WPF Controls and DependencyProperty on Custom Controls

Question

I have a C# custom WPF control. I have properties on the control that are based on DependencyProperty's.

public static readonly DependencyProperty CurrentStateProperty = 
 DependencyProperty.Register( "CurrentState", typeof(ControlStateEnum),
 typeof(MyCustomControl), new PropertyMetadata(ControlStateEnum.Started));

public ControlStateEnum CurrentState
{
    get { return (ControlStateEnum) GetValue(CurrentStateProperty); }
    set { SetValue(CurrentStateProperty, value); }
}

Now, if I use the control, and try to use it, ala:

<myControls:MyCustomControl CurrentState="Loaded" />

The CurrentState never gets set to "Loaded" and remains "Started". I want to make it capable of binding, but also capable of being set without binding... Is there something I don't understand or am missing?

When I set a breakpoint on the setter, it doesn't update on the window load.

possible duplicate of [Setters not run on Dependency Properties?](http://stackoverflow.com/questions/4225373/setters-not-run-on-dependency-properties) — parapura rajkumar, Jul 20 '12 at 19:50
So, in the end the value was being set on the control from the XAML after the control had been initialized and loaded. So the way to handle it was to add a PropertyChangedHandler on the DependencyProperty. Thanks for the help in diagnosing it, parapura. — Locke, Jul 20 '12 at 20:32

score 1 · Answer 1 · answered Jul 20 '12 at 20:14

1

Are you sure your not changed the enum somewhere else after the controls get loaded, because that should work as intended

answered Jul 20 '12 at 20:14

MyKuLLSKI

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Unfortunately, it does not appear that the setter is firing at all. – Locke Jul 20 '12 at 20:24
1

Its not going to...Not on initialization – MyKuLLSKI Jul 20 '12 at 20:32
The value does get changed and updated. Unfortunately, this happens AFTER the control is loaded and constructed. And as the other link suggests, the Setters/Getters are called via Get/SetValue, and we don't see it change. Therefore, the only way to handle changes and catch them in the XAML is by having a callback. – Locke Jul 20 '12 at 20:37
After every sentence I said yes. I dont see the problem here – MyKuLLSKI Jul 20 '12 at 21:01
1

When you write `new PropertyMetadata(ControlStateEnum.Started))` that means the default value is started no matter when you do when constructing the control. Then this `CurrentState="Loaded"` overrides it. This is how ALL WPF controls work – MyKuLLSKI Jul 20 '12 at 21:06

score 0 · Accepted Answer · answered Sep 06 '12 at 18:12

So, in the end the value was being set on the control from the XAML after the control had been initialized and loaded. So the way to handle it was to add a PropertyChangedHandler on the DependencyProperty.

parapura had a link to the right answer (http://stackoverflow.com/questions/4225373/setters-not-run-on-dependency-properties).

WPF Controls and DependencyProperty on Custom Controls

2 Answers2