WPF中鼠标/键盘/拖拽事件以及用行为封装事件详解

private void TextBox_KeyDown(object sender, KeyEventArgs e)
{
    if(e.Key == Key.Enter)
    {
        //e.Handled = true;//表示已经处理完成
        //具体逻辑
    }
}

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition/>
        <ColumnDefinition/>
    </Grid.ColumnDefinitions>
    <StackPanel x:Name="panel"  Background="#F7F9FA">
        <Border Background="Orange" Height="30" Width="30" MouseLeftButtonDown="Border_MouseLeftButtonDown"/>
    </StackPanel>
    <!--必须设置Background,否则默认为null,null是没有背景和Transparent不同-->
    <!--AllowDrop="True"必须设置-->
    <Canvas x:Name="canvas" Grid.Column="1" Drop="Canvas_Drop" AllowDrop="True" 
            Background="Transparent">
    </Canvas>
</Grid>

private void Canvas_Drop(object sender, DragEventArgs e)
{
    var data = e.Data.GetData(typeof(Border));
    //canvas.Children.Add(data);//直接这样不可以，因为同一个实例不允许在于两个容器中
    //先在之前的容器中移除，再添加
    panel.Children.Remove(data as UIElement);
    canvas.Children.Add(data as UIElement);

    //获得鼠标相对于canvas的位置
    var point = e.GetPosition((Canvas)sender);
    Canvas.SetLeft(data as UIElement, point.X);
    Canvas.SetTop(data as UIElement, point.Y);
}

private void Border_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    Border border = sender as Border;
    DragDrop.DoDragDrop(border, border, DragDropEffects.Copy);
}

<Canvas>
    <Border Background="Orange" Width="100" Height="50" Canvas.Left="100" Canvas.Top="100"
            MouseLeftButtonDown="Border_MouseLeftButtonDown"
            MouseLeftButtonUp="Border_MouseLeftButtonUp"
            MouseMove="Border_MouseMove"
            />
</Canvas>

private Canvas _parentCanvas = null;
private bool _isDragging = false;
private Point _mouseCurrentPoint;
private void Border_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    //获得承载Border的父对象
    if (_parentCanvas == null)
        _parentCanvas = (Canvas)VisualTreeHelper.GetParent(sender as Border);

    this._isDragging = true;
    //获得相对于border的坐标
    this._mouseCurrentPoint = e.GetPosition(sender as Border);
    //关键，锁定鼠标即不让鼠标选中其他元素
    (sender as Border).CaptureMouse();
}

private void Border_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    if (_isDragging)
    {
        //关键，取消锁定鼠标
        (sender as Border).ReleaseMouseCapture();
        _isDragging = false;
    }
}

private void Border_MouseMove(object sender, MouseEventArgs e)
{
    if (_isDragging)
    {
        //获得相对于Canvas的坐标
        Point point = e.GetPosition(_parentCanvas);

        (sender as Border).SetValue(Canvas.TopProperty, point.Y - _mouseCurrentPoint.Y);
        (sender as Border).SetValue(Canvas.LeftProperty, point.X - _mouseCurrentPoint.X);
    }
}

(sender as Border).CaptureMouse()//锁定
(sender as Border).ReleaseMouseCapture();//解锁

System.Windows.Input.Mouse.Capture(sender as Border);//锁定
System.Windows.Input.Mouse.Capture(null);//解锁

public class DragMoveBehavior : Behavior<Border>
{
    // 当挂载到对应的对象上的时候触发
    protected override void OnAttached()
    {
        base.OnAttached();
		//方法与上面相同
        //this.AssociatedObject表示关联的对象
        this.AssociatedObject.MouseLeftButtonDown += AssociatedObject_MouseLeftButtonDown;
        this.AssociatedObject.MouseLeftButtonUp += AssociatedObject_MouseLeftButtonUp;
        this.AssociatedObject.MouseMove += AssociatedObject_MouseMove;
    }

    private Canvas _parentCanvas = null;
    private bool _isDragging = false;
    private Point _mouseCurrentPoint;
    private void AssociatedObject_MouseMove(object sender, System.Windows.Input.MouseEventArgs e)
    {
        if (_isDragging)
        {
            // 相对于Canvas的坐标
            Point point = e.GetPosition(_parentCanvas);
            // 设置最新坐标
            this.AssociatedObject.SetValue(Canvas.TopProperty, point.Y - _mouseCurrentPoint.Y);
            this.AssociatedObject.SetValue(Canvas.LeftProperty, point.X - _mouseCurrentPoint.X);
        }
    }

    private void AssociatedObject_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        if (_isDragging)
        {
            // 释放鼠标锁定
            //this.AssociatedObject.ReleaseMouseCapture();
            System.Windows.Input.Mouse.Capture(null);
            _isDragging = false;
        }
    }

    private void AssociatedObject_MouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        this._isDragging = true;
        // Canvas
        if (_parentCanvas == null)
            _parentCanvas = (Canvas)VisualTreeHelper.GetParent(sender as Border);
        // 当前鼠标坐标
        this._mouseCurrentPoint = e.GetPosition(sender as Border);
        // 鼠标锁定
        //this.AssociatedObject.CaptureMouse();
        System.Windows.Input.Mouse.Capture(this.AssociatedObject);
    }

    // 对象销毁
    protected override void OnDetaching()
    {
        this.AssociatedObject.MouseLeftButtonDown -= AssociatedObject_MouseLeftButtonDown;
        this.AssociatedObject.MouseLeftButtonUp -= AssociatedObject_MouseLeftButtonUp;
        this.AssociatedObject.MouseMove -= AssociatedObject_MouseMove;
    }
}

<Canvas>
    <Border Background="Orange" Width="100" Height="50" Canvas.Left="100" Canvas.Top="100">
        <i:Interaction.Behaviors>
            <local:DragMoveBehavior/>
        </i:Interaction.Behaviors>
    </Border>
</Canvas>