How can I bind a xaml property to a static variable in another class?

Question

I have this xaml file in which I try to bind a Text-block Background to a static variable in another class, how can I achieve this ?

I know this might be silly but I just moved from Win-forms and feeling a little bit lost.

here is what I mean:

<TextBlock Text="some text"
           TextWrapping="WrapWithOverflow"
           Background="{Binding Path=SomeVariable}" />

score 62 · Accepted Answer · answered Apr 06 '13 at 18:52

62

First of all you can't bind to variable. You can bind only to properties from XAML. For binding to static property you can do in this way (say you want to bind Text property of TextBlock) -

<TextBlock Text="{Binding Source={x:Static local:YourClassName.PropertyName}}"/>

where local is namespace where your class resides which you need to declare above in xaml file like this -

xmlns:local="clr-namespace:YourNameSpace"

answered Apr 06 '13 at 18:52

Rohit Vats

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Check your `Output` window. There might be some binding issue log there. – Rohit Vats Apr 06 '13 at 19:07
Have you make the variable `Property`? – Rohit Vats Apr 06 '13 at 19:07
Aha its a converter issue it tells me that i can't assign Color to a Brush and should use a converter in normal c# code we used to do something like this textblock.BackGround = new SolidColorBrush(GivenColor); – a7madx7 Apr 06 '13 at 19:11
but still lost and don't know how to achieve that either ! – a7madx7 Apr 06 '13 at 19:12
2

Return brush from your converter - `return new SolidColorBrush(value as Color)` – Rohit Vats Apr 06 '13 at 19:14
I guess this working with a bindable properties , right ?? – Osama AbuSitta Aug 29 '16 at 08:37

NSGaga-mostly-inactive · Answer 2 · 2018-03-07T20:24:30.617

You can't actually bind to a static property (INotifyPropertyChanged makes sense on instances only), so this should be enough...

{x:Static my:MyTestStaticClass.MyProperty}

or e.g.

<TextBox Text="{x:Static my:MyTestStaticClass.MyProperty}" Width="500" Height="100" />

make sure you include the namespace - i.e. define the my in the XAML like xmlns:my="clr-namespace:MyNamespace"

EDIT: binding from code
(There're some mixed answers on this part so I thought it made sense to expand, have it in one place)

`OneTime` binding:

You could just use textBlock.Text = MyStaticClass.Left (just careful where you place that, post-init)

`TwoWay` (or `OneWayToSource`) binding:

Binding binding = new Binding();
//binding.Source = typeof(MyStaticClass);
// System.InvalidOperationException: 'Binding.StaticSource cannot be set while using Binding.Source.'
binding.Path = new PropertyPath(typeof(MyStaticClass).GetProperty(nameof(MyStaticClass.Left)));
binding.Mode = BindingMode.TwoWay;
binding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
this.SetBinding(Window.LeftProperty, binding);

...of course if you're setting Binding from the code remove any bindings in XAML.

`OneWay` (property changes from the source):

And if you'd need to update the target (i.e. the control's property, Window.Left in this case) on the source property changes, that can't be achieved with the static class (as per my comment above, you'd need the INotifyPropertyChanged implemented, so you could just use a wrapper class, implement INotifyPropertyChanged and wire that to a static property of your interest (providing you know how to track you static property's changes, i.e. this is more of a 'design' issue from this point on, I'd suggest redesigning and putting it all within one 'non-static' class).

@jbyrd which way do you want to bind from static property to control, or to static, or two way? — NSGaga-mostly-inactive, Mar 07 '18 at 19:38
This should be the accepted answer, not the answer by @RohitVats — this.myself, Jul 30 '19 at 15:03

score 2 · Answer 3 · answered Feb 26 '18 at 15:39

2

You can use the newer x:Bind to do this simply using:

<TextBlock Text="{x:Bind YourClassName.PropertyName}"/>

answered Feb 26 '18 at 15:39

slayernoah

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5

x:Bind is not available in WPF, that's UWP that you're talking about – NSGaga-mostly-inactive Mar 07 '18 at 19:44

How can I bind a xaml property to a static variable in another class?

3 Answers3

`OneTime` binding:

`TwoWay` (or `OneWayToSource`) binding:

`OneWay` (property changes from the source):

Linked

How can I bind a xaml property to a static variable in another class?

3 Answers3

OneTime binding:

TwoWay (or OneWayToSource) binding:

OneWay (property changes from the source):

Linked

`OneTime` binding:

`TwoWay` (or `OneWayToSource`) binding:

`OneWay` (property changes from the source):