feat: add basic hide function

src/core/draw/hide.typ

@@ -0,0 +1,15 @@
+#import "/src/core/utils.typ": get-ctx, set-ctx
+
+#let render(sync) = get-ctx(ctx => {
+  set-ctx(c => {
+    c.hidden = true
+    return c
+  })
+})
+
+#let render-end(sync) = get-ctx(ctx => {
+  set-ctx(c => {
+    c.hidden = false
+    return c
+  })
+})

src/core/renderer.typ

@@ -319,7 +319,8 @@
       level: 0,
       lines: ()
     )),
-    in-sync: false
+    in-sync: false,
+    hidden: false,
   )
   chronos-ctx.insert(
     "widths",
@@ -379,11 +380,15 @@
       (elmt,)
     } else if "draw" in elmt and elmt.type != "par" {
       get-ctx(ctx => {
-        if ctx.in-sync and elmt.type != "sync-end" {
+        let drawn = if ctx.in-sync and elmt.type != "sync-end" {
           in-sync-render(elmt)
         } else {
           (elmt.draw)(elmt)
         }
+        if ctx.hidden and elmt.type != "hide-end" {
+          drawn = draw.hide(drawn)
+        }
+        drawn
       })
     }
   }

src/core/setup.typ

@@ -1,4 +1,5 @@
 #import "draw/group.typ": render-end as grp-render-end
+#import "draw/hide.typ": render-end as hide-render-end
 #import "draw/sync.typ": render-end as sync-render-end
 #import "utils.typ": get-group-span, is-elmt
 #import "/src/participant.typ": _exists as par-exists, _par
@@ -37,6 +38,21 @@
   )
 }
 
+#let flatten-hide(elmts, i) = {
+  let hide = elmts.at(i)
+  elmts.at(i) = hide
+  return (
+    elmts.slice(0, i + 1) +
+    hide.elmts +
+    ((
+      type: "hide-end",
+      draw: hide-render-end,
+      start-i: i
+    ),) +
+    elmts.slice(i+1)
+  )
+}
+
 #let update-group-children(elmts, i) = {
   let elmts = elmts
   let group-end = elmts.at(i)
@@ -81,6 +97,9 @@
     } else if elmt.type == "sync" {
       elmts = flatten-sync(elmts, i)
     
+    } else if elmt.type == "hide" {
+      elmts = flatten-hide(elmts, i)
+
     } else if elmt.type == "seq" {
       if elmt.enable-dst {
         activation-history.push(elmt)

src/lib.typ

@@ -4,5 +4,5 @@
 #import "sequence.typ": _seq, _ret
 #import "group.typ": _grp, _loop, _alt, _opt, _break
 #import "participant.typ": _par
-#import "misc.typ": _sep, _delay, _sync, _gap, _evt, _col
+#import "misc.typ": _sep, _delay, _sync, _gap, _evt, _col, _hide
 #import "note.typ": _note

src/misc.typ

@@ -1,5 +1,6 @@
 #import "core/draw/delay.typ"
 #import "core/draw/event.typ": render as evt-render
+#import "core/draw/hide.typ"
 #import "core/draw/separator.typ"
 #import "core/draw/sync.typ"
 #import "core/utils.typ": set-ctx
@@ -63,3 +64,11 @@
     max-width: max-width
   ),)
 }
+
+#let _hide(elmts) = {
+  return ((
+    type: "hide",
+    draw: hide.render,
+    elmts: elmts
+  ),)
+}