wpf mvvmlight 实现鼠标拖拽改变rectangle大小以及鼠标操作控制旋转

要实现鼠标拖拽改变Rectangle大小以及鼠标操作控制旋转，可以使用WPF的MVVMLight框架来实现。

首先，在ViewModel中定义Rectangle的位置、大小和角度等属性，以及鼠标拖拽和鼠标操作的事件处理函数。

public class MainViewModel : ViewModelBase
{
    private double _left;
    private double _top;
    private double _width;
    private double _height;
    private double _angle;
    private bool _isDragging;
    private bool _isRotating;
    private Point _lastMousePosition;

    public double Left
    {
        get { return _left; }
        set { Set(ref _left, value); }
    }

    public double Top
    {
        get { return _top; }
        set { Set(ref _top, value); }
    }

    public double Width
    {
        get { return _width; }
        set { Set(ref _width, value); }
    }

    public double Height
    {
        get { return _height; }
        set { Set(ref _height, value); }
    }

    public double Angle
    {
        get { return _angle; }
        set { Set(ref _angle, value); }
    }

    public void OnMouseDown(object sender, MouseButtonEventArgs e)
    {
        if (e.LeftButton == MouseButtonState.Pressed)
        {
            _lastMousePosition = e.GetPosition(Application.Current.MainWindow);
            if (e.OriginalSource is FrameworkElement element)
            {
                // 判断鼠标操作类型
                if (element.Name == "ResizeThumb")
                {
                    _isDragging = false;
                    _isRotating = false;
                }
                else if (element.Name == "RotateThumb")
                {
                    _isDragging = false;
                    _isRotating = true;
                }
                else
                {
                    _isDragging = true;
                    _isRotating = false;
                }
            }
        }
    }

    public void OnMouseMove(object sender, MouseEventArgs e)
    {
        if (_isDragging)
        {
            // 鼠标拖拽改变Rectangle大小
        }
        else if (_isRotating)
        {
            // 鼠标操作控制Rectangle旋转
        }
    }

    public void OnMouseUp(object sender, MouseButtonEventArgs e)
    {
        _isDragging = false;
        _isRotating = false;
    }
}

接着，在View中使用MVVMLight框架提供的Binding绑定属性和事件处理函数。

<Window.DataContext>
    <vm:MainViewModel />
</Window.DataContext>
<Grid>
    <Rectangle Fill="Blue" Width="{Binding Width}" Height="{Binding Height}"
               Canvas.Left="{Binding Left}" Canvas.Top="{Binding Top}"
               RenderTransformOrigin="0.5,0.5">
        <Rectangle.RenderTransform>
            <RotateTransform Angle="{Binding Angle}" />
        </Rectangle.RenderTransform>
        <Thumb x:Name="ResizeThumb" Width="10" Height="10" Cursor="SizeNWSE"
               DragDelta="{Binding ResizeThumb_DragDelta}" />
        <Thumb x:Name="RotateThumb" Width="10" Height="10" Cursor="SizeAll"
               Canvas.Left="{Binding Width, Converter={StaticResource AngleToXConverter}}"
               Canvas.Top="{Binding Height, Converter={StaticResource AngleToYConverter}}"
               DragDelta="{Binding RotateThumb_DragDelta}" />
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="MouseDown">
                <i:InvokeCommandAction Command="{Binding MouseDownCommand}" />
            </i:EventTrigger>
            <i:EventTrigger EventName="MouseMove">
                <i:InvokeCommandAction Command="{Binding MouseMoveCommand}" />
            </i:EventTrigger>
            <i:EventTrigger EventName="MouseUp">
                <i:InvokeCommandAction Command="{Binding MouseUpCommand}" />
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </Rectangle>
</Grid>

最后，在ViewModel中实现鼠标拖拽和鼠标操作事件处理函数，计算Rectangle的位置、大小和角度。

public RelayCommand<DragDeltaEventArgs> ResizeThumb_DragDelta { get; private set; }
public RelayCommand<DragDeltaEventArgs> RotateThumb_DragDelta { get; private set; }

public MainViewModel()
{
    ResizeThumb_DragDelta = new RelayCommand<DragDeltaEventArgs>(OnResizeThumbDragDelta);
    RotateThumb_DragDelta = new RelayCommand<DragDeltaEventArgs>(OnRotateThumbDragDelta);
}

public void OnResizeThumbDragDelta(DragDeltaEventArgs e)
{
    Width = Math.Max(0, Width + e.HorizontalChange);
    Height = Math.Max(0, Height + e.VerticalChange);
}

public void OnRotateThumbDragDelta(DragDeltaEventArgs e)
{
    var center = new Point(Width / 2, Height / 2);
    var currentMousePosition = e.GetPosition(Application.Current.MainWindow);
    var delta = currentMousePosition - _lastMousePosition;
    _lastMousePosition = currentMousePosition;
    var angle = Math.Atan2(delta.Y, delta.X) * 180 / Math.PI;
    Angle = (Angle + angle) % 360;
    RotateThumbUpdatePosition(center);
}

private void RotateThumbUpdatePosition(Point center)
{
    var angleRad = Angle * Math.PI / 180.0;
    var x = center.X + (Width / 2) * Math.Cos(angleRad) + (Height / 2) * Math.Sin(angleRad);
    var y = center.Y - (Width / 2) * Math.Sin(angleRad) + (Height / 2) * Math.Cos(angleRad);
    Canvas.SetLeft(RotateThumb, x - RotateThumb.ActualWidth / 2);
    Canvas.SetTop(RotateThumb, y - RotateThumb.ActualHeight / 2);
}

public void OnMouseMove(MouseEventArgs e)
{
    if (_isDragging)
    {
        var currentMousePosition = e.GetPosition(Application.Current.MainWindow);
        var delta = currentMousePosition - _lastMousePosition;
        _lastMousePosition = currentMousePosition;

        Left = Math.Max(0, Left + delta.X);
        Top = Math.Max(0, Top + delta.Y);
    }
    else if (_isRotating)
    {
        var center = new Point(Width / 2, Height / 2);
        var currentMousePosition = e.GetPosition(Application.Current.MainWindow);
        var delta = currentMousePosition - _lastMousePosition;
        _lastMousePosition = currentMousePosition;
        var angle = Math.Atan2(delta.Y, delta.X) * 180 / Math.PI;
        Angle = (Angle + angle) % 360;
        RotateThumbUpdatePosition(center);
    }
}

public void OnMouseUp(MouseButtonEventArgs e)
{
    _isDragging = false;
    _isRotating = false;
}

这样就可以通过MVVMLight框架实现鼠标拖拽改变Rectangle大小以及鼠标操作控制旋转了。