added column width options

src/diagram.typ

@@ -18,6 +18,17 @@
   ),)
 }
 
+#let _col(p1, p2, width: auto, margin: 0, min-width: 0) = {
+  return ((
+    type: "col",
+    p1: p1,
+    p2: p2,
+    width: width,
+    margin: margin,
+    min-width: min-width
+  ),)
+}
+
 #let diagram(elements, width: auto) = {
   if elements == none {
     return

src/lib.typ

@@ -1,5 +1,5 @@
 #let version = version(0, 1, 1)
-#import "diagram.typ": diagram, from-plantuml, _gap, _evt
+#import "diagram.typ": diagram, from-plantuml, _gap, _evt, _col
 
 #import "sequence.typ": _seq
 #import "group.typ": _grp

src/renderer.typ

@@ -1,5 +1,5 @@
 #import "@preview/cetz:0.2.2": canvas, draw
-#import "utils.typ": get-participants-i, get-style
+#import "utils.typ": get-participants-i, get-style, normalize-units
 #import "group.typ"
 #import "participant.typ"
 #import participant: PAR-SPECIALS
@@ -194,6 +194,37 @@
     }
     widths.at(i) = w
   }
+
+  for elmt in elements {
+    if elmt.type == "col" {
+      let i1 = pars-i.at(elmt.p1)
+      let i2 = pars-i.at(elmt.p2)
+      if calc.abs(i1 - i2) != 1 {
+        let i-min = calc.min(i1, i2)
+        let i-max = calc.max(i1, i2)
+        let others = pars-i.pairs()
+                           .sorted(key: p => p.last())
+                           .slice(i-min + 1, i-max)
+                           .map(p => "'" + p.first() + "'")
+                           .join(", ")
+        panic(
+          "Column participants must be consecutive (participants (" +
+          others +
+          ") are in between)"
+        )
+      }
+      let i = calc.min(i1, i2)
+
+      if elmt.width != auto {
+        widths.at(i) = normalize-units(elmt.width)
+      }
+      widths.at(i) = calc.max(
+        widths.at(i),
+        normalize-units(elmt.min-width)
+      ) + normalize-units(elmt.margin)
+    }
+  }
+
   return widths
 }
 

src/utils.typ

@@ -1,3 +1,12 @@
+#let normalize-units(value) = {
+  if type(value) == int or type(value) == float {
+    return value
+  }
+  if type(value) == length {
+    return value / 1pt
+  }
+  panic("Unsupported type '" + str(type(value)) + "'")
+}
 #let get-participants-i(participants) = {
   let pars-i = (:)
   for (i, p) in participants.enumerate() {