This article has been excerpted from book "Graphics Programming with GDI+ ".
A polygon is a closed shape with three of more straight sides. Examples of polygons include triangles and rectangles.
The Graphics class provides a DrawPolygon method to draw polygons. DrawPolygon draws a polygon defined by an array of points. It takes two arguments: a pen and an array of Points or PointF structures.
To draw a polygon, an application first creates a pen and an array of points and then calls the DrawPolygon method with these parameters. Listing 3.19 draws a polygon with five points.
LISTING 3.19: Drawing a polygon
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication11
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Paint(object sender,
System.Windows.Forms.PaintEventArgs e)
{
Graphics g = e.Graphics;
// Create a pen
Pen greenPen = new Pen(Color.Green, 2);
Pen redPen = new Pen(Color.Red, 2);
// Create points for polygon
PointF pt1 = new PointF(40.0F, 50.0F);
PointF pt2 = new PointF(60.0F, 70.0F);
PointF pt3 = new PointF(80.0F, 34.0F);
PointF pt4 = new PointF(120.0F, 180.0F);
PointF pt5 = new PointF(200.0F, 150.0F);
PointF[] ptsArray =
{
pt1, pt2, pt3, pt4, pt5
};
// Draw polygon
e.Graphics.DrawPolygon(greenPen, ptsArray);
// Dispose of object
greenPen.Dispose();
redPen.Dispose();
}
}
}
Figure 3.26 shows the output from Listing 3.19
FIGURE 3.26: Drawing a polygon
Conclusion
Hope the article would have helped you in understanding how to draw a Polygon in GDI+. Read other articles on GDI+ on the website.
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This book teaches .NET developers how to work with GDI+ as they develop applications that include graphics, or that interact with monitors or printers. It begins by explaining the difference between GDI and GDI+, and covering the basic concepts of graphics programming in Windows. |