Draw triangle with GDI+

Question

Hi,

 

How can you draw a traingle with GDI+. I know the basics of GDI+, but I can't figure it out by myself. I think you need to set up an array of points and then connect then into a path? Can somebody supply me with a code sample and it would also be usefull to see how to fill it. using FillPath???

Answer 1

Hi,

Regarding triangle as a kind of Polygon, you can draw it with DrawPolygon method and fill it with FillPolygon method.

Sample code:

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Point[] points ={ new Point(10, 10), new Point(100, 10), new Point(50, 100) };
            e.Graphics.DrawPolygon(new Pen(Color.Blue), points);
            Point[] points2 ={ new Point(100, 100), new Point(200, 100), new Point(150, 10) };
            e.Graphics.FillPolygon(new SolidBrush(Color.Red), points2);
        }

Run it, you'll see the effect.

Thanks

Answer 2

You might want to use anti-aliasing while drawing triangles.  Otherwise the points sometimes look like they're off by one.  If you do use anti-aliasing you'll want to set the smoothing mode back to what it was before otherwise it can change the appearance of other things.

Also, there is a collection of Pens and Brushes if you are using simple colors (Color.Red -> Pens.Red -> Brushes.Red).

SmoothingMode smoothingModeTmp = e.Graphics.SmoothingMode;
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
e.Graphics.FillPolygon(Brushes.Red, points);
e.Graphics.SmoothingMode = smoothingModeTmp;