优化返回顶部图标

apps/jingrow/frontend/src/app/layouts/BackToTop.vue

@@ -3,8 +3,13 @@
     <div
       v-if="visible"
       class="back-to-top-btn"
-      @click="scrollToTop"
+      role="button"
+      tabindex="0"
+      :aria-label="t('Back to top')"
       :title="t('Back to top')"
+      @click="scrollToTop"
+      @keydown.enter="scrollToTop"
+      @keydown.space.prevent="scrollToTop"
     >
       <!-- SVG 圆形进度条 -->
       <svg class="progress-ring" viewBox="0 0 48 48">
@@ -109,9 +114,7 @@ const getScrollInfo = (container: Element | Window): { scrollTop: number; scroll
 
 // 滚动到顶部
 const scrollToTop = () => {
-  const containers = registeredContainers.value.length > 0 
-    ? registeredContainers.value 
-    : findScrollContainers()
+  const containers = registeredContainers.value
   
   containers.forEach(container => {
     if (container === window) {
@@ -129,43 +132,54 @@ const scrollToTop = () => {
   })
 }
 
+// 使用 requestAnimationFrame 优化滚动处理性能
+let rafId: number | null = null
+
 // 处理滚动事件
 const handleScroll = () => {
-  const containers = registeredContainers.value.length > 0 
-    ? registeredContainers.value 
-    : findScrollContainers()
-  
-  if (containers.length === 0) {
+  // 使用 requestAnimationFrame 节流，避免过度计算
+  if (rafId !== null) {
     return
   }
   
-  // 检查所有容器，取最大滚动值和总高度
-  let maxScrollTop = 0
-  let maxProgress = 0
-  
-  containers.forEach(container => {
-    const info = getScrollInfo(container)
-    const scrollTop = info.scrollTop
-    const maxScroll = info.scrollHeight - info.clientHeight
+  rafId = requestAnimationFrame(() => {
+    const containers = registeredContainers.value
     
-    if (scrollTop > maxScrollTop) {
-      maxScrollTop = scrollTop
+    if (containers.length === 0) {
+      rafId = null
+      return
     }
     
-    // 计算当前容器的滚动进度
-    if (maxScroll > 0) {
-      const progress = Math.min(scrollTop / maxScroll, 1)
-      if (progress > maxProgress) {
-        maxProgress = progress
+    // 检查所有容器，取最大滚动值和总高度
+    let maxScrollTop = 0
+    let maxProgress = 0
+    
+    containers.forEach(container => {
+      const info = getScrollInfo(container)
+      const scrollTop = info.scrollTop
+      const maxScroll = info.scrollHeight - info.clientHeight
+      
+      if (scrollTop > maxScrollTop) {
+        maxScrollTop = scrollTop
       }
-    }
+      
+      // 计算当前容器的滚动进度
+      if (maxScroll > 0) {
+        const progress = Math.min(scrollTop / maxScroll, 1)
+        if (progress > maxProgress) {
+          maxProgress = progress
+        }
+      }
+    })
+    
+    // 更新滚动进度
+    scrollProgress.value = maxProgress
+    
+    // 根据最大滚动值判断是否显示按钮
+    visible.value = maxScrollTop > SCROLL_THRESHOLD
+    
+    rafId = null
   })
-  
-  // 更新滚动进度
-  scrollProgress.value = maxProgress
-  
-  // 根据最大滚动值判断是否显示按钮
-  visible.value = maxScrollTop > SCROLL_THRESHOLD
 }
 
 onMounted(() => {
@@ -192,6 +206,12 @@ onUnmounted(() => {
     container.removeEventListener('scroll', handleScroll)
   })
   registeredContainers.value = []
+  
+  // 取消待处理的 requestAnimationFrame
+  if (rafId !== null) {
+    cancelAnimationFrame(rafId)
+    rafId = null
+  }
 })
 </script>
 
@@ -219,6 +239,15 @@ onUnmounted(() => {
   box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
 }
 
+.back-to-top-btn:focus {
+  outline: 2px solid #22c55e;
+  outline-offset: 2px;
+}
+
+.back-to-top-btn:focus:not(:focus-visible) {
+  outline: none;
+}
+
 .progress-ring {
   position: absolute;
   top: 0;