Reanimate.Animation

Declarative animation API based on combinators. For a higher-level interface, see Scene.

Documentation

type Duration = Double

Duration of an animation or effect. Usually measured in seconds.

type Time = Double

Time signal. Goes from 0 to 1, inclusive.

type SVG = Tree

SVG node.

data Animation

Animations are SVGs over a finite time.

Creating animations

mkAnimation :: Duration -> (Time -> SVG) -> Animation

Construct an animation with a given duration. If the duration is not positive throws error.

unsafeMkAnimation :: Duration -> (Time -> SVG) -> Animation

Construct an animation with a given duration, without checking that the duration is positive.

animate :: (Time -> SVG) -> Animation

Construct an animation with a duration of 1.

staticFrame :: Duration -> SVG -> Animation

Create an animation with provided duration, which consists of stationary frame displayed for its entire duration.

pause :: Duration -> Animation

Empty animation (no SVG output) with a fixed duration. If the duration is not positive throws error.

Example:

pause 1 `seqA` drawProgress

Querying animations

duration :: Animation -> Duration

Query the duration of an animation.

frameAt :: Time -> Animation -> SVG

Calculate the frame that would be displayed at given point in time of running animation.

The provided time parameter is clamped between 0 and animation duration.

Composing animations

seqA :: Animation -> Animation -> Animation

Play animations in sequence. The lhs animation is removed after it has completed. New animation duration is 'duration lhs + duration rhs'.

Example:

drawBox `seqA` drawCircle

andThen :: Animation -> Animation -> Animation

Play left animation and freeze on the last frame, then play the right animation. New duration is 'duration lhs + duration rhs'.

Example:

drawBox `andThen` drawCircle

parA :: Animation -> Animation -> Animation

Play two animation concurrently. Shortest animation freezes on last frame. New animation duration is 'max (duration lhs) (duration rhs)'.

Example:

drawBox `parA` adjustDuration (*2) drawCircle

parLoopA :: Animation -> Animation -> Animation

Play two animation concurrently. Shortest animation loops. New animation duration is 'max (duration lhs) (duration rhs)'.

Example:

drawBox `parLoopA` adjustDuration (*2) drawCircle

parDropA :: Animation -> Animation -> Animation

Play two animation concurrently. Animations disappear after playing once. New animation duration is 'max (duration lhs) (duration rhs)'.

Example:

drawBox `parDropA` adjustDuration (*2) drawCircle

Modifying animations

setDuration :: Duration -> Animation -> Animation

Set the duration of an animation by adjusting its playback rate. The animation is still played from start to finish without being cropped. If the duration is not positive throws error.

adjustDuration :: (Duration -> Duration) -> Animation -> Animation

Change the duration of an animation. Animates are stretched or squished (rather than truncated) to fit the new duration. If a changed duration is not positive throws error.

mapA :: (SVG -> SVG) -> Animation -> Animation

Map over the SVG produced by an animation at every frame.

Example:

mapA (scale 0.5) drawCircle

takeA :: Duration -> Animation -> Animation

takeA duration animation creates a new animation consisting of initial segment of animation of given duration, played at the same rate as the original animation. If the duration is not positive throws error.

The duration parameter is clamped to be up to the animation's duration. New animation duration is equal to (eventually clamped) duration.

dropA :: Duration -> Animation -> Animation

dropA duration animation creates a new animation by dropping initial segment of length duration from the provided animation, played at the same rate as the original animation. If the duration greater than or equal to the animation's duration throws error.

The duration parameter is clamped to be non-negative. The duration of the resulting animation is duration of provided animation minus duration.

lastA :: Duration -> Animation -> Animation

lastA duration animation return the last duration seconds of the animation. If the duration is not positive throws error.

pauseAtEnd :: Duration -> Animation -> Animation

Freeze the last frame for t seconds at the end of the animation. If the duration is negative throws error.

Example:

pauseAtEnd 1 drawProgress

pauseAtBeginning :: Duration -> Animation -> Animation

Freeze the first frame for t seconds at the beginning of the animation. If the duration is negative throws error.

Example:

pauseAtBeginning 1 drawProgress

pauseAround :: Duration -> Duration -> Animation -> Animation

Freeze the first and the last frame of the animation for a specified duration. If a duration is negative throws error.

Example:

pauseAround 1 1 drawProgress

repeatA :: Double -> Animation -> Animation

Loop animation n number of times. This number may be fractional and it may be less than 1. It must be greater than 0, though. New duration is n*duration input. If the duration is not positive throws error.

Example:

repeatA 1.5 drawCircle

reverseA :: Animation -> Animation

Play an animation in reverse. Duration remains unchanged. Shorthand for: signalA reverseS.

Example:

reverseA drawCircle

playThenReverseA :: Animation -> Animation

Play animation before playing it again in reverse. Duration is twice the duration of the input.

Example:

playThenReverseA drawCircle

signalA :: Signal -> Animation -> Animation

Modify the time component of an animation. Animation duration is unchanged.

Example:

signalA (fromToS 0.25 0.75) drawCircle

freezeAtPercentage

Arguments

:: Time

value between 0 and 1. The frame displayed at this point in the original animation will be displayed for the duration of the new animation

-> Animation

original animation, from which the frame will be taken

-> Animation

new animation consisting of static frame displayed for the duration of the original animation

freezeAtPercentage time animation creates an animation consisting of stationary frame, that would be displayed in the provided animation at given time. The duration of the new animation is the same as the duration of provided animation.

addStatic :: SVG -> Animation -> Animation

Overlay animation on top of static SVG image.

Example:

addStatic (mkBackground "lightblue") drawCircle

Misc

getAnimationFrame :: Sync -> Animation -> Time -> Duration -> SVG

Ask for an animation frame using a given synchronization policy.

data Sync

Animation synchronization policies.

Constructors

SyncStretch

SyncLoop

SyncDrop

SyncFreeze

Rendering

renderTree :: SVG -> String

Helper function for pretty-printing SVG nodes.

renderSvg

Arguments

:: Maybe Number

The number to use as value of the width attribute of the resulting top-level svg element. If Nothing, the width attribute won't be rendered.

-> Maybe Number

Similar to previous argument, but for height attribute.

-> SVG

SVG to render

-> String

String representation of SVG XML markup

Helper function for pretty-printing SVG nodes as SVG documents.