PointToScreen使用

 通过改变子窗体Canvas中的thumb控件的margin位置给父窗体Grid控件的margin赋值，一直出错，代码如下：

 

MainWindow mw = (MainWindow)this.Owner;
            mw.photogrid.Width = this.thumb.Width;
            mw.photogrid.Height = this.thumb.Height;

            mw.photogrid.Margin = new Thickness(Canvas.GetTop(thumb), Canvas.GetLeft(thumb), 0, 0);

坐标转换后，解决：

Canvas.SetLeft(thumb, Canvas.GetLeft(thumb) + e.HorizontalChange);
            Canvas.SetTop(thumb, Canvas.GetTop(thumb) + e.VerticalChange);
            
           MainWindow mw = (MainWindow)this.Owner;
           Point p = thumb.PointToScreen(new Point());//将坐标转为屏幕坐标
           mw.photogrid.Margin = new Thickness(p.X,p.Y,0,0);
          mw.photogrid.Width = this.thumb.Width;
          mw.photogrid.Height = this.thumb.Height;