wpf:无法识别左键单击

Question

我最近在WPF,当我学习我遇到的奇怪问题的材料.

我构建了一个按钮,包含带有文本块的图层,我想要识别用户点击"按钮本身,'第一','第二或'第三'的位置(我输出一条消息).

一切正常,但当用户点击左键(只有中间或右键)时,按钮不会引发事件.

所以我的问题:为什么当我用鼠标左键按下按钮时我没有收到消息框(我收到带有其他鼠标按钮的消息框)？

XAML:

<Button Margin="145,152,144,102" Padding="5,5,5,5" HorizontalAlignment="Center" VerticalAlignment="Center" MouseDown="Button_MouseDown" Height="57" Width="214">
    <WrapPanel>
        <WrapPanel HorizontalAlignment="Center" VerticalAlignment="Center"></WrapPanel>
        <TextBlock Foreground="Black" FontSize="24" MouseDown="TextBlockFirst_MouseDown" >First  </TextBlock>
        <TextBlock Foreground="Red" FontSize="24"   MouseDown="TextBlockSecond_MouseDown">Second </TextBlock>
        <TextBlock Foreground="Blue" FontSize="24"  MouseDown="TextBlockThird_MouseDown" >Third  </TextBlock>
    </WrapPanel>
</Button>

码:

private void TextBlockFirst_MouseDown(object sender, MouseButtonEventArgs e)
{
    MessageBox.Show("You click on first");
}

private void TextBlockSecond_MouseDown(object sender, MouseButtonEventArgs e)
{
    MessageBox.Show("You click on second");
}

private void TextBlockThird_MouseDown(object sender, MouseButtonEventArgs e)
{
    MessageBox.Show("You click on third");
}

private void Button_MouseDown(object sender, MouseButtonEventArgs e)
{
    // This event not working good
    // only middle & right mouse buttons are recognized
    MessageBox.Show("You click on the button");
}

谢谢!

Answer 1

MouseDown事件是bubbling event从其发起者到其根父母的气泡.但Click事件会影响MouseDown事件,并且不允许事件冒泡到Button.

您可以使用PreviewMouseDown事件,这是一个tunnelling event从根隧道,它的鼻祖.因此按钮将首先获得此事件,然后是后续的textBlock.

<Button PreviewMouseDown="Button_MouseDown">
   .......
</Button>

有关清晰的图片,请参阅下面的快照:

UPDATE

仅挂钩PreviewMouseDown按钮上的事件并从单个textBlocks中删除处理程序.检查e.OrignialSource是否TextBlock是实际原始来源或按钮.

private void Button_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
    if (!(e.OriginalSource is TextBlock))
    {
        MessageBox.Show("You click on the button");
    }
    else
    {
        switch ((e.OriginalSource as TextBlock).Text)
        {
            case "First":
                MessageBox.Show("You click on first");
                break;
            case "Second":
                MessageBox.Show("You click on second");
                break;
            case "Third":
                MessageBox.Show("You click on third");
                break;
        }
    }
}

XAML

<Button PreviewMouseDown="Button_PreviewMouseDown" Height="57" Width="214">
    <WrapPanel>
        <WrapPanel HorizontalAlignment="Center" VerticalAlignment="Center"/>
        <TextBlock Foreground="Black" FontSize="24">First</TextBlock>
        <TextBlock Foreground="Red" FontSize="24">Second</TextBlock>
        <TextBlock Foreground="Blue" FontSize="24">Third</TextBlock>
    </WrapPanel>
</Button>