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指针事件的问题

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<Grid >
        <Canvas x:Name="ceshi" HorizontalAlignment="Left" Height="620" Margin="10,10,0,0" VerticalAlignment="Top" Width="380" PointerEntered="ceshi_PointerEntered" PointerExited="ceshi_PointerExited">
            <TextBlock x:Name="textblock1" HorizontalAlignment="Left" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Height="390" Width="300" Canvas.Left="40" Canvas.Top="93"/>
        </Canvas>
    </Grid>

后台

public MainPage()
        {
            this.InitializeComponent();
            ceshi.PointerEntered += new PointerEventHandler(ceshi_PointerEntered);
            ceshi.PointerExited += new PointerEventHandler(ceshi_PointerExited);
            this.Loaded += new RoutedEventHandler(Rect_Loaded);
        }

private void ceshi_PointerEntered(object sender, PointerRoutedEventArgs e)
        {
            start = e.GetCurrentPoint(textblock1).Position;
        }

        private void ceshi_PointerExited(object sender, PointerRoutedEventArgs e)
        {
            Point end = e.GetCurrentPoint(textblock1).Position;
            double angle = 0;
            if (Math.Abs(end.X - start.X) < 1 && Math.Abs(end.Y - start.Y) < 1)
            {
                angle = 0;
            }
            else if (end.X > start.X)
            {
                if (end.Y > start.Y)
                {
                    angle = 360 - Math.Atan((end.Y - start.Y) * 1.0 / (end.X - start.X)) * 180 / Math.PI;
                }
                else
                {
                    angle = Math.Atan((start.Y - end.Y) * 1.0 / (end.X - start.X)) * 180 / Math.PI;
                }
            }
            else if (end.X < start.X)
            {
                if (end.Y > start.Y)
                {
                    angle = Math.Atan((end.Y - start.Y) * 1.0 / (start.X - end.X)) * 180 / Math.PI + 180;
                }
                else
                {
                    angle = 180 - Math.Atan((start.Y - end.Y) * 1.0 / (start.X - end.X)) * 180 / Math.PI;
                }
            }
            if (angle >= 45 && angle < 135)
            {

                m = "w";
            }
            else if (angle <= 45 || angle > 315)
            {

                m = "d";
            }
            else if (angle >= 135 && angle < 225)
            {

                m = "a";
            }
            else if (angle >= 225 && angle < 315)
            {

                m = "s";
            }
        }

为什么只有textblock区域可以监控的指针事件？我明明在Canvas添加的事件处理？

2014年12月10日 5:47

答案

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你好，

>>为什么只有textblock区域可以监控的指针事件？我明明在Canvas添加的事件处理？

这个问题和WPF中的Panel类似，比如说可以看这个WPF的Panel文档：http://msdn.microsoft.com/en-us/library/system.windows.controls.panel.background(v=vs.110).aspx

Remarks:

Panel elements do not receive mouse or stylus events if a Background is not defined. If you need to handle mouse or stylus events but do not want a background for your Panel, use Transparent.

意思是如果一个面板控件的背景色没有指定，是不会接受鼠标和手写笔的事件的，我们要是想要响应，可以使用透明色，即 Background="Transparent"

<Canvas x:Name="ceshi" HorizontalAlignment="Left" Background="Transparent" Height="620" Margin="10,10,0,0" VerticalAlignment="Top" Width="380" PointerEntered="ceshi_PointerEntered" PointerExited="ceshi_PointerExited"> <TextBlock x:Name="textblock1" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Height="390" Width="300" Canvas.Left="40" Canvas.Top="93" Text="This is a TextBlock" Foreground="#FFF90000"/> </Canvas>

这样在我这边测试，一切正常。
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- 已标记为答案崔東 2014年12月11日 10:27
2014年12月11日 9:55

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