wpf.fs

open System
open System.Windows
open System.Windows.Controls
open System.Windows.Shapes
open System.Windows.Media

let move sh x y =
    Canvas.SetLeft(sh, x)
    Canvas.SetTop(sh, y)

let mutable canvas : Canvas = null
let mutable elem : UIElement = null
let mutable click = new Point()
let mutable orig = new Point()

let down (el : UIElement) (e : Input.MouseButtonEventArgs) =
    elem <- el
    orig <- new Point(Canvas.GetLeft(el), Canvas.GetTop(el))
    click <- e.GetPosition(canvas)
    ignore <| canvas.CaptureMouse()

[<STAThread>]
do
    let w = new Window(Title = "Test", Width = 256.0, Height = 256.0)
    w.Show()

    canvas <- new Canvas()
    w.Content <- canvas

    let r = new Rectangle(Width = 40.0, Height = 40.0)
    move r 20.0 60.0
    r.Stroke <- new SolidColorBrush(Colors.Black)
    r.Fill <- new SolidColorBrush(Colors.Yellow)
    ignore <| canvas.Children.Add(r)

    let tb = new TextBlock(Text = "abcdefg", FontSize = 24.0)
    move tb 20.0 30.0
    ignore <| canvas.Children.Add(tb)

    r.MouseDown.Add <| down r
    tb.MouseDown.Add <| down tb
    canvas.MouseMove.Add <| fun e ->
        if elem <> null then
            let p = e.GetPosition(canvas)
            move elem (orig.X + p.X - click.X) (orig.Y + p.Y - click.Y)
    canvas.MouseUp.Add <| fun _ ->
        elem <- null
        canvas.ReleaseMouseCapture()

    ignore <| (new Application()).Run(w)

Hi Art.
Thank you for your interest in my gist.
In fact, this gist is a translation from C#. https://gist.github.com/1207814
How implement drag and drop is an another problem. I like the coroutine for drag and drop. https://gist.github.com/1275258
Best regards. 7shi