How to Open a WPF Form in Outlook VSTO with Parameters More Cleanly

Описание: Discover a more efficient way to open a WPF form in Outlook VSTO with parameters, improve your coding practices, and avoid unnecessary window blinking.
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This video is based on the question https://stackoverflow.com/q/63634991/ asked by the user 'Kili' ( https://stackoverflow.com/u/11116194/ ) and on the answer https://stackoverflow.com/a/63748853/ provided by the user 'Jozef Izso' ( https://stackoverflow.com/u/67420/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Open a WPF Form in Outlook VSTO with Parameters More Cleanly

When developing an Outlook VSTO add-in, developers often encounter scenarios where they need to trigger a WPF form to open in response to user actions, such as clicking a button. In this guide, we’ll explore a common issue faced by developers—passing parameters while ensuring that the user interface is seamless and visually appealing.

The Problem

Imagine you have developed an Outlook VSTO add-in that adds a custom button to the preview pane of a selected mail item. When a user clicks this button, you intend to open a WPF window that allows them to edit the email's metadata and manage its storage process. However, the initial setup causes the window to blink or flash, leading to a poor user experience. A portion of your existing code is as follows:

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You are currently using a workaround involving two constructors in your MainWindow to handle both WPF styling and the mail item parameter. This approach, while functional, can be improved for clarity and performance.

The Solution: Streamlining Your WPF Form Opening

To enhance your implementation, let's simplify the process and eliminate the window blinking issue. Here’s how to do it:

Step 1: Remove the StartupUri Definition

One of the key fixes is to modify your App.xaml file. If you have a StartupUri defined, WPF automatically creates the window based on that URI, which can cause flickering when you try to open a new instance of the window manually. To prevent this, simply remove or comment out the StartupUri line in App.xaml.

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Step 2: Modify the MainWindow Constructor

Next, you can focus on your MainWindow constructor. Instead of relying on two constructors, you can keep the one that accepts the MailItem parameter and ensure it sets up the window correctly without initializing and closing unnecessary instances.

Here’s what your updated MainWindow might look like:

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Step 3: Launch the Window without Flickering

With this configuration, when you click the button, it will now open the MainWindow in a cleaner manner without displaying a flicker. Here’s your revised button click event:

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Conclusion

By removing the StartupUri from your App.xaml file and refining your MainWindow constructor, you can substantially improve the user interface of your Outlook VSTO add-in while passing necessary parameters seamlessly. This approach not only enhances user experience but also keeps your codebase clean and maintainable.

If you have any questions or experiences related to WPF forms in Outlook VSTO, feel free to share them in the comments below!