AnimSequence

Simple Animation Controller with Timeline

Simple lightweight library for high performance animation in a web page, makes preparations for each frame and calls the frames with optimized timeline for animation.

For example, all positions of the red arrow below in each frame are calculated beforehand, and it is moved to those positions in each frame.

Also, AnimSequence allows the animation to synchronize with mouse-dragging. These animations are controlled by mouse-dragging event of PlainDraggable.

Note that the speed of the red arrow above and the motorcycle below changes even if the each blue pointer is moved at a constant speed.

Methods

AnimSequence.add

animId = AnimSequence.add(valueCallback, frameCallback, duration, count, timing, reverse, timeRatio)

Add new animation, and return animId that is used to start and remove the animation.

For example:

animId = AnimSequence.add(
  function(outputRatio) {
    return 80 + (680 - 80) * outputRatio + 'px';
  },
  function(value) {
    element.style.left = value;
  },
  3000, 0, 'ease-in-out');

Arguments:

valueCallback

Type: function or undefined
Default: undefined

value = valueCallback(outputRatio)

A function that returns a value that is used to draw each frame.
For high performance animation, the function is called for all frames before the animation starts. That is, it makes preparations for each value that is used to draw the frame.

outputRatio is a number ranging from 0 to 1 to calculate a value.
The function can return something that is used to draw an frame. The value can be an Object or Array that contains multiple values.

For example, move an element rightward, it changes a left CSS property, from 80px to 680px.

// Return `80px` when `outputRatio` is `0%` (0), `680px` when `outputRatio` is `100%` (1).
function(outputRatio) {
  // This value is used by `frameCallback` to draw a frame.
  return 80 + (680 - 80) * outputRatio + 'px';
}

frameCallback

Type: function

toNext = frameCallback(value, finish, timeRatio, outputRatio)

A function that draws a frame.
The function is called when it should draw a frame, it draws a frame with passed arguments.

• value is something that was returned by valueCallback.
• finish is true if the function should draw a last frame.
• timeRatio is a number ranging from 0 to 1 to indicate the progress time of the animation played. It means also the ratio of the progress time and duration.
• outputRatio is the same as an argument of valueCallback.

If the function returns false, stop the animation forcedly.

For example, move an element rightward, it changes a left CSS property.

function(value, finish, timeRatio, outputRatio) {
  element.style.left = value; // It was already calculated by `valueCallback`.
  if (finish) {
    element.style.backgroundColor = 'red'; // Change the color to red at the right.
  }
}

duration

Type: number

A number determining how long (milliseconds) the animation will run.

count

Type: number
Default: 0

A number of times the animation should repeat. The animation will repeat forever if 0 is specified.

timing

Type: Array or string

An Array that is [x1, y1, x2, y2] as a "timing function" that indicates how to change the speed. It works same as that of CSS animation.

You can specify one of the following keywords also. These values mean keywords for common timing functions.

• ease
• linear
• ease-in
• ease-out
• ease-in-out

reverse

Type: boolean
Default: false

The animation plays backward if true is specified.
It can be specified by AnimSequence.start also.

timeRatio

Type: number or boolean
Default: 0

A number ranging from 0 to 1 to play from the midst or false that prevents it starting.
It can be specified by AnimSequence.start also.

AnimSequence.remove

AnimSequence.remove(animId)

Remove an animation.

Arguments:

animId

Type: number

The animId that was returned by AnimSequence.add.

AnimSequence.start

AnimSequence.start(animId, reverse, timeRatio)

Start an animation.

Arguments:

animId

Type: number

The animId that was returned by AnimSequence.add.

reverse

Type: boolean
Default: false

The animation plays backward if true is specified.

timeRatio

Type: number
Default: 0

A number ranging from 0 to 1 to play from the midst.

AnimSequence.stop

timeRatio = AnimSequence.stop(animId, getTimeRatioByFrame)

Stop an animation.
timeRatio is a number ranging from 0 to 1 for restarting the animation from the frame that was stopped.

Arguments:

animId

Type: number

The animId that was returned by AnimSequence.add.

getTimeRatioByFrame

Type: boolean
Default: false

If true is specified, return timeRatio of the last played frame.

AnimSequence.validTiming

isValid = AnimSequence.validTiming(timing)

Check whether an Array or string as timing is valid.

Thanks for images: CGvector, Vecteezy