From a07cfee644a6b854c977903775e083c2a3d827b8 Mon Sep 17 00:00:00 2001
From: Akihiko Odaki <akihiko.odaki.4i@stu.hosei.ac.jp>
Date: Tue, 6 Mar 2018 15:45:31 +0900
Subject: [PATCH] Extract columns area from UI component (#6650)

UI component used to toggle isComposing state by directly manipulating the
DOM element to avoid the expensive rendering.

However, it is hacky, and is not effective for other states. Instead,
this change makes the rendering cheaper by extracting the huge columns
area.
---
 app/javascript/mastodon/features/ui/index.js | 163 +++++++++++--------
 1 file changed, 93 insertions(+), 70 deletions(-)

diff --git a/app/javascript/mastodon/features/ui/index.js b/app/javascript/mastodon/features/ui/index.js
index ef909136f..9960758af 100644
--- a/app/javascript/mastodon/features/ui/index.js
+++ b/app/javascript/mastodon/features/ui/index.js
@@ -1,3 +1,4 @@
+import classNames from 'classnames';
 import React from 'react';
 import NotificationsContainer from './containers/notifications_container';
 import PropTypes from 'prop-types';
@@ -84,10 +85,93 @@ const keyMap = {
   goToMuted: 'g m',
 };
 
+class SwitchingColumnsArea extends React.PureComponent {
+
+  static propTypes = {
+    children: PropTypes.node,
+    location: PropTypes.object,
+    onLayoutChange: PropTypes.func.isRequired,
+  };
+
+  state = {
+    mobile: isMobile(window.innerWidth),
+  };
+
+  componentWillMount () {
+    window.addEventListener('resize', this.handleResize, { passive: true });
+  }
+
+  componentDidUpdate (prevProps) {
+    if (![this.props.location.pathname, '/'].includes(prevProps.location.pathname)) {
+      this.node.handleChildrenContentChange();
+    }
+  }
+
+  componentWillUnmount () {
+    window.removeEventListener('resize', this.handleResize);
+  }
+
+  handleResize = debounce(() => {
+    // The cached heights are no longer accurate, invalidate
+    this.props.onLayoutChange();
+
+    this.setState({ mobile: isMobile(window.innerWidth) });
+  }, 500, {
+    trailing: true,
+  });
+
+  setRef = c => {
+    this.node = c.getWrappedInstance().getWrappedInstance();
+  }
+
+  render () {
+    const { children } = this.props;
+    const { mobile } = this.state;
+
+    return (
+      <ColumnsAreaContainer ref={this.setRef} singleColumn={mobile}>
+        <WrappedSwitch>
+          <Redirect from='/' to='/getting-started' exact />
+          <WrappedRoute path='/getting-started' component={GettingStarted} content={children} />
+          <WrappedRoute path='/keyboard-shortcuts' component={KeyboardShortcuts} content={children} />
+          <WrappedRoute path='/timelines/home' component={HomeTimeline} content={children} />
+          <WrappedRoute path='/timelines/public' exact component={PublicTimeline} content={children} />
+          <WrappedRoute path='/timelines/public/local' component={CommunityTimeline} content={children} />
+          <WrappedRoute path='/timelines/tag/:id' component={HashtagTimeline} content={children} />
+          <WrappedRoute path='/timelines/list/:id' component={ListTimeline} content={children} />
+
+          <WrappedRoute path='/notifications' component={Notifications} content={children} />
+          <WrappedRoute path='/favourites' component={FavouritedStatuses} content={children} />
+          <WrappedRoute path='/pinned' component={PinnedStatuses} content={children} />
+
+          <WrappedRoute path='/statuses/new' component={Compose} content={children} />
+          <WrappedRoute path='/statuses/:statusId' exact component={Status} content={children} />
+          <WrappedRoute path='/statuses/:statusId/reblogs' component={Reblogs} content={children} />
+          <WrappedRoute path='/statuses/:statusId/favourites' component={Favourites} content={children} />
+
+          <WrappedRoute path='/accounts/:accountId' exact component={AccountTimeline} content={children} />
+          <WrappedRoute path='/accounts/:accountId/with_replies' component={AccountTimeline} content={children} componentParams={{ withReplies: true }} />
+          <WrappedRoute path='/accounts/:accountId/followers' component={Followers} content={children} />
+          <WrappedRoute path='/accounts/:accountId/following' component={Following} content={children} />
+          <WrappedRoute path='/accounts/:accountId/media' component={AccountGallery} content={children} />
+
+          <WrappedRoute path='/follow_requests' component={FollowRequests} content={children} />
+          <WrappedRoute path='/blocks' component={Blocks} content={children} />
+          <WrappedRoute path='/mutes' component={Mutes} content={children} />
+          <WrappedRoute path='/lists' component={Lists} content={children} />
+
+          <WrappedRoute component={GenericNotFound} content={children} />
+        </WrappedSwitch>
+      </ColumnsAreaContainer>
+    );
+  }
+
+}
+
 @connect(mapStateToProps)
 @injectIntl
 @withRouter
-export default class UI extends React.Component {
+export default class UI extends React.PureComponent {
 
   static contextTypes = {
     router: PropTypes.object.isRequired,
@@ -103,7 +187,6 @@ export default class UI extends React.Component {
   };
 
   state = {
-    width: window.innerWidth,
     draggingOver: false,
   };
 
@@ -118,14 +201,10 @@ export default class UI extends React.Component {
     }
   }
 
-  handleResize = debounce(() => {
+  handleLayoutChange = () => {
     // The cached heights are no longer accurate, invalidate
     this.props.dispatch(clearHeight());
-
-    this.setState({ width: window.innerWidth });
-  }, 500, {
-    trailing: true,
-  });
+  }
 
   handleDragEnter = (e) => {
     e.preventDefault();
@@ -193,7 +272,6 @@ export default class UI extends React.Component {
 
   componentWillMount () {
     window.addEventListener('beforeunload', this.handleBeforeUnload, false);
-    window.addEventListener('resize', this.handleResize, { passive: true });
     document.addEventListener('dragenter', this.handleDragEnter, false);
     document.addEventListener('dragover', this.handleDragOver, false);
     document.addEventListener('drop', this.handleDrop, false);
@@ -214,28 +292,8 @@ export default class UI extends React.Component {
     };
   }
 
-  shouldComponentUpdate (nextProps) {
-    if (nextProps.isComposing !== this.props.isComposing) {
-      // Avoid expensive update just to toggle a class
-      this.node.classList.toggle('is-composing', nextProps.isComposing);
-
-      return false;
-    }
-
-    // Why isn't this working?!?
-    // return super.shouldComponentUpdate(nextProps, nextState);
-    return true;
-  }
-
-  componentDidUpdate (prevProps) {
-    if (![this.props.location.pathname, '/'].includes(prevProps.location.pathname)) {
-      this.columnsAreaNode.handleChildrenContentChange();
-    }
-  }
-
   componentWillUnmount () {
     window.removeEventListener('beforeunload', this.handleBeforeUnload);
-    window.removeEventListener('resize', this.handleResize);
     document.removeEventListener('dragenter', this.handleDragEnter);
     document.removeEventListener('dragover', this.handleDragOver);
     document.removeEventListener('drop', this.handleDrop);
@@ -247,10 +305,6 @@ export default class UI extends React.Component {
     this.node = c;
   }
 
-  setColumnsAreaRef = c => {
-    this.columnsAreaNode = c.getWrappedInstance().getWrappedInstance();
-  }
-
   handleHotkeyNew = e => {
     e.preventDefault();
 
@@ -350,8 +404,8 @@ export default class UI extends React.Component {
   }
 
   render () {
-    const { width, draggingOver } = this.state;
-    const { children } = this.props;
+    const { draggingOver } = this.state;
+    const { children, isComposing, location } = this.props;
 
     const handlers = {
       help: this.handleHotkeyToggleHelp,
@@ -374,43 +428,12 @@ export default class UI extends React.Component {
 
     return (
       <HotKeys keyMap={keyMap} handlers={handlers} ref={this.setHotkeysRef}>
-        <div className='ui' ref={this.setRef}>
+        <div className={classNames('ui', { 'is-composing': isComposing })} ref={this.setRef}>
           <TabsBar />
 
-          <ColumnsAreaContainer ref={this.setColumnsAreaRef} singleColumn={isMobile(width)}>
-            <WrappedSwitch>
-              <Redirect from='/' to='/getting-started' exact />
-              <WrappedRoute path='/getting-started' component={GettingStarted} content={children} />
-              <WrappedRoute path='/keyboard-shortcuts' component={KeyboardShortcuts} content={children} />
-              <WrappedRoute path='/timelines/home' component={HomeTimeline} content={children} />
-              <WrappedRoute path='/timelines/public' exact component={PublicTimeline} content={children} />
-              <WrappedRoute path='/timelines/public/local' component={CommunityTimeline} content={children} />
-              <WrappedRoute path='/timelines/tag/:id' component={HashtagTimeline} content={children} />
-              <WrappedRoute path='/timelines/list/:id' component={ListTimeline} content={children} />
-
-              <WrappedRoute path='/notifications' component={Notifications} content={children} />
-              <WrappedRoute path='/favourites' component={FavouritedStatuses} content={children} />
-              <WrappedRoute path='/pinned' component={PinnedStatuses} content={children} />
-
-              <WrappedRoute path='/statuses/new' component={Compose} content={children} />
-              <WrappedRoute path='/statuses/:statusId' exact component={Status} content={children} />
-              <WrappedRoute path='/statuses/:statusId/reblogs' component={Reblogs} content={children} />
-              <WrappedRoute path='/statuses/:statusId/favourites' component={Favourites} content={children} />
-
-              <WrappedRoute path='/accounts/:accountId' exact component={AccountTimeline} content={children} />
-              <WrappedRoute path='/accounts/:accountId/with_replies' component={AccountTimeline} content={children} componentParams={{ withReplies: true }} />
-              <WrappedRoute path='/accounts/:accountId/followers' component={Followers} content={children} />
-              <WrappedRoute path='/accounts/:accountId/following' component={Following} content={children} />
-              <WrappedRoute path='/accounts/:accountId/media' component={AccountGallery} content={children} />
-
-              <WrappedRoute path='/follow_requests' component={FollowRequests} content={children} />
-              <WrappedRoute path='/blocks' component={Blocks} content={children} />
-              <WrappedRoute path='/mutes' component={Mutes} content={children} />
-              <WrappedRoute path='/lists' component={Lists} content={children} />
-
-              <WrappedRoute component={GenericNotFound} content={children} />
-            </WrappedSwitch>
-          </ColumnsAreaContainer>
+          <SwitchingColumnsArea location={location} onLayoutChange={this.handleLayoutChange}>
+            {children}
+          </SwitchingColumnsArea>
 
           <NotificationsContainer />
           <LoadingBarContainer className='loading-bar' />