Book Image

Dart By Example

By : David Mitchell
Book Image

Dart By Example

By: David Mitchell

Overview of this book

Table of Contents (17 chapters)
Dart By Example
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Timing the presentation


The presenter will want to keep to their allotted time slot. We will include a timer in the editor to aid in rehearsal.

Introducing the Stopwatch class

The Stopwatch class (from dart:core) provides much of the functionality needed for this feature, as shown in this small command-line application:

main() {
  Stopwatch sw = new Stopwatch();
  sw.start();
  print(sw.elapsed);
  sw.stop();
  print(sw.elapsed);
}

The elapsed property can be checked at any time to give the current duration. This is a very useful class as, for example, it can be used to compare different functions to see which is the fastest.

Implementing the presentation timer

The clock will be stopped and started with a single button handled by the toggleTimer method. A recurring timer will update the duration text on the screen, as follows:

If the timer is running, the update Timer and the Stopwatch in the field slidesTime is stopped. No update to the display is required as the user will need to see the final...