Merge pull request #1334

crates/script/src/tests_ease_presets.rs

@@ -180,7 +180,8 @@ fn the_ease_presets_panel_eases_every_selected_pair_in_one_undo_step() {
     assert!(list.as_array().unwrap().iter().any(|e| e["name"] == PANEL && e["panel"] == true && e["source"] == "extension"));
     let steps = s.history.undo.len();
     set(&mut s, win, "presets", json!("Ease In-Out"));
-    assert_eq!(status(&mut s, win), "Eased 3 keyframe pair(s) with \u{201c}Ease In-Out\u{201d}");
+    // In-Out (the default) on every key: each pair gets the whole curve, as before.
+    assert_eq!(status(&mut s, win), "Eased 5 keyframe(s) (In-Out) with \u{201c}Ease In-Out\u{201d}");
     assert_eq!(s.history.undo.len(), steps + 1, "one undo step");
     assert_eq!(s.history.undo.last().map(|(label, _)| label.as_str()), Some("Apply Ease Preset"));
     assert_eq!(s.state.selected_keys, selected, "the keys stay selected for the next preset");
@@ -203,10 +204,298 @@ fn the_ease_presets_panel_eases_every_selected_pair_in_one_undo_step() {
     s.execute("edit.deselectAll", json!({})).unwrap();
     let steps = s.history.undo.len();
     set(&mut s, win, "presets", json!("Linear"));
-    assert_eq!(status(&mut s, win), "Select two or more neighbouring keyframes of a property");
+    assert_eq!(status(&mut s, win), "Select keyframes with another keyframe next to it");
     assert_eq!(s.history.undo.len(), steps);
 }
 
+/// Select only the keys at `keys` (property path, time in seconds).
+fn select_keys(s: &mut Session, l: u64, keys: &[(&str, f64)]) {
+    s.execute("edit.deselectAll", json!({})).unwrap();
+    let keys: Vec<Value> = keys.iter().map(|(path, t)| json!({"layer": l, "path": path, "time": t})).collect();
+    s.execute("keys.select", json!({"keys": keys})).unwrap();
+}
+
+/// Type a curve (Out %, Out speed, In %, In speed), choose the sides to ease and click Apply.
+fn apply_typed(s: &mut Session, win: u64, mode: &str, c: [f64; 4]) {
+    for (name, v) in ["outInfluence", "outSpeed", "inInfluence", "inSpeed"].iter().zip(c) {
+        set(s, win, name, json!(v.to_string()));
+    }
+    set(s, win, "mode", json!(mode));
+    click(s, win, "apply");
+}
+
+fn eased(e: Ease, speed: f64, influence: f64) -> bool {
+    close(e.speed, speed, 1e-9) && close(e.influence, influence, 1e-9)
+}
+
+/// #1329: one selected keyframe eases its incoming side (In), its outgoing side (Out) or both,
+/// each scaled to the segment on that side (+100/s in, −40/s out here), without changing its
+/// neighbours, key times, values or the selection; one undo step restores it.
+#[test]
+fn one_selected_keyframe_eases_its_in_out_or_both_sides() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    animate(&mut s, l, "transform/opacity", &[(0.0, json!(0)), (1.0, json!(100)), (3.0, json!(20))]);
+    let win = open_panel(&mut s);
+    // In-Out is the default.
+    assert_eq!(control(&mut s, win, "mode")["selection"], json!([2]));
+    let before = prop(&s, l, "transform/opacity");
+    for mode in ["In", "Out", "In-Out"] {
+        select_keys(&mut s, l, &[("transform/opacity", 1.0)]);
+        let selected = s.state.selected_keys.clone();
+        let steps = s.history.undo.len();
+        apply_typed(&mut s, win, mode, [30.0, 0.5, 60.0, 2.0]);
+        assert_eq!(status(&mut s, win), format!("Eased 1 keyframe(s) ({mode}) with the curve"));
+        assert_eq!(s.history.undo.len(), steps + 1, "{mode}: one undo step");
+        assert_eq!(s.state.selected_keys, selected, "{mode}: the selection stays");
+        let op = prop(&s, l, "transform/opacity");
+        assert_eq!((&op.keys[0], &op.keys[2]), (&before.keys[0], &before.keys[2]), "{mode}: the neighbours don't change");
+        assert_eq!((op.keys[1].time, op.keys[1].value.as_f64()), (before.keys[1].time, 100.0), "{mode}");
+        let k = &op.keys[1];
+        let (ins, outs) = (mode != "Out", mode != "In");
+        assert_eq!(k.in_interp, if ins { Interp::Bezier } else { Interp::Linear }, "{mode}");
+        assert_eq!(k.out_interp, if outs { Interp::Bezier } else { Interp::Linear }, "{mode}");
+        if ins {
+            assert!(eased(k.in_ease[0], 2.0 * 100.0, 0.6), "{mode}: {:?}", k.in_ease);
+        } else {
+            assert!(close(op.value_at(at(0.5)).as_f64(), 50.0, 1e-6), "{mode}: the in side still plays linearly");
+        }
+        if outs {
+            assert!(eased(k.out_ease[0], 0.5 * -40.0, 0.3), "{mode}: {:?}", k.out_ease);
+        } else {
+            assert!(close(op.value_at(at(2.0)).as_f64(), 60.0, 1e-6), "{mode}: the out side still plays linearly");
+        }
+        s.execute("edit.undo", json!({})).unwrap();
+        assert_eq!(prop(&s, l, "transform/opacity").keys, before.keys, "{mode}: undone");
+    }
+}
+
+/// A side without a neighbouring key isn't eased; when no selected key has one, nothing changes
+/// (no undo step) and the panel says why. Keys that aren't neighbours, and keys of several
+/// properties, each ease on their own.
+#[test]
+fn first_last_and_scattered_keyframes_ease_the_sides_that_have_a_segment() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    animate(&mut s, l, "transform/opacity", &[(0.0, json!(0)), (1.0, json!(100)), (3.0, json!(20))]);
+    animate(&mut s, l, "transform/rotation", &[(0.0, json!(0)), (2.0, json!(90))]);
+    let win = open_panel(&mut s);
+    let before = prop(&s, l, "transform/opacity");
+    let c = [30.0, 0.5, 60.0, 2.0];
+    for (mode, t, why) in [("In", 0.0, "before it"), ("Out", 3.0, "after it")] {
+        select_keys(&mut s, l, &[("transform/opacity", t)]);
+        let steps = s.history.undo.len();
+        apply_typed(&mut s, win, mode, c);
+        assert_eq!(status(&mut s, win), format!("Select keyframes with another keyframe {why}"));
+        assert_eq!(s.history.undo.len(), steps, "{mode}: no undo step");
+        assert_eq!(prop(&s, l, "transform/opacity").keys, before.keys);
+    }
+    // In-Out on the first key eases only its out side.
+    select_keys(&mut s, l, &[("transform/opacity", 0.0)]);
+    apply_typed(&mut s, win, "In-Out", c);
+    let op = prop(&s, l, "transform/opacity");
+    assert_eq!((op.keys[0].in_interp, op.keys[0].out_interp), (Interp::Linear, Interp::Bezier));
+    assert!(eased(op.keys[0].out_ease[0], 0.5 * 100.0, 0.3), "{:?}", op.keys[0].out_ease);
+    assert_eq!(op.keys[1..], before.keys[1..]);
+    s.execute("edit.undo", json!({})).unwrap();
+    // The first and last Opacity keys (not neighbours) and the last Rotation key.
+    select_keys(&mut s, l, &[("transform/opacity", 0.0), ("transform/opacity", 3.0), ("transform/rotation", 2.0)]);
+    let steps = s.history.undo.len();
+    apply_typed(&mut s, win, "In-Out", c);
+    assert_eq!(status(&mut s, win), "Eased 3 keyframe(s) (In-Out) with the curve");
+    assert_eq!(s.history.undo.len(), steps + 1);
+    let op = prop(&s, l, "transform/opacity");
+    assert!(eased(op.keys[0].out_ease[0], 0.5 * 100.0, 0.3), "{:?}", op.keys[0].out_ease);
+    assert!(eased(op.keys[2].in_ease[0], 2.0 * -40.0, 0.6), "{:?}", op.keys[2].in_ease);
+    assert_eq!(op.keys[1], before.keys[1], "the unselected middle key");
+    let rot = prop(&s, l, "transform/rotation");
+    assert!(eased(rot.keys[1].in_ease[0], 2.0 * 45.0, 0.6), "{:?}", rot.keys[1].in_ease);
+    assert_eq!(rot.keys[0].out_interp, Interp::Linear, "the unselected neighbour");
+    s.execute("edit.undo", json!({})).unwrap();
+    assert_eq!(prop(&s, l, "transform/opacity").keys, before.keys);
+    assert!(prop(&s, l, "transform/rotation").keys.iter().all(|k| k.in_interp == Interp::Linear && k.out_interp == Interp::Linear));
+}
+
+/// A change from the pair-only panel: In-Out on a selected pair also eases the pair's outer sides
+/// that face an unselected key (the selected keys' own sides), and Out on the pair eases only
+/// out sides.
+#[test]
+fn a_selected_pair_eases_the_sides_its_mode_names() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    animate(&mut s, l, "transform/opacity", &[(0.0, json!(0)), (1.0, json!(100)), (3.0, json!(20))]);
+    let win = open_panel(&mut s);
+    let before = prop(&s, l, "transform/opacity");
+    let c = [30.0, 0.5, 60.0, 2.0];
+    select_keys(&mut s, l, &[("transform/opacity", 0.0), ("transform/opacity", 1.0)]);
+    apply_typed(&mut s, win, "In-Out", c);
+    let op = prop(&s, l, "transform/opacity");
+    assert!(eased(op.keys[0].out_ease[0], 50.0, 0.3) && eased(op.keys[1].in_ease[0], 200.0, 0.6));
+    assert!(eased(op.keys[1].out_ease[0], -20.0, 0.3), "the side facing the unselected key: {:?}", op.keys[1].out_ease);
+    assert_eq!(op.keys[2], before.keys[2]);
+    s.execute("edit.undo", json!({})).unwrap();
+    apply_typed(&mut s, win, "Out", c);
+    let op = prop(&s, l, "transform/opacity");
+    assert!(eased(op.keys[0].out_ease[0], 50.0, 0.3) && eased(op.keys[1].out_ease[0], -20.0, 0.3));
+    assert_eq!((op.keys[0].in_interp, op.keys[1].in_interp), (Interp::Linear, Interp::Linear));
+}
+
+/// Easing one side of a key leaves the other playing as it did: a Hold stays a Hold, and an
+/// auto-Bezier side keeps its shape. A preset click uses the chosen sides too.
+#[test]
+fn the_side_not_eased_keeps_playing_hold_and_auto_bezier() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    animate(&mut s, l, "transform/opacity", &[(0.0, json!(0)), (1.0, json!(100)), (3.0, json!(20))]);
+    animate(&mut s, l, "transform/rotation", &[(0.0, json!(0)), (1.0, json!(90)), (3.0, json!(30))]);
+    ok(
+        &mut s,
+        r#"var t = app.project.activeItem.layer(1).transform, K = KeyframeInterpolationType;
+        t.opacity.setInterpolationTypeAtKey(2, K.LINEAR, K.HOLD);
+        t.rotation.setInterpolationTypeAtKey(2, K.BEZIER, K.BEZIER);
+        t.rotation.setTemporalAutoBezierAtKey(2, true);"#,
+    );
+    let rot = prop(&s, l, "transform/rotation");
+    let after: Vec<f64> = [1.5, 2.0, 2.5].iter().map(|t| rot.value_at(at(*t)).as_f64()).collect();
+    let win = open_panel(&mut s);
+    set(&mut s, win, "mode", json!("In"));
+    select_keys(&mut s, l, &[("transform/opacity", 1.0), ("transform/rotation", 1.0)]);
+    set(&mut s, win, "presets", json!("Ease In-Out"));
+    assert_eq!(status(&mut s, win), "Eased 2 keyframe(s) (In) with \u{201c}Ease In-Out\u{201d}");
+    let op = prop(&s, l, "transform/opacity");
+    assert_eq!((op.keys[1].in_interp, op.keys[1].out_interp), (Interp::Bezier, Interp::Hold));
+    assert!(eased(op.keys[1].in_ease[0], 0.0, 0.5), "{:?}", op.keys[1].in_ease);
+    assert_eq!(op.value_at(at(2.0)).as_f64(), 100.0, "still holds");
+    let eased_rot = prop(&s, l, "transform/rotation");
+    assert!(eased(eased_rot.keys[1].in_ease[0], 0.0, 0.5), "{:?}", eased_rot.keys[1].in_ease);
+    for (t, want) in [1.5, 2.0, 2.5].iter().zip(after) {
+        assert!(close(eased_rot.value_at(at(*t)).as_f64(), want, 1e-6), "the auto-Bezier out side at {t}");
+    }
+    assert!(!close(eased_rot.value_at(at(0.25)).as_f64(), rot.value_at(at(0.25)).as_f64(), 1e-3), "the in side changed");
+}
+
+/// Roving keys pass speed straight through (the engine keeps their sides linear), so an ease set
+/// on one wouldn't play: they are skipped and the panel says so, rather than reporting them eased.
+#[test]
+fn roving_keyframes_are_skipped_and_reported() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    animate(&mut s, l, "transform/position", &[(0.0, json!([0, 0, 0])), (1.0, json!([100, 0, 0])), (2.0, json!([200, 0, 0]))]);
+    animate(&mut s, l, "transform/opacity", &[(0.0, json!(0)), (1.0, json!(100)), (3.0, json!(20))]);
+    ok(&mut s, "app.project.activeItem.layer(1).transform.position.setRovingAtKey(2, true)");
+    let pos = prop(&s, l, "transform/position");
+    assert!(pos.keys[1].roving);
+    let roving_at = pos.keys[1].time.seconds();
+    let win = open_panel(&mut s);
+    // Only the roving key: nothing changes, no undo step.
+    select_keys(&mut s, l, &[("transform/position", roving_at)]);
+    let steps = s.history.undo.len();
+    set(&mut s, win, "presets", json!("Ease In-Out"));
+    assert_eq!(status(&mut s, win), "Nothing eased: skipped 1 roving keyframe(s); turn off Roving to ease them");
+    assert_eq!(s.history.undo.len(), steps);
+    assert_eq!(prop(&s, l, "transform/position").keys, pos.keys);
+    // With an ordinary key: that one is eased, the roving one is counted as skipped.
+    select_keys(&mut s, l, &[("transform/position", roving_at), ("transform/opacity", 1.0)]);
+    set(&mut s, win, "presets", json!("Linear"));
+    set(&mut s, win, "presets", json!("Ease In-Out"));
+    assert_eq!(
+        status(&mut s, win),
+        "Eased 1 keyframe(s) (In-Out) with \u{201c}Ease In-Out\u{201d}; skipped 1 roving keyframe(s); turn off Roving to ease them"
+    );
+    let k = &prop(&s, l, "transform/position").keys[1];
+    assert!(k.roving && k.in_interp == Interp::Linear && k.out_interp == Interp::Linear, "{k:?}");
+    let op = prop(&s, l, "transform/opacity");
+    assert!(eased(op.keys[1].in_ease[0], 0.0, 0.5) && eased(op.keys[1].out_ease[0], 0.0, 0.5));
+}
+
+/// Out alone leaves an auto-Bezier in side playing as it did, and undo and redo restore each state.
+#[test]
+fn out_alone_keeps_the_in_side_playing_through_undo_and_redo() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    animate(&mut s, l, "transform/rotation", &[(0.0, json!(0)), (1.0, json!(90)), (3.0, json!(30))]);
+    ok(
+        &mut s,
+        r#"var r = app.project.activeItem.layer(1).transform.rotation, K = KeyframeInterpolationType;
+        r.setInterpolationTypeAtKey(2, K.BEZIER, K.BEZIER);
+        r.setTemporalAutoBezierAtKey(2, true);"#,
+    );
+    let before = prop(&s, l, "transform/rotation");
+    let win = open_panel(&mut s);
+    select_keys(&mut s, l, &[("transform/rotation", 1.0)]);
+    apply_typed(&mut s, win, "Out", [60.0, 0.0, 33.0, 1.0]);
+    let after = prop(&s, l, "transform/rotation");
+    assert!(eased(after.keys[1].out_ease[0], 0.0, 0.6), "{:?}", after.keys[1].out_ease);
+    for t in [0.25, 0.5, 0.75] {
+        assert!(close(after.value_at(at(t)).as_f64(), before.value_at(at(t)).as_f64(), 1e-6), "the in side at {t}");
+    }
+    assert!(!close(after.value_at(at(2.0)).as_f64(), before.value_at(at(2.0)).as_f64(), 1e-3), "the out side changed");
+    s.execute("edit.undo", json!({})).unwrap();
+    assert_eq!(prop(&s, l, "transform/rotation").keys, before.keys);
+    s.execute("edit.redo", json!({})).unwrap();
+    assert_eq!(prop(&s, l, "transform/rotation").keys, after.keys);
+}
+
+/// On a curved path, a single key's in and out speeds follow the length of the path on each side
+/// (unequal lengths and durations), and the side not eased plays as it did.
+#[test]
+fn a_single_key_on_a_curved_path_eases_along_each_side() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    animate(&mut s, l, "transform/position", &[(0.0, json!([0, 0, 0])), (1.0, json!([100, 0, 0])), (3.0, json!([100, 300, 0]))]);
+    let before = prop(&s, l, "transform/position");
+    let (len_in, len_out) = (effectcraft_keyframe::spatial_segment_length(&before.keys, 0), effectcraft_keyframe::spatial_segment_length(&before.keys, 1));
+    let win = open_panel(&mut s);
+    select_keys(&mut s, l, &[("transform/position", 1.0)]);
+    apply_typed(&mut s, win, "In", [40.0, 1.5, 50.0, 2.0]);
+    let pos = prop(&s, l, "transform/position");
+    let k = &pos.keys[1];
+    // In speed: twice the incoming segment's average (its path length over 1 s).
+    assert!(k.in_ease.iter().all(|e| close(e.speed, 2.0 * len_in, 0.05 * len_in) && close(e.influence, 0.5, 1e-9)), "{:?} vs {len_in}", k.in_ease);
+    // The out side (2 s along a longer path) plays as before.
+    for t in [1.5, 2.0, 2.5] {
+        let (a, b) = (pos.value_at(at(t)).as_vec2(), before.value_at(at(t)).as_vec2());
+        assert!(close(a[0], b[0], 1e-6) && close(a[1], b[1], 1e-6), "out side at {t}: {a:?} vs {b:?}");
+    }
+    // Playback on the in side: arriving at twice the average speed, the last tenth of a second
+    // covers more of the path than a constant speed would (len_in / 10).
+    let (p9, p10) = (pos.value_at(at(0.9)).as_vec2(), pos.value_at(at(1.0)).as_vec2());
+    let step = ((p10[0] - p9[0]).powi(2) + (p10[1] - p9[1]).powi(2)).sqrt();
+    assert!(step > len_in / 10.0 * 1.2, "{step} vs {len_in}");
+    assert!(len_out > len_in, "{len_out} {len_in}");
+}
+
+/// On one key, each side scales to its own segment: per dimension, and along the motion path.
+#[test]
+fn single_keys_scale_each_side_to_its_dimensions_and_motion_path() {
+    let store = Arc::new(MemoryConfig::default());
+    let mut s = session(&store);
+    let l = setup(&mut s);
+    // Scale: +100/−50 per second into the key, 0/+50 per second out of it.
+    animate(&mut s, l, "transform/scale", &[(0.0, json!([100, 100])), (1.0, json!([200, 50])), (3.0, json!([200, 150]))]);
+    // Position on a straight path: 100 px/s into the key, 50 px/s out of it.
+    animate(&mut s, l, "transform/position", &[(0.0, json!([0, 0, 0])), (1.0, json!([100, 0, 0])), (3.0, json!([200, 0, 0]))]);
+    let win = open_panel(&mut s);
+    select_keys(&mut s, l, &[("transform/scale", 1.0), ("transform/position", 1.0)]);
+    apply_typed(&mut s, win, "In-Out", [40.0, 1.5, 50.0, 2.0]);
+    assert_eq!(status(&mut s, win), "Eased 2 keyframe(s) (In-Out) with the curve");
+    let k = prop(&s, l, "transform/scale").keys[1].clone();
+    assert!(eased(k.in_ease[0], 200.0, 0.5) && eased(k.in_ease[1], -100.0, 0.5), "{:?}", k.in_ease);
+    assert!(eased(k.out_ease[0], 0.0, 0.4) && eased(k.out_ease[1], 75.0, 0.4), "{:?}", k.out_ease);
+    let k = prop(&s, l, "transform/position").keys[1].clone();
+    assert!(k.in_ease.iter().all(|e| close(e.speed, 200.0, 0.5) && close(e.influence, 0.5, 1e-9)), "{:?}", k.in_ease);
+    assert!(k.out_ease.iter().all(|e| close(e.speed, 75.0, 0.5) && close(e.influence, 0.4, 1e-9)), "{:?}", k.out_ease);
+    let pos = prop(&s, l, "transform/position");
+    assert_eq!(pos.value_at(at(1.0)).as_vec2()[0], 100.0, "the key's value stays");
+}
+
 #[test]
 fn a_typed_curve_scales_to_each_dimension_and_follows_motion_paths() {
     let store = Arc::new(MemoryConfig::default());

docs/plugins.md

@@ -103,17 +103,24 @@ name in your Scripts folders takes their place.
 
 ### Ease Presets (`extensions/scriptui-panels/Ease Presets.jsx`)
 
-Window ▸ Ease Presets.jsx: easing curves kept by name and applied to pairs of neighbouring
-selected keyframes (#254; it was a core panel in v0.6.0). A curve is the out side of a segment's
+Window ▸ Ease Presets.jsx: easing curves kept by name and applied to the sides of selected
+keyframes (#254; it was a core panel in v0.6.0). A curve is the out side of a segment's
 first key and the in side of its second, in the Keyframe Velocity dialog's terms: influence in
 percent, and speed relative to the segment's average speed (1 = as fast as a straight line, 0 = at
 rest), so one curve fits any duration and change of value.
 
-* Click a preset to apply it to every pair of neighbouring selected keyframes of each selected
-  property, in one undo step (per dimension, and along the motion path for spatial properties;
-  the keys' other sides keep playing as they did). The keys stay selected, so you can try another.
+* Click a preset to apply it to the selected keyframes of each selected property, in one undo
+  step. **Ease** chooses the sides (#1329): **In** eases each key's incoming side with the curve's
+  in side, **Out** its outgoing side with the curve's out side, **In-Out** (the default) both. A
+  side is eased when it has a neighbouring keyframe, selected or not (the neighbour doesn't
+  change), with its speeds scaled to the segment on that side: per dimension, and along the
+  motion path for spatial properties. So a single keyframe works, a selected pair gets the whole
+  curve, and the first and last keys ease the side that has a segment. The side not eased keeps
+  playing as it did (a Hold stays a Hold). Roving keyframes are skipped, and the status says how
+  many: they pass speed straight through, so an ease on one wouldn't play (turn off Roving to
+  ease it). The keys stay selected, so you can try another.
 * The drawing shows the working curve; type its numbers (Out % and Speed, In % and Speed) and
-  click Apply, or click From Keys to read the curve between the first selected pair.
+  click Apply, or click From Keys to read the curve between the first selected pair of neighbouring keys.
 * Save keeps the working curve under the typed name (replacing a preset of that name); Rename
   and Delete act on the selected preset of your own. The twelve built-in presets can't change.
 * User presets are kept with `app.settings` (section `Ease Presets`, key `userPresets`, in

extensions/scriptui-panels/Ease Presets.jsx

@@ -1,4 +1,4 @@
-// Ease Presets: easing curves kept by name and applied to pairs of neighbouring selected keyframes.
+// Ease Presets: easing curves kept by name and applied to the sides of selected keyframes.
 //
 // A ScriptUI panel that ships with EffectCraft as an optional extension (Window ▸ Ease
 // Presets.jsx). It uses only After Effects' documented scripting API: comp.selectedProperties,
@@ -12,6 +12,13 @@
 // speeds are scaled to it: per dimension, along the motion path for spatial properties, or as
 // overall progress for shapes.
 //
+// Applied to selected keyframes, In eases each key's incoming side with the curve's in side, Out
+// its outgoing side with the curve's out side, In-Out both: a side is eased when it has a
+// neighbouring key (selected or not; the neighbour isn't changed), its speeds scaled to the
+// segment on that side. So a selected pair gets the whole curve, and a single key works too.
+// Roving keys are skipped: they pass speed straight through (their sides stay linear), so an ease
+// set on them wouldn't play.
+//
 // User presets are kept with app.settings (section "Ease Presets", key "userPresets") as JSON:
 // {"version": 1, "presets": [{"name": …, "curve": {"outInfluence", "outSpeed", "inInfluence",
 // "inSpeed"}}]}.
@@ -98,9 +105,8 @@
 
   // ------------------------------------------------------------------ keyframes
 
-  // Pairs of neighbouring selected keyframes of the active comp: {prop, key} (the earlier key's
-  // index), by property.
-  function selectedPairs() {
+  // Selected properties of the active comp whose keys can ease: {prop, keys} (their selected keys).
+  function selectedKeyed() {
     var comp = app.project.activeItem;
     var out = [];
     if (!(comp instanceof CompItem)) return out;
@@ -109,7 +115,17 @@
       var p = props[i];
       if (p.propertyType !== PropertyType.PROPERTY || p.numKeys < 2 || !p.isInterpolationTypeValid(BEZIER)) continue;
       var keys = p.selectedKeys;
-      for (var k = 0; k + 1 < keys.length; k++) if (keys[k + 1] === keys[k] + 1) out.push({ prop: p, key: keys[k] });
+      if (keys.length) out.push({ prop: p, keys: keys });
+    }
+    return out;
+  }
+
+  // Pairs of neighbouring selected keyframes: {prop, key} (the earlier key's index), by property.
+  function selectedPairs() {
+    var keyed = selectedKeyed(), out = [];
+    for (var i = 0; i < keyed.length; i++) {
+      var keys = keyed[i].keys;
+      for (var k = 0; k + 1 < keys.length; k++) if (keys[k + 1] === keys[k] + 1) out.push({ prop: keyed[i].prop, key: keys[k] });
     }
     return out;
   }
@@ -175,29 +191,43 @@
     }
   }
 
-  // Ease every pair of neighbouring selected keyframes with `c` (one undo step). Returns the
-  // number of pairs eased.
-  function applyCurve(c) {
-    var pairs = selectedPairs(), n = 0;
-    if (!pairs.length) return 0;
+  // The eases of one side with `speed` (relative to the segment's average) and `influence`.
+  function eases(s, speed, influence) {
+    var out = [];
+    for (var d = 0; d < s.length; d++) out.push(new KeyframeEase(speed * s[d], influence));
+    return out;
+  }
+
+  // Ease the sides `mode` names ("In", "Out" or "In-Out") of every selected keyframe with `c`, in
+  // one undo step: a side with a neighbouring key, scaled to the segment on that side. Returns
+  // {eased, roving}: the number of keyframes eased, and of selected roving keyframes skipped.
+  function applyCurve(c, mode) {
+    var keyed = selectedKeyed(), sides = [], keys = 0, roving = 0;
+    var doIn = mode !== "Out", doOut = mode !== "In";
+    // Every side and its eases first: the segments are measured before any key changes.
+    for (var i = 0; i < keyed.length; i++) {
+      var p = keyed[i].prop;
+      for (var j = 0; j < keyed[i].keys.length; j++) {
+        var k = keyed[i].keys[j], before = sides.length;
+        if (p.keyRoving(k)) {
+          roving++;
+          continue;
+        }
+        var s = doIn && k > 1 ? slopes(p, k - 1) : null;
+        if (s) sides.push({ prop: p, key: k, out: false, eases: eases(s, c.inSpeed, c.inInfluence) });
+        s = doOut && k < p.numKeys ? slopes(p, k) : null;
+        if (s) sides.push({ prop: p, key: k, out: true, eases: eases(s, c.outSpeed, c.outInfluence) });
+        if (sides.length > before) keys++;
+      }
+    }
+    if (!sides.length) return { eased: 0, roving: roving };
     app.beginUndoGroup("Apply Ease Preset");
     try {
-      for (var i = 0; i < pairs.length; i++) {
-        var p = pairs[i].prop, a = pairs[i].key, s = slopes(p, a);
-        if (!s) continue;
-        var outE = [], inE = [];
-        for (var d = 0; d < s.length; d++) {
-          outE.push(new KeyframeEase(c.outSpeed * s[d], c.outInfluence));
-          inE.push(new KeyframeEase(c.inSpeed * s[d], c.inInfluence));
-        }
-        easeSide(p, a, true, outE);
-        easeSide(p, a + 1, false, inE);
-        n++;
-      }
+      for (var e = 0; e < sides.length; e++) easeSide(sides[e].prop, sides[e].key, sides[e].out, sides[e].eases);
     } finally {
       app.endUndoGroup();
     }
-    return n;
+    return { eased: keys, roving: roving };
   }
 
   // The curve between the first selected pair of keyframes (measured on the dimension that
@@ -288,6 +318,13 @@
   var inInfluence = field(inRow, "In %", "inInfluence");
   var inSpeed = field(inRow, "Speed", "inSpeed");
 
+  var modeRow = ui.add("group");
+  modeRow.add("statictext", undefined, "Ease");
+  var MODES = ["In", "Out", "In-Out"];
+  var mode = modeRow.add("dropdownlist", undefined, MODES, { name: "mode" });
+  mode.selection = 2;
+  mode.helpTip = "The sides of each selected keyframe to ease: incoming, outgoing or both";
+
   var actions = ui.add("group");
   var applyButton = actions.add("button", undefined, "Apply", { name: "apply" });
   var fromKeys = actions.add("button", undefined, "From Keys", { name: "fromKeys" });
@@ -346,8 +383,12 @@
   }
 
   function apply(c, what) {
-    var n = applyCurve(c);
-    status.text = n > 0 ? "Eased " + n + " keyframe pair(s) with " + what : "Select two or more neighbouring keyframes of a property";
+    var m = mode.selection ? mode.selection.text : "In-Out";
+    var r = applyCurve(c, m), n = r.eased;
+    var side = m === "In" ? "before it" : m === "Out" ? "after it" : "next to it";
+    var skipped = r.roving > 0 ? "skipped " + r.roving + " roving keyframe(s); turn off Roving to ease them" : "";
+    if (n > 0) status.text = "Eased " + n + " keyframe(s) (" + m + ") with " + what + (skipped ? "; " + skipped : "");
+    else status.text = skipped ? "Nothing eased: " + skipped : "Select keyframes with another keyframe " + side;
     return n;
   }