def matrix_coords(rows, cols, rowh, colw, ox=0, oy=0):
    "Generate coords for a matrix of rects"
    for i, f, c in rowmajor(rows, cols):
        x = ox + c * colw
        y = oy + f * rowh
        x1 = x + colw
        y1 = y + rowh
        yield (i, x, y, x1, y1)
Generate coords for a matrix of rects