refactor(useSmoothStream): optimize chunk handling and state management (#8514)

* refactor(useSmoothStream): optimize chunk handling and state management

- Replaced state management with refs for chunk queue to improve performance and reduce unnecessary re-renders.
- Introduced Intl.Segmenter for better character segmentation based on language support.
- Updated rendering logic to ensure final text is displayed correctly when the stream ends.
- Cleaned up unused effects and comments for improved code clarity.

* refactor(useSmoothStream): move segmenter initialization outside of addChunk function

- Moved the initialization of Intl.Segmenter to the top of the file for better performance and to avoid redundant instantiation within the addChunk callback.
- This change enhances the efficiency of chunk processing in the useSmoothStream hook.

src/renderer/src/hooks/useSmoothStream.ts

@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useRef, useState } from 'react'
+import { useCallback, useEffect, useRef } from 'react'
 
 interface UseSmoothStreamOptions {
   onUpdate: (text: string) => void
@@ -7,15 +7,18 @@ interface UseSmoothStreamOptions {
   initialText?: string
 }
 
+const languages = ['en-US', 'es-ES', 'zh-CN', 'zh-TW', 'ja-JP', 'ru-RU', 'el-GR', 'fr-FR', 'pt-PT']
+const segmenter = new Intl.Segmenter(languages)
+
 export const useSmoothStream = ({ onUpdate, streamDone, minDelay = 10, initialText = '' }: UseSmoothStreamOptions) => {
-  const [chunkQueue, setChunkQueue] = useState<string[]>([])
+  const chunkQueueRef = useRef<string[]>([])
   const animationFrameRef = useRef<number | null>(null)
   const displayedTextRef = useRef<string>(initialText)
   const lastUpdateTimeRef = useRef<number>(0)
 
   const addChunk = useCallback((chunk: string) => {
-    const chars = Array.from(chunk)
-    setChunkQueue((prev) => [...prev, ...(chars || [])])
+    const chars = Array.from(segmenter.segment(chunk)).map((s) => s.segment)
+    chunkQueueRef.current = [...chunkQueueRef.current, ...(chars || [])]
   }, [])
 
   const reset = useCallback(
@@ -23,7 +26,7 @@ export const useSmoothStream = ({ onUpdate, streamDone, minDelay = 10, initialTe
       if (animationFrameRef.current) {
         cancelAnimationFrame(animationFrameRef.current)
       }
-      setChunkQueue([])
+      chunkQueueRef.current = []
       displayedTextRef.current = newText
       onUpdate(newText)
     },
@@ -32,12 +35,16 @@ export const useSmoothStream = ({ onUpdate, streamDone, minDelay = 10, initialTe
 
   const renderLoop = useCallback(
     (currentTime: number) => {
-      // 1. 如果队列为空，等待下一帧
-      if (chunkQueue.length === 0) {
-        // 如果流还没结束但队列空了，就等待下一帧
-        if (!streamDone) {
-          animationFrameRef.current = requestAnimationFrame(renderLoop)
+      // 1. 如果队列为空
+      if (chunkQueueRef.current.length === 0) {
+        // 如果流已结束，确保显示最终状态并停止循环
+        if (streamDone) {
+          const finalText = displayedTextRef.current
+          onUpdate(finalText)
+          return
         }
+        // 如果流还没结束但队列空了，等待下一帧
+        animationFrameRef.current = requestAnimationFrame(renderLoop)
         return
       }
 
@@ -48,25 +55,29 @@ export const useSmoothStream = ({ onUpdate, streamDone, minDelay = 10, initialTe
       }
       lastUpdateTimeRef.current = currentTime
 
-      setChunkQueue((prevQueue) => {
-        // 3. 动态计算本次渲染的字符数
-        // 如果队列积压严重，就一次性渲染更多字符来"追赶"
-        const charsToRenderCount = Math.max(1, Math.floor(prevQueue.length / 5)) // 每次至少渲染1个，最多渲染队列的1/5
+      // 3. 动态计算本次渲染的字符数
+      let charsToRenderCount = Math.max(1, Math.floor(chunkQueueRef.current.length / 5))
 
-        const charsToRender = prevQueue.slice(0, charsToRenderCount)
-        displayedTextRef.current += charsToRender.join('')
+      // 如果流已结束，一次性渲染所有剩余字符
+      if (streamDone) {
+        charsToRenderCount = chunkQueueRef.current.length
+      }
 
-        // 4. 立即更新UI
-        onUpdate(displayedTextRef.current)
+      const charsToRender = chunkQueueRef.current.slice(0, charsToRenderCount)
+      displayedTextRef.current += charsToRender.join('')
 
-        // 返回新的队列
-        return prevQueue.slice(charsToRenderCount)
-      })
+      // 4. 立即更新UI
+      onUpdate(displayedTextRef.current)
 
-      // 5. 请求下一帧动画
-      animationFrameRef.current = requestAnimationFrame(renderLoop)
+      // 5. 更新队列
+      chunkQueueRef.current = chunkQueueRef.current.slice(charsToRenderCount)
+
+      // 6. 如果还有内容需要渲染，继续下一帧
+      if (chunkQueueRef.current.length > 0) {
+        animationFrameRef.current = requestAnimationFrame(renderLoop)
+      }
     },
-    [chunkQueue, streamDone, onUpdate, minDelay]
+    [streamDone, onUpdate, minDelay]
   )
 
   useEffect(() => {
@@ -81,22 +92,5 @@ export const useSmoothStream = ({ onUpdate, streamDone, minDelay = 10, initialTe
     }
   }, [renderLoop])
 
-  // 当外部流结束，且队列即将变空时，进行最后一次"瞬移"渲染
-  useEffect(() => {
-    if (streamDone && chunkQueue.length > 0) {
-      const remainingText = chunkQueue.join('')
-      const finalText = displayedTextRef.current + remainingText
-
-      // 取消正在进行的动画循环
-      if (animationFrameRef.current) {
-        cancelAnimationFrame(animationFrameRef.current)
-      }
-
-      // 直接更新到最终状态
-      onUpdate(finalText)
-      setChunkQueue([]) // 清空队列
-    }
-  }, [streamDone, chunkQueue, onUpdate])
-
   return { addChunk, reset }
 }