draw2dkit/draw2dkit.go
func RoundedRectangle(path draw2d.PathBuilder, x1, y1, x2, y2, arcWidth, arcHeight float64) {
	arcWidth = arcWidth / 2
	arcHeight = arcHeight / 2
	path.MoveTo(x1, y1+arcHeight)
	path.QuadCurveTo(x1, y1, x1+arcWidth, y1)
	path.LineTo(x2-arcWidth, y1)
	path.QuadCurveTo(x2, y1, x2, y1+arcHeight)
	path.LineTo(x2, y2-arcHeight)
	path.QuadCurveTo(x2, y2, x2-arcWidth, y2)
	path.LineTo(x1+arcWidth, y2)
	path.QuadCurveTo(x1, y2, x1, y2-arcHeight)
	path.Close()
}
func RoundedRectangle(path draw2d.PathBuilder, x1, y1, x2, y2, arcWidth, arcHeight float64) {
	arcWidth = arcWidth / 2
	arcHeight = arcHeight / 2
	path.MoveTo(x1, y1+arcHeight)
	path.QuadCurveTo(x1, y1, x1+arcWidth, y1)
	path.LineTo(x2-arcWidth, y1)
	path.QuadCurveTo(x2, y1, x2, y1+arcHeight)
	path.LineTo(x2, y2-arcHeight)
	path.QuadCurveTo(x2, y2, x2-arcWidth, y2)
	path.LineTo(x1+arcWidth, y2)
	path.QuadCurveTo(x1, y2, x1, y2-arcHeight)
	path.Close()
}
// RoundedRectangle draws a rectangle using a path between (x1,y1) and (x2,y2)