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
var numColors = 1 << bpp;
var colorTable = new Rgbquad[numColors];
foreach (Rgbquad color in colors.Keys)
{
var colorIndex = Convert.ToInt32(colors[color]);
colorTable[colorIndex] = color;
}
return(colorTable);
}
public static IconHolder BitmapToIconHolder(BitmapHolder bmp)
{
var mapColors = bmp.Info.InfoHeader.BiBitCount <= 24;
var maximumColors = 1 << bmp.Info.InfoHeader.BiBitCount;
//Hashtable uniqueColors = new Hashtable(maximumColors);
// actual colors is probably nowhere near maximum, so dont try to initialize the hashtable
var uniqueColors = new Hashtable();
var sourcePosition = 0;
var 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(
$"The source image contains more than {byte.MaxValue} colors.");
}
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(
$"The source image contains more than {byte.MaxValue} colors.");
}
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.");
}
}
var 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 = 0;
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");
}
var bytesPerRow = ico.IconDirectory.Entries[0].Width / pixelsPerByte;
var 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)
{
var 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)
{
continue;
}
// 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);
}