Hi,

This may be a simple issue, but im gettin nowhere trying to fix it.
I have a form with a picturebox, the picturebox shows a map of our greenhouses. I want to be able to create clickable areas on the image.
I have created a class to store each area, and can create them fine.
The issue comes in trying to draw the areas onto the picture.
Heres what i have:

Bay _bay = new Bay();
                _bay.Points = newBay;
                _bay.Color = Color.Red;
                _bay.Highlight = false;
                Bays.Add(_bay);
                pictureBox1.Invalidate();

each clickable area will be a bay in the greenhouse. I create an instance of the Bay class, instantiate it with a set of 4 PointF values (newBay) which denote the area.
next:

void pictureBox1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
        {
            foreach (Bay b in Bays)
            {
                b.Draw(e.Graphics);
            }
        }

each Bay's draw method is called...

public void Draw(Graphics g)
        {
            SolidBrush b = new SolidBrush(this.Color);
            g.FillPolygon(b, _points);
            b.Dispose();

            if (Highlight)
            {
                Pen p = new Pen(Color.Red, 3);
                p.DashStyle = DashStyle.DashDot;
                g.DrawPolygon(p, _points);
                p.Dispose();
            }
        }

My problem is that only the LAST polygon is showing up : / i think the Graphics object may be overwritten by each call...but i cant figure out why or how to stop it...someone help..please! :)

Don't know if it helps, but have you ever tried to remove(comment them out) all the Dispose methods from your Draw method?

hmmm...how typical is that...i spent ALL day on this and get nowhere...as soon as i put it in a post i make a breakthrough : /

Its NOT a graphics issue at all...all of the polygons are being drawn!!
I had a random insight and checked the collection of Bays to see if there was something odd going on there, and there is. Each time i add a new bay the old bay's have their _points changed to match :/
I think i may inadvertantly be storing a reference instead of a copy when i set the instance varaible...can anyone confirm that?

PointF[] _points;

 public Bay()
        {
            _points = new PointF[4];
        }

 public PointF[] Points
        {
            get { return _points; }
            set { _points = value; }
        }

>>as soon as i put it in a post i make a breakthrough;)
Have that all the time. Dozens of posts I did not have to send because while posting them I found the solution!!!
As with your last code snippet, with every new Bay you declare an array of 4 new PointF structures. I do not know if that is the intention.

Yeah, thats the aim.
Each bay is square so all the polygons will be formed by 4 connected points.
I cant understand why its creating a reference. Its my understanding that parameters are passed by value by default.
newBay is an array of 4 PointF structures created in the main class. This is then passed to the instance of the Bay class.
Ive gone in line by line with a watch and as soon as i change a point in newBay, each instance of the Bay class has its matching point changed. Gah, why is it doing that? I ahevnt used 'ref' anywhere : /

Got to the bottom of it..i was passing the arrays not the values! Sjtoepit mistake! Arrays are reference type. I changed

public PointF[] Points
        {
            get { return _points; }
            set { _points = value; }
        }

to

public PointF[] Points
        {
            get { return _points; }
        }
        public void SetPoints(PointF p1, PointF p2, PointF p3, PointF p4)
        {
            _points[0] = p1;
            _points[1] = p2;
            _points[2] = p3;
            _points[3] = p4;
        }

to feed in the 4 points as values and it all works fine. A whole day wasted on a daft error. Glad i'm not the one paying my wages haha.
CHeers for the help :)

Glad to be of "some" assistance Ryshad. But most of the work was done by you, you may be proud of yourself!

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