blinc_lottie

Lottie animation player for Blinc sketches.

Implements blinc_canvas_kit::Player so a parsed Lottie scene can be dropped directly into any Sketch:

use blinc_canvas_kit::prelude::*;
use blinc_core::layer::Rect;
use blinc_lottie::LottiePlayer;

struct Hero {
    logo: LottiePlayer,
}

impl Sketch for Hero {
    fn draw(&mut self, ctx: &mut SketchContext, t: f32, _dt: f32) {
        ctx.play(&mut self.logo, Rect::new(40.0, 40.0, 200.0, 200.0), t);
    }
}

fn build() -> Div {
    let logo = LottiePlayer::from_json(include_str!("logo.json")).unwrap();
    sketch("hero", Hero { logo })
}

Loading

Raw Bodymovin JSON:

let player = LottiePlayer::from_json(include_str!("scene.json"))?;

dotLottie archives (zipped bundles of .json + image / font assets — what most exporters and marketplace sites ship now):

let player = LottiePlayer::from_dotlottie_bytes(include_bytes!("scene.lottie"))?;

Both v1 (animations/ layout) and v2 (a/) archive shapes are accepted. Bundled fonts (f/ in v2, fonts referenced by a layer's t.d.k[].fn) are extracted and registered against the global font registry at load time so ty: 5 text layers resolve against the author's intended face.

Supported features

Area	Support
Layer kinds	Solid (ty: 1), Image (ty: 2), Null (ty: 3), Shape (ty: 4), Text (ty: 5), Precomp (ty: 0)
Transforms	Animated position / scale / rotation / anchor / opacity / skew with linear, hold, and cubic-Bezier eased keyframes
Shape items	rc, el, sh, gr, tr, fl, st, gf, gs, tm
Paths	Cubic-Bezier sh with per-vertex in/out tangents; keyframed path morphing when vertex count is stable
Strokes	Width / opacity keyframes, dash patterns, miter limit, butt / round / square caps, miter / round / bevel joins
Gradients	Linear + radial, multi-stop with animated stops and alpha stops, object-bounding-box normalised
Trim paths	tm with start / end / offset animation, simultaneous + individual modes, identity and empty-window fast paths
Effects	Drop Shadow (ty: 25), Gaussian Blur (ty: 29), Outer Glow preset (drop-shadow with zero distance)
Masks	Layer-level masksProperties with Add mode — composite under the layer's clip stack
Track mattes	Alpha matte (tt: 1) pairing the preceding td-marked layer as the mask source; polygon clip in the GPU path
Parent chains	Arbitrary-depth layer parenting with forward-reference + cycle guards
Playback	play, pause, seek, loop, reverse, per-sketch scene-time drift, marker events on the frame interval
dotLottie state machines	LottieStateMachine executes the .lottie archive's state-machine spec — numeric / string / boolean inputs, transitions, event sending

Playback controls

player.set_playing(true);
player.seek(1.25); // seconds into the scene timeline
player.set_loop(true);
player.on_marker("handshake", |player| { /* ... */ });

When paused, the player freezes at the last rendered scene time (via last_scene_t) rather than snapping to t = 0, so pausing looks continuous with the previous frame.

dotLottie state machines

let mut sm = LottieStateMachine::from_dotlottie_bytes(bytes)?;
sm.set_boolean("hovered", true);
sm.send("click"); // dispatches to the current state's transitions

The state machine wraps a LottiePlayer and drives its play / seek / reverse state from the transitions defined in the archive. Input slots (set_numeric / set_string / set_boolean) and explicit send calls cover the two transition triggers the spec defines.

Cargo features

• dotlottie (default) — .lottie archive parsing plus the state- machine runtime. Pulls in zip. Callers who only load raw JSON can disable with default-features = false.
• images (default) — ty: 2 image-layer support. Pulls in blinc_image for PNG / JPEG / base64 decoding. Disable on vector-only consumers to shed the image-decoding dep.

Non-goals

• Expression layers (x: "..." JavaScript on property values). Porting the AE expression runtime roughly doubles the library footprint for a feature most exports don't use. Revisit when a real consumer actually needs it.
• After Effects-only effects outside the ty: 25 / ty: 29 pair — 3D lights, advanced particle emitters, tritone, fill / colour-balance effects. Out of scope — users can stack Blinc's own filter / effect primitives on top of the player.

See BACKLOG.md for the open items and rough priority.

License

Apache-2.0.