C# - 在带有“Paint”的面板中绘图

Question

I've been working on a project for class where I need to display on screen polygons (drawed in a Panel), but I've been reading arround here that I should work with Paint event, tho I can't make it work (started learning C# a little ago).

private void drawView()
{
//"playerView" is the panel I'm working on
Graphics gr = playerView.CreateGraphics();
Pen pen = new Pen(Color.White, 1);


 //Left Wall 1
 Point lw1a = new Point(18, 7); 
 Point lw1b = new Point(99, 61); 
 Point lw1c = new Point(99, 259); 
 Point lw1d = new Point(18, 313);

 Point[] lw1 = { lw1a, lw1b, lw1c, lw1d };

 gr.DrawPolygon(pen, lw1);
}

I was doing something like this to draw it on screen, it would be possible to do this with a Paint method? (it is called method, or event? I'm really lost here).

Thanks!

Answer 1

I think you are referring to the Control.Paint event from windows forms .

Basically, you would attach a listener to the Paint event of a windows forms element, like this :

//this should happen only once! put it in another handler, attached to the load event of your form, or find a different solution
//as long as you make sure that playerView is instantiated before trying to attach the handler, 
//and that you only attach it once.
playerView.Paint += new System.Windows.Forms.PaintEventHandler(this.playerView_Paint);

private void playerView_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
    // Create a local version of the graphics object for the playerView.
    Graphics g = e.Graphics;
    //you can now draw using g

    //Left Wall 1
    Point lw1a = new Point(18, 7); 
    Point lw1b = new Point(99, 61); 
    Point lw1c = new Point(99, 259); 
    Point lw1d = new Point(18, 313);

    Point[] lw1 = { lw1a, lw1b, lw1c, lw1d };

    //we need to dispose this pen when we're done with it.
    //a handy way to do that is with a "using" clause
    using(Pen pen = new Pen(Color.White, 1))
    {
        g.DrawPolygon(pen, lw1);
    }
}