相关疑难解决方法(0)

我正在尝试处理拖放交互,包括鼠标按下,鼠标移动和鼠标移动.

以下是我的解决方案的简化版本:

• 在鼠标按下时,创建一个椭圆并将其添加到画布
• 在鼠标移动时,重新定位椭圆以跟随鼠标

• 在鼠标向上时,更改画布的颜色,以便明显拖动哪一个.

  var mouseDown = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonDown");
  var mouseUp = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonUp");
  var mouseMove = Observable.FromEvent<MouseEventArgs>(canvas, "MouseMove");
  
  Ellipse ellipse = null;
  
  var q = from start in mouseDown.Do(x =>
              {
                  // handle mousedown by creating a red ellipse, 
                  // adding it to the canvas at the right position
                  ellipse = new Ellipse() { Width = 10, Height = 10, Fill = Brushes.Red };
                  Point position = x.EventArgs.GetPosition(canvas);
                  Canvas.SetLeft(ellipse, position.X);
                  Canvas.SetTop(ellipse, position.Y);
                  canvas.Children.Add(ellipse);
              })
          from delta in mouseMove.Until(mouseUp.Do(x …

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