func DrawAccLine(gc *cairo.Context, x1, y1 float64, p2 image.Point) {
gc.MoveTo(x1, y1)
gc.LineTo(float64(p2.X), float64(p2.Y))
gc.Stroke()
}
func DrawLine(gc *cairo.Context, p1, p2 image.Point) {
gc.MoveTo(float64(p1.X), float64(p1.Y))
gc.LineTo(float64(p2.X), float64(p2.Y))
gc.Stroke()
}