/// <summary>
/// Creates a PNG image from the specified pixels.
/// </summary>
/// <param name="pixels">The pixels (bottom line first).</param>
/// <returns>An OxyImage.</returns>
public static OxyImage PngFromArgb(OxyColor[,] pixels)
{
return(new OxyImage(PngEncoder.Encode(pixels)));
}
private OxyImage GetGradientImage(OxyColor color1, OxyColor color2)
{
int n = 256;
var imageData = new OxyColor[1, n];
for (int i = 0; i < n; i++) {
imageData[0, i] = OxyColor.Interpolate(color1, color2, i / (n - 1.0));
}
var encoder = new PngEncoder(new PngEncoderOptions());
return new OxyImage(encoder.Encode(imageData));
}
/// <summary>
/// Decodes an image from the specified byte array.
/// </summary>
/// <param name="bytes">The image data.</param>
/// <returns>The 32-bit pixel data, indexed as [x,y].</returns>
public OxyColor[,] Decode(byte[] bytes)
{
// http://www.w3.org/TR/PNG/
// http://en.wikipedia.org/wiki/Portable_Network_Graphics
var s = new MemoryStream(bytes);
var inputReader = new BinaryReader(s);
var signature = inputReader.ReadBytes(8);
if (signature[0] != 0x89 || signature[1] != 0x50 || signature[2] != 0x4E || signature[3] != 0x47 ||
signature[4] != 0x0D || signature[5] != 0x0A || signature[6] != 0x1A || signature[7] != 0x0A)
{
throw new FormatException("Invalid signature.");
}
var headerLength = inputReader.ReadBigEndianUInt32();
if (headerLength != 13)
{
throw new FormatException("Header not supported.");
}
var headerType = inputReader.ReadString(4);
if (headerType != "IHDR")
{
throw new FormatException("Invalid header.");
}
var width = (int)inputReader.ReadBigEndianUInt32();
var height = (int)inputReader.ReadBigEndianUInt32();
var bitDepth = inputReader.ReadByte();
var colorType = (ColorType)inputReader.ReadByte();
var compressionMethod = (CompressionMethod)inputReader.ReadByte();
var filterMethod = (FilterMethod)inputReader.ReadByte();
var interlaceMethod = (InterlaceMethod)inputReader.ReadByte();
inputReader.ReadBigEndianUInt32(); // headerCRC
if (bitDepth != 8)
{
throw new NotImplementedException();
}
if (colorType != ColorType.TrueColorWithAlpha)
{
throw new NotImplementedException();
}
if (compressionMethod != CompressionMethod.Deflate)
{
throw new NotImplementedException();
}
if (filterMethod != FilterMethod.None)
{
throw new NotImplementedException();
}
if (interlaceMethod != InterlaceMethod.None)
{
throw new NotImplementedException();
}
var ms = new MemoryStream();
while (true)
{
var length = (int)inputReader.ReadBigEndianUInt32();
var type = inputReader.ReadString(4);
if (type == "IEND")
{
break;
}
switch (type)
{
case "PLTE":
throw new NotImplementedException();
case "IDAT":
{
inputReader.ReadByte(); // method
inputReader.ReadByte(); // check
var chunkBytes = inputReader.ReadBytes(length - 6);
var expectedCheckSum = inputReader.ReadBigEndianUInt32();
var deflatedBytes = Deflate(chunkBytes);
var actualCheckSum = PngEncoder.Adler32(deflatedBytes);
if (actualCheckSum != expectedCheckSum)
{
throw new FormatException("Invalid checksum.");
}
ms.Write(deflatedBytes, 0, deflatedBytes.Length);
break;
}
default:
{
inputReader.ReadBytes(length);
break;
}
}
inputReader.ReadBigEndianUInt32(); // crc
}
var pixels = new OxyColor[width, height];
ms.Position = 0;
for (int y = height - 1; y >= 0; y--)
{
ms.ReadByte();
for (int x = 0; x < width; x++)
{
var red = (byte)ms.ReadByte();
var green = (byte)ms.ReadByte();
var blue = (byte)ms.ReadByte();
var alpha = (byte)ms.ReadByte();
pixels[x, y] = OxyColor.FromArgb(alpha, red, green, blue);
}
}
/*
* var bitReader = new ByteBitReader(ms);
* for (int y = 0; y < height; y++)
* {
* var filterType = bitReader.readByte();
* for (int x = 0; x < width; x++)
* {
* var red = (byte)bitReader.ReadBits(bitDepth);
* var green = (byte)bitReader.ReadBits(bitDepth);
* var blue = (byte)bitReader.ReadBits(bitDepth);
* var alpha = (byte)bitReader.ReadBits(bitDepth);
*
* pixels[x, y] = OxyColor.FromArgb(alpha, red, green, blue);
* }
* }*/
if (ms.Position != ms.Length)
{
throw new InvalidOperationException();
}
return(pixels);
}