Fixed memory management issues in OpacityMaskView

[HotCakeX]

OpacityMaskView wasn't handling resources properly on unload, causing memory leaks and also changing

private static CompositionBrush GetVisualBrush(UIElement element)

to

   private static CompositionSurfaceBrush GetVisualBrush(UIElement element)

improves performance.

[Copilot]

Pull request overview

This PR addresses memory management issues in the OpacityMaskView control by adding proper disposal of composition resources. The changes introduce cleanup logic when the control unloads and track composition objects for explicit disposal.

Key Changes:

• Added CleanupComposition method and Unloaded event handler to dispose composition resources
• Changed GetVisualBrush return type from CompositionBrush to CompositionSurfaceBrush
• Added fields to track composition resources (_sourceBrush, _rootGrid, _redirectVisual) for proper cleanup

Comments suppressed due to low confidence (2)

AIDevGallery/Controls/OpacityMask.xaml.cs:45

• The XML documentation contains duplicate sentences with slightly different wording. The summary should only contain one clear description. Remove the redundant "Creates a new instance of the OpacityMaskView class." line.

    /// Initializes a new instance of the <see cref="OpacityMaskView"/> class.
    /// Creates a new instance of the <see cref="OpacityMaskView"/> class.
    /// </summary>

AIDevGallery/Controls/OpacityMask.xaml.cs:112

• The GetVisualBrush method creates CompositionVisualSurface and ExpressionAnimation objects that are never disposed, creating a memory leak. These composition resources should be tracked as fields (similar to _sourceBrush) and disposed in CleanupComposition, or the method should return a tuple/wrapper that includes these resources so they can be disposed properly.

    private static CompositionSurfaceBrush GetVisualBrush(UIElement element)
    {
        Visual visual = ElementCompositionPreview.GetElementVisual(element);

        Compositor compositor = visual.Compositor;

        CompositionVisualSurface visualSurface = compositor.CreateVisualSurface();
        visualSurface.SourceVisual = visual;
        ExpressionAnimation sourceSizeAnimation = compositor.CreateExpressionAnimation($"{nameof(visual)}.Size");
        sourceSizeAnimation.SetReferenceParameter(nameof(visual), visual);
        visualSurface.StartAnimation(nameof(visualSurface.SourceSize), sourceSizeAnimation);

        CompositionSurfaceBrush brush = compositor.CreateSurfaceBrush(visualSurface);

        visual.Opacity = 0;

        return brush;

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