open System.Windows.Forms
open System.Drawing

let DEF_SPEED()=new PointF(0.f,0.f) //velocità di default
let DEF_DENSITY= 1.f

let f= new Form(TopMost=true)

f.Size <- Size(800,600)

f.Show()

type Pyshape(d:float32,v:PointF) =
    let mutable density = d
    let mutable speed = v
    abstract member drawshape:Graphics -> unit
    default this.drawshape(g:Graphics) = (printfn "metodo del supertipo")

type Circle(d,v,c:PointF,r:float32) =
    inherit Pyshape(d,v)
    let mutable rad = r
    let mutable center = c
    let mutable mass = r*r*(single System.Math.PI)*d
    let getRadius() = r
    let setRadius(r1) =
        rad <- r1;
    override this.drawshape (g:Graphics)=
    g.FillEllipse(Brushes.Aquamarine, int center.X - int rad, int center.Y - int rad, 2* int rad, 2* int rad)



type Editor() =
    inherit UserControl()

    let shapes= new System.Collections.Generic.List<Pyshape>()
    let mutable tool=0
    let mutable tmp_radius = 0.f
    let mutable tmp_center = new PointF()
    let mutable drawing = false

    let abort() =
        match tool with
            |0->
                drawing <- false
                tmp_radius <- 0.f;
            | _ -> ()

    let acquireShape(list:System.Collections.Generic.List<Pyshape>)=
        match tool with
            |1->
                let c= new Circle(DEF_DENSITY,DEF_SPEED(),tmp_center,tmp_radius)
                list.Add(c)
            |_-> ()
    let pitagora(x1:float32,y1:float32,x2:float32,y2:float32) =
        sqrt( (x1-x2)*(x1-x2)+(y1-y2)*(y1-y2) )

    override this.OnMouseDown e=
        let tmp_loc = e.Location
        tmp_center <- PointF(single tmp_loc.X, single tmp_loc.Y)
        drawing <- true;


    override this.OnMouseMove e=
        let tmp_loc = new PointF(single e.Location.X,single e.Location.Y)
        match drawing with
          |true ->
              tmp_radius <- pitagora(tmp_loc.X,tmp_loc.Y,tmp_center.X,tmp_center.Y)
              this.Invalidate()

          |false ->
            this.Invalidate()

     override this.OnMouseUp e=
        match drawing with
            |true ->
                acquireShape(shapes)
                drawing <- false;
                tmp_radius <- 0.f;
                this.Invalidate()
            |false ->()

    override this.OnKeyDown e=

        match e.KeyCode with
            |Keys.Escape ->
                match drawing with
                |true ->
                   abort()
                   this.Invalidate()
                | _ -> ()
            | _ -> ()

     override this.OnPaint e =
        let g = e.Graphics

        g.DrawEllipse(Pens.Black, int tmp_center.X - int tmp_radius, int tmp_center.Y - int tmp_radius, 2* int tmp_radius, 2* int tmp_radius);
        for c in shapes do(
            c.drawshape(g)
        )
let e=new Editor(Dock=DockStyle.Fill)

f.Controls.Add(e)

e.Focus()