# Cranpose Animation
A physics-based animation library designed for the Cranpose composition model.
## When to Use
Use this crate to create smooth, interruptible animations. Unlike traditional timeline-based animation systems, Cranpose animations are driven by state changes. When a target value changes, the animation system automatically calculates the transition from the current value to the new target, maintaining velocity and continuity.
## Key Concepts
- **`Animatable<T, V>`**: A low-level value holder that tracks the current value and velocity. It is the primitive used to build higher-level animation APIs.
- **`AnimationSpec`**: Defines the behavior of an animation. Common types include:
- **`Spring`**: Physical simulation based on stiffness and damping ratio.
- **`Tween`**: Duration-based interpolation with an easing curve.
- **`animate*AsState`**: Composable functions that subscribe to a target value and return a `State` object representing the current animated value.
## Example: Interruptible Spring Animation
```rust
use cranpose::prelude::*;
#[composable]
fn AnimatedBox(target_size: f32) {
// animateFloatAsState automatically handles interruptions.
// If target_size changes while animating, it will seamlessly retarget
// preserving current velocity.
let size = animateFloatAsState(
target_size,
Some(spring(Spring::DampingRatioMediumBouncy, Spring::StiffnessLow))
);
Box(
Modifier
.size(size.value())
.background(Color::Blue)
);
}
```