TaskDialog for WinForms

Introduction

Vista's new TaskDialog API’s are really cool and should see lame message boxes banished from you application. We've already seen some articles on using them from C++ but they are not trivial to use from managed code, so here is some code that makes using all the features of the new Task Dialogs really easy in WinForms.

The code is C# and is StyleCop, FXCop and PreSharp clean. Usability and discoverability were given preference to performance and size, with plenty of comments that should be really useful in Intellisense as you explore what Task Dialogs can do. You don’t have to use anything with a shouted (all capitals) name and all the features of Task Dialog are exposed including the callback and actions you can perform on an active Task Dialog. If you hate the very idea of wrappers and want the raw interop declarations, they are all there too.

Using the code

The main class is TaskDialog. The simplest usage gets you MessageBox behavior:

    TaskDialog taskDialog = new TaskDialog();
    taskDialog.WindowTitle = "My Application";
    taskDialog.MainInstruction = "Do you want to do this?";
    taskDialog.CommonButtons = TaskDialogCommonButtons.Yes | TaskDialogCommonButtons.No;
    int result = taskDialog.Show();
    if (result == (int)DialogResult.Yes)
    {
        // Do it.
    }

TaskDialog with Yes No buttons

From there you can add hyperlinks for help, more structure (adding content, extended info and footer to main instruction), a checkbox for "don’t ask me again", custom button names, etc.:

    private void SampleUsageComplex()
    {
        TaskDialog taskDialog = new TaskDialog();
        taskDialog.WindowTitle = "My Application";
        taskDialog.MainInstruction = "Do you want to do this?";

        taskDialog.EnableHyperlinks = true;
        taskDialog.Content = "If you do this there could be all sorts of consequences. " +
            "If you don't there will be other consequences. " +
            "You can <A HREF=\"Learn\">learn more about those consequences </A> or more " +
            "about <A HREF=\"blah\">blah blah blah</A>.";
        taskDialog.Callback = new TaskDialogCallback(this.MyTaskDialogCallback);
 
        taskDialog.VerificationText = "Don't ask me this ever again.";
        taskDialog.VerificationFlagChecked = false;
 
        TaskDialogButton doItButton = new TaskDialogButton();
        doItButton.ButtonId = 101;
        doItButton.ButtonText = "Do It";
 
        TaskDialogButton dontDoItButton = new TaskDialogButton();
        dontDoItButton.ButtonId = 102;
        dontDoItButton.ButtonText = "Don't Do It";

        taskDialog.Buttons = new TaskDialogButton[] { doItButton, dontDoItButton };
 
        bool dontShowAgain;
        int result = taskDialog.Show(null, out dontShowAgain);
        if (dontShowAgain)
        {
            // Suppress future asks.
        }
        if (result == doItButton.ButtonId)
        {
            // Do it.
        }
    }

    private bool MyTaskDialogCallback(
        ActiveTaskDialog taskDialog, 
        TaskDialogNotificationArgs args, 
        object callbackData)
    {
        if (args.Notification == TaskDialogNotification.HyperlinkClicked)
        {
            if (args.Hyperlink.Equals("Learn", StringComparison.Ordinal))
            {
                // Show a help topic.
            }
            else if (args.Hyperlink.Equals("blah", StringComparison.Ordinal))
            {
                // Show a different help topic.
            }
        }
        return false;
    }

TaskDialog with hyperlink and verify checkbox

To get a better idea of all the things you can do with a TaskDialog download the demo, extract the TaskDialogTest.exe and TaskDialog.dll to the same directory and run TaskDialogTest.exe. You'll get a rather large dialog which, while not beautiful, will let you try out the TaskDialog and perhaps sample what different uses in your application would look like.

TaskDialog with hyperlink and verify checkbox

To make use of TaskDialog in your own solution, download the source and include the following source files in your project and adapt them as you see fit:

ActiveTaskDialog.cs
TaskDialog.cs
TaskDialogNotificationArgs.cs
UnsafeNativeMethods.cs

Alternatively you could include the TaskDialog project into you solution.

I look forward to seeing a lot fewer Message Boxes in you applications and I hope this makes it easier. Keep in mind good UI design when you're tempted to use all those features in the one dialog.