Programming .NET Windows Applications

Timer Component

The Timer component raises a Tick event at specified time intervals. The Tick event handler can then process a regularly occurring event, such as repainting the screen for animation or a clock display, updating a status report, or terminating a program based on elapsed time.

The interval between Tick events, specified by the Interval property, is measured in milliseconds, with valid values between 1 and 2,147,483,647, inclusive. The maximum value corresponds to approximately 597 hours, or a little over 24 days.

If there are heavy demands on the system running the application, either from the current or other applications, the Tick events may not be raised as often as specified by the Interval property, especially if the Interval is very short. Under any circumstances, the interval is not guaranteed to be accurate. If accuracy is required, the system clock should be checked as needed, especially for long intervals.

Although the Interval property is in milliseconds, the system clock generates only 18 ticks per second. Therefore, the true precision of the Timer is no better than one-eighteenth of a second, which is about 55 milliseconds.

Three types of timers are provided in the .NET Framework. The first is a member of the System.Threading namespace. It is used primarily for multi-threaded applications and will not be covered in this book. It is not represented in any Visual Studio .NET Toolbox.

The second is a member of the System.Timers namespace. It is primarily intended ...