即使光标位于画布之外也会调用 MouseMove 事件

我不知道我的代码或 WPF 是否有问题，但问题是：我想创建一个小程序，您可以在其中用光标在画布上绘图。 我有一个简单的 WPF 窗口：

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="475" Width="544">
<Grid>    
    <Grid.RowDefinitions>
        <RowDefinition Height="100px"></RowDefinition>
        <RowDefinition Height ="*"></RowDefinition>
        <RowDefinition Height="100px"></RowDefinition>
    </Grid.RowDefinitions>    
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="100px"></ColumnDefinition>
        <ColumnDefinition Width="*"></ColumnDefinition>
        <ColumnDefinition Width="100px"></ColumnDefinition>
    </Grid.ColumnDefinitions>
        <Canvas Grid.Row="1" Grid.Column="1"  Name="imageCanvas" MouseEnter="StackPanel_MouseEnter" MouseLeave="StackPanel_MouseLeave" Background="LightGray" 
                      MouseDown="StackPan_MouseDown" MouseUp="StackPan_MouseUp" MouseMove="StackPan_MouseMove">

        </Canvas>        
</Grid>

这是后台代码：

   private void StackPan_MouseDown(object sender, MouseButtonEventArgs e)
    {
        draw = true;
    }

    private void StackPan_MouseUp(object sender, MouseButtonEventArgs e)
    {
        draw = false;
    }

    private void StackPan_MouseMove(object sender, MouseEventArgs e)
    {
        if (draw)
        {
            var pos = Mouse.GetPosition(imageCanvas);
            Rectangle rec = new Rectangle()
                    {
                        Width = 10,
                        Height = 10,
                        Fill = Brushes.Red,
                    };
            Canvas.SetTop(rec, pos.Y);
            Canvas.SetLeft(rec, pos.X);
            imageCanvas.Children.Add(rec);
        }

    }

我能做的是：https://www.dropbox.com/s/7moq4p8f8f409b3/wpf_canvas.png https://www.dropbox.com/s/7moq4p8f8f409b3/wpf_canvas.png

为什么当光标位于画布之外时会调用 StackPan_MouseMove？

这是可执行文件，您可以在其中注意到此行为：https://www.dropbox.com/s/ye1w2j9chld2oif/WpfApplication1.exe https://www.dropbox.com/s/ye1w2j9chld2oif/WpfApplication1.exe

尝试将 Canvas 放置在 Border 控件内并设置Border控制的剪辑到边界 http://msdn.microsoft.com/en-us/library/system.windows.uielement.cliptobounds.aspx财产给true.

<Border ClipToBounds="true" Grid.Row="1" Grid.Column="1" >
    <Canvas Name="imageCanvas" MouseEnter="StackPanel_MouseEnter" MouseLeave="StackPanel_MouseLeave" Background="LightGray" 
            MouseDown="StackPan_MouseDown" MouseUp="StackPan_MouseUp" MouseMove="StackPan_MouseMove">
    </Canvas>
</Border>

稍微不同的是，似乎墨水演示器 http://msdn.microsoft.com/en-us/library/system.windows.controls.inkpresenter.aspx/墨水画布 http://msdn.microsoft.com/en-us/library/system.windows.controls.inkcanvas.aspx可能是更适合您尝试执行的操作的控件，除非您出于特定原因而避免使用它们。