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

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)
    );
}

Example: Infinite Transition

use cranpose_animation::{
    infiniteRepeatable, rememberInfiniteTransition, AnimationSpec, Easing, RepeatMode, StartOffset,
};
use cranpose_ui::*;

#[composable]
fn PulsingDot() {
    let transition = rememberInfiniteTransition("pulse");
    let alpha = transition.animateFloat(
        0.0,
        1.0,
        infiniteRepeatable(
            AnimationSpec::tween(900, Easing::EaseInOut),
            RepeatMode::Reverse,
            StartOffset::default(),
        ),
        "pulse_alpha",
    );

    Box(
        Modifier::empty()
            .width(24.0)
            .height(24.0)
            .background(Color(0.2, 0.5, 0.9, alpha.value())),
        BoxSpec::default(),
        || {},
    );
}