TextBlock宽度绑定到GridView

Question

On my XAML page I have a text block with following binding:

<TextBlock Width="{Binding ActualWidth, ElementName=SessionList, Mode=OneWay}" ...  />

This binds to a grid view:

<GridView x:Name="SessionList" ItemsSource="{Binding Sessions}"... />

Now when the page first loads and data is available, the text block will be visible and have the correct width. When the page loads and there is no data, the text box will not be visible because of the bound width.

But ... when I load up data in the background and after a while the data comes in (through MVVM) the list will be show, but the text block width will not change accordingly, and setting it as TwoWay has no effect.

Any ideas/tips?

Answer 1

ActualWidth is not a property that you can bind to within WinRT. Not sure if you are showing static text or bound text. If bound text and data is same as GridView has then it should go away if data is null. If static data, then use a ValueConverter to set the visibility of the TextBlock based on the data being null/empty

Answer 2

Binding issues like this are usually caused by properties that are not bindable, ie they are not dependency properties and/or do not implement INotifyPropertyChanged. Whatever. I use a Attached Dependency Property or, if that does not cover enough, a behavior. Now behavior are not included in WinRT, but that problem has already been addressed ;-)