Implement a Resize/Move/Save Visitor Pattern

Question

I am making a paint program where i can make Rectangle/Ellipse. In that program i can move/resize them but also save them.

My problem is now that i need to make a visitor pattern(Resize/Move and save) But I don't know where i should start.

These are the method i use at the moment:

public abstract void ResizeShape(PosSizableRect posSizableRect, float lastX, float lastY, float newX, float newY);
public abstract void MoveShape(int x, int y);
private void Write(List<Shape> shapes, StreamWriter streamWriter, string tabs = "")

sorry can't give you pictures because of my reputation...

Answer 1

public interface IShape
{
    void Resize(PosSizableRect posSizableRect, float lastX, float lastY, float newX, float newY);
    void Move(int dx, int dy);
    void Write (StreamWriter writer, string tabs ="");
    void AcceptVisitor(IVisitor visitor);
}

public interface IVisitor
{
    void Visit(IShape shape);
}

Thats the interfaces, now the implementation (one example)

public class MoveVisitor : IVisitor
{
    private int dx;
    private int dy;

    public MoveVisitor(int dx, int dy)
    {
         this.dx = dx;
         this.dy = dy;
    }
    public void Visit(IShape shape)
    {
         shape.Move(dx,dy);
    }
}