Emulating ShowDialog functionality

Question

I am writing an application (c# + wpf) where all modal style dialogs are implemented as a UserControl on top of a translucent grid covering the main Window. This means there is only one Window and it maintains the look and feel of all the firms applications.

To show a MessageBox, the syntax is as following:

CustomMessageBox b = new CustomMessageBox("hello world");
c.DialogClosed += ()=>
{
   // the rest of the function
}
// this raises an event listened for by the main window view model,
// displaying the message box and greying out the rest of the program.
base.ShowMessageBox(b); 

As you can see, not only is the flow of execution actually inverted, but its horribly verbose compared to the classic .NET version:

MessageBox.Show("hello world");
// the rest of the function

What I am really looking for is a way to not return from base.ShowMessageBox until the dialog closed event has been raised by it, but I cant see how it is possible to wait for this without hanging the GUI thread and thus preventing the user ever clicking OK. I am aware I can take a delegate function as a parameter to the ShowMessageBox function which kind of prevents the inversion of execution, but still causes some crazy syntax/indenting.

Am I missing something obvious or is there a standard way to do this?

Answer 1

You might want to take a look at this article on CodeProject and this article on MSDN. The first article walks you through manually creating a blocking modal dialog, and the second article illustrates how to create custom dialogs.

Answer 2

The way to do this is by using a DispatcherFrame object.

var frame = new DispatcherFrame();
CustomMessageBox b = new CustomMessageBox("hello world");
c.DialogClosed += ()=>
{
    frame.Continue = false; // stops the frame
}
// this raises an event listened for by the main window view model,
// displaying the message box and greying out the rest of the program.
base.ShowMessageBox(b);

// This will "block" execution of the current dispatcher frame
// and run our frame until the dialog is closed.
Dispatcher.PushFrame(frame);