feat(metronome): 升级到 BackgroundAudioManager,iOS 真后台播放

iOS 微信小程序硬限制:
  InnerAudioContext 切到后台/锁屏一定被挂起,
  即使配置 requiredBackgroundModes 也无效。
  唯一支持 iOS 真后台的音频 API 是 BackgroundAudioManager。

新增预合成档位音轨(ffmpeg 拼接 click + click-wood):
- loop_80bpm_2.mp3   慢走 6.0s 4 周期循环 (72 KB)
- loop_110bpm_2.mp3  健走 5.45s 5 周期循环 (66 KB)
- loop_130bpm_2.mp3  快走 5.54s 6 周期循环 (67 KB)
- cover.jpg          200×200 emerald 占位封面 (474B)

新 hook training/hooks/useMetronomeBg.ts:
- 封装 uni.getBackgroundAudioManager() 单例
- 必填 metadata: title/coverImgUrl/singer/epname/webUrl
- onEnded 重赋 src 实现循环 (BgAudio 无原生 loop 属性)
- onPause 同步 isPlaying,用户从锁屏控制条点暂停 UI 自动同步
- 暴露 playLoop(id)/pause/resume/stop API

metronome.vue 改造:
- 切换为 useMetronomeBg,移除右下角微调和拍号选择
  (预合成 mp3 改不了 BPM/拍号,要么砍要么扩 9 个 mp3)
- 中央圆按钮逻辑:
  · 未选档位 → 默认开"健走"
  · 选了档位且在播 → 暂停
  · 选了档位且暂停 → 恢复
- 视频 playbackRate 跟当前档位 BPM 同步(80→0.65× / 110→0.89× / 130→1.05×)
- 加底部提示"🔒 锁屏可继续播放,放兜里走也能听到"
- onHide 不 stop,onUnmounted 才 stop(避免锁屏控制条挂死)

副作用:
- 锁屏/通知栏会显示带封面+暂停按钮的音乐控制条(老人友好)
- 切档位有 200~500ms 延迟 (用户主动操作可接受)
- 不再支持任意 BPM 微调 (3 档已覆盖大部分场景)

旧的 useMetronome.ts 暂时保留,如 BgAudio 真机验证 OK 再清理。

Co-authored-by: Cursor <cursoragent@cursor.com>

TUICallKit-Vue3/training/hooks/useMetronomeBg.ts

@@ -0,0 +1,196 @@
+import { ref, onUnmounted } from 'vue'
+
+/**
+ * 节拍器后台播放专版 - 基于 BackgroundAudioManager
+ *
+ * 解决 InnerAudioContext 在 iOS 微信小程序中无法后台播放的硬限制:
+ * - iOS 真机切到后台/锁屏 InnerAudioContext 必被挂起,requiredBackgroundModes 无效
+ * - BackgroundAudioManager 是微信唯一支持 iOS 真后台/锁屏播放的音频 API
+ *
+ * 取舍:
+ * - BgAudio 是全局单例,一次只能播一个音频,不适合短促 click 高频重复
+ * - 因此提前用 ffmpeg 合成 3 个档位的"完整节拍循环"音轨(80/110/130 BPM × 2 拍)
+ *   每个 mp3 是 5~6 秒无缝循环,设 onEnded 重赋 src 实现永久循环
+ *
+ * 副作用:
+ * - 播放时锁屏/通知栏会显示带封面+暂停按钮的音乐控制条(可被用户从锁屏暂停)
+ * - 必须声明 requiredBackgroundModes:["audio"](已配在 manifest+pages)
+ * - 切档位有 200~500ms 切换延迟,但用户主动操作时可接受
+ */
+
+export type LoopId = 'slow' | 'normal' | 'brisk'
+
+export interface LoopPreset {
+    id: LoopId
+    bpm: number
+    accent: number
+    src: string
+    label: string
+}
+
+export const LOOP_PRESETS: readonly LoopPreset[] = [
+    {
+        id: 'slow',
+        bpm: 80,
+        accent: 2,
+        src: '/training/static/audio/loop_80bpm_2.mp3',
+        label: '慢走 80 BPM',
+    },
+    {
+        id: 'normal',
+        bpm: 110,
+        accent: 2,
+        src: '/training/static/audio/loop_110bpm_2.mp3',
+        label: '健走 110 BPM',
+    },
+    {
+        id: 'brisk',
+        bpm: 130,
+        accent: 2,
+        src: '/training/static/audio/loop_130bpm_2.mp3',
+        label: '快走 130 BPM',
+    },
+]
+
+const COVER_URL = '/training/static/audio/cover.jpg'
+
+export function useMetronomeBg() {
+    const isPlaying = ref<boolean>(false)
+    const currentLoop = ref<LoopId | null>(null)
+
+    /* @dcloudio/types 没有 BackgroundAudioManager 类型,直接 any */
+    let bgm: any = null
+    /* 当前期望的 src,onEnded 时用它重新赋值实现循环 */
+    let desiredSrc = ''
+
+    /* 懒初始化 BackgroundAudioManager + 绑定事件
+       BgAudio 是全局单例,跨页面共享,只能在第一次需要时初始化 */
+    const ensureBgm = () => {
+        if (bgm) return bgm
+
+        const m = uni.getBackgroundAudioManager()
+
+        /* 必填 metadata,缺一会报错或不显示锁屏控制条 */
+        m.title = '节拍器'
+        m.epname = '甄养堂 · 健走'
+        m.singer = '健走配速'
+        m.coverImgUrl = COVER_URL
+        m.webUrl = ''
+
+        m.onPlay(() => {
+            isPlaying.value = true
+        })
+        m.onPause(() => {
+            /* 用户从锁屏控制条点暂停,同步 UI 状态 */
+            isPlaying.value = false
+        })
+        m.onStop(() => {
+            isPlaying.value = false
+            currentLoop.value = null
+        })
+
+        /* 实现无限循环:每段 mp3 播完时立即重赋 src 再次播放
+           BgAudio 没有原生 loop 属性,只能用这招 */
+        m.onEnded(() => {
+            if (desiredSrc && isPlaying.value) {
+                try {
+                    m.src = desiredSrc
+                } catch (_) {}
+            }
+        })
+
+        m.onError((err) => {
+            console.error('[BgAudio] error:', err)
+            isPlaying.value = false
+            uni.showToast({
+                title: '音频播放失败,请重试',
+                icon: 'none',
+                duration: 2000,
+            })
+        })
+
+        bgm = m
+        return m
+    }
+
+    /**
+     * 切到指定档位并开始播放
+     * 如果已经在播同一档位 → 切到 pause/play 状态
+     * 如果在播别的档位 → 切换 src(有 200~500ms 延迟)
+     */
+    const playLoop = (id: LoopId) => {
+        const preset = LOOP_PRESETS.find((p) => p.id === id)
+        if (!preset) return
+
+        const m = ensureBgm()
+
+        /* 同档位再点一下 = 暂停 */
+        if (currentLoop.value === id && isPlaying.value) {
+            m.pause()
+            return
+        }
+
+        /* 切换档位或从暂停恢复 */
+        currentLoop.value = id
+        desiredSrc = preset.src
+
+        /* 重设 title 让锁屏控制条显示当前档位 */
+        m.title = `节拍器 · ${preset.label}`
+
+        /* 赋值 src 会自动播放(微信 API 设计如此) */
+        m.src = preset.src
+        /* isPlaying 由 onPlay 回调置 true */
+    }
+
+    const pause = () => {
+        if (bgm && isPlaying.value) {
+            bgm.pause()
+        }
+    }
+
+    const resume = () => {
+        if (bgm && !isPlaying.value && desiredSrc) {
+            /* 从暂停态恢复:直接 play 即可 */
+            try {
+                bgm.play()
+            } catch (_) {
+                /* 部分基础库 play() 不可用时,重赋 src */
+                bgm.src = desiredSrc
+            }
+        }
+    }
+
+    /**
+     * 完全停止 + 清掉锁屏控制条
+     * 注意 BgAudio 是全局单例,stop 会影响所有页面共享的实例
+     */
+    const stop = () => {
+        if (bgm) {
+            try {
+                bgm.stop()
+            } catch (_) {}
+        }
+        currentLoop.value = null
+        desiredSrc = ''
+        isPlaying.value = false
+    }
+
+    /* hook 卸载时不主动 stop,因为用户离开节拍器页时
+       仍希望音乐持续(走在路上拿出手机切别的页面应该不停)
+       真正停止的责任在 metronome.vue 的退出按钮里 */
+    onUnmounted(() => {
+        /* 仅解绑回调? BgAudio 是全局单例,我们的回调还在,
+           不解会导致内存中保留无用引用,但回调里都判断了 isPlaying,
+           且新页面再 ensureBgm 时会覆盖回调,可接受 */
+    })
+
+    return {
+        isPlaying,
+        currentLoop,
+        playLoop,
+        pause,
+        resume,
+        stop,
+        LOOP_PRESETS,
+    }
+}

TUICallKit-Vue3/training/pages/metronome.vue

@@ -1,11 +1,11 @@
 <template>
     <view class="page" :style="rootStyle">
         <!-- ===== 主舞台:节拍器圆 ===== -->
-        <view class="stage" @click="togglePlay">
+        <view class="stage" @click="onCenterTap">
             <view class="ring r1" :class="{ playing: isPlaying }" />
             <view class="ring r2" :class="{ playing: isPlaying }" />
-            <view class="core" :class="{ playing: isPlaying, accent: isAccent }">
-                <text class="bpm-num">{{ bpm }}</text>
+            <view class="core" :class="{ playing: isPlaying }">
+                <text class="bpm-num">{{ currentBpm }}</text>
                 <text class="bpm-label">BPM</text>
                 <view class="ctrl">
                     <view v-if="isPlaying" class="icon-pause">
@@ -38,10 +38,8 @@
                     @error="onVideoError"
                     @loadedmetadata="onVideoLoaded"
                 />
-                <!-- 微信原生 video 右上角的 PIP/小窗按钮无法靠属性彻底关掉,
-                     用 cover-view 覆盖一个跟背景同色的小色块盖住它 -->
                 <!-- #ifdef MP-WEIXIN -->
-                <!-- <cover-view class="pip-mask">&nbsp;</cover-view> -->
+                <cover-view class="pip-mask">&nbsp;</cover-view>
                 <!-- #endif -->
             </view>
         </view>
@@ -49,39 +47,22 @@
         <!-- ===== 推荐档位(3 选 1) ===== -->
         <view class="presets">
             <view
-                v-for="p in PRESETS"
+                v-for="p in LOOP_PRESETS"
                 :key="p.id"
                 class="preset"
-                :class="{ active: activePreset === p.id }"
-                @click="applyPreset(p)"
+                :class="{ active: currentLoop === p.id }"
+                @click="onPresetTap(p.id)"
             >
-                <text class="preset-icon">{{ p.icon }}</text>
-                <text class="preset-name">{{ p.name }}</text>
+                <text class="preset-icon">{{ presetIcon(p.id) }}</text>
+                <text class="preset-name">{{ presetName(p.id) }}</text>
                 <text class="preset-bpm">{{ p.bpm }} BPM</text>
-                <text class="preset-desc">{{ p.desc }}</text>
+                <text class="preset-desc">{{ presetDesc(p.id) }}</text>
             </view>
         </view>
 
-        <!-- ===== 右下角微调(不显眼) ===== -->
-        <view class="quick-adjust">
-            <view class="qa-group">
-                <view class="qa-btn" @click.stop="adjustBpm(-1)">−</view>
-                <text class="qa-label">微调</text>
-                <view class="qa-btn" @click.stop="adjustBpm(1)">+</view>
-            </view>
-            <view class="qa-divider" />
-            <view class="qa-group">
-                <view
-                    v-for="m in METER_OPTIONS"
-                    :key="m.value"
-                    class="qa-meter"
-                    :class="{ active: accentEvery === m.value }"
-                    @click.stop="onMeterChange(m.value)"
-                >
-                    {{ m.label }}
-                </view>
-                <text class="qa-label">拍</text>
-            </view>
+        <!-- 提示信息(锁屏可继续播放) -->
+        <view class="hint">
+            <text>🔒 锁屏可继续播放,放兜里走也能听到</text>
         </view>
     </view>
 </template>
@@ -89,7 +70,7 @@
 <script setup lang="ts">
 import { computed, onMounted, onUnmounted, ref, watch } from 'vue'
 import { onShow, onHide } from '@dcloudio/uni-app'
-import { useMetronome } from '../hooks/useMetronome'
+import { useMetronomeBg, type LoopId } from '../hooks/useMetronomeBg'
 
 /**
  * 跑步动画视频(腾讯云 COS CDN)
@@ -99,104 +80,63 @@ import { useMetronome } from '../hooks/useMetronome'
 const RUNNER_VIDEO_URL =
     'https://gz-1349751149.cos.ap-guangzhou.myqcloud.com/uploads/video/20260525/20260525164014ef89f8862.mp4'
 
-/**
- * 视频原速对应的 BPM 基准(参见 hooks 实现注释)
- * playback-rate 范围 [0.5, 2.0]
- */
+/** 视频原速对应的 BPM 基准, playback-rate 范围 [0.5, 2.0] */
 const VIDEO_BASE_BPM = 124
 
-/**
- * 推荐档位:覆盖大多数老人健走场景,一键切换 BPM + 拍号
- * 不在档位的中间数值用右下角微调即可
- */
-const PRESETS = [
-    {
-        id: 'slow',
-        icon: '🚶',
-        name: '慢走',
-        bpm: 80,
-        accent: 2,
-        desc: '热身 · 恢复',
-    },
-    {
-        id: 'normal',
-        icon: '🏃‍♀️',
-        name: '健走',
-        bpm: 110,
-        accent: 2,
-        desc: '日常 · 通勤',
-    },
-    {
-        id: 'brisk',
-        icon: '🏃',
-        name: '快走',
-        bpm: 130,
-        accent: 2,
-        desc: '提速 · 燃脂',
-    },
-] as const
+const { isPlaying, currentLoop, playLoop, pause, resume, stop, LOOP_PRESETS } =
+    useMetronomeBg()
 
-const METER_OPTIONS = [
-    { label: '2', value: 2 },
-    { label: '3', value: 3 },
-    { label: '4', value: 4 },
-]
+/* 档位元数据(图标/名称/描述) */
+const presetIcon = (id: LoopId) =>
+    id === 'slow' ? '🚶' : id === 'normal' ? '🏃‍♀️' : '🏃'
+const presetName = (id: LoopId) =>
+    id === 'slow' ? '慢走' : id === 'normal' ? '健走' : '快走'
+const presetDesc = (id: LoopId) =>
+    id === 'slow' ? '热身 · 恢复' : id === 'normal' ? '日常 · 通勤' : '提速 · 燃脂'
 
-const metronome = useMetronome({
-    initialBpm: 80,
-    accentEvery: 4,
-    clickSrc: '/training/static/audio/click.mp3',
-    accentSrc: '/training/static/audio/click-wood.mp3',
-})
-const {
-    bpm,
-    isPlaying,
-    isAccent,
-    accentEvery,
-    intervalMs,
-    start,
-    stop,
-    setBpm,
-    setAccentEvery,
-    preload,
-} = metronome
+const currentPreset = computed(() =>
+    currentLoop.value
+        ? LOOP_PRESETS.find((p) => p.id === currentLoop.value) ?? null
+        : null,
+)
 
-const adjustBpm = (delta: number) => {
-    setBpm(bpm.value + delta)
-}
+const currentBpm = computed(() => currentPreset.value?.bpm ?? 110)
+const intervalMs = computed(() => 60000 / currentBpm.value)
 
-const onMeterChange = (val: number) => {
-    setAccentEvery(val)
-}
-
-const togglePlay = () => {
+/* 中央圆按钮:
+   - 没选档位 → 默认开"健走"
+   - 选了档位且在播 → 暂停
+   - 选了档位且暂停 → 恢复 */
+const onCenterTap = () => {
+    if (!currentLoop.value) {
+        playLoop('normal')
+        uni.setKeepScreenOn({ keepScreenOn: true })
+        return
+    }
     if (isPlaying.value) {
-        stop()
+        pause()
         uni.setKeepScreenOn({ keepScreenOn: false })
     } else {
-        start()
+        resume()
         uni.setKeepScreenOn({ keepScreenOn: true })
     }
 }
 
-/* 当前命中的档位(BPM + 拍号都匹配才算选中) */
-const activePreset = computed(() => {
-    const hit = PRESETS.find(
-        (p) => p.bpm === bpm.value && p.accent === accentEvery.value,
-    )
-    return hit?.id ?? null
-})
-
-const applyPreset = (p: (typeof PRESETS)[number]) => {
-    setBpm(p.bpm)
-    setAccentEvery(p.accent)
+/* 档位卡片:
+   - 点未选档位 → 切到该档位并播放
+   - 点当前档位 → 切到暂停/恢复 */
+const onPresetTap = (id: LoopId) => {
+    playLoop(id)
+    uni.setKeepScreenOn({ keepScreenOn: true })
 }
 
-/* 视频实例与 BPM 同步 */
+/* ============================================================
+ * 视频实例与 BPM 同步
+ * ============================================================ */
 let videoCtx: UniApp.VideoContext | null = null
 
 const playbackRate = computed(() => {
-    const rate = bpm.value / VIDEO_BASE_BPM
+    const rate = currentBpm.value / VIDEO_BASE_BPM
     return Math.max(0.5, Math.min(2.0, +rate.toFixed(2)))
 })
 
@@ -207,11 +147,6 @@ onMounted(() => {
 
 const onVideoError = (e: any) => {
     console.error('[runner-video] error:', e?.detail || e)
-    uni.showToast({
-        title: '视频加载失败,请用真机预览',
-        icon: 'none',
-        duration: 2500,
-    })
 }
 
 const onVideoLoaded = (e: any) => {
@@ -237,27 +172,25 @@ watch(playbackRate, (rate) => {
 
 const rootStyle = computed(() => ({
     '--beat-duration': `${intervalMs.value}ms`,
-    '--step-duration': `${intervalMs.value}ms`,
 }))
 
 onShow(() => {
-    preload()
+    /* BgAudio 全局单例,无需特殊预热,首次 setSrc 时自动初始化 */
 })
 
 /**
  * onHide 故意不 stop:
- *   - 切到后台 / 微信"小窗" 都会触发 onHide
- *   - 配合 pages.json 的 requiredBackgroundModes:["audio"],
- *     小程序退到后台后节拍声仍然可以继续(健走时把手机放兜里也能听到响)
- *   - 真正离开节拍器页(navigateBack/重启) 会 onUnload+onUnmounted,
- *     在那里清理屏幕常亮
+ *   - 切到后台/锁屏/小窗 都会触发 onHide
+ *   - 配合 BackgroundAudioManager,音频会通过系统层继续播放
+ *   - 用户能从锁屏控制条主动暂停(通过 onPause 回调同步 UI)
  */
 onHide(() => {
-    /* 不再主动 stop, 让节拍器在后台继续工作 */
+    /* 不停止,让节拍声后台继续 */
 })
 
 onUnmounted(() => {
-    /* 页面卸载才真正停 + 释放屏幕常亮 */
+    /* 页面被销毁(navigateBack/重启)时才真正停止
+       否则锁屏控制条会一直挂着无主的"节拍器" */
     if (isPlaying.value) stop()
     uni.setKeepScreenOn({ keepScreenOn: false })
 })
@@ -276,12 +209,8 @@ $text-3: #94a3b8;
 $brand: #10b981;
 $brand-soft: #d1fae5;
 $brand-deep: #047857;
-$accent: #f59e0b;
-$accent-soft: #fef3c7;
 $radius-card: 24rpx;
-$radius-btn: 18rpx;
 $shadow-sm: 0 4rpx 12rpx rgba(15, 23, 42, 0.04);
-$shadow-md: 0 12rpx 28rpx rgba(15, 23, 42, 0.08);
 
 /* ============================================================
  * 页面容器
@@ -365,14 +294,6 @@ $shadow-md: 0 12rpx 28rpx rgba(15, 23, 42, 0.08);
         animation: core-beat var(--beat-duration, 750ms) ease-in-out infinite;
     }
 
-    &.playing.accent {
-        background: linear-gradient(140deg, #fbbf24 0%, #d97706 100%);
-        box-shadow:
-            inset 0 -16rpx 50rpx rgba(0, 0, 0, 0.18),
-            inset 0 16rpx 50rpx rgba(255, 255, 255, 0.22),
-            0 16rpx 40rpx rgba(245, 158, 11, 0.4);
-    }
-
     .bpm-num {
         font-size: 168rpx;
         font-weight: 800;
@@ -434,7 +355,7 @@ $shadow-md: 0 12rpx 28rpx rgba(15, 23, 42, 0.08);
 }
 
 /* ============================================================
- * 跑步小人(无边框,跟白底融合)
+ * 跑步小人
  * ============================================================ */
 .walker {
     width: 100%;
@@ -445,9 +366,6 @@ $shadow-md: 0 12rpx 28rpx rgba(15, 23, 42, 0.08);
 }
 
 .walker-box {
-    /* 1:1 矩形,跟 video 内容比例一致,消除左右黑边
-       background 设成 video 内容右上角的浅灰白色,
-       万一还有 1rpx 缝隙也不会出现刺眼黑边 */
     position: relative;
     width: 260rpx;
     height: 260rpx;
@@ -460,14 +378,9 @@ $shadow-md: 0 12rpx 28rpx rgba(15, 23, 42, 0.08);
 .runner-video {
     width: 100%;
     height: 100%;
-    /* 微信 native video 自身默认是 #000 黑底,父容器 bg 在 web 看不到,
-       只能让 video 占满 + 让父 bg 跟 video 内容色融合 */
     background: #e8ecf2;
 }
 
-/* 覆盖在 video 右上角原生 PIP/小窗按钮上的色块
-   颜色取 video 内容右上角的浅灰白渐变(#dde2eb 左右),让色块融入视频画面
-   仅小程序端有效(cover-view 是小程序唯一能盖住 native 组件的元素) */
 .pip-mask {
     position: absolute;
     top: 0;
@@ -549,84 +462,16 @@ $shadow-md: 0 12rpx 28rpx rgba(15, 23, 42, 0.08);
 }
 
 /* ============================================================
- * 右下角微调(不显眼)
+ * 底部提示
  * ============================================================ */
-.quick-adjust {
-    position: absolute;
-    right: 28rpx;
-    bottom: 22rpx;
-    display: flex;
-    align-items: center;
-    gap: 14rpx;
-    padding: 10rpx 18rpx;
-    background: rgba(255, 255, 255, 0.7);
-    border: 1rpx solid rgba(15, 23, 42, 0.05);
-    border-radius: 999rpx;
-    backdrop-filter: blur(10rpx);
-    opacity: 0.7;
-    transition: opacity 0.2s;
-
-    &:active {
-        opacity: 1;
-    }
-}
-
-.qa-group {
-    display: flex;
-    align-items: center;
-    gap: 6rpx;
-}
-
-.qa-label {
-    font-size: 20rpx;
-    color: $text-3;
-    margin: 0 4rpx;
-    letter-spacing: 1rpx;
-}
-
-.qa-btn {
-    width: 40rpx;
-    height: 40rpx;
-    border-radius: 50%;
-    background: rgba(15, 23, 42, 0.05);
-    color: $text-2;
-    font-size: 26rpx;
-    font-weight: 700;
-    display: flex;
-    align-items: center;
-    justify-content: center;
-    line-height: 1;
-
-    &:active {
-        background: rgba(16, 185, 129, 0.18);
-        color: $brand-deep;
-    }
-}
-
-.qa-meter {
-    min-width: 36rpx;
-    height: 36rpx;
-    padding: 0 10rpx;
-    border-radius: 999rpx;
+.hint {
+    margin-top: 8rpx;
     font-size: 22rpx;
     color: $text-3;
-    font-weight: 600;
-    display: flex;
-    align-items: center;
-    justify-content: center;
-    line-height: 1;
-    transition: all 0.15s;
+    letter-spacing: 1rpx;
 
-    &.active {
-        background: $brand;
-        color: #fff;
-        box-shadow: 0 2rpx 6rpx rgba(16, 185, 129, 0.4);
+    text {
+        line-height: 1.6;
     }
 }
-
-.qa-divider {
-    width: 1rpx;
-    height: 22rpx;
-    background: rgba(15, 23, 42, 0.08);
-}
 </style>