CODEWITHSUNDEEP
wpfxamlf#
nicolas
nicolas

Reputation: 9825

Declarative progress bar binding

After binding the command of a button to an action, I call an object which exposes a progress event.

event System.EventHandler<ProgressChangedEventArgs> ProgressChanged

I would like to display that in my XAML in the best way.

One way can be to expose two bindable fields in my VM

member x.Iteration with get()     = _iteration
                   and set(v:int) = _iteration <- v
                                    x.NotifyPropertyChanged <@this.Iteration@>

member x.IterationVisible with get()      = _iterationVisible
                          and set(v:bool) = _iterationVisible <- v
                                            x.NotifyPropertyChanged <@this.IterationVisible@>

then where I am called to perform the action I would just update the properties 

member x.CompleteInference(algorithm:IGeneratedAlgorithm) =
    x.IterationVisible <- true
    algorithm.ProgressChanged.Add(fun args -> x.Iteration <- args.Iteration)
    algorithm.run()
    x.IterationVisible <- false

That leads to 2 questions :

Upvotes: 8

Views: 340

Answers (2)

kidshaw
kidshaw

Reputation: 3451

You look to be doing this correctly although I am new to F#.

Wpf is typically used with an MVVM pattern, so wiring your button to a command property and your progress bar to an int property is correct. Your command then does something to cause the progress value to change and bindings take care of the rest.

Handling events in xaml requires code behind, which personally I don't mind if it serves only to enhance the UI. It certainly shouldn't be interacting with other objects. That means no event handlers.

This brings in event to command behaviours which can be used to bind control events to commands. See msdn.

Hope this helps in some way.

Upvotes: 1

N_A
N_A

Reputation: 19897

To my knowledge there is no way to handle events in xaml, so exposing the event changes through a property is probably the best you can do.

To achieve "'state machine' binding" in xaml, you could expose the progress as a size and then bind the width of your progress bar to that property. See here for an example of this.

Upvotes: 1

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