open System.Windows.Forms
open System.Drawing

Application.EnableVisualStyles()

type Azione =
| Move

type CircleIns() as this =

    inherit Control()

    let mutable r,cx,cy = 2,2,2
    let mutable pressed = false
    let mutable action = None
    let w2v = new Drawing2D.Matrix()
    let v2w = new Drawing2D.Matrix()
    let isClose (p : Point) (l : Point) =
        let dx = p.X - l.X
        let dy = p.Y - l.Y
        (dx * dx + dy * dy) < this.Raggio * this.Raggio
    let scrollTimer = new Timer(Interval=30)


    do
        scrollTimer.Tick.Add(fun _ ->
            match action with
            | Some a -> this.DoAction a
            | None ->()
        )

    member this.Raggio
        with get() = r
        and set(v) = r <- v

    member this.CentroX
        with get() = cx
        and set(v) = cx <- v

    member this.CentroY
        with get() = cy
        and set(v) = cy <- v

    override this.OnMouseDown e =
        let pc = new Point(this.CentroX,this.CentroY)
        let pmouse = new Point(e.X,e.Y)
        if (isClose pc pmouse) then
            if pressed then pressed <- false
            else
                pressed <- true
                action <- Some(Azione.Move)
                scrollTimer.Start()

        this.Invalidate()

    override this.OnMouseUp e =
        if pressed <> true then
            scrollTimer.Stop()

        this.Invalidate()

    override this.OnPaint e =
        let g = e.Graphics
        let d = this.Raggio*2
        if pressed then
            g.DrawEllipse(Pens.Green,this.CentroX-r,this.CentroY-r, d,d)
            g.FillEllipse(Brushes.Green,this.CentroX-r,this.CentroY-r, d,d)
            g.DrawRectangle(Pens.Blue,this.CentroX-r,this.CentroY-r,d,d)

        else
            g.DrawEllipse(Pens.Red,this.CentroX-r,this.CentroY-r, d,d)
            g.FillEllipse(Brushes.Red,this.CentroX-r,this.CentroY-r, d,d)
            g.DrawRectangle(Pens.Blue,this.CentroX-r,this.CentroY-r,d,d)
        g.DrawEllipse(Pens.Black,this.CentroX+d,this.CentroY+d,r/4,r/4)

    override this.OnResize e =
    this.Invalidate()

    member this.DoAction (act:Azione) =
        match act with
        | Azione.Move ->
          w2v.Translate(0.f, -10.f, Drawing2D.MatrixOrder.Append)
          v2w.Translate(0.f, -10.f)
          this.Invalidate()





let f = new Form(Text="ciao", TopMost=true)
f.Size <- new Size(500,500)
let c = new CircleIns(Dock=DockStyle.Fill)
c.Raggio <- 40
c.CentroX <- 240
c.CentroY <- 240
f.Controls.Add(c)
f.Show()