Question

I currently have a WPF project which has one main Window, and many UserControls which are children of this Window. Many of the children of this window are Tabs. I have successfully replaced my main Window with a User Control that implements almost exactly the same functionality as the Main Window.

Replacing the Window with a UserControl introduced one problem - currently our application determines which programming tab to display based on the parent window by using the Window.FindName method shown below. Therefore I need to replace the Application.Current.MainWindow with an appropriate description of my main user control. See the erroring C# method below and wpf instantiation of the tabs for clarification.

Note Regarding Window.FindName() method - the reason why it does not work after I replaced it with a UserControl is because the FindName method searches upwards in the visual tree, as described here.

Does anyone know how to find a user control based on the x:Name, similar to Application.Current.MainWindow ? Also, is there a better way to find the UserControl than looking for the x:Name string in case it gets renamed?

How we currently find the MainWindow - need to now find MainUserControl:

(C#)
private static void SetCurrentProgram(int num)
    {
        Window window = Application.Current.MainWindow;
        ProgrammingTab programmingTab1 = window.FindName("ProgrammingTab1") as ProgrammingTab;
        ProgrammingTab programmingTab2 = window.FindName("ProgrammingTab2") as ProgrammingTab;

        programmingTab1.Visibility = num == 1 ? Visibility.Visible : Visibility.Collapsed;
        programmingTab2.Visibility = num == 2 ? Visibility.Visible : Visibility.Collapsed;

    }

Instantiation of programming tabs.

(xaml)
<Grid>
 <ProgrammingControl:ProgrammingTab x:Name="ProgrammingTab1" Program="1" IsVisibleChanged="ProgrammingTab_IsVisibleChanged" />
 <ProgrammingControl:ProgrammingTab x:Name="ProgrammingTab2" Program="2" IsVisibleChanged="ProgrammingTab_IsVisibleChanged" />
</Grid>

Answer 1

I figured out a workaround to this problem: I created a new algorithm based on another StackOverflow user s algorithm that recursively found any children of a DependencyObject. Find my solution here. If you declare the FindChild() method in my other post within public static class UIHelper {} you can then solve the problem by doing this:

  ProgrammingTab programmingTab1 = UIHelper.FindChild<ProgrammingTab>(Application.Current.MainWindow, "ProgrammingTab1");
  ProgrammingTab programmingTab2 = UIHelper.FindChild<ProgrammingTab>(Application.Current.MainWindow, "ProgrammingTab2");

This still uses procedural code instead of declarative XAML for bindings like RayBurns suggested. If it works, his solution will be much more efficient as it wont be traversing a whole tree but rather just changing the visibility of tabs based on a converter. I ll test that solution now and see how it turns out.

The reason why FindName() doesn t work properly is described in the post here.

Answer 2

It sounds like your app is developed in a very WinForms-like style. To stick with that style and simply answer your question, you can FindName() to find the UserControl and again to find the ProgrammingTab, like this:

var userControl = (MyUserControl)Application.Current.MainWindow.FindName("userControlName");
var programmingTab1 = (ProgrammingTab)userControl.FindName("ProgrammingTab1");
var programmingTab2 = (ProgrammingTab)userControl.FindName("ProgrammingTab2");
...

However I would recommend you look into using WPF s advanced capabilities such as data binding. You can have a DependencyProperty "CurrentProgram" on a singleton object referenced by a static property, and simply databind Visiblity to it using a converter.

<ProgrammingTab Visibilty="{Binding CurrentProgram,
   Source={x:Static MyState.Instance},
   Converter={x:Static VisibleIfEqualConverter},
   ConverterParameter=1}" ...>
  ...

With this change, your SetCurrentProgram becomes simply:

public void SetCurrentProgram(int num)
{
   MyState.Instance.CurrentProgram = num;
}

The beauty of this technique is that any ProgrammingTab anywhere in your application will automatically appear or disappear every time MyState.Instance.CurrentProgram s vaulue changes, with no need to find them with FindName() or otherwise.

Answer 3

This article may helps you : http://blog.lexique-du-net.com/index.php?post/2010/09/14/UserControl/Control-how-to-get-a-reference-to-an-element-of-the-template

友情链接