void WriteBitArray(BitArray ba)
{
WriteInt32(ba.bitcount);
m_stream.Write(ba.bytes, 0, (ba.bitcount + 7) / 8);
}
void CrushSlice(int[] lbm, int resx, int resy)
{
BitArray ba = new BitArray();
int top = resy;
int left = resx;
int bottom = 0;
int right = 0;
int npix = resx * resy;
int nWhitePixels = 0;
bool curPixelWhite = lbm[0] != 0;
int currentPos = 0;
int dataLen;
ba.PushBits(resx, 16);
ba.PushBits(resy, 16);
ba.PushBits(curPixelWhite ? 1 : 0, 1);
do
{
dataLen = 0;
curPixelWhite = lbm[currentPos] > 0; //returns true if pixel is white
// count the pixels until the color changes
while ((currentPos < npix) && (curPixelWhite == lbm[currentPos] > 0))
{
currentPos++;
dataLen++;
}
if (curPixelWhite)
{
nWhitePixels += dataLen;
// update extents
int origpos = currentPos - dataLen;
int endpos = currentPos - 1;
int xstart = origpos % resx;
int xend = endpos % resx;
if (xstart + dataLen - 1 >= resx)
{
xend = resx - 1;
if (xstart + dataLen - 1 > resx)
xstart = 0;
}
if (top == resy)
top = (origpos / resx);
if (bottom < (endpos / resx))
bottom = (endpos / resx);
if (left > xstart)
left = xstart;
if (right < xend)
right = xend;
}
// store the count
int keyLen = computeKeySize(dataLen);
if (keyLen < 0)
{
// should not happen!
CancelExport = true;
return;
}
ba.PushBits(keyLen, 5);
ba.PushBits(dataLen, keyLen + 1);
} while (currentPos < npix);
// write crushed slice to file
WriteInt32(nWhitePixels);
WriteInt32(left);
WriteInt32(top);
WriteInt32(right);
WriteInt32(bottom);
WriteBitArray(ba);
}
