@nogc void ditherColorLine(LineT,ColT)(auto ref LineT line, int x0, int x1, int y, in ColT col1, in ColT col2) pure nothrow
{
    enum W = 8;
    enum H = 8;
    immutable ColT[2] cols = [col1, col2];
    static immutable patterns = [
        [0,0,0,0,1,1,1,1],
        [0,0,0,1,0,1,1,1],
        [0,0,1,0,1,0,1,1],
        [0,1,0,1,0,1,0,1],

        [0,0,1,0,1,0,1,1],
        [0,1,0,1,0,1,0,1],
        [0,0,1,0,1,0,1,1],
        [0,0,0,1,0,1,1,1]];
    static assert(patterns.length    == H);
    static assert(patterns[0].length == W);
    const p = patterns[y % H];
    auto l = line[x0..x1];
    foreach(x;0..l.length)
    {
        const xw = x % W;
        l[x] = cols[p[xw]];
    }
}