Animation

Animate elements on a web page with Dart. Similar to jQuery's animate().

Features

  • Quick and simple animations via the simple animate() function.
  • More powerful StyleAnimation class for "low level" operations.
  • Pause.
  • Stop.
  • Resume.
  • Delay.
  • Forward.
  • Finish.
  • Reset.
  • Queueing animations with AnimationQueue.
  • Clear queue.
  • Jump between animations in the queue.
  • Same pause, stop, resume, finish features as with StyleAnimation.
  • Manipulate queue (remove, add).
  • Run multiple animations at the same time (why not?).
  • Uses requestAnimationFrame() instead of setTimeout() for optimal performance and smoother animations.
  • Plenty of easing methods to use (different sorts of easing in/out/in-out).
  • Linear.
  • Quadratic.
  • Cubic.
  • Quartic.
  • Quintic.
  • Sinusoidal.
  • Exponential.
  • Circular.

Missing features

Effects (fade, drop, slide, etc.)

Support for effects will come at some point.

Color and text-shadow animations

Currently you can't animate colors or text-shadow, this will change at some point.

Examples

Let's assume we have this HTML:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
  </head>
  <body>
    <div id="box" style="left: 100px;"></div>

    <script type="application/dart" src="test.dart"></script>
    <script src="https://dart.googlecode.com/svn/branches/bleeding_edge/dart/client/dart.js"></script>
  </body>
</html>

Quick and simple

The simplest way to animate elements directly is to use the helper top-level function animate():

import 'dart:html';
import 'package:animation/animation.dart');

main() {
  var el = query('#box');
  
  var properties = {
    'left': 1000,
    'top': 350
  };

  animate(element: el, properties: properties, duration: 5000);
}

Using StyleAnimation class

The animate() function uses StyleAnimation class internally. This class is more useful in "advanced" scenarios. The following example will not run the animation directly, instead the animation will be instantiated first, and after 2 seconds we run the animation.

import 'dart:html';
import 'package:animation/animation.dart');

main() {
  var el = query('#box');
  
  var anim = new StyleAnimation(el);
    ..duration = 5000
    ..setProperties({
      'left': 1000,
      'top': 350
    })

  // Let's wait 2 seconds before we run the animation, for the sake of demoing this for you.
  new Timer(2000, (Timer t) {
    anim.run(); // Here we go!
  });
}

Manipulating animations

You may manipulate animations in a few ways. In this example we will run an animation for 2.5 seconds, pause it for 2.5 seconds and then let it finish.

import 'dart:html';
import 'package:animation/animation.dart');

main() {
  var el = query('#box');
  
  var anim = new StyleAnimation(el)
    ..duration = 5000
    ..setProperties({
      'left': 1000,
      'top': 350
    })
    ..run(); // Run immediately.

  // Let the animation run for 2.5 seconds, then we pause it.
  new Timer(2500, (Timer timer) {
    anim.pause();

    // Let it be paused for 2.5 seconds, then resume.
    new Timer(2500, (Timer timer) {
      anim.run(); // Calling run again will resume the animation.
    });
  });
}

animate() helper returns a StyleAnimation

The previous code could also be written using the animate() function if you will:

import 'dart:html';
import 'package:animation/animation.dart');

main() {
  var el = query('#box');
  
  // These two lines are different:
  var properties = {'left': 1000, 'top': 350};
  var anim = animate(element: el, properties: properties, duration: 5000);

  // Let the animation run for 2.5 seconds, then we pause it.
  new Timer(2500, (Timer timer) {
    anim.pause();

    // Let it be paused for 2.5 seconds, then resume.
    new Timer(2500, (Timer timer) {
      anim.run(); // Calling run again will resume the animation.
    });
  });
}

In case you wonder, animate() is just a simple helper function that produces a StyleAnimation. Use it if it works for you. Note: using animate() will run the animation immediately after calling it. If you use StyleAnimation, you only construct a class instance and you can start the animation later by calling run() on it.

Using AnimationQueue class

Sometimes you want to queue up a few animations. This can be done easily:

import 'dart:html';
import 'package:animation/animation.dart');

main() {
  var el = query('#box');
  
  // The first animation moves the box.
  var anim = new StyleAnimation(el)
    ..duration = 1000
    ..setProperties({
      'left': 500,
      'top': 250
    });

  // The second animation makes the box taller.
  var anim2 = new StyleAnimation(el)
    ..duration = 500
    ..setProperties({
      'height': 250
    });

  // Create a queue, add both animations to it and run the queue.
  var queue = new AnimationQueue()
    ..addAll([anim, anim2])
    ..run();
}

You may also pause() the queue, finish() it or stop() it. You can add() or remove() animations at any point. You may also jump() to a specific position if you wanted to skip some animations for instance.

License

This library is licensed under MIT.

Libraries

animation