void decodeIdat() {
int nbitDepth = bitDepth;
if (nbitDepth == 16) nbitDepth = 8;
int size = -1;
bytesPerPixel = (bitDepth == 16) ? 2 : 1;
switch (colorType) {
case 0:
size = (nbitDepth * width + 7) / 8 * height;
break;
case 2:
size = width * 3 * height;
bytesPerPixel *= 3;
break;
case 3:
if (interlaceMethod == 1) size = (nbitDepth * width + 7) / 8 * height;
bytesPerPixel = 1;
break;
case 4:
size = width * height;
bytesPerPixel *= 2;
break;
case 6:
size = width * 3 * height;
bytesPerPixel *= 4;
break;
}
if (size >= 0) image = new byte[size];
if (palShades) smask = new byte[width * height];
else if (genBWMask) smask = new byte[(width + 7) / 8 * height];
ByteArrayInputStream bai = new ByteArrayInputStream(idat.getBuf(), 0, idat.size());
InputStream infStream = new InflaterInputStream(bai, new Inflater());
dataStream = new DataInputStream(infStream);
if (interlaceMethod != 1) {
decodePass(0, 0, 1, 1, width, height);
} else {
decodePass(0, 0, 8, 8, (width + 7) / 8, (height + 7) / 8);
decodePass(4, 0, 8, 8, (width + 3) / 8, (height + 7) / 8);
decodePass(0, 4, 4, 8, (width + 3) / 4, (height + 3) / 8);
decodePass(2, 0, 4, 4, (width + 1) / 4, (height + 3) / 4);
decodePass(0, 2, 2, 4, (width + 1) / 2, (height + 1) / 4);
decodePass(1, 0, 2, 2, width / 2, (height + 1) / 2);
decodePass(0, 1, 1, 2, width, height / 2);
}
}
