setPosition method
Set the coordinates of the pixel.
Implementation
@override
void setPosition(int x, int y) {
_x = x;
_y = y;
final bpp = image.numChannels * 4;
final w = image.width;
final rowStride = image.rowStride;
_index = bpp == 4
? _y * rowStride + (_x >> 1)
: bpp == 8
? _y * w + _x
: bpp == 16
? _y * rowStride + (_x << 1)
: _y * rowStride + ((_x * bpp) >> 3);
_bitIndex = bpp > 7 ? (_x * bpp) & 0x4 : (_x * bpp) & 0x7;
}