email article printer friendly get the code more resources

Rotate Text Easily With GDI+
Drawing rotated text was a painful endeavor using the old Windows Graphics Device Interface. In .NET, it's simple.
by Bill Wagner

Posted October 31, 2002

Figure 1. Rotate Text the .NET Way

GDI+ simplifies this process greatly. In Microsoft's new graphics device interface implementation, the company creates a consistent graphics model whose services are exposed through a set of C++ classes.

I've written a simple sample that shows you how easy it is to rotate text. My sample draws a text string in the middle of a window, rotated at any angle you want. Two features in GDI+ make this easy: graphics translations and graphics rotations.

To center the text, translate the coordinates so that the origin is in the center of the window:

Size sz = MyWindow.Size;
Point Middle = new Point (sz.Width / 2, 
   sz.Height / 2);
e.Graphics.TranslateTransform 
   (Middle.X, Middle.Y);

Rotate the text simply by applying another transform:

e.Graphics.RotateTransform (_angle);

Once the transforms are in place, just draw your text:

StringFormat format = new StringFormat 
   (StringFormatFlags.NoClip);
format.Alignment = 
   StringAlignment.Center;
format.LineAlignment = 
   StringAlignment.Center;
e.Graphics.DrawString 
   ("A simple TextString ", f, 
   Brushes.Black, 0, 0, format);

The string format objects control the alignment for the string. In this case, I chose the center of the string.

Now you can rotate your text at any angle you want. If you play with the sample, you'll notice that a positive angle, say 45 degrees, seems to rotate the text by –45 degrees (see Figure 1). Remember the standard coordinate system for GDI: y increases downward. With that kind of coordinate system, positive angles of rotation are clockwise from the horizontal axis.

This sample shows you one way that .NET's GDI+ API makes graphics programs simpler and more consistent. Download the sample code and modify the angles for the transformations. Notice that you can draw text at any angle, on any platform. And this works with any other shape rotated at any angle.