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0.1.0 | Sep 20, 2024 |
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#4 in #animate
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Used in iced_anim
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Iced Animations
This package is designed to make it easy to animate between values using the Iced framework.
Overview
There are two main widgets exposed: AnimationBuilder
and Animation
. Both
work off the core Animate
trait defining how a value is animated, but differ
on where the animated state is kept. The AnimationBuilder
stores the animated
value within the widget itself while the Animation
widget takes the animated
value from props and allows you to emit a message to update the value.
Both widgets animate values using spring physics instead of easing functions to allow for more natural and interruptible animations.
AnimationBuilder
widget
The AnimationBuilder
widget takes some sort of value that implements
Animate
and a closure to build out a UI based on the current interpolated
value. The benefit is that you don't have to emit messages for very simple
animations but has a couple limitations mentioned below. Typical usage might
look something like this, where self.size
is an f32
in your app state:
AnimationBuilder::new(self.size, |size| {
container(text(size as isize))
.center(size)
.into()
})
.animates_layout(true)
NOTE:
.animates_layout(true)
is what allows re-rendering certain properties like the app layout or text. This is off by default to avoid unnecessarily invalidating the app layout, but will be necessary in certain situations.
The UI will automatically re-render when self.size
is changed. The closure
provides the current animated value and will be called to generate the next
view as appropriate. To see more for this particular example, refer to the
animated_size
example.
Limitations
It might not be easy/possible to pass in non-clonable content like custom
elements to AnimationBuilder
's closure to due the closure being having to be
invoked multiple times to animate between values. Making reusable functions
that use this widget and also take a generic element might be difficult.
Nested animations also don't work if both properties are actively being
animated. One animation at a time will function correctly, but trying to adjust
both at the same time leads to the inner property skipping to the final value.
Use the Animation
widget if you need any of these properties.
Animation
widget
The Animation
widget works by taking a Spring<T>
value and some element,
then emitting a message when the value needs to change. Your app state and
message would look something like this:
use iced_anim::{Animation, Spring, SpringEvent};
#[derive(Default)]
struct State {
size: Spring<f32>,
}
#[derive(Clone)]
enum Message {
UpdateSize(SpringEvent<f32>),
}
Then, somewhere in your view, have a way to change the spring's target and
update the animated value. You can use .into()
as a shorthand to create a
SpringEvent::Target
for changing where the spring should animate towards.
use iced::widget::{Column, button, text};
Column::new()
.push(
button(text("+50"))
.on_press(Message::UpdateSize((self.size.value() + 50.0).into()))
)
.push(
Animation::new(self.size, text(self.size.value().to_string()))
.on_update(Message::UpdateSize)
)
Finally, your update function will forward the event to self.size.update
to
update the spring's inner state correctly.
impl State {
fn update(&mut self, message: Message) {
match message {
Message::UpdateSize(event) => self.size.update(event),
}
}
}
See the stateful_animation
example for a complete example.
Which one should I use?
Generally, if you're animating a tiny value that might not be directly within
your state and the element won't contain any nested animated values, then use
AnimationBuilder
. Otherwise, use the state-driven Animation
to avoid the
limitations of widget-driven animations. Also, use Animation
anytime you want
your state to contain the animated value.
Types that implement Animate
Several types implement Animate
by default, such as f32
, iced::Color
,
and iced::Theme
, with support for others being added in the future. You can
also derive Animate
on your own structs if you enable the derive
feature
and all inner properties already implement Animate
:
use iced_anim::Animate;
#[derive(Animate)]
struct CustomRectangle {
width: f32,
height: f32,
color: iced::Color,
}
You can also animate multiple values at once by providing a tuple up to a length of four:
AnimationBuilder::new((self.size, self.color), |(size, color)| {
container(text(size as isize).color(color))
.center(size)
.into()
})
.animates_layout(true)
Controlling the spring motion
The spring motion of an AnimationBuilder
can be customized. There are a few
defaults like SpringMotion::Smooth
and SpringMotion::Bouncy
, but you can
provide a custom response and damping fraction with SpringMotion::Custom
:
AnimationBuilder::new(self.size, |size| {
container(text(size as isize))
.center(size)
.into()
})
.animates_layout(true)
.motion(SpringMotion::Custom {
response: Duration::from_millis(500),
damping: 0.5
})
Examples
Refer to the examples
directory for a variety of ways to use this crate.
You can also run these examples locally with cargo run --example <package>
,
e.g. cargo run --example animated_color
.
Dependencies
~230–680KB
~16K SLoC