation.ChannelsPerColor);
int amount = scanlineLength % 8;
if (amount != 0)
{
scanlineLength += 8 - amount;
}
return(scanlineLength / 8);
}
private void ReadScanlines(MemoryStream dataStream, byte[] pixels, IColorReader colorReader, PngColorTypeInformation colorTypeInformation)
{
// Read the zlib header : http://tools.ietf.org/html/rfc1950
// CMF(Compression Method and flags)
// This byte is divided into a 4 - bit compression method and a
// 4-bit information field depending on the compression method.
// bits 0 to 3 CM Compression method
// bits 4 to 7 CINFO Compression info
//
// 0 1
// +---+---+
// |CMF|FLG|
// +---+---+
int cmf = dataStream.ReadByte();
int flag = dataStream.ReadByte();
//please note that position=2
int scanlineLength = CalculateScanlineLength(colorTypeInformation);
int scanlineStep = CalculateScanlineStep(colorTypeInformation);
byte[] lastScanline = new byte[scanlineLength];
byte[] currScanline = new byte[scanlineLength];
byte a = 0;
byte b = 0;
byte c = 0;
int row = 0, filter = 0, column = -1;
//using (InflaterInputStream compressedStream = new InflaterInputStream(dataStream))
//{
// int readByte = 0;
// while ((readByte = compressedStream.ReadByte()) >= 0)
// {
// if (column == -1)
// {
// filter = readByte;
// column++;
// }
// else
// {
// currScanline[column] = (byte)readByte;
// if (column >= scanlineStep)
// {
// a = currScanline[column - scanlineStep];
// c = lastScanline[column - scanlineStep];
// }
// else
// {
// a = 0;
// c = 0;
// }
// b = lastScanline[column];
// if (filter == 1)
// {
// currScanline[column] = (byte)(currScanline[column] + a);
// }
// else if (filter == 2)
// {
// currScanline[column] = (byte)(currScanline[column] + b);
// }
// else if (filter == 3)
// {
// currScanline[column] = (byte)(currScanline[column] + (byte)Math.Floor((double)(a + b) / 2));
// }
// else if (filter == 4)
// {
// currScanline[column] = (byte)(currScanline[column] + PaethPredicator(a, b, c));
// }
// column++;
// if (column == scanlineLength)
// {
// colorReader.ReadScanline(currScanline, pixels, _header);
// column = -1;
// row++;
// Extensions.Swap(ref currScanline, ref lastScanline);
// }
// }
// }
//}
//using (Ionic.Zlib.DeflateStream compressedStream = new Ionic.Zlib.DeflateStream(dataStream, Ionic.Zlib.CompressionMode.Decompress))
using (System.IO.Compression.DeflateStream compressedStream = new System.IO.Compression.DeflateStream(
dataStream,
System.IO.Compression.CompressionMode.Decompress, true))
{
int readByte = 0;
//byte[] singleByte = new byte[1];
//compressedStream.Read(singleByte, 0, 1);
while ((readByte = compressedStream.ReadByte()) >= 0)
{
if (column == -1)
{
filter = readByte;
column++;
}
else
{
currScanline[column] = (byte)readByte;
if (column >= scanlineStep)
{
a = currScanline[column - scanlineStep];
c = lastScanline[column - scanlineStep];
}
else
{
a = 0;
c = 0;
}
b = lastScanline[column];
if (filter == 1)
{
currScanline[column] = (byte)(currScanline[column] + a);
}
else if (filter == 2)
{
currScanline[column] = (byte)(currScanline[column] + b);
}
else if (filter == 3)
{
currScanline[column] = (byte)(currScanline[column] + (byte)Math.Floor((double)(a + b) / 2));
}
else if (filter == 4)
{
currScanline[column] = (byte)(currScanline[column] + PaethPredicator(a, b, c));
}
column++;
if (column == scanlineLength)
{
colorReader.ReadScanline(currScanline, pixels, _header);
column = -1;
row++;
//
//Extensions.Swap(ref currScanline, ref lastScanline);
var tmpA = currScanline;
var tmpB = lastScanline;
lastScanline = tmpA;
currScanline = tmpB;
}
}
}
}
}
/// <summary>
/// Decodes the image from the specified stream and sets
/// the data to image.
/// </summary>
/// <param name="image">The image, where the data should be set to.
/// Cannot be null (Nothing in Visual Basic).</param>
/// <param name="stream">The stream, where the image should be
/// decoded from. Cannot be null (Nothing in Visual Basic).</param>
/// <exception cref="ArgumentNullException">
/// <para><paramref name="image"/> is null (Nothing in Visual Basic).</para>
/// <para>- or -</para>
/// <para><paramref name="stream"/> is null (Nothing in Visual Basic).</para>
/// </exception>
public void Decode(ExtendedImage image, Stream stream)
{
_image = image;
_stream = stream;
_stream.Seek(8, SeekOrigin.Current);
bool isEndChunckReached = false;
PngChunk currentChunk = null;
byte[] palette = null;
byte[] paletteAlpha = null;
using (MemoryStream dataStream = new MemoryStream())
{
while ((currentChunk = ReadChunk()) != null)
{
if (isEndChunckReached)
{
throw new ImageFormatException("Image does not end with end chunk.");
}
if (currentChunk.Type == PngChunkTypes.Header)
{
ReadHeaderChunk(currentChunk.Data);
ValidateHeader();
}
else if (currentChunk.Type == PngChunkTypes.Physical)
{
ReadPhysicalChunk(currentChunk.Data);
}
else if (currentChunk.Type == PngChunkTypes.Data)
{
dataStream.Write(currentChunk.Data, 0, currentChunk.Data.Length);
}
else if (currentChunk.Type == PngChunkTypes.Palette)
{
palette = currentChunk.Data;
}
else if (currentChunk.Type == PngChunkTypes.PaletteAlpha)
{
paletteAlpha = currentChunk.Data;
}
else if (currentChunk.Type == PngChunkTypes.Text)
{
ReadTextChunk(currentChunk.Data);
}
else if (currentChunk.Type == PngChunkTypes.End)
{
isEndChunckReached = true;
}
}
byte[] pixels = new byte[_header.Width * _header.Height * 4];
PngColorTypeInformation colorTypeInformation = _colorTypes[_header.ColorType];
if (colorTypeInformation != null)
{
IColorReader colorReader = colorTypeInformation.CreateColorReader(palette, paletteAlpha);
ReadScanlines(dataStream, pixels, colorReader, colorTypeInformation);
}
image.SetPixels(_header.Width, _header.Height, pixels);
}
}
private void ReadScanlines(MemoryStream dataStream, byte[] pixels, IColorReader colorReader, PngColorTypeInformation colorTypeInformation)
{
dataStream.Position = 0;
int scanlineLength = CalculateScanlineLength(colorTypeInformation);
int scanlineStep = CalculateScanlineStep(colorTypeInformation);
byte[] lastScanline = new byte[scanlineLength];
byte[] currScanline = new byte[scanlineLength];
byte a = 0;
byte b = 0;
byte c = 0;
int row = 0, filter = 0, column = -1;
using (InflaterInputStream compressedStream = new InflaterInputStream(dataStream))
{
int readByte = 0;
while ((readByte = compressedStream.ReadByte()) >= 0)
{
if (column == -1)
{
filter = readByte;
column++;
}
else
{
currScanline[column] = (byte)readByte;
if (column >= scanlineStep)
{
a = currScanline[column - scanlineStep];
c = lastScanline[column - scanlineStep];
}
else
{
a = 0;
c = 0;
}
b = lastScanline[column];
if (filter == 1)
{
currScanline[column] = (byte)(currScanline[column] + a);
}
else if (filter == 2)
{
currScanline[column] = (byte)(currScanline[column] + b);
}
else if (filter == 3)
{
currScanline[column] = (byte)(currScanline[column] + (byte)Math.Floor((a + b) / 2d));
}
else if (filter == 4)
{
currScanline[column] = (byte)(currScanline[column] + PaethPredicator(a, b, c));
}
column++;
if (column == scanlineLength)
{
colorReader.ReadScanline(currScanline, pixels, _header);
column = -1;
row++;
Extensions.Swap(ref currScanline, ref lastScanline);
}
}
}
}
}
private int CalculateScanlineStep(PngColorTypeInformation colorTypeInformation)
{
int scanlineStep = 1;
if (_header.BitDepth >= 8)
{
scanlineStep = (colorTypeInformation.ChannelsPerColor * _header.BitDepth) / 8;
}
return scanlineStep;
}
private int CalculateScanlineLength(PngColorTypeInformation colorTypeInformation)
{
int scanlineLength = (_header.Width * _header.BitDepth * colorTypeInformation.ChannelsPerColor);
int amount = scanlineLength % 8;
if (amount != 0)
{
scanlineLength += 8 - amount;
}
return scanlineLength / 8;
}
private void ReadScanlines(MemoryStream dataStream, byte[] pixels, IColorReader colorReader, PngColorTypeInformation colorTypeInformation)
{
dataStream.Position = 0;
int scanlineLength = CalculateScanlineLength(colorTypeInformation);
int scanlineStep = CalculateScanlineStep(colorTypeInformation);
byte[] lastScanline = new byte[scanlineLength];
byte[] currScanline = new byte[scanlineLength];
byte a = 0;
byte b = 0;
byte c = 0;
int row = 0, filter = 0, column = -1;
using (InflaterInputStream compressedStream = new InflaterInputStream(dataStream))
{
int readByte = 0;
while ((readByte = compressedStream.ReadByte()) >= 0)
{
if (column == -1)
{
filter = readByte;
column++;
}
else
{
currScanline[column] = (byte)readByte;
if (column >= scanlineStep)
{
a = currScanline[column - scanlineStep];
c = lastScanline[column - scanlineStep];
}
else
{
a = 0;
c = 0;
}
b = lastScanline[column];
if (filter == 1)
{
currScanline[column] = (byte)(currScanline[column] + a);
}
else if (filter == 2)
{
currScanline[column] = (byte)(currScanline[column] + b);
}
else if (filter == 3)
{
currScanline[column] = (byte)(currScanline[column] + (byte)Math.Floor((a + b) / 2d));
}
else if (filter == 4)
{
currScanline[column] = (byte)(currScanline[column] + PaethPredicator(a, b, c));
}
column++;
if (column == scanlineLength)
{
colorReader.ReadScanline(currScanline, pixels, _header);
column = -1;
row++;
Extensions.Swap(ref currScanline, ref lastScanline);
}
}
}
}
}
private void ReadScanlines(MemoryStream dataStream, byte[] pixels, IColorReader colorReader, PngColorTypeInformation colorTypeInformation)
{
// Read the zlib header : http://tools.ietf.org/html/rfc1950
// CMF(Compression Method and flags)
// This byte is divided into a 4 - bit compression method and a
// 4-bit information field depending on the compression method.
// bits 0 to 3 CM Compression method
// bits 4 to 7 CINFO Compression info
//
// 0 1
// +---+---+
// |CMF|FLG|
// +---+---+
int cmf = dataStream.ReadByte();
int flag = dataStream.ReadByte();
//please note that position=2
int scanlineLength = CalculateScanlineLength(colorTypeInformation);
int scanlineStep = CalculateScanlineStep(colorTypeInformation);
byte[] lastScanline = new byte[scanlineLength];
byte[] currScanline = new byte[scanlineLength];
byte a = 0;
byte b = 0;
byte c = 0;
int row = 0, filter = 0, column = -1;
//using (InflaterInputStream compressedStream = new InflaterInputStream(dataStream))
//{
// int readByte = 0;
// while ((readByte = compressedStream.ReadByte()) >= 0)
// {
// if (column == -1)
// {
// filter = readByte;
// column++;
// }
// else
// {
// currScanline[column] = (byte)readByte;
// if (column >= scanlineStep)
// {
// a = currScanline[column - scanlineStep];
// c = lastScanline[column - scanlineStep];
// }
// else
// {
// a = 0;
// c = 0;
// }
// b = lastScanline[column];
// if (filter == 1)
// {
// currScanline[column] = (byte)(currScanline[column] + a);
// }
// else if (filter == 2)
// {
// currScanline[column] = (byte)(currScanline[column] + b);
// }
// else if (filter == 3)
// {
// currScanline[column] = (byte)(currScanline[column] + (byte)Math.Floor((double)(a + b) / 2));
// }
// else if (filter == 4)
// {
// currScanline[column] = (byte)(currScanline[column] + PaethPredicator(a, b, c));
// }
// column++;
// if (column == scanlineLength)
// {
// colorReader.ReadScanline(currScanline, pixels, _header);
// column = -1;
// row++;
// Extensions.Swap(ref currScanline, ref lastScanline);
// }
// }
// }
//}
using (System.IO.Compression.DeflateStream compressedStream = new System.IO.Compression.DeflateStream(
dataStream,
System.IO.Compression.CompressionMode.Decompress, true))
//using (Ionic.Zlib.DeflateStream compressedStream = new Ionic.Zlib.DeflateStream(dataStream, Ionic.Zlib.CompressionMode.Decompress))
{
int readByte = 0;
//byte[] singleByte = new byte[1];
//compressedStream.Read(singleByte, 0, 1);
while ((readByte = compressedStream.ReadByte()) >= 0)
{
if (column == -1)
{
filter = readByte;
column++;
}
else
{
currScanline[column] = (byte)readByte;
if (column >= scanlineStep)
{
a = currScanline[column - scanlineStep];
c = lastScanline[column - scanlineStep];
}
else
{
a = 0;
c = 0;
}
b = lastScanline[column];
if (filter == 1)
{
currScanline[column] = (byte)(currScanline[column] + a);
}
else if (filter == 2)
{
currScanline[column] = (byte)(currScanline[column] + b);
}
else if (filter == 3)
{
currScanline[column] = (byte)(currScanline[column] + (byte)Math.Floor((double)(a + b) / 2));
}
else if (filter == 4)
{
currScanline[column] = (byte)(currScanline[column] + PaethPredicator(a, b, c));
}
column++;
if (column == scanlineLength)
{
colorReader.ReadScanline(currScanline, pixels, _header);
column = -1;
row++;
//
//Extensions.Swap(ref currScanline, ref lastScanline);
var tmpA = currScanline;
var tmpB = lastScanline;
lastScanline = tmpA;
currScanline = tmpB;
}
}
}
}
}
