Forward Picker: Smooth scroll on mobile

src/components/common/ChatOrUserPicker.scss

@@ -46,7 +46,7 @@
       height: 100%;
       overflow-x: hidden;
       overflow-y: auto;
-      padding: 0 1rem 1rem;
+      padding: 0 0.5rem;
     }
   }
 
@@ -60,6 +60,15 @@
     color: var(--color-text-secondary);
   }
 
+  .scroll-container {
+    position: relative;
+  }
+
+  .ListItem {
+    position: absolute;
+    width: 100%;
+  }
+
   .ListItem.chat-item-clickable {
     &:not(.force-rounded-corners) {
       @media (max-width: 600px) {

src/components/common/ChatOrUserPicker.tsx

@@ -3,6 +3,8 @@ import React, {
   FC, memo, useRef, useCallback,
 } from '../../lib/teact/teact';
 
+import { CHAT_HEIGHT_PX } from '../../config';
+import { IS_ANDROID } from '../../util/environment';
 import useInfiniteScroll from '../../hooks/useInfiniteScroll';
 import useLang from '../../hooks/useLang';
 import useKeyboardListNavigation from '../../hooks/useKeyboardListNavigation';
@@ -27,10 +29,11 @@ export type OwnProps = {
   filterRef: RefObject<HTMLInputElement>;
   filterPlaceholder: string;
   filter: string;
-  onFilterChange: (filter: string) => void;
   loadMore: NoneToVoidFunction;
+  onFilterChange: (filter: string) => void;
   onSelectChatOrUser: (chatOrUserId: string) => void;
   onClose: NoneToVoidFunction;
+  onCloseAnimationEnd?: NoneToVoidFunction;
 };
 
 const ChatOrUserPicker: FC<OwnProps> = ({
@@ -40,10 +43,11 @@ const ChatOrUserPicker: FC<OwnProps> = ({
   filterRef,
   filter,
   filterPlaceholder,
-  onFilterChange,
-  onClose,
   loadMore,
+  onFilterChange,
   onSelectChatOrUser,
+  onClose,
+  onCloseAnimationEnd,
 }) => {
   const lang = useLang();
   const [viewportIds, getMore] = useInfiniteScroll(loadMore, chatOrUserIds, Boolean(filter));
@@ -85,35 +89,47 @@ const ChatOrUserPicker: FC<OwnProps> = ({
     </div>
   );
 
+  const viewportOffset = chatOrUserIds!.indexOf(viewportIds![0]);
+
   return (
     <Modal
       isOpen={isOpen}
-      onClose={onClose}
       className="ChatOrUserPicker"
       header={modalHeader}
+      onClose={onClose}
+      onCloseAnimationEnd={onCloseAnimationEnd}
     >
       {viewportIds?.length ? (
         <InfiniteScroll
+          ref={containerRef}
           className="picker-list custom-scroll"
           items={viewportIds}
           onLoadMore={getMore}
-          noScrollRestore={Boolean(filter)}
-          ref={containerRef}
+          noFastList
+          noScrollRestore
           onKeyDown={handleKeyDown}
         >
-          {viewportIds.map((id) => (
-            <ListItem
-              key={id}
-              className="chat-item-clickable force-rounded-corners"
-              onClick={() => onSelectChatOrUser(id)}
-            >
-              {isUserId(id) ? (
-                <PrivateChatInfo status={id === currentUserId ? lang('SavedMessagesInfo') : undefined} userId={id} />
-              ) : (
-                <GroupChatInfo chatId={id} />
-              )}
-            </ListItem>
-          ))}
+          <div
+            className="scroll-container"
+            // @ts-ignore
+            style={IS_ANDROID ? `height: ${chatOrUserIds!.length * CHAT_HEIGHT_PX}px` : undefined}
+            teactFastList
+          >
+            {viewportIds.map((id, i) => (
+              <ListItem
+                key={id}
+                className="chat-item-clickable force-rounded-corners"
+                style={`top: ${(viewportOffset + i) * CHAT_HEIGHT_PX}px;`}
+                onClick={() => onSelectChatOrUser(id)}
+              >
+                {isUserId(id) ? (
+                  <PrivateChatInfo status={id === currentUserId ? lang('SavedMessagesInfo') : undefined} userId={id} />
+                ) : (
+                  <GroupChatInfo chatId={id} />
+                )}
+              </ListItem>
+            ))}
+          </div>
         </InfiniteScroll>
       ) : viewportIds && !viewportIds.length ? (
         <p className="no-results">{lang('lng_blocked_list_not_found')}</p>

src/components/main/ForwardPicker.tsx

@@ -1,5 +1,5 @@
 import React, {
-  FC, useMemo, useState, memo, useRef, useCallback,
+  FC, useMemo, useState, memo, useRef, useCallback, useEffect,
 } from '../../lib/teact/teact';
 import { getDispatch, getGlobal, withGlobal } from '../../lib/teact/teactn';
 
@@ -14,6 +14,7 @@ import {
 import { unique } from '../../util/iteratees';
 import useLang from '../../hooks/useLang';
 import useCurrentOrPrev from '../../hooks/useCurrentOrPrev';
+import useFlag from '../../hooks/useFlag';
 
 import ChatOrUserPicker from '../common/ChatOrUserPicker';
 
@@ -50,6 +51,13 @@ const ForwardPicker: FC<OwnProps & StateProps> = ({
   // eslint-disable-next-line no-null/no-null
   const filterRef = useRef<HTMLInputElement>(null);
 
+  const [isShown, markIsShown, unmarkIsShown] = useFlag();
+  useEffect(() => {
+    if (isOpen) {
+      markIsShown();
+    }
+  }, [isOpen, markIsShown]);
+
   const chatAndContactIds = useMemo(() => {
     if (!isOpen) {
       return undefined;
@@ -82,7 +90,11 @@ const ForwardPicker: FC<OwnProps & StateProps> = ({
     setForwardChatId({ id: userId });
   }, [setForwardChatId]);
 
-  const renderingChatAndContactIds = useCurrentOrPrev(chatAndContactIds)!;
+  const renderingChatAndContactIds = useCurrentOrPrev(chatAndContactIds, true)!;
+
+  if (!isOpen && !isShown) {
+    return undefined;
+  }
 
   return (
     <ChatOrUserPicker
@@ -96,6 +108,7 @@ const ForwardPicker: FC<OwnProps & StateProps> = ({
       loadMore={loadMoreChats}
       onSelectChatOrUser={handleSelectUser}
       onClose={exitForwardMode}
+      onCloseAnimationEnd={unmarkIsShown}
     />
   );
 };

src/components/ui/ListItem.scss

@@ -147,8 +147,6 @@
   }
 
   &.chat-item-clickable {
-    margin: 0 -0.5rem;
-
     body.is-ios &,
     body.is-macos & {
       --color-text-secondary: var(--color-text-secondary-apple);

src/hooks/useInfiniteScroll.ts

@@ -34,6 +34,10 @@ const useInfiniteScroll = <ListId extends string | number>(
 
   const forceUpdate = useForceUpdate();
 
+  if (isDisabled) {
+    lastParamsRef.current = {};
+  }
+
   const prevListIds = usePrevious(listIds);
   const prevIsDisabled = usePrevious(isDisabled);
   if (listIds && !isDisabled && (listIds !== prevListIds || isDisabled !== prevIsDisabled)) {