Animation¶

Animation and AnimationTransition are used to animate Widget properties. You must specify at least a property name and target value. To use an Animation, follow these steps:

Setup an Animation object

Use the Animation object on a Widget

Simple animation¶

To animate a Widget’s x or y position, simply specify the target x/y values where you want the widget positioned at the end of the animation:

anim = Animation(x=100, y=100)
anim.start(widget)

The animation will last for 1 second unless duration is specified. When anim.start() is called, the Widget will move smoothly from the current x/y position to (100, 100).

Multiple properties and transitions¶

You can animate multiple properties and use built-in or custom transition functions using transition (or the t= shortcut). For example, to animate the position and size using the ‘in_quad’ transition:

anim = Animation(x=50, size=(80, 80), t='in_quad')
anim.start(widget)

Note that the t= parameter can be the string name of a method in the AnimationTransition class or your own animation function.

Sequential animation¶

To join animations sequentially, use the ‘+’ operator. The following example will animate to x=50 over 1 second, then animate the size to (80, 80) over the next two seconds:

anim = Animation(x=50) + Animation(size=(80, 80), duration=2.)
anim.start(widget)

Parallel animation¶

To join animations in parallel, use the ‘&’ operator. The following example will animate the position to (80, 10) over 1 second, whilst in parallel animating the size to (800, 800):

anim = Animation(pos=(80, 10))
anim &= Animation(size=(800, 800), duration=2.)
anim.start(widget)

Keep in mind that creating overlapping animations on the same property may have unexpected results. If you want to apply multiple animations to the same property, you should either schedule them sequentially (via the ‘+’ operator or using the on_complete callback) or cancel previous animations using the cancel_all method.

Repeating animation¶

New in version 1.8.0.

Note

This is currently only implemented for ‘Sequence’ animations.

To set an animation to repeat, simply set the Sequence.repeat property to True:

anim = Animation(...) + Animation(...)
anim.repeat = True
anim.start(widget)

For flow control of animations such as stopping and cancelling, use the methods already in place in the animation module.

class kivy.animation.Animation(**kw)[source]¶

Bases: kivy.event.EventDispatcher

Create an animation definition that can be used to animate a Widget.

Parameters:

duration or d: float, defaults to 1.

Duration of the animation, in seconds.

transition or t: str or func

Transition function for animate properties. It can be the name of a method from AnimationTransition.

step or s: float

Step in milliseconds of the animation. Defaults to 0, which means the animation is updated for every frame.

To update the animation less often, set the step value to a float. For example, if you want to animate at 30 FPS, use s=1/30.

Events:

on_start: animation, widget: Fired when the animation is started on a widget.
on_complete: animation, widget: Fired when the animation is completed or stopped on a widget.
on_progress: animation, widget, progression: Fired when the progression of the animation is changing.

Changed in version 1.4.0: Added s/step parameter.

Changed in version 1.10.0: The default value of the step parameter was changed from 1/60. to 0.

property animated_properties¶: Return the properties used to animate.

cancel(widget)[source]¶: Cancel the animation previously applied to a widget. Same effect as stop, except the on_complete event will not be triggered!

New in version 1.4.0.

static cancel_all(widget, *largs)[source]¶

Cancel all animations that concern a specific widget / list of properties. See cancel.

Example:

anim = Animation(x=50)
anim.start(widget)

# and later
Animation.cancel_all(widget, 'x')

New in version 1.4.0.

Changed in version 2.1.0: If the parameter widget is None, all animated widgets will be the target and cancelled. If largs is also given, animation of these properties will be canceled for all animated widgets.

cancel_property(widget, prop)[source]¶: Even if an animation is running, remove a property. It will not be animated further. If it was the only/last property being animated, the animation will be canceled (see cancel)

New in version 1.4.0.

property duration¶: Return the duration of the animation.

have_properties_to_animate(widget)[source]¶: Return True if a widget still has properties to animate.

New in version 1.8.0.

start(widget)[source]¶: Start the animation on a widget.

stop(widget)[source]¶: Stop the animation previously applied to a widget, triggering the on_complete event.

static stop_all(widget, *largs)[source]¶

Stop all animations that concern a specific widget / list of properties.

Example:

anim = Animation(x=50)
anim.start(widget)

# and later
Animation.stop_all(widget, 'x')

stop_property(widget, prop)[source]¶: Even if an animation is running, remove a property. It will not be animated further. If it was the only/last property being animated, the animation will be stopped (see stop).

property transition¶: Return the transition of the animation.

class kivy.animation.AnimationTransition[source]¶

Bases: builtins.object

Collection of animation functions to be used with the Animation object. Easing Functions ported to Kivy from the Clutter Project https://developer.gnome.org/clutter/stable/ClutterAlpha.html

The progress parameter in each animation function is in the range 0-1.