effectcraft/crates/engine/src/keyframe_text.rs

//! Copied keyframes as After Effects keyframe text, for the system clipboard (#1908). Other
//! applications read this tab-separated format (AE2Blend brings it into Blender). Like After
//! Effects it covers one layer: its Transform properties, keyframed ones as one row per key
//! (frame number in comp time, then the value) and static ones as a single row with no frame.
//! Easing and tangents aren't part of the format; EffectCraft's own paste keeps them.

use effectcraft_project::{AutoOrient, Comp, Layer, LayerId, Project, Uid};

use crate::KeyRef;

/// Transform properties in After Effects' order, with the unit each column is labelled with.
const CHANNELS: &[(&str, &str)] = &[
    ("poi", "pixels"),
    ("anchor", "pixels"),
    ("position", "pixels"),
    ("scale", "percent"),
    ("orientation", "degrees"),
    ("rotationX", "degrees"),
    ("rotationY", "degrees"),
    ("rotation", "degrees"),
    ("opacity", "percent"),
];

/// The text for copied keys (layer times) and unanimated properties. `None` unless they all come
/// from one layer and at least one is a Transform property.
pub(crate) fn text(project: &Project, comp: &Comp, keys: &[KeyRef], statics: &[(LayerId, Uid)]) -> Option<String> {
    let lid = keys.first().map(|k| k.layer).or_else(|| statics.first().map(|s| s.0))?;
    if keys.iter().any(|k| k.layer != lid) || statics.iter().any(|s| s.0 != lid) {
        return None;
    }
    let layer = comp.layer(lid)?;
    let fps = comp.frame_rate.as_f64();
    let mut blocks = String::new();
    for (id, unit) in CHANNELS {
        let Some(pr) = layer.props.prop(&format!("transform/{id}")) else { continue };
        if !active(layer, id) || (pr.three_d_only && !layer.is_3d()) {
            continue;
        }
        let mut times: Vec<_> = keys.iter().filter(|k| k.prop == pr.uid).map(|k| k.time).collect();
        times.sort();
        times.dedup();
        let rows: Vec<(String, Vec<f64>)> = if !times.is_empty() {
            let frame = |t| num(layer.comp_time(t).seconds() * fps);
            times.into_iter().filter_map(|t| Some((frame(t), pr.keys.iter().find(|k| k.time == t)?.value.components()))).collect()
        } else if statics.iter().any(|s| s.1 == pr.uid) {
            vec![(String::new(), pr.value.components())]
        } else {
            continue;
        };
        let Some(dims) = rows.first().map(|(_, v)| v.len()).filter(|n| *n > 0) else { continue };
        // After Effects labels only the first of Orientation's three columns, and names Z
        // Rotation plain Rotation (as AE2Blend expects).
        let columns = match dims {
            1 => vec![unit.to_string()],
            _ if *id == "orientation" => vec![format!("X {unit}")],
            _ => ["X", "Y", "Z"].iter().take(dims).map(|axis| format!("{axis} {unit}")).collect(),
        };
        blocks.push_str(&format!("Transform\t{}\n\tFrame\t{}\n", pr.name, columns.join("\t")));
        for (frame, mut values) in rows {
            // A 2D layer ignores the Z it may keep (from pasted 3D keys): write the one it shows.
            if !layer.is_3d()
                && let Some(z) = values.get_mut(2)
            {
                *z = if *id == "scale" { 100.0 } else { 0.0 };
            }
            let values: Vec<String> = values.into_iter().map(num).collect();
            blocks.push_str(&format!("\t{frame}\t{}\n", values.join("\t")));
        }
        blocks.push('\n');
    }
    if blocks.is_empty() {
        return None;
    }
    let (w, h) = match effectcraft_render::eval::source_size(project, layer) {
        (0, 0) => (comp.width, comp.height),
        size => size,
    };
    Some(format!(
        "Adobe After Effects 8.0 Keyframe Data\n\n\tUnits Per Second\t{}\n\tSource Width\t{w}\n\tSource Height\t{h}\n\tSource Pixel Aspect Ratio\t1\n\tComp Pixel Aspect Ratio\t{}\n\n{blocks}End of Keyframe Data\n",
        num(fps),
        num(comp.pixel_aspect)
    ))
}

/// Whether the layer uses this Transform property: one-node cameras (and lights not aimed at
/// it) have no Point of Interest, and Separate Dimensions replaces Position with X / Y / Z
/// Position (which this text doesn't cover).
fn active(layer: &Layer, id: &str) -> bool {
    match id {
        "poi" => !(layer.is_camera() || layer.is_light()) || layer.auto_orient == AutoOrient::TowardsPointOfInterest,
        "position" => layer.transform().is_none_or(|tr| tr.get("positionX").is_none()),
        _ => true,
    }
}

/// A number with at most three decimals and no trailing zeros (`23.976`, `960`, `-0.5`).
fn num(v: f64) -> String {
    let s = format!("{:.3}", if v.is_finite() { v } else { 0.0 });
    let s = s.trim_end_matches('0').trim_end_matches('.');
    if s == "-0" { "0".into() } else { s.into() }
}