Forum Panel: Optimize opening animation on Android (#2856)

src/components/left/ArchivedChats.tsx

@@ -64,7 +64,11 @@ const ArchivedChats: FC<OwnProps> = ({
     transitionClassNames: titleClassNames,
   } = useShowTransition(!isForumPanelOpen);
 
-  const { shouldRenderForumPanel, handleForumPanelAnimationEnd } = useForumPanelRender(isForumPanelOpen);
+  const {
+    shouldRenderForumPanel, handleForumPanelAnimationEnd,
+    handleForumPanelAnimationStart, isAnimationStarted,
+  } = useForumPanelRender(isForumPanelOpen);
+  const isForumPanelVisible = isForumPanelOpen && isAnimationStarted;
 
   return (
     <div className="ArchivedChats">
@@ -78,7 +82,7 @@ const ArchivedChats: FC<OwnProps> = ({
           ariaLabel="Return to chat list"
           className={buildClassName(
             lang.isRtl && 'rtl',
-            isForumPanelOpen && lang.isRtl && 'right-aligned',
+            isForumPanelVisible && lang.isRtl && 'right-aligned',
             shouldDisableDropdownMenuTransitionRef.current && lang.isRtl && 'disable-transition',
           )}
           onTransitionEnd={handleDropdownMenuTransitionEnd}
@@ -101,7 +105,7 @@ const ArchivedChats: FC<OwnProps> = ({
       <ChatList
         folderType="archived"
         isActive={isActive}
-        isForumPanelOpen={isForumPanelOpen}
+        isForumPanelOpen={isForumPanelVisible}
         onSettingsScreenSelect={onSettingsScreenSelect}
         onLeftColumnContentChange={onLeftColumnContentChange}
         foldersDispatch={foldersDispatch}
@@ -111,6 +115,7 @@ const ArchivedChats: FC<OwnProps> = ({
         <ForumPanel
           isOpen={isForumPanelOpen}
           onTopicSearch={onTopicSearch}
+          onOpenAnimationStart={handleForumPanelAnimationStart}
           onCloseAnimationEnd={handleForumPanelAnimationEnd}
         />
       )}

src/components/left/main/ChatFolders.tsx

@@ -15,7 +15,7 @@ import { captureEvents, SwipeDirection } from '../../../util/captureEvents';
 import buildClassName from '../../../util/buildClassName';
 import captureEscKeyListener from '../../../util/captureEscKeyListener';
 import { selectCurrentLimit } from '../../../global/selectors/limits';
-import { selectTabState, selectIsForumPanelOpen } from '../../../global/selectors';
+import { selectTabState } from '../../../global/selectors';
 import useShowTransition from '../../../hooks/useShowTransition';
 import useLang from '../../../hooks/useLang';
 import useHistoryBack from '../../../hooks/useHistoryBack';
@@ -30,6 +30,7 @@ type OwnProps = {
   foldersDispatch: FolderEditDispatch;
   onLeftColumnContentChange: (content: LeftColumnContent) => void;
   shouldHideFolderTabs?: boolean;
+  isForumPanelOpen?: boolean;
 };
 
 type StateProps = {
@@ -37,7 +38,6 @@ type StateProps = {
   orderedFolderIds?: number[];
   activeChatFolder: number;
   currentUserId?: string;
-  isForumPanelOpen?: boolean;
   lastSyncTime?: number;
   shouldSkipHistoryAnimations?: boolean;
   maxFolders: number;
@@ -275,7 +275,6 @@ export default memo(withGlobal<OwnProps>(
       orderedFolderIds,
       activeChatFolder,
       currentUserId,
-      isForumPanelOpen: selectIsForumPanelOpen(global),
       lastSyncTime,
       shouldSkipHistoryAnimations,
       hasArchivedChats: Boolean(archived?.length),

src/components/left/main/ForumPanel.tsx

@@ -20,6 +20,7 @@ import { getOrderedTopics } from '../../../global/helpers';
 import captureEscKeyListener from '../../../util/captureEscKeyListener';
 import { waitForTransitionEnd } from '../../../util/cssAnimationEndListeners';
 import { captureEvents, SwipeDirection } from '../../../util/captureEvents';
+import { fastRaf } from '../../../util/schedulers';
 
 import useInfiniteScroll from '../../../hooks/useInfiniteScroll';
 import { useIntersectionObserver, useOnIntersect } from '../../../hooks/useIntersectionObserver';
@@ -46,6 +47,7 @@ type OwnProps = {
   isHidden?: boolean;
   onTopicSearch?: NoneToVoidFunction;
   onCloseAnimationEnd?: VoidFunction;
+  onOpenAnimationStart?: VoidFunction;
 };
 
 type StateProps = {
@@ -65,6 +67,7 @@ const ForumPanel: FC<OwnProps & StateProps> = ({
   lastSyncTime,
   onTopicSearch,
   onCloseAnimationEnd,
+  onOpenAnimationStart,
   animationLevel,
 }) => {
   const {
@@ -143,20 +146,27 @@ const ForumPanel: FC<OwnProps & StateProps> = ({
 
   useEffect(() => {
     if (prevIsVisible !== isVisible) {
-      const dispatchHeavyAnimationStop = dispatchHeavyAnimationEvent();
-      waitForTransitionEnd(ref.current!, () => {
-        dispatchHeavyAnimationStop();
-      });
+      // For performance reasons, we delay animation of the topic list panel to the next animation frame
+      fastRaf(() => {
+        if (!ref.current) return;
 
-      if (isVisible) {
-        shouldRenderRef.current = true;
-        ref.current!.style.transform = 'none';
-      } else {
-        shouldRenderRef.current = false;
-        ref.current!.style.transform = '';
-      }
+        const dispatchHeavyAnimationStop = dispatchHeavyAnimationEvent();
+        waitForTransitionEnd(ref.current, () => {
+          dispatchHeavyAnimationStop();
+        });
+
+        onOpenAnimationStart?.();
+
+        if (isVisible) {
+          shouldRenderRef.current = true;
+          ref.current!.style.transform = 'none';
+        } else {
+          shouldRenderRef.current = false;
+          ref.current!.style.transform = '';
+        }
+      });
     }
-  }, [isVisible, prevIsVisible]);
+  }, [isVisible, onOpenAnimationStart, prevIsVisible]);
 
   useEffect(() => {
     if (!IS_TOUCH_ENV) {

src/components/left/main/LeftMain.tsx

@@ -2,6 +2,7 @@ import type { FC } from '../../../lib/teact/teact';
 import React, {
   memo, useCallback, useEffect, useRef, useState,
 } from '../../../lib/teact/teact';
+import { getActions } from '../../../global';
 
 import type { SettingsScreens } from '../../../types';
 import { LeftColumnContent } from '../../../types';
@@ -23,7 +24,6 @@ import Button from '../../ui/Button';
 import ForumPanel from './ForumPanel';
 
 import './LeftMain.scss';
-import { getActions } from '../../../global';
 
 type OwnProps = {
   content: LeftColumnContent;
@@ -66,8 +66,12 @@ const LeftMain: FC<OwnProps> = ({
   const { closeForumPanel } = getActions();
   const [isNewChatButtonShown, setIsNewChatButtonShown] = useState(IS_TOUCH_ENV);
 
-  const { shouldRenderForumPanel, handleForumPanelAnimationEnd } = useForumPanelRender(isForumPanelOpen);
-  const isForumPanelVisible = isForumPanelOpen && content === LeftColumnContent.ChatList;
+  const {
+    shouldRenderForumPanel, handleForumPanelAnimationEnd,
+    handleForumPanelAnimationStart, isAnimationStarted,
+  } = useForumPanelRender(isForumPanelOpen);
+  const isForumPanelRendered = isForumPanelOpen && content === LeftColumnContent.ChatList;
+  const isForumPanelVisible = isForumPanelRendered && isAnimationStarted;
 
   const {
     shouldRender: shouldRenderUpdateButton,
@@ -178,6 +182,7 @@ const LeftMain: FC<OwnProps> = ({
                   onSettingsScreenSelect={onSettingsScreenSelect}
                   onLeftColumnContentChange={onContentChange}
                   foldersDispatch={foldersDispatch}
+                  isForumPanelOpen={isForumPanelVisible}
                 />
               );
             case LeftColumnContent.GlobalSearch:
@@ -209,8 +214,9 @@ const LeftMain: FC<OwnProps> = ({
       {shouldRenderForumPanel && (
         <ForumPanel
           isOpen={isForumPanelOpen}
-          isHidden={!isForumPanelVisible}
+          isHidden={!isForumPanelRendered}
           onTopicSearch={onTopicSearch}
+          onOpenAnimationStart={handleForumPanelAnimationStart}
           onCloseAnimationEnd={handleForumPanelAnimationEnd}
         />
       )}

src/hooks/useForumPanelRender.ts

@@ -5,6 +5,7 @@ import useSyncEffect from './useSyncEffect';
 
 export default function useForumPanelRender(isForumPanelOpen = false) {
   const shouldRenderForumPanelRef = useRef(isForumPanelOpen);
+  const isAnimationStartedRef = useRef(false);
   const forceUpdate = useForceUpdate();
 
   useSyncEffect(() => {
@@ -15,11 +16,19 @@ export default function useForumPanelRender(isForumPanelOpen = false) {
 
   const handleForumPanelAnimationEnd = useCallback(() => {
     shouldRenderForumPanelRef.current = false;
+    isAnimationStartedRef.current = false;
     forceUpdate();
   }, [forceUpdate]);
 
+  const handleForumPanelAnimationStart = useCallback(() => {
+    isAnimationStartedRef.current = true;
+    forceUpdate();
+  }, []);
+
   return {
     shouldRenderForumPanel: shouldRenderForumPanelRef.current,
+    isAnimationStarted: isAnimationStartedRef.current,
     handleForumPanelAnimationEnd,
+    handleForumPanelAnimationStart,
   };
 }