private static Size DecodePng(BinaryReader binaryReader)
{
binaryReader.ReadBytes(8);
int width = ByteHelper.ReadInt32BE(binaryReader);
int height = ByteHelper.ReadInt32BE(binaryReader);
return(new Size(width, height));
}
private static Size DecodeTiffBE(BinaryReader binaryReader)
{
int idfStart = ByteHelper.ReadInt32BE(binaryReader);
binaryReader.BaseStream.Seek(idfStart, SeekOrigin.Begin);
int numberOfIDF = ByteHelper.ReadInt16BE(binaryReader);
int width = -1;
int height = -1;
for (int i = 0; i < numberOfIDF; i++)
{
short field = ByteHelper.ReadInt16BE(binaryReader);
switch (field)
{
// https://www.awaresystems.be/imaging/tiff/tifftags/baseline.html
default:
binaryReader.ReadBytes(10);
break;
case 256: // image width
binaryReader.ReadBytes(6);
width = ByteHelper.ReadInt32BE(binaryReader);
break;
case 257: // image length
binaryReader.ReadBytes(6);
height = ByteHelper.ReadInt32BE(binaryReader);
break;
}
if (width != -1 && height != -1)
{
return(new Size(width, height));
}
}
return(Size.Empty);
}
// https://www.cyotek.com/blog/reading-photoshop-color-swatch-aco-files-using-csharp
private static List <Color> ReadSwatches(Stream stream, FileVersion version)
{
int colorCount;
List <Color> results;
results = new List <Color>();
// read the number of colors, which also occupies two bytes
colorCount = ByteHelper.ReadInt16BE(stream);
for (int i = 0; i < colorCount; i++)
{
ColorSpace colorSpace;
int value1;
int value2;
int value3;
int value4;
// again, two bytes for the color space
colorSpace = (ColorSpace)(ByteHelper.ReadInt16BE(stream));
value1 = ByteHelper.ReadInt16BE(stream);
value2 = ByteHelper.ReadInt16BE(stream);
value3 = ByteHelper.ReadInt16BE(stream);
value4 = ByteHelper.ReadInt16BE(stream);
if (version == FileVersion.Version2)
{
int length;
// need to read the name even though currently our colour collection doesn't support names
length = ByteHelper.ReadInt32BE(stream);
Helper.ReadString(stream, length);
}
switch (colorSpace)
{
case ColorSpace.Rgb:
int red;
int green;
int blue;
// RGB.
// The first three values in the color data are red , green , and blue . They are full unsigned
// 16-bit values as in Apple's RGBColor data structure. Pure red = 65535, 0, 0.
red = value1 / 256; // 0-255
green = value2 / 256; // 0-255
blue = value3 / 256; // 0-255
results.Add(ARGB.FromARGB(red.ToByte(), green.ToByte(), blue.ToByte()));
break;
case ColorSpace.Hsb:
float hue;
float saturation;
float brightness;
// HSB.
// The first three values in the color data are hue , saturation , and brightness . They are full
// unsigned 16-bit values as in Apple's HSVColor data structure. Pure red = 0,65535, 65535.
hue = value1 / 182.04f; // 0-359
saturation = value2 / 655.35f; // 0-100
brightness = value3 / 655.35f; // 0-100
results.Add(new HSB(hue, saturation, brightness).ToColor());
break;
case ColorSpace.Grayscale:
int gray;
// Grayscale.
// The first value in the color data is the gray value, from 0...10000.
gray = (int)(value1 / 39.0625); // 0-255
results.Add(ARGB.FromARGB(gray.ToByte(), gray.ToByte(), gray.ToByte()));
break;
default:
throw new InvalidDataException(string.Format("Color space '{0}' not supported.", colorSpace));
}
}
return(results);
}
// https://www.cyotek.com/blog/loading-the-color-palette-from-a-bbm-lbm-image-file-using-csharp#files
public static List <Color> ReadColorMap(string fileName)
{
List <Color> colorPalette;
colorPalette = new List <Color>();
using (FileStream stream = File.OpenRead(fileName))
{
byte[] buffer;
string header;
// read the FORM header that identifies the document as an IFF file
buffer = new byte[4];
stream.Read(buffer, 0, buffer.Length);
if (Encoding.ASCII.GetString(buffer) != "FORM")
{
throw new InvalidDataException("Form header not found.");
}
// the next value is the size of all the data in the FORM chunk
// We don't actually need this value, but we have to read it
// regardless to advance the stream
ByteHelper.ReadInt32BE(stream);
// read either the PBM or ILBM header that identifies this document as an image file
stream.Read(buffer, 0, buffer.Length);
header = Encoding.ASCII.GetString(buffer);
if (header != "PBM " && header != "ILBM")
{
throw new InvalidDataException("Bitmap header not found.");
}
while (stream.Read(buffer, 0, buffer.Length) == buffer.Length)
{
int chunkLength;
chunkLength = ByteHelper.ReadInt32BE(stream);
if (Encoding.ASCII.GetString(buffer) != "CMAP")
{
// some other LBM chunk, skip it
if (stream.CanSeek)
{
stream.Seek(chunkLength, SeekOrigin.Current);
}
else
{
for (int i = 0; i < chunkLength; i++)
{
stream.ReadByte();
}
}
}
else
{
// color map chunk!
for (int i = 0; i < chunkLength / 3; i++)
{
int r;
int g;
int b;
r = stream.ReadByte();
g = stream.ReadByte();
b = stream.ReadByte();
colorPalette.Add(ARGB.FromARGB(255, r.ToByte(), g.ToByte(), b.ToByte()));
}
// all done so stop reading the rest of the file
break;
}
// chunks always contain an even number of bytes even if the recorded length is odd
// if the length is odd, then there's a padding byte in the file - just read and discard
if (chunkLength % 2 != 0)
{
stream.ReadByte();
}
}
}
return(colorPalette);
}
