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https://github.com/storytold/effectcraft.git
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Brandon ThomasandClaude Opus 5.5
1da7dc4659
Lottie stores line cap, line join, merge mode and some text-selector enums 1-based, and the importer subtracted 1 from whatever number the file held: -1e308 (rounded to i64::MIN) overflowed, a panic in debug builds (found by structural fuzzing). Use saturating_sub. Denies the panic lints in the crate. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
102 lines
3.5 KiB
Rust
102 lines
3.5 KiB
Rust
//! Lottie JSON import and export.
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//!
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//! Implemented from the public Lottie format description (the lottie-spec 1.0 schema and the
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//! LottieFiles format documentation); no player or exporter source was used.
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//!
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//! **Export** ([`export_comp`]) turns a composition into a Lottie document: nested compositions
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//! become precomp assets, still footage becomes embedded base64 image assets, and shape, solid,
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//! null, precomp, image and text layers map to their Lottie layer types (text optionally as glyph
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//! shapes). Transforms (with parenting, separated position and anchor), keyframes (temporal ease
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//! converted from speed/influence to normalised Bezier `i`/`o` tangents, hold keys, spatial
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//! `ti`/`to` tangents), shape contents, masks, track mattes, blend modes, time remapping, layer
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//! timing and composition markers are exported. Anything Lottie cannot express (most effects,
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//! cameras and lights, layer styles, audio, video footage…) is listed in
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//! [`ExportResult::warnings`].
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//!
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//! **Import** ([`import`]) is the inverse mapping into a new composition.
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//!
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//! Keyframe times in Lottie are frames of the layer's local time, which is EffectCraft's layer
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//! time; layer `ip`/`op`/`st` are composition frames and `sr` is the stretch factor.
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#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
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mod anim;
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mod base64;
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mod export;
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mod import;
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mod shapes;
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mod text;
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pub mod zip;
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use effectcraft_color::BlendMode;
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use effectcraft_time::{FrameRate, TICKS_PER_SECOND, Tick};
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pub use export::{ExportOptions, ExportResult, export_comp, to_dotlottie};
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pub use import::{ImportResult, ImportedImage, import};
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#[derive(Debug, thiserror::Error)]
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pub enum LottieError {
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#[error("not a Lottie document: {0}")]
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Parse(String),
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#[error("{0}")]
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Invalid(String),
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}
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/// Frame ↔ tick conversion at a frame rate.
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#[derive(Clone, Copy, Debug)]
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pub(crate) struct Timebase {
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pub rate: FrameRate,
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}
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impl Timebase {
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/// Frame number (fractional) of a time.
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pub fn frame(&self, t: Tick) -> f64 {
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let f = t.0 as f64 * self.rate.num as f64 / (self.rate.den as f64 * TICKS_PER_SECOND as f64);
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// Keep exact frame numbers clean (no 23.999999).
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if (f - f.round()).abs() < 1e-6 { f.round() } else { f }
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}
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pub fn tick(&self, f: f64) -> Tick {
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Tick((f * TICKS_PER_SECOND as f64 * self.rate.den as f64 / self.rate.num as f64).round() as i64)
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}
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}
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/// Lottie layer / shape blend modes (`bm`) in order.
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const LOTTIE_BLEND: [BlendMode; 18] = [
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BlendMode::Normal,
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BlendMode::Multiply,
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BlendMode::Screen,
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BlendMode::Overlay,
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BlendMode::Darken,
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BlendMode::Lighten,
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BlendMode::ColorDodge,
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BlendMode::ColorBurn,
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BlendMode::HardLight,
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BlendMode::SoftLight,
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BlendMode::Difference,
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BlendMode::Exclusion,
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BlendMode::Hue,
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BlendMode::Saturation,
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BlendMode::Color,
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BlendMode::Luminosity,
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BlendMode::Add,
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BlendMode::HardMix,
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];
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/// Lottie `bm` of a blend mode (`None` = Lottie has no equivalent).
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pub(crate) fn blend_to_lottie(m: BlendMode) -> Option<u32> {
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LOTTIE_BLEND.iter().position(|b| *b == m).map(|i| i as u32).or(match m {
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BlendMode::LinearDodge => Some(16),
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BlendMode::ClassicColorDodge => Some(6),
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BlendMode::ClassicColorBurn => Some(7),
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BlendMode::ClassicDifference => Some(10),
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_ => None,
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})
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}
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pub(crate) fn blend_from_lottie(bm: u64) -> BlendMode {
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LOTTIE_BLEND.get(bm as usize).copied().unwrap_or_default()
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}
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#[cfg(test)]
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mod tests;
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