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Graphics using GDI+

By Mike Gold on February 05, 2002
This sample project shows how to draw various graphics objects on a Form using GDI+ objects.
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In .NET, GDI+ functionality resides in the System.Drawing.dll. Before you start using GDI+ classes, you must add reference to the System.Drawing.dll and import System.Drawing namespace. In this sample, I use class GraphicsPath, which is defined in the System.Drawing.Drawing2D namespace.

Creating this project is simple. Create a Windows application and add reference to the System.Drawing.dll using Project->Add Reference menu item. See Figure 1.



Figure 1. Adding reference to System.Drawing.dll

After that add these two lines.

using System.Drawing;
using System.Drawing.Drawing2D;

Note: If you create a Windows application using VS.NET, you only need write only one line.

using System.Drawing.Drawing2D;

After that add a Form_Paint event handler using the Properties Window. See Figure 2.

Figure 2. Adding Form_Paint event handler.

And write the following code on the Form_Paint event handler.

private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
Graphics g = e.Graphics ;
Rectangle rect =
this.ClientRectangle;
// Rectangle rect = new Rectangle(50, 30, 100, 100);
// paints a gradiant background to the whole window
LinearGradientBrush lBrush = new LinearGradientBrush(rect, Color.Red, Color.Yellow,
LinearGradientMode.BackwardDiagonal);
g.FillRectangle(lBrush, rect);
// draws an arc
Pen pn = new Pen( Color.Blue );
rect =
new Rectangle(50, 50, 200, 100);
g.DrawArc( pn, rect, 12, 84 );
// Rectangle rect = new Rectangle(50, 50, 200, 100);
// draws a line with a blue violet pen
Pen pn2 = new Pen( Color.BlueViolet );
Point pt1 =
new Point( 30, 30);
Point pt2 =
new Point( 110, 100);
g.DrawLine( pn2, pt1, pt2 );
// illustrates how to draw graphic test
g.DrawString("Welcome to the Graphics World", this.Font, new SolidBrush(Color.Azure ), 10,10);
// draws an ellipse in the bottom corner of the screen
Pen pn3 = new Pen( Color.Aqua , 5 );
rect =
new Rectangle(ClientRectangle.Right - 60, ClientRectangle.Bottom - 60, 50, 50);
g.DrawEllipse( pn3, rect );
// draw a graphic path with bezier curves
GraphicsPath path = new GraphicsPath(new Point[] {
new Point(40, 140), new Point(275, 200),
new Point(105, 225), new Point(190, ClientRectangle.Bottom),
new Point(50, ClientRectangle.Bottom), new Point(20, 180), },
new byte[] {
(
byte)PathPointType.Start,
(
byte)PathPointType.Bezier,
(
byte)PathPointType.Bezier,
(
byte)PathPointType.Bezier,
(
byte)PathPointType.Line,
(
byte)PathPointType.Line,
});
PathGradientBrush pgb =
new PathGradientBrush(path);
pgb.SurroundColors =
new Color[] { Color.Green,Color.Yellow,Color.Red, Color.Blue,
Color.Orange, Color.White, };
g.FillPath(pgb, path);
}

Compile and run the project. The output looks like Figure 3.

Figure 3.

Mike Gold

Michael Gold is President of Microgold Software Inc., makers of the WithClass UML Tool. His company is a Microsoft VBA Partner and Borland Partner. Mike is a Microsoft MVP and founding member of C# Corner. He has a BSEE ... Read more

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