Question

我有一个可滚动的时间轴，由列表视图构成。当我的鼠标聚焦在列表视图上时。

使用代码

，光标是张开的手

<ControlTemplate.Triggers>
    <Trigger Property="IsMouseOver" Value="True">
        <Setter Property="Cursor" Value="openHand.cur"/>
    </Trigger>                    
</ControlTemplate.Triggers>

但我很想知道。如果在列表视图上按下鼠标左键，我可以做些什么。如果是，那么将光标更改为闭合的手？提前谢谢！

Answer 1

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，然后触发它。这往往比将MouseLeftButtonDown事件处理程序添加到单个控件要清晰得多。

要做到这一点：

为IsMouseLeftButtonDown（以及其他按钮）创建继承的附加属性
创建“已启用”附加属性以自动设置所需的事件处理程序。
直接在您的控件或任何包含控件上设置“已启用”属性。
在Trigger或MultiTrigger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>

以下是附加属性的实现方式：

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：“Enabled”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“Enabled”设置为true的元素上更新Is___ButtonDown属性。从那里，这些属性通过逻辑和可视树继承。但是，如果收到MouseLeave，则所有这些属性都设置为false，因为再次接收鼠标事件，直到鼠标再次位于设置为“Enabled”的元素上。

WPF ListView光标更改

1 个答案: