WPF ListView光标更改

WPF没有“IsMouseLeftButtonDown”属性,但您可以创建自己的附加属性来执行此操作,然后对其进行触发。这比向单个控件添加mouseLeftButtonDown事件处理程序要干净得多。

这样做:

1. 为ismouseLeftButtonDown(以及其他按钮)创建继承的附加属性
2. 创建“已启用”的附加属性以自动设置所需的事件处理程序。
3. 直接在控件或任何包含控件上设置“已启用”属性。
4. 在触发器或多触发器中使用“IsMouseLeftButtonDown”属性

以下是它的外观:

<Window ...
        local:MouseExtensions.Enabled="true" />  <!-- Set the handlers -->
  ...
  <ControlTemplate.Triggers>
    <Trigger Property="IsMouseOver" Value="True" >
      <Setter Property="Cursor" Value="openHand.cur"/>
    </Trigger>
    <MultiTrigger>
      <MultiTrigger.Conditions>
        <Condition Property="IsMouseOver" Value="True" />
        <Condition Property="local:MouseExtensions.IsMouseLeftButtonDown" Value="True" />
      </MultiTrigger.Conditions>
      <Setter Property="Cursor" Value="closedHand.cur" />
    </MultiTrigger>
  </ControlTemplate.Triggers>

下面是如何实现附加属性:

public class MouseExtensions : DependencyObject
{
  // IsMouseLeftButtonDown
  public static bool GetIsMouseLeftButtonDown(DependencyObject obj) { return (bool)obj.GetValue(IsMouseLeftButtonDownProperty); }
  public static void SetIsMouseLeftButtonDown(DependencyObject obj, bool value) { obj.SetValue(IsMouseLeftButtonDownProperty, value); }
  public static readonly DependencyProperty IsMouseLeftButtonDownProperty = DependencyProperty.RegisterAttached("IsMouseLeftButtonDown", typeof(bool), typeof(MouseExtensions), new FrameworkPropertyMetadata
  {
    Inherits=true,
  });


  // IsMouseMiddleButtonDown
  public static bool GetIsMouseMiddleButtonDown(DependencyObject obj) { return (bool)obj.GetValue(IsMouseMiddleButtonDownProperty); }
  public static void SetIsMouseMiddleButtonDown(DependencyObject obj, bool value) { obj.SetValue(IsMouseMiddleButtonDownProperty, value); }
  public static readonly DependencyProperty IsMouseMiddleButtonDownProperty = DependencyProperty.RegisterAttached("IsMouseMiddleButtonDown", typeof(bool), typeof(MouseExtensions), new FrameworkPropertyMetadata
  {
    Inherits=true,
  });

  // IsMouseRightButtonDown
  public static bool GetIsMouseRightButtonDown(DependencyObject obj) { return (bool)obj.GetValue(IsMouseRightButtonDownProperty); }
  public static void SetIsMouseRightButtonDown(DependencyObject obj, bool value) { obj.SetValue(IsMouseRightButtonDownProperty, value); }
  public static readonly DependencyProperty IsMouseRightButtonDownProperty = DependencyProperty.RegisterAttached("IsMouseRightButtonDown", typeof(bool), typeof(MouseExtensions), new FrameworkPropertyMetadata
  {
    Inherits=true,
  });

  // Enabled
  public static bool GetEnabled(DependencyObject obj) { return (bool)obj.GetValue(EnabledProperty); }
  public static void SetEnabled(DependencyObject obj, bool value) { obj.SetValue(EnabledProperty, value); }
  public static readonly DependencyProperty EnabledProperty = DependencyProperty.RegisterAttached("Enabled", typeof(bool), typeof(MouseExtensions), new PropertyMetadata
  {
    PropertyChangedCallback = (obj, e) =>
      {
        var element = (FrameworkElement)obj;
        if((bool)e.OldValue)
        {
          element.PreviewMouseDown -= Update;
          element.PreviewMouseUp -= Update;
          element.MouseEnter -= Update;
          element.MouseLeave -= Update;
        }
        if((bool)e.NewValue)
        {
          element.PreviewMouseDown += Update;
          element.PreviewMouseUp += Update;
          element.MouseEnter += Update;
          element.MouseLeave += Update;
        }
      }
  });

  private static void Update(object sender, MouseEventArgs e)
  {
    var element = (FrameworkElement)sender;
    bool inside = e.RoutedEvent!=Mouse.MouseLeaveEvent;
    SetIsMouseLeftButtonDown(element, inside && e.LeftButton==MouseButtonState.Pressed);
    SetIsMouseMiddleButtonDown(element, inside && e.MiddleButton==MouseButtonState.Pressed);
    SetIsMouseRightButtonDown(element, inside && e.RightButton==MouseButtonState.Pressed);
  }
}

工作原理:“已启用”propertychangedcallback将“update”方法添加为四个鼠标事件的处理程序。当其中一个事件发生时,将检查当前鼠标按钮状态,并在“已启用”设置为true的元素上更新is_uuu ButtonDown属性。从那里,这些属性通过逻辑树和可视化树继承下来。但是,如果收到mouseleave,则所有这些属性都设置为false,因为在鼠标再次位于“启用”的元素上之前,不会再次收到任何鼠标事件。