81 lines
3.2 KiB
C#
81 lines
3.2 KiB
C#
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Input;
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using PropertyMetadata = System.Windows.PropertyMetadata;
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namespace YY.Admin.Core.Helper
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{
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/// <summary>
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/// ScrollViewer 辅助类：
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/// 解决 ScrollViewer 包裹 TreeView / ListBox 等控件时，
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/// 鼠标滚轮在内部控件上无法触发外层 ScrollViewer 滚动的问题。
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/// </summary>
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public static class ScrollViewerHelper
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{
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/// <summary>
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/// 附加属性：是否启用鼠标滚轮事件向上传递
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/// </summary>
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public static readonly DependencyProperty EnableMouseWheelPropagationProperty =
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DependencyProperty.RegisterAttached(
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"EnableMouseWheelPropagation", // 属性名
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typeof(bool), // 属性类型
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typeof(ScrollViewerHelper), // 所属类型
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new PropertyMetadata(false, OnEnableMouseWheelPropagationChanged)); // 默认值+回调
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/// <summary>
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/// 获取附加属性值（XAML 绑定/读取）
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/// </summary>
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public static bool GetEnableMouseWheelPropagation(DependencyObject obj)
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=> (bool)obj.GetValue(EnableMouseWheelPropagationProperty);
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/// <summary>
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/// 设置附加属性值（XAML 设置）
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/// </summary>
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public static void SetEnableMouseWheelPropagation(DependencyObject obj, bool value)
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=> obj.SetValue(EnableMouseWheelPropagationProperty, value);
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/// <summary>
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/// 当附加属性值发生变化时触发
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/// </summary>
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private static void OnEnableMouseWheelPropagationChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
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{
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if (d is UIElement element)
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{
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// 如果启用，则订阅 PreviewMouseWheel 事件
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if ((bool)e.NewValue)
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element.PreviewMouseWheel += Element_PreviewMouseWheel;
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else
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// 否则移除事件
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element.PreviewMouseWheel -= Element_PreviewMouseWheel;
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}
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}
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/// <summary>
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/// 当鼠标滚轮在目标控件上滚动时触发，
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/// 将事件手动冒泡到上层（如 ScrollViewer）以实现滚动。
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/// </summary>
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private static void Element_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
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{
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// 若事件已被处理，则直接返回
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if (e.Handled) return;
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// 标记事件已处理，防止重复触发
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e.Handled = true;
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// 构造一个新的 MouseWheelEventArgs，用于向父级转发
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var eventArg = new MouseWheelEventArgs(e.MouseDevice, e.Timestamp, e.Delta)
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{
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RoutedEvent = UIElement.MouseWheelEvent, // 指定为标准鼠标滚轮事件
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Source = sender // 来源设为当前控件
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};
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// 获取父元素，并将事件重新抛出
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if (sender is Control control)
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{
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var parent = control.Parent as UIElement;
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parent?.RaiseEvent(eventArg);
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}
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}
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}
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}
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