open System.Windows.Forms
open System.Drawing
open System.Timers

type ThrobberApple() as x =
    inherit UserControl()

    let mutable rotation = 0
    let mutable pensize = 0
    let colors : Color array = Array.zeroCreate 12

    do
        let timer = new Timer(Interval = 60.0, Enabled = true)

        for i in 0..11 do
            colors.[i] <- Color.FromArgb((i * 20) + 15, Color.Black)

        timer.AutoReset <- true
        timer.Elapsed.Add(fun _ ->
            rotation <- (rotation + 1) % 12
            x.Refresh()
        )

        x.DoubleBuffered <- true

    override x.OnPaint e =
        let graphics = e.Graphics

        graphics.SmoothingMode <- Drawing2D.SmoothingMode.HighQuality

        let pensize = x.Width / 15

        let pen = new Pen(Color.Black, single pensize)
        pen.StartCap <- Drawing2D.LineCap.Round
        pen.EndCap <- Drawing2D.LineCap.Round

        let from = int (single (x.Width - 2 * pensize) * 0.28f)
        let len = (x.Width - 2 * pensize) / 2 - from

        graphics.TranslateTransform(single (x.Width / 2), single (x.Width / 2))

        graphics.RotateTransform(30.f * single rotation)

        for i in 0..11 do
            pen.Color <- colors.[i]
            graphics.DrawLine(pen, from, 0, from + len, 0)
            graphics.RotateTransform(30.f)
        done