Drawing new rectangle while preserving the existing rectangles

[Daniel EXBN]

Hi!

I use this code to draw rectangles while mouse is clicked in Panel.

The rectangle is drawn in the position of the click.

For now it works good but each time i click in new location in the Panel, the previous rectangle is deleted.

This is my code to draw:

       private void click_AddLocation(object sender, EventArgs e)
        {
	.
	.
	.
	.

            this.Panel1.Paint += new System.Windows.Forms.PaintEventHandler(this.PaintOnMap);
            Panel1.Refresh();
        }

        private void PaintOnMap(object sender, PaintEventArgs e)
        {
            RedPen = new Pen(Color.Red, 7);
            Graphics g = e.Graphics;
            PosXDraw = PosX;
            PosYDraw = PosY;
            Rect = new Rectangle(PosXDraw * 3, PosYDraw * 3, 1, 1);
            g.DrawRectangle(RedPen,Rect);
        }

Thanks in advance!

[GaryTexmo]

You didn't post the code for it but I'm assuming that during the "..." portion of your click you're updating PosX and PosY? If that's the case, you're adding a paint event handler that's going to draw the same rectangle every single time.

Instead, try creating objects when you click and storing them in a list, then drawing them all. You could easily add a private member to your form that was something like..

private List<Point> m_points = new List<Point>();

Then when you click...

int x = /* however you're currently getting PosX */;
int y = /* however you're currently getting PosY */;
m_points.Add(new Point(x, y));

Finally, only use a single paint event and just draw all the points how you want...

/* in some paint event */
Graphics g = e.Graphics;
foreach (Point p in m_points)
{
  g.DrawRectangle(Pens.Red, p.X, p.Y, 1, 1);
}

You'll likely still want to trigger a refresh in your click method so your form updates.

[Daniel EXBN]

Thanks! works like a charm