added comment alignment

src/sequence.typ

@@ -1,4 +1,4 @@
-#import "@preview/cetz:0.2.2": draw
+#import "@preview/cetz:0.2.2": draw, vector
 #import "consts.typ": *
 #import "participant.typ"
 #import "note.typ"
@@ -48,6 +48,7 @@
   p1,
   p2,
   comment: none,
+  comment-align: "left",
   dashed: false,
   start-tip: "",
   end-tip: ">",
@@ -67,6 +68,7 @@
     p1: p1,
     p2: p2,
     comment: comment,
+    comment-align: comment-align,
     dashed: dashed,
     start-tip: start-tip,
     end-tip: end-tip,
@@ -208,6 +210,10 @@
   }
 
   let pts
+  let comment-pt
+  let comment-anchor
+  let comment-angle = 0deg
+
   if elmt.p1 == elmt.p2 {
     if elmt.flip {
       x1 = start-info.lx
@@ -221,15 +227,6 @@
       calc.max(x1, x2) + 20
     }
 
-    if elmt.comment != none {
-      shapes += draw.content(
-        (x1, start-info.y),
-        elmt.comment,
-        anchor: if elmt.flip {"south-east"} else {"south-west"},
-        padding: 3pt
-      )
-    }
-
     pts = (
       (x1, start-info.y),
       (x-mid, start-info.y),
@@ -237,24 +234,62 @@
       (x2, end-info.y)
     )
 
-  } else {
     if elmt.comment != none {
-      let x = calc.min(x1, x2)
-      if x2 < x1 {
-        x += COMMENT-PAD
-      }
-      shapes += draw.content(
-        (x, start-info.y),
-        elmt.comment,
-        anchor: "south-west",
-        padding: 3pt
-      )
+      comment-anchor = (
+        start: if x-mid < x1 {"south-east"} else {"south-west"},
+        end: if x-mid < x1 {"south-west"} else {"south-east"},
+        left: "south-west",
+        right: "south-east",
+        center: "south",
+      ).at(elmt.comment-align)
+
+      comment-pt = (
+        start: pts.first(),
+        end: pts.at(1),
+        left: if x-mid < x1 {pts.at(1)} else {pts.first()},
+        right: if x-mid < x1 {pts.first()} else {pts.at(1)},
+        center: (pts.first(), 50%, pts.at(1))
+      ).at(elmt.comment-align)
     }
 
+  } else {
     pts = (
       (x1, start-info.y),
       (x2, end-info.y)
     )
+
+    if elmt.comment != none {
+      let start-pt = pts.first()
+      let end-pt = pts.last()
+      if elmt.start-tip != "" {
+        start-pt = (pts.first(), COMMENT-PAD, pts.last())
+      }
+      if elmt.end-tip != "" {
+        end-pt = (pts.last(), COMMENT-PAD, pts.first())
+      }
+
+      comment-pt = (
+        start: start-pt,
+        end: end-pt,
+        left: if x2 < x1 {end-pt} else {start-pt},
+        right: if x2 < x1 {start-pt} else {end-pt},
+        center: (start-pt, 50%, end-pt)
+      ).at(elmt.comment-align)
+
+      comment-anchor = (
+        start: if x2 < x1 {"south-east"} else {"south-west"},
+        end: if x2 < x1 {"south-west"} else {"south-east"},
+        left: "south-west",
+        right: "south-east",
+        center: "south",
+      ).at(elmt.comment-align)
+    }
+
+    let (p1, p2) = pts
+    if x2 < x1 {
+      (p1, p2) = (p2, p1)
+    }
+    comment-angle = vector.angle2(p1, p2)
   }
 
   // Start circle tip
@@ -303,6 +338,16 @@
 
   shapes += draw.line(..pts, ..style)
 
+  if elmt.comment != none {
+    shapes += draw.content(
+      comment-pt,
+      elmt.comment,
+      anchor: comment-anchor,
+      angle: comment-angle,
+      padding: 3pt
+    )
+  }
+
   if elmt.enable-dst {
     let dst-line = lifelines.at(i2)
     dst-line.lines.push(("enable", end-info.y, elmt.lifeline-style))