docs/sequences.typ

@@ -22,6 +22,7 @@
 /// - destroy-src (bool): If true, destroy the source lifeline and participant
 /// - lifeline-style (auto, dict): Optional styling options for lifeline rectangles (see CeTZ documentation for more information on all possible values)
 /// - slant (none, int): Optional slant of the arrow
+/// - outer-lifeline-connect (bool): If true, enables legacy anchoring, making sequences connect to the leftmost lifeline when arriving from the left side. If false, all connections are made with the latest/rightmost lifeline
 /// -> array
 #let _seq(
   p1,
@@ -40,7 +41,8 @@
   disable-src: false,
   destroy-src: false,
   lifeline-style: auto,
-  slant: none
+  slant: none,
+  outer-lifeline-connect: false
 ) = {}
 
 /// Creates a return sequence

src/core/draw/sequence.typ

@@ -137,13 +137,19 @@
   end-info.ll-lvl = ctx.lifelines.at(i2).level * LIFELINE-W / 2
 
   // Compute left/right position at start/end
-  start-info.insert("lx", start-info.x)
-  if start-info.ll-lvl != 0 { start-info.lx -= LIFELINE-W / 2 }
-  end-info.insert("lx", end-info.x)
-  if end-info.ll-lvl != 0 { end-info.lx -= LIFELINE-W / 2 }
-
   start-info.insert("rx", start-info.x + start-info.ll-lvl)
   end-info.insert("rx", end-info.x + end-info.ll-lvl)
+  let start-lx = start-info.x
+  let end-lx = end-info.x
+  if seq.outer-lifeline-connect {
+    if start-info.ll-lvl != 0 {start-lx -= LIFELINE-W / 2}
+    if end-info.ll-lvl != 0 {end-lx -= LIFELINE-W / 2}
+  } else {
+    if start-info.ll-lvl != 0 {start-lx = start-info.rx - LIFELINE-W}
+    if end-info.ll-lvl != 0 {end-lx = end-info.rx - LIFELINE-W}
+  }
+  start-info.insert("lx", start-lx)
+  end-info.insert("lx", end-lx)
 
   // Choose correct points to link
   let x1 = start-info.rx

src/sequence.typ

@@ -17,7 +17,8 @@
   disable-src: false,
   destroy-src: false,
   lifeline-style: auto,
-  slant: none
+  slant: none,
+  outer-lifeline-connect: false
 ) = {
   return ((
     type: "seq",
@@ -39,6 +40,7 @@
     destroy-src: destroy-src,
     lifeline-style: lifeline-style,
     slant: slant,
+    outer-lifeline-connect: outer-lifeline-connect,
     linked-notes: ()
   ),)
 }

tests/sequence/outer-lifeline/.gitignore

@@ -0,0 +1,4 @@
+# generated by tytanic, do not edit
+
+diff/**
+out/**

tests/sequence/outer-lifeline/test.typ

@@ -0,0 +1,29 @@
+#set page(width: auto, height: auto)
+#import "/src/lib.typ": *
+
+#let make-diagram(_seq) = {
+  diagram({
+    _par("a")
+    _par("b")
+    _par("c")
+    _seq("a", "b")
+    _seq("c", "b")
+    _seq("a", "b", enable-dst: true)
+    _seq("a", "b")
+    _seq("c", "b")
+    _seq("a", "b", enable-dst: true)
+    _seq("a", "b")
+    _seq("c", "b")
+    _seq("a", "b", enable-dst: true)
+    _seq("a", "b")
+    _seq("c", "b")
+
+    _evt("b", "disable")
+    _evt("b", "disable")
+    _evt("b", "disable")
+  })
+}
+
+#make-diagram(_seq)
+#pagebreak()
+#make-diagram(_seq.with(outer-lifeline-connect: true))