private void MainPage_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
if (_curRectangle != null)
{
_curRectangle.ClearStartTemp();
_curRectangle = null;
}
}
private void MainPage_MouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
_curRectangle = new RealRect((int)e.GetPosition(sender as Canvas).X, (int)e.GetPosition(sender as Canvas).Y, false);
mainCanvas.Children.Insert(0, _curRectangle.Rect);
_curRectangle.StartRect();
}