public static IconHolder BitmapToIconHolder(BitmapHolder bmp)
{
var mapColors = (bmp.Info.InfoHeader.BiBitCount <= 24);
//Hashtable uniqueColors = new Hashtable(maximumColors);
// actual colors is probably nowhere near maximum, so dont try to initialize the hashtable
var uniqueColors = new Hashtable();
int sourcePosition = 0;
int numPixels = bmp.Info.InfoHeader.BiHeight*bmp.Info.InfoHeader.BiWidth;
var indexedImage = new byte[numPixels];
byte colorIndex;
if (mapColors)
{
for (var i = 0; i < indexedImage.Length; i++)
{
//TODO: currently assumes source bitmap is 24bit color
//read 3 bytes, convert to color
var pixel = new byte[3];
Array.Copy(bmp.ImageData, sourcePosition, pixel, 0, 3);
sourcePosition += 3;
var color = new RGBQUAD(pixel);
if (uniqueColors.Contains(color))
{
colorIndex = Convert.ToByte(uniqueColors[color]);
}
else
{
if (uniqueColors.Count > byte.MaxValue)
{
throw new NotSupportedException(
String.Format("The source image contains more than {0} colors.", byte.MaxValue));
}
colorIndex = Convert.ToByte(uniqueColors.Count);
uniqueColors.Add(color, colorIndex);
}
// store pixel as an index into the color table
indexedImage[i] = colorIndex;
}
}
else
{
// added by Pavel Janda on 14/11/2006
if (bmp.Info.InfoHeader.BiBitCount == 32)
{
for (var i = 0; i < indexedImage.Length; i++)
{
//TODO: currently assumes source bitmap is 32bit color with alpha set to zero
//ignore first byte, read another 3 bytes, convert to color
var pixel = new byte[4];
Array.Copy(bmp.ImageData, sourcePosition, pixel, 0, 4);
sourcePosition += 4;
var color = new RGBQUAD(pixel[0], pixel[1], pixel[2], pixel[3]);
if (uniqueColors.Contains(color))
{
colorIndex = Convert.ToByte(uniqueColors[color]);
}
else
{
if (uniqueColors.Count > byte.MaxValue)
{
throw new NotSupportedException(
String.Format("The source image contains more than {0} colors.", byte.MaxValue));
}
colorIndex = Convert.ToByte(uniqueColors.Count);
uniqueColors.Add(color, colorIndex);
}
// store pixel as an index into the color table
indexedImage[i] = colorIndex;
}
// end of addition
}
else
{
//TODO: implement converting an indexed bitmap
throw new NotImplementedException("Unable to convert indexed bitmaps.");
}
}
ushort bitCount = GetBitCount(uniqueColors.Count);
// *** Build Icon ***
var ico = new IconHolder {IconDirectory = {Entries = new IconDirEntry[1]}};
//TODO: is it really safe to assume the bitmap width/height are bytes?
ico.IconDirectory.Entries[0].Width = (byte) bmp.Info.InfoHeader.BiWidth;
ico.IconDirectory.Entries[0].Height = (byte) bmp.Info.InfoHeader.BiHeight;
ico.IconDirectory.Entries[0].BitCount = bitCount; // maybe 0?
ico.IconDirectory.Entries[0].ColorCount = (uniqueColors.Count > byte.MaxValue)
? (byte) 0
: (byte) uniqueColors.Count;
//HACK: safe to assume that the first imageoffset is always 22
ico.IconDirectory.Entries[0].ImageOffset = 22;
ico.IconDirectory.Entries[0].Planes = 0;
ico.IconImages[0].Header.BiBitCount = bitCount;
ico.IconImages[0].Header.BiWidth = ico.IconDirectory.Entries[0].Width;
// height is doubled in header, to account for XOR and AND
ico.IconImages[0].Header.BiHeight = ico.IconDirectory.Entries[0].Height << 1;
ico.IconImages[0].XOR = new byte[ico.IconImages[0].NumBytesInXor()];
ico.IconImages[0].AND = new byte[ico.IconImages[0].NumBytesInAnd()];
ico.IconImages[0].Header.BiSize = 40; // always
ico.IconImages[0].Header.BiSizeImage = (uint) ico.IconImages[0].XOR.Length;
ico.IconImages[0].Header.BiPlanes = 1;
ico.IconImages[0].Colors = BuildColorTable(uniqueColors, bitCount);
//BytesInRes = biSize + colors * 4 + XOR + AND
ico.IconDirectory.Entries[0].BytesInRes = (uint) (ico.IconImages[0].Header.BiSize
+ (ico.IconImages[0].Colors.Length*4)
+ ico.IconImages[0].XOR.Length
+ ico.IconImages[0].AND.Length);
// copy image data
var bytePosXOR = 0;
var bytePosAND = 0;
byte transparentIndex = indexedImage[0];
//initialize AND
ico.IconImages[0].AND[0] = byte.MaxValue;
int pixelsPerByte;
int[] shiftCounts;
switch (bitCount)
{
case 1:
pixelsPerByte = 8;
shiftCounts = new[] {7, 6, 5, 4, 3, 2, 1, 0};
break;
case 4:
pixelsPerByte = 2;
shiftCounts = new[] {4, 0};
break;
case 8:
pixelsPerByte = 1;
shiftCounts = new[] {0};
break;
default:
throw new NotSupportedException("Bits per pixel must be 1, 4, or 8");
}
int bytesPerRow = ico.IconDirectory.Entries[0].Width/pixelsPerByte;
int padBytes = bytesPerRow%4;
if (padBytes > 0)
padBytes = 4 - padBytes;
sourcePosition = 0;
for (var row = 0; row < ico.IconDirectory.Entries[0].Height; ++row)
{
for (var rowByte = 0; rowByte < bytesPerRow; ++rowByte)
{
byte currentByte = 0;
for (var pixel = 0; pixel < pixelsPerByte; ++pixel)
{
byte index = indexedImage[sourcePosition++];
var shiftedIndex = (byte) (index << shiftCounts[pixel]);
currentByte |= shiftedIndex;
}
ico.IconImages[0].XOR[bytePosXOR] = currentByte;
++bytePosXOR;
}
// make sure each scan line ends on a long boundary
bytePosXOR += padBytes;
}
for (var i = 0; i < indexedImage.Length; i++)
{
var index = indexedImage[i];
var bitPosAND = 128 >> (i%8);
if (index != transparentIndex)
ico.IconImages[0].AND[bytePosAND] ^= (byte) bitPosAND;
if (bitPosAND == 1)
{
// need to start another byte for next pixel
if (bytePosAND%2 == 1)
{
//TODO: fix assumption that icon is 16px wide
//skip some bytes so that scanline ends on a long barrier
bytePosAND += 3;
}
else
{
bytePosAND += 1;
}
if (bytePosAND < ico.IconImages[0].AND.Length)
ico.IconImages[0].AND[bytePosAND] = byte.MaxValue;
}
}
return ico;
}
private static RGBQUAD[] BuildColorTable(Hashtable colors, ushort bpp)
{
//RGBQUAD[] colorTable = new RGBQUAD[colors.Count];
//HACK: it looks like the color array needs to be the max size based on bitcount
int numColors = 1 << bpp;
var colorTable = new RGBQUAD[numColors];
foreach (RGBQUAD color in colors.Keys)
{
int colorIndex = Convert.ToInt32(colors[color]);
colorTable[colorIndex] = color;
}
return colorTable;
}