From 1fbb9f29ffbad905be70bd76ba453419008b07e9 Mon Sep 17 00:00:00 2001
From: Erik Demaine <edemaine@mit.edu>
Date: Wed, 1 Nov 2023 14:17:00 -0400
Subject: [PATCH] Fix dragging multiple anchors of a polyline object

---
 CHANGELOG.md              | 5 +++++
 client/Anchor.coffee      | 3 +++
 client/tools/modes.coffee | 8 +++++---
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index deb4b4a..a392986 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ To see every change with descriptions aimed at developers, see
 As a continuously updated web app, Cocreate uses dates
 instead of version numbers.
 
+## 2023-11-01
+
+* Fix dragging multiple anchors of a polyline object
+  [[#226](https://github.com/edemaine/cocreate/issues/226)]
+
 ## 2023-08-09
 
 * New polygonal line tool!
diff --git a/client/Anchor.coffee b/client/Anchor.coffee
index 58ba8b9..0a64e01 100644
--- a/client/Anchor.coffee
+++ b/client/Anchor.coffee
@@ -33,6 +33,9 @@ export anchorsOf = (obj) ->
     y: y + ty
 
 pointMove = (obj, moved, index, coords) ->
+  old = moved[index] ? obj.pts[index]
+  if old?
+    console.log old.x, old.y, 'vs', coords.x, coords.y
   if (old = moved[index] ? obj.pts[index])? and
      old.x == coords.x and old.y == coords.y
     false
diff --git a/client/tools/modes.coffee b/client/tools/modes.coffee
index fa0411b..2027da9 100644
--- a/client/tools/modes.coffee
+++ b/client/tools/modes.coffee
@@ -349,9 +349,11 @@ defineTool
           h.moved[id] ?= {}
           moved = false
           for index in anchorSelection.indicesForId id
-            x = obj.anchors[index].x + motion.x
-            y = obj.anchors[index].y + motion.y
-            moved or= anchorMove obj, h.moved[id], index, {x, y}
+            # Can't write `moved or=` because we don't want to short-circuit
+            if anchorMove obj, h.moved[id], index,
+              x: obj.anchors[index].x + motion.x
+              y: obj.anchors[index].y + motion.y
+            then moved = true
           continue unless moved
           diffs[id] = {id, pts: h.moved[id]}
         h.edit diffs if (id for id of diffs).length