C# WPF OnMouseEnter 和 OnMouseLeave 循环

Question

我有 WPF UI 元素，当鼠标光标进入此元素时应隐藏这些元素，当鼠标光标离开此元素时应显示这些元素。为此，我使用事件 OnMouseEnter 和 OnMouseLeave，如下所示:

private void TextBlock_MouseEnter(object sender, MouseEventArgs e)
{
    (e.Source as UIElement).Visibility = Visibility.Hidden;
}

private void TextBlock_MouseLeave(object sender, MouseEventArgs e)
{
    (e.Source as UIElement).Visibility = Visibility.Visible;
}

(以下代码来自 https://learn.microsoft.com/en-us/dotnet/api/system.windows.controls.panel.zindex?view=netframework-4.8 )

<Canvas>
            <Rectangle Canvas.ZIndex="1" Width="100" Height="100" Canvas.Top="100" Canvas.Left="100" Fill="blue" MouseEnter="TextBlock_MouseEnter" MouseLeave="TextBlock_MouseLeave"/>
            <Rectangle Canvas.ZIndex="2" Width="100" Height="100" Canvas.Top="150" Canvas.Left="150" Fill="yellow" MouseEnter="TextBlock_MouseEnter" MouseLeave="TextBlock_MouseLeave"/>
            <Rectangle Canvas.ZIndex="3" Width="100" Height="100" Canvas.Top="200" Canvas.Left="200" Fill="green" MouseEnter="TextBlock_MouseEnter" MouseLeave="TextBlock_MouseLeave"/>

            <!-- Reverse the order to illustrate z-index property -->

            <Rectangle Canvas.ZIndex="3" Width="100" Height="100" Canvas.Top="300" Canvas.Left="200" Fill="green" MouseEnter="TextBlock_MouseEnter" MouseLeave="TextBlock_MouseLeave"/>
            <Rectangle Canvas.ZIndex="2" Width="100" Height="100" Canvas.Top="350" Canvas.Left="150" Fill="yellow" MouseEnter="TextBlock_MouseEnter" MouseLeave="TextBlock_MouseLeave"/>
            <Rectangle Canvas.ZIndex="1" Width="100" Height="100" Canvas.Top="400" Canvas.Left="100" Fill="blue" MouseEnter="TextBlock_MouseEnter" MouseLeave="TextBlock_MouseLeave"/>
        </Canvas>

但是当我运行程序并将光标悬停在元素上时，it starts to flicker and eat up quite a lot of CPU resources .

调试显示当我将光标悬停在元素上时，events loops直到我将光标从元素上移开。

我看到了this article ，但我不明白那里附带的解决方案。

我需要做什么来防止这些事件循环发生？

Answer 1

当您将 UIElement 的 Visibility 更改为 Hidden 时，您实际上是在触发 MouseLeave 事件，因为鼠标 HitTest 现在是在它后面的元素上执行的。然后运行您的事件处理程序，它将 Visibility 设置为 Visible，然后触发 MouseEnter 事件。因此会出现闪烁。

解决这个问题的一个想法是使用不透明度而不是可见性。尝试:

private void TextBlock_MouseEnter(object sender, MouseEventArgs e)
{
  (e.Source as UIElement).Opacity = 0;
}

private void TextBlock_MouseLeave(object sender, MouseEventArgs e)
{
  (e.Source as UIElement).Opacity = 1;
}