canvas.go
func DrawHorizontalLine(x, y, w int, r rune) {
	x, y, w, _ = clip(x, y, w, 1)
	if w == 0 {
		return
	}

	for i := x; i < x+w; i++ {
		putCharUnsafe(i, y, r)
	}
}
func DrawHorizontalLine(x, y, w int, r rune) {
	x, y, w, _ = clip(x, y, w, 1)
	if w == 0 {
		return
	}

	for i := x; i < x+w; i++ {
		putCharUnsafe(i, y, r)
	}
}
// DrawHorizontalLine draws the part of the horizontal line that is inside
// current clipping rectangle