How can I make a Rectangle on a canvas which is draggable?

Question

I have these three functions to trigger the events. I already have a static version of my needs, but I need a dynamically version of it.

    bool ca         


        

Answer 1

I'm sure this sample code will help you.

XAML:

C#:

    bool drag = false;
    Point startPoint;

    public MainWindow()
    {
        InitializeComponent();
    }

    // this creates and adds rectangles dynamically
    private void addRectangleButton_Click(object sender, RoutedEventArgs e)
    {
        // create new Rectangle
        Rectangle rectangle = new Rectangle();
        // assign properties
        rectangle.Width = 100;
        rectangle.Height = 50;
        rectangle.Fill = new SolidColorBrush(Colors.RoyalBlue);
        // assign handlers
        rectangle.MouseDown += rectangle_MouseDown;
        rectangle.MouseMove += rectangle_MouseMove;
        rectangle.MouseUp += rectangle_MouseUp;
        // set default position
        Canvas.SetLeft(rectangle, 0);
        Canvas.SetTop(rectangle, 0);
        // add it to canvas
        canvas.Children.Add(rectangle);
    }

    private void rectangle_MouseDown(object sender, MouseButtonEventArgs e)
    {
        // start dragging
        drag = true;
        // save start point of dragging
        startPoint = Mouse.GetPosition(canvas);
    }

    private void rectangle_MouseMove(object sender, MouseEventArgs e)
    {
        // if dragging, then adjust rectangle position based on mouse movement
        if (drag)
        {
            Rectangle draggedRectangle = sender as Rectangle;
            Point newPoint = Mouse.GetPosition(canvas);
            double left = Canvas.GetLeft(draggedRectangle);
            double top = Canvas.GetTop(draggedRectangle);
            Canvas.SetLeft(draggedRectangle, left + (newPoint.X - startPoint.X));
            Canvas.SetTop(draggedRectangle, top + (newPoint.Y - startPoint.Y));

            startPoint = newPoint;
        }
    }

    private void rectangle_MouseUp(object sender, MouseButtonEventArgs e)
    {
        // stop dragging
        drag = false;
    }