// draw the piece on the canvas
func (self *MainWindow) DrawSelector(cr *cairo.Context, x, y float64) {
cr.SetSourceRGBA(0.2, 0.8, 0.2, 0.8)
cr.SetLineWidth(5)
cr.Rectangle(x*self.tileWidth, y*self.tileHeight, self.tileWidth, self.tileHeight)
cr.Stroke()
}
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()
}