c# List of interfaces

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C#

hi,

I have to do application like Paint. I have to paint Line, Rectangule and Ellipse. I want to use STATE deisgn patern. I made class Line, Rect and Ellipse and Interface IPaint.


In class main I made IPaint paint, and List<IPaint> list= new Line<IPaint>(); Then by 3 buttons i add paint = new Line(); or rect or ellipse() depends on wich button are clicked. But when I`m use list.Add(paint) this not working correct.

When i add first element it`s OK, But when i add second element then first element look like second. When i`m add thirth element then first, and second el. have value like thitrh.

How can i do this right ?

/////edit
Yes it`s just a typo in post. In code is

List<IPaint> list = new List<IPaint>;

Im in work now and i dont have acces to code.
But full code look like:

Interface IPaint

Interface IPaint
{
void Paint{PrintEvenArgs e}
Point BeginPoint{get;set;}
Point EndPoint(get;set)
}

Class Line, Rect and Ellipse look the same:

Class Line: IPaint{
public Begin/Endpoint {get;set;}
void Paint(PrintEventArgs e)
{
Pen p = new Pen(Color red,2)
e.drawLine(p,BeginPoint,EndPoint)
}
//in Rect and ellipse only change drawRectangle or DrawEllipse
}

In Form1 i do:

Class Main{
IPaint point;
List<IPaint> lista = new List<IPaint>();

 Void Main
 {


    Inicianization();
 }

  event MouseDown(Obiect Sender, MouseArgs e)
  {
     point.BeginPoint = e.location;

  }
  
  event mouseMove(...)
  {
    point.EndPoint = e.location;
    Invalidate();
  }

  event mouseup(..)
  {
    lista.Add(point);
  }

event Form1_Paint(Object Sender, PrintEventArgs e)

  If (!Point.BeginPoint.IsNull & !Point.EndPoint.IsnuLL)
  {
    point.Paint(e);
  }

  for (int i =0, i< lista.Count, i++)
  {
    lista[i].Paint(e);
  }

event button1_click(...)
{
point = new Line();
// button 2 - point = New Rectangle or ellipse button 3
}
}

Problem is in add to list. When i Add first element with point`s (2,2)m second (3,3) then first change value to second element on the list, when i add thirth with points (5,6) then first and secont element change value to thirth element and list look like:

list[0] - Begin point - 5
- EndPoint - 6
list[1] - Begin point - 5
- EndPoint - 6
list[2] - Begin point - 5
- EndPoint - 6


It is look like when i add to list object point, it is add by reference. But why ?