Added ContextMenu/Flyout animations. Added platform services. Use bitmap cache for all views.

Harmonia.UI/Controls/AnimatedFlyout.cs

@@ -0,0 +1,103 @@
+using Avalonia;
+using Avalonia.Animation;
+using Avalonia.Controls;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Media;
+using Avalonia.Rendering;
+using Avalonia.Styling;
+using Avalonia.VisualTree;
+using System;
+using System.Threading.Tasks;
+
+namespace Harmonia.UI.Controls;
+
+public class AnimatedMenuFlyout : MenuFlyout
+{
+    protected override Control CreatePresenter()
+    {
+        Control presenter = base.CreatePresenter();
+        presenter.AttachedToVisualTree += OnPresenterAttachedToVisualTree;
+
+        return presenter;
+    }
+
+    private async void OnPresenterAttachedToVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
+    {
+        if (sender is not MenuFlyoutPresenter menuFlyoutPresenter)
+            return;
+
+        await ApplyAnimationAsync(menuFlyoutPresenter);
+    }
+
+    private async Task ApplyAnimationAsync(MenuFlyoutPresenter presenter)
+    {
+        double translateYStart = ShouldSlideDown(presenter) ? - 100 : 100;
+
+        Animation animation = new()
+        {
+            Duration = TimeSpan.FromMilliseconds(200),
+            Children =
+            {
+                new KeyFrame
+                {
+                    Cue = new Cue(0f),
+                    Setters =
+                    {
+                        new Setter(Visual.OpacityProperty, 0.0),
+                        new Setter(TranslateTransform.YProperty, translateYStart)
+                    }
+                },
+                new KeyFrame
+                {
+                    Cue = new Cue(1f),
+                    Setters =
+                    {
+                        new Setter(Visual.OpacityProperty, 1.0),
+                        new Setter(TranslateTransform.YProperty, 0.0)
+                    }
+                }
+            }
+        };
+
+        await animation.RunAsync(presenter);
+    }
+
+    private static bool ShouldSlideDown(MenuFlyoutPresenter presenter)
+    {
+        if (presenter.Parent is not Control targetControl)
+            return true;
+
+        Rect? topLevelBounds = GetTopLevelBounds();
+
+        if (topLevelBounds == null)
+            return true;
+
+        Rect targetBounds = targetControl.Bounds;
+
+        double availableSpaceBelow = topLevelBounds.Value.Height - (targetBounds.Y + targetBounds.Height);
+        double availableSpaceAbove = targetBounds.Y;
+
+        return availableSpaceBelow >= availableSpaceAbove; // Slide down if more space below
+    }
+
+    private static Rect? GetTopLevelBounds()
+    {
+        //Desktop
+        if (Application.Current?.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+        {
+            return desktop.MainWindow?.Bounds;
+        }
+        //Android (and iOS?)
+        else if (Application.Current?.ApplicationLifetime is ISingleViewApplicationLifetime singleViewPlatform)
+        {
+            IRenderRoot? visualRoot = singleViewPlatform.MainView?.GetVisualRoot();
+
+            if (visualRoot is TopLevel topLevel)
+            {
+                return topLevel.Bounds;
+            }
+        }
+
+        return null;
+    }
+}