WPF中的陷阱鼠标 [英] Trap mouse in WPF

问题描述

我有一个画布，其中有图像.我可以使用鼠标(拖放)来移动该图像.我想防止用户将图像移到画布之外.

I have a canvas in which I have an image. I can move that image using the mouse (drag-n-drop). I want to prevent the user to move the image outside of the canvas.

有什么办法可以捕获鼠标指针，使其只能在画布内移动?因此，当用户尝试将鼠标移到画布之外时，光标将停留在画布的边缘.

Is there any way I can trap the mouse pointer so it can only move inside the canvas? So when the user tries to move the mouse outside the canvas, the cursor would remain at the edge of the canvas.

此行为的一个示例是在移动窗口时，您无法在任务栏上将其移动.当您尝试在任务栏上移动它时，鼠标光标停留在任务栏的边缘，拒绝在任务栏的顶部移动.

One example of this behavior would be when moving a window, you can't move it on the taskbar. When you try to move it on the taskbar, the mouse cursor stays on the edge of the taskbar, refusing to move on top of the taskbar.

推荐答案

更多搜索后，我发现user32.dll中有一个名为ClipCursor的函数，可以完全满足我的需求.

After more searching, I found there is a function in user32.dll called ClipCursor that does exactly what I want.

这是捕获鼠标光标的示例应用程序的示例.单击Button1时，光标将被限制在(10,10,500,500)处的矩形中.按Button2(或关闭应用程序)时，光标将再次释放.

Here is an example of a sample app that traps the mouse cursor. When clicking Button1, the cursor will be constrained in a rectangle at (10,10,500,500). When pressing Button2 (or closing the app), the cursor will be free again.

XAML:

<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="350" Width="525">
    <Grid>
        <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="12,12,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
        <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="12,41,0,0" Name="button2" VerticalAlignment="Top" Width="75" Click="button2_Click" />
    </Grid>
</Window>

CS:

[DllImport("user32.dll")]
static extern void ClipCursor(ref System.Drawing.Rectangle rect);

[DllImport("user32.dll")]
static extern void ClipCursor(IntPtr rect);

public MainWindow()
{
    InitializeComponent();
}

private void button1_Click(object sender, RoutedEventArgs e)
{
    System.Drawing.Rectangle r = new System.Drawing.Rectangle(10, 10, 500, 500);
    ClipCursor(ref r);
}

private void button2_Click(object sender, RoutedEventArgs e)
{
    ClipCursor(IntPtr.Zero);
}

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