Layer Styles: Blending Options can be edited on a layer with no styles (#1389)

crates/engine/src/cmd/styles.rs

@@ -25,13 +25,23 @@ fn add_styles(s: &mut Session, p: &Value, cmd: &str, styles: &[&str], enabled: b
     if ids.is_empty() {
         return Err(bad(cmd, "no layer that takes layer styles (footage, solid, precomp, text or shape layer)"));
     }
-    let uids = s.edit(label, None, |proj, state| {
+    let uids = s.edit(label, super::merge_p(p), |proj, state| {
         let gl = proj.comp(cid).ok_or(EngineError::NoComp)?.global_light.clone();
         let mut out = vec![];
         let mut sel = vec![];
         for lid in &ids {
             let mut next = proj.next_id;
             let l = layer_mut(proj, cid, *lid)?;
+            // No style: Blending Options alone (the Layer Style dialog's first change on a layer
+            // without styles).
+            if styles.is_empty() {
+                let uid = st::add_blending_options(l, &mut Ids(&mut next), &gl).ok_or_else(|| bad(cmd, "no Blending Options"))?;
+                if let Some(g) = l.props.sub_mut(GROUP) {
+                    g.enabled = true;
+                }
+                out.push(json!({"layer": lid.0, "style": st::BLENDING, "uid": uid}));
+                sel.push((*lid, uid));
+            }
             for id in styles {
                 let had = l.layer_styles().and_then(|g| g.sub(id)).is_some();
                 let uid = st::add_style(l, &mut Ids(&mut next), id, &gl, enabled).ok_or_else(|| bad(cmd, format!("unknown style `{id}`")))?;
@@ -58,6 +68,9 @@ fn add_styles(s: &mut Session, p: &Value, cmd: &str, styles: &[&str], enabled: b
 
 fn add(s: &mut Session, p: &Value) -> Result<Value> {
     let name = str_p(p, "style").ok_or_else(|| bad("layer.style.add", "missing `style` (e.g. dropShadow or \"Drop Shadow\")"))?;
+    if name.eq_ignore_ascii_case(st::BLENDING) || name.eq_ignore_ascii_case("Blending Options") {
+        return add_styles(s, p, "layer.style.add", &[], true, "Blending Options");
+    }
     let id = st::style_id(name)
         .ok_or_else(|| bad("layer.style.add", format!("unknown style `{name}`; one of {}", STYLES.iter().map(|s| s.0).collect::<Vec<_>>().join(", "))))?;
     let label = STYLES.iter().find(|s| s.0 == id).map(|s| s.1).unwrap_or(id);
@@ -224,7 +237,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Add Layer Style",
             [],
             None,
-            "{style: dropShadow|innerShadow|outerGlow|innerGlow|bevelEmboss|satin|colorOverlay|gradientOverlay|stroke (or display name), layers?}",
+            "{style: dropShadow|innerShadow|outerGlow|innerGlow|bevelEmboss|satin|colorOverlay|gradientOverlay|stroke (or display name), or blendingOptions (the Layer Styles group with Blending Options only), layers?, merge?}",
             has_layers,
             add
         ),

crates/engine/src/tests/styles.rs

@@ -117,3 +117,30 @@ fn styles_render_and_round_trip() {
     assert_eq!(back, *s.project);
     assert_eq!(back.comp(cid).unwrap().global_light.angle.value.as_f64(), 33.0);
 }
+
+/// #1389: Blending Options on a layer with no styles. `layer.style.add` with `blendingOptions`
+/// creates the Layer Styles group with Blending Options only; with the same merge key as the
+/// value set right after it, both are one undo step, and undoing it leaves no group behind.
+#[test]
+fn blending_options_alone_create_the_group_in_one_undo_step() {
+    let (mut s, a, b) = session();
+    let undo = s.history.undo.len();
+    let r = s.execute("layer.style.add", json!({"layers": [a], "style": "blendingOptions", "merge": "bo"})).unwrap();
+    assert_eq!(r["styles"][0]["style"], "blendingOptions", "{r}");
+    let layer = s.active_comp().unwrap().layer(effectcraft_project::LayerId(a)).unwrap().clone();
+    let g = layer.layer_styles().expect("the group is created");
+    assert!(g.sub("blendingOptions").is_some());
+    assert!(styles_of(&s, a).is_empty(), "no style is added with it");
+    s.execute("prop.set", json!({"layer": a, "path": "layerStyles/blendingOptions/advancedBlending/fillOpacity", "value": 40, "merge": "bo"})).unwrap();
+    s.execute("prop.set", json!({"layer": a, "path": "layerStyles/blendingOptions/advancedBlending/fillOpacity", "value": 30, "merge": "bo"})).unwrap();
+    assert_eq!(s.history.undo.len(), undo + 1, "creating the group and setting the value are one step");
+    // The other layer is untouched, and Global Light is the comp's.
+    assert!(s.active_comp().unwrap().layer(effectcraft_project::LayerId(b)).unwrap().layer_styles().is_none());
+    let gl = s.execute("prop.get", json!({"layer": a, "path": "layerStyles/blendingOptions/globalLightAngle"})).unwrap();
+    assert!(gl.to_string().contains("120"), "{gl}");
+    s.execute("edit.undo", json!({})).unwrap();
+    assert!(s.active_comp().unwrap().layer(effectcraft_project::LayerId(a)).unwrap().layer_styles().is_none(), "one undo removes the group");
+    // By display name too.
+    s.execute("layer.style.add", json!({"layers": [a], "style": "Blending Options"})).unwrap();
+    assert!(s.active_comp().unwrap().layer(effectcraft_project::LayerId(a)).unwrap().layer_styles().is_some());
+}