feat: 增加聊天列表滚动到底部按钮

client/web/src/components/ChatBox/ChatMessageList/NormalList.tsx

@@ -1,7 +1,8 @@
-import React, { useCallback, useEffect, useRef } from 'react';
+import React, { useCallback, useEffect, useRef, useState } from 'react';
 import { useMemoizedFn, useSharedEventHandler } from 'tailchat-shared';
 import { ChatMessageHeader } from './ChatMessageHeader';
 import { buildMessageItemRow } from './Item';
+import { ScrollToBottom } from './ScrollToBottom';
 import type { MessageListProps } from './types';
 
 /**
@@ -9,6 +10,7 @@ import type { MessageListProps } from './types';
  * 并处理在某些场景下计算位置会少1px导致无法正确触发加载的问题
  */
 const topTriggerBuffer = 100;
+const bottomTriggerBuffer = 40;
 
 /**
  * 没有虚拟化版本的聊天列表
@@ -17,6 +19,7 @@ export const NormalMessageList: React.FC<MessageListProps> = React.memo(
   (props) => {
     const containerRef = useRef<HTMLDivElement>(null);
     const lockRef = useRef(false);
+    const [showScrollToBottom, setShowScrollToBottom] = useState(false);
 
     const scrollToBottom = useMemoizedFn(() => {
       containerRef.current?.scrollTo({ top: 0, behavior: 'smooth' });
@@ -44,9 +47,10 @@ export const NormalMessageList: React.FC<MessageListProps> = React.memo(
         return;
       }
 
-      if (containerRef.current.scrollTop === 0) {
+      if (-containerRef.current.scrollTop <= bottomTriggerBuffer) {
         // 滚动到最底部
         lockRef.current = false;
+        setShowScrollToBottom(false);
       } else if (
         -containerRef.current.scrollTop + containerRef.current.clientHeight >=
         containerRef.current.scrollHeight - topTriggerBuffer
@@ -57,6 +61,7 @@ export const NormalMessageList: React.FC<MessageListProps> = React.memo(
         // 滚动在中间
         // 锁定位置不自动滚动
         lockRef.current = true;
+        setShowScrollToBottom(true);
       }
     }, [props.messages]);
 
@@ -72,6 +77,8 @@ export const NormalMessageList: React.FC<MessageListProps> = React.memo(
           )}
         </div>
 
+        {showScrollToBottom && <ScrollToBottom onClick={scrollToBottom} />}
+
         {/* 因为是倒过来的，因此要前面的要放在后面 */}
         {props.title && !props.hasMoreMessage && (
           <ChatMessageHeader title={props.title} />

client/web/src/components/ChatBox/ChatMessageList/ScrollToBottom.tsx

@@ -0,0 +1,21 @@
+import React from 'react';
+import { Icon } from 'tailchat-design';
+
+interface Props {
+  onClick: () => void;
+}
+
+/**
+ * 滚动到底部的按钮
+ */
+export const ScrollToBottom: React.FC<Props> = React.memo((props) => {
+  return (
+    <div
+      className="absolute right-6 bottom-18 px-3 py-2 rounded-full bg-white dark:bg-black bg-opacity-50 shadow cursor-pointer z-10 w-11 h-11 flex justify-center items-center text-2xl hover:bg-opacity-80"
+      onClick={props.onClick}
+    >
+      <Icon icon="mdi:chevron-double-down" />
+    </div>
+  );
+});
+ScrollToBottom.displayName = 'ScrollToBottom';

client/web/src/components/ChatBox/ChatMessageList/VirtualizedList.tsx

@@ -1,4 +1,4 @@
-import React, { useMemo, useRef } from 'react';
+import React, { useEffect, useMemo, useRef, useState } from 'react';
 import { buildMessageItemRow } from './Item';
 import type { MessageListProps } from './types';
 import {
@@ -11,6 +11,7 @@ import {
   useMemoizedFn,
   useSharedEventHandler,
 } from 'tailchat-shared';
+import { ScrollToBottom } from './ScrollToBottom';
 
 const PREPEND_OFFSET = 10 ** 7;
 
@@ -18,6 +19,11 @@ const virtuosoStyle: React.CSSProperties = {
   height: '100%',
 };
 
+const overscan = {
+  main: 1000,
+  reverse: 1000,
+};
+
 /**
  * 新版的虚拟列表
  * 参考: https://github.com/GetStream/stream-chat-react/blob/master/src/components/MessageList/VirtualizedMessageList.tsx
@@ -25,16 +31,18 @@ const virtuosoStyle: React.CSSProperties = {
 export const VirtualizedMessageList: React.FC<MessageListProps> = React.memo(
   (props) => {
     const listRef = useRef<VirtuosoHandle>(null);
+    const scrollerRef = useRef<HTMLElement>();
     const numItemsPrepended = usePrependedMessagesCount(props.messages);
 
-    useSharedEventHandler('sendMessage', () => {
-      listRef.current?.scrollToIndex({
-        index: 'LAST',
-        align: 'end',
+    const scrollToBottom = useMemoizedFn(() => {
+      listRef.current?.scrollTo({
+        top: scrollerRef.current?.scrollHeight,
         behavior: 'smooth',
       });
     });
 
+    useSharedEventHandler('sendMessage', scrollToBottom);
+
     const handleLoadMore = useMemoizedFn(() => {
       if (props.isLoadingMore) {
         return;
@@ -71,27 +79,38 @@ export const VirtualizedMessageList: React.FC<MessageListProps> = React.memo(
       return buildMessageItemRow(props.messages, index);
     });
 
+    const [showScrollToBottom, setShowScrollToBottom] = useState(false);
+    const atBottomStateChange = useMemoizedFn((atBottom: boolean) => {
+      if (atBottom) {
+        setShowScrollToBottom(false);
+      } else {
+        setShowScrollToBottom(true);
+      }
+    });
+
     return (
       <div className="flex-1">
         <Virtuoso
           style={virtuosoStyle}
           ref={listRef}
+          scrollerRef={(ref) => (scrollerRef.current = ref as HTMLElement)}
           firstItemIndex={PREPEND_OFFSET - numItemsPrepended}
           initialTopMostItemIndex={Math.max(props.messages.length - 1, 0)}
           computeItemKey={computeItemKey}
           totalCount={props.messages.length}
-          overscan={{
-            main: 1000,
-            reverse: 1000,
-          }}
+          overscan={overscan}
           itemContent={itemContent}
           alignToBottom={true}
           startReached={handleLoadMore}
+          atBottomStateChange={atBottomStateChange}
           followOutput={followOutput}
           defaultItemHeight={25}
           atTopThreshold={100}
           atBottomThreshold={40}
+          useWindowScroll={false}
         />
+
+        {showScrollToBottom && <ScrollToBottom onClick={scrollToBottom} />}
       </div>
     );
   }

client/web/src/components/ChatBox/index.tsx

@@ -46,7 +46,7 @@ const ChatBoxInner: React.FC<ChatBoxProps> = React.memo((props) => {
   }
 
   return (
-    <div className="w-full h-full flex flex-col select-text">
+    <div className="w-full h-full flex flex-col select-text relative">
       <ChatMessageList
         key={converseId}
         title={converseTitle}