选择屏幕快照会使程序崩溃C＃

Question

i have a program which takes a screen shot of the selected area (which I select with a mouse) and saves it to a clipboard. The problem is it works only if i make a selection from top to bottom. If I try to make a selection in any other direction (bottom to top, right to left, left to right) the program crashes. This is the code for MouseMove:

 public  void Window_MouseMove(object sender, System.Windows.Input.MouseEventArgs e)
    {
        if (this.isMouseDown)
        {
            double curx = e.GetPosition(null).X;
            double cury = e.GetPosition(null).Y;


            System.Windows.Shapes.Rectangle r = new System.Windows.Shapes.Rectangle();
            SolidColorBrush brush = new SolidColorBrush(Colors.White);
            r.Stroke = brush;
            r.Fill = brush;
            r.StrokeThickness = 1;

            r.Width = Math.Abs(curx - x);
            r.Height = Math.Abs(cury - y);
            selekt.Children.Clear();
            selekt.Children.Add(r);
            Canvas.SetLeft(r, x);
            Canvas.SetTop(r, y);
            if (e.LeftButton == MouseButtonState.Released)
            {
                selekt.Children.Clear();
                width = e.GetPosition(null).X - x;
                height = e.GetPosition(null).Y - y;
                this.CaptureScreen(x, y, width, height);
                this.x = this.y = 0;
                this.isMouseDown = false;
                this.Close();
            }
        }
    }

And this is for CaptureScreen:

 public void CaptureScreen(double x, double y, double width, double height)
    {
        int ix, iy, iw, ih;
        ix = Convert.ToInt32(x);
        iy = Convert.ToInt32(y);
        iw = Convert.ToInt32(width);
        ih = Convert.ToInt32(height);
        Bitmap slika = new Bitmap(iw, ih, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
        Graphics g = Graphics.FromImage(slika);
        g.CopyFromScreen(ix, iy, 0, 0,new System.Drawing.Size(iw, ih),CopyPixelOperation.SourceCopy);
       System.Windows.Forms.Clipboard.SetImage(slika);

Answer 1

are you getting error the below mentioned code? That seems to be the place where you would get one.

 Canvas.SetLeft(r, x);
        Canvas.SetTop(r, y);

If yes, then thats because SetLeft takes UIElement and a double values

public static void SetLeft(
UIElement element,
double length)

And also, I am guessing that x and y are double and declared public.