Any reason why PresentationTraceSources.TraceLevel

问题:

I've been trying to get to the bottom of an issue with binding the SelectedItem of my ComboBox and since I've had not success thusfar I started looking at ways to get more detailed debugging information by setting PresentationTraceSources.TraceLevel=High for specific bindings. Unfortunately after doing so I don't see any related items in my Ouput window under the Debug category.

I'm using Visual Studio 2010 and my project is a WinForms project with heavy usage of interop using ElementHost to host WPF content. All related projects are currently being built for .NET 3.5. Any thoughts or suggestions that may lead me to the solution of seeing the extra trace information in the output window will be appreciated.

Below is a snippet of the code I'm using.

<ComboBox xmlns:diagnostics="clr-namespace:System.Diagnostics;assembly=WindowsBase"
            SelectedItem="{Binding Path=MyCollection.SelectedItem, Mode=TwoWay, diagnostics:PresentationTraceSources.TraceLevel=High}"
            ItemsSource="{Binding MyCollection, diagnostics:PresentationTraceSources.TraceLevel=High}"
            SelectedValuePath="Value"
            DisplayMemberPath="Value.DisplayName" />

回答1:

It's a setting in the Visual Studio 2010:

Tools -> Options -> Debugging -> Output Window -> WPF Trace Settings -> Data Binding -> set to Warning (or whatever you like).

Standard was Off.

This solution worked for me.

回答2:

Make sure that your DataContext is not null. If it is, no information will be logged to the output window