整理

NeuWPF/NeoUI/Behaviors/ListBoxSlideBehavior.cs

@@ -0,0 +1,138 @@
+using System.Windows.Media.Animation;
+
+namespace NeoUI.Behaviors;
+
+/// <summary>
+/// ListBoxSlideBehavior 类提供了附加属性 EnableSlideAnimation，用于控制 ListBox 控件是否启用滑动动画效果。
+/// 通过设置该属性，可以为 ListBox 添加平滑的滑动过渡效果，增强用户体验。
+/// </summary>
+public static class ListBoxSlideBehavior
+{
+    /// <summary>
+    /// 获取指定对象的滑动动画启用状态。
+    /// </summary>
+    /// <param name="obj">要获取属性值的对象。</param>
+    /// <returns>如果为 true，则表示启用了滑动动画；否则为 false。</returns>
+    public static bool GetEnableSlideAnimation(DependencyObject obj)
+    {
+        return (bool)obj.GetValue(EnableSlideAnimationProperty);
+    }
+
+    /// <summary>
+    /// 设置指定对象的滑动动画启用状态。
+    /// </summary>
+    /// <param name="obj">要设置属性值的对象。</param>
+    /// <param name="value">一个布尔值，表示是否启用滑动动画。如果为 true，则启用滑动动画；否则不启用。</param>
+    public static void SetEnableSlideAnimation(DependencyObject obj, bool value)
+    {
+        obj.SetValue(EnableSlideAnimationProperty, value);
+    }
+
+    /// <summary>
+    /// 用于控制 ListBox 控件是否启用滑动动画效果的依赖属性。通过设置此属性，可以为 ListBox 添加平滑的滑动过渡效果，从而增强用户体验。
+    /// </summary>
+    public static readonly DependencyProperty EnableSlideAnimationProperty =
+        DependencyProperty.RegisterAttached("EnableSlideAnimation", typeof(bool), typeof(ListBoxSlideBehavior), new PropertyMetadata(false, OnEnableSlideAnimationChanged));
+
+    private static void OnEnableSlideAnimationChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        if (d is not ListBox listBox) return;
+        if ((bool)e.NewValue)
+        {
+            listBox.Loaded += ListBox_Loaded;
+            listBox.SelectionChanged += ListBox_SelectionChanged;
+        }
+        else
+        {
+            listBox.Loaded -= ListBox_Loaded;
+            listBox.SelectionChanged -= ListBox_SelectionChanged;
+        }
+    }
+
+    private static void ListBox_Loaded(object sender, RoutedEventArgs e)
+    {
+        var listBox = sender as ListBox;
+        if (listBox != null && listBox.IsVisible)
+        {
+            UpdateIndicator(listBox, false);
+        }
+    }
+
+    private static void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        var listBox = sender as ListBox;
+        if (listBox != null && listBox.IsLoaded)
+        {
+            UpdateIndicator(listBox, true);
+        }
+    }
+
+    private static void UpdateIndicator(ListBox? listBox, bool useAnimation)
+    {
+        if (listBox?.SelectedItem == null) return;
+
+        var indicator = listBox.Template.FindName("PART_SelectionIndicator", listBox) as FrameworkElement;
+        var itemsPresenter = FindVisualChild<ItemsPresenter>(listBox);
+
+        if (indicator == null || itemsPresenter == null) return;
+
+        var selectedItemUI = listBox.ItemContainerGenerator.ContainerFromItem(listBox.SelectedItem) as FrameworkElement;
+        if (selectedItemUI == null) return;
+
+        var position = selectedItemUI.TransformToAncestor(itemsPresenter).Transform(new Point(0, 0));
+
+        indicator.Width = selectedItemUI.ActualWidth;
+        indicator.Height = selectedItemUI.ActualHeight;
+
+        var transform = indicator.RenderTransform as TranslateTransform;
+
+        // 如果 transform 为 null，或者它是一个被冻结的（只读）实例，
+        // 那么我们就需要创建一个新的、可写的实例来替换它。
+        if (transform == null || transform.IsFrozen)
+        {
+            transform = new TranslateTransform();
+            indicator.RenderTransform = transform;
+        }
+
+        if (useAnimation)
+        {
+            var animationX = new DoubleAnimation(position.X, new Duration(TimeSpan.FromMilliseconds(300)))
+            {
+                EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut }
+            };
+            var animationY = new DoubleAnimation(position.Y, new Duration(TimeSpan.FromMilliseconds(300)))
+            {
+                EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut }
+            };
+            transform.BeginAnimation(TranslateTransform.XProperty, animationX);
+            transform.BeginAnimation(TranslateTransform.YProperty, animationY);
+        }
+        else
+        {
+            // 现在 transform 保证是可写的，所以这里不会再抛出异常
+            transform.X = position.X;
+            transform.Y = position.Y;
+        }
+    }
+
+    private static T? FindVisualChild<T>(DependencyObject? parent) where T : Visual
+    {
+        if (parent == null) return null;
+        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
+        {
+            var child = VisualTreeHelper.GetChild(parent, i);
+            if (child is T correctlyTyped)
+            {
+                return correctlyTyped;
+            }
+
+            var descendent = FindVisualChild<T>(child);
+            if (descendent != null)
+            {
+                return descendent;
+            }
+        }
+
+        return null;
+    }
+}