How to Trigger a Dependency Property Callback When Set in XAML?

Handling XAML-Driven Changes in WPF Dependency Properties

WPF's dependency properties offer robust change tracking, but their callbacks might not always fire when the property is modified via XAML. This article addresses a scenario where a dependency property (e.g., IsClosedProperty) set in XAML fails to trigger its associated callback (OnIsClosedChanged()).

The Solution: Leverage PropertyChangedCallback

To guarantee callback execution regardless of the property's modification source (XAML or runtime code), register a PropertyChangedCallback within the dependency property's metadata. This callback executes custom logic whenever the property value changes.

Here's how to incorporate the PropertyChangedCallback:

<code class="language-csharp">public static readonly DependencyProperty IsClosedProperty =
    DependencyProperty.Register(
        "IsClosed", typeof(bool), typeof(GroupBox),
        new FrameworkPropertyMetadata(false,
            FrameworkPropertyMetadataOptions.AffectsRender,
            OnIsClosedChanged)); // Note: simplified callback registration</code>

By adding the OnIsClosedChanged method directly as the callback, the method will now be invoked consistently, ensuring your intended behavior executes whether IsClosed is set in XAML or programmatically. This provides reliable event handling for dependency property changes originating from any source.

The above is the detailed content of How to Trigger a Dependency Property Callback When Set in XAML?. For more information, please follow other related articles on the PHP Chinese website!