改变pictureabox的Top和Left改变图片的显示位置，提示“尝试读取或写入受保护的内存”

这是个pictureabox加载的事件
private void picBox_MouseMove(object sender, MouseEventArgs e)
{
richTextBox1.Text = e.X.ToString() + "," + e.Y.ToString();
if (MoveFlag)
{
pictureBox1.Left += Convert.ToInt16(e.X - xPos);//设置x坐标.
pictureBox1.Top += Convert.ToInt16(e.Y - yPos);//设置y坐标.
falg_pict1 = true;
}
}
这是错误提示：
System.Drawing.SafeNativeMethods.Gdip.GdipDrawImageRectI(HandleRef graphics, HandleRef image, Int32 x, Int32 y, Int32 width, Int32 height)
System.Drawing.Graphics.DrawImage(Image image, Int32 x, Int32 y, Int32 width, Int32 height)
System.Drawing.Graphics.DrawImage(Image image, Rectangle rect)
System.Windows.Forms.PictureBox.OnPaint(PaintEventArgs pe)
System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer)
System.Windows.Forms.Control.WmPaint(Message& m)
System.Windows.Forms.Control.WndProc(Message& m)
System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

https://blog.csdn.net/trbbadboy/article/details/20131181 看看这个