From c1b9d46fa7fc7a8d39edba555bc0c9d88c29da17 Mon Sep 17 00:00:00 2001
From: Max Goodhart <c@chromakode.com>
Date: Wed, 11 Nov 2020 23:39:52 -0800
Subject: [PATCH] Skip unnecessary view re-positions

---
 src/node/viewStateMachine.js | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/src/node/viewStateMachine.js b/src/node/viewStateMachine.js
index 0da3995..b590489 100644
--- a/src/node/viewStateMachine.js
+++ b/src/node/viewStateMachine.js
@@ -86,15 +86,19 @@ const viewStateMachine = Machine(
             type: 'parallel',
             entry: 'positionView',
             on: {
-              DISPLAY: {
-                actions: [
-                  assign({
-                    pos: (context, event) => event.pos,
-                  }),
-                  'positionView',
-                ],
-                cond: 'contentUnchanged',
-              },
+              DISPLAY: [
+                // Noop if nothing changed.
+                { cond: 'contentPosUnchanged' },
+                {
+                  actions: [
+                    assign({
+                      pos: (context, event) => event.pos,
+                    }),
+                    'positionView',
+                  ],
+                  cond: 'contentUnchanged',
+                },
+              ],
             },
             states: {
               audio: {
@@ -167,6 +171,12 @@ const viewStateMachine = Machine(
       contentUnchanged: (context, event) => {
         return isEqual(context.content, event.content)
       },
+      contentPosUnchanged: (context, event) => {
+        return (
+          isEqual(context.content, event.content) &&
+          isEqual(context.pos, event.pos)
+        )
+      },
       optionsChanged: (context, event) => {
         return !isEqual(context.options, event.options)
       },