feat(meeting): 实现投屏用户UID计算和显示优化

- 添加calculateScreenActualUid函数用于计算投屏实际声网UID
- 新增screenShareActualUid计算属性获取投屏实际UID
- 优化teacherPreferredPrimaryUid逻辑优先使用投屏实际UID
- 更新secondaryUid计算逻辑适配投屏实际UID判断
- 修改小窗标题显示逻辑使用实际投屏UID判断
- 调整isPrimaryScreenSharing计算方式匹配实际投屏UID
- 添加投屏开始和结束的消息日志记录功能

src/views/meeting/meeting-room/meeting-room-student.vue

@@ -176,8 +176,25 @@
 
   const isTeacherDualStream = computed(() => Boolean(teacherUid.value && screenShareOwnerUid.value));
 
+  /** 根据投屏用户短 UID 计算实际的声网 UID */
+  function calculateScreenActualUid(uid: number): number {
+    return uid + 1000000;
+  }
+
+  /** 获取当前投屏的实际声网 UID（如果有） */
+  const screenShareActualUid = computed<number | null>(() => {
+    if (typeof screenShareOwnerUid.value === 'number' && screenShareOwnerUid.value > 0) {
+      return calculateScreenActualUid(screenShareOwnerUid.value);
+    }
+    return null;
+  });
+
   const teacherPreferredPrimaryUid = computed<number | string | null>(() => {
-    return screenShareOwnerUid.value ?? speakerUid.value ?? (teacherUid.value || null);
+    // 如果有投屏，优先使用投屏的实际 UID
+    if (screenShareActualUid.value) {
+      return screenShareActualUid.value;
+    }
+    return speakerUid.value ?? (teacherUid.value || null);
   });
 
   const primaryUid = computed<number | string | null>(() => {
@@ -197,7 +214,9 @@
     if (!teacherUid.value || !screenShareOwnerUid.value) {
       return null;
     }
-    return primaryUid.value === screenShareOwnerUid.value ? teacherUid.value : screenShareOwnerUid.value;
+    // 如果主讲是投屏，小窗显示老师摄像头；否则显示投屏
+    const primaryIsScreen = primaryUid.value === screenShareActualUid.value;
+    return primaryIsScreen ? teacherUid.value : screenShareActualUid.value;
   });
 
   const selfWindowUid = computed<number | string | null>(() => secondaryUid.value);
@@ -215,7 +234,7 @@
     if (!selfWindowUid.value) {
       return userName.value;
     }
-    if (selfWindowUid.value === screenShareOwnerUid.value) {
+    if (selfWindowUid.value === screenShareActualUid.value) {
       return `${screenOwnerName.value || '主讲'}（投屏）`;
     }
     return '主讲（摄像头）';
@@ -235,7 +254,7 @@
   });
 
   /** 是否为投屏主画面 */
-  const isPrimaryScreenSharing = computed(() => Boolean(primaryUid.value && screenShareOwnerUid.value === primaryUid.value));
+  const isPrimaryScreenSharing = computed(() => Boolean(primaryUid.value && primaryUid.value === screenShareActualUid.value));
 
   /** 舞台容器 DOM */
   const stageRef = ref<HTMLDivElement | null>(null);
@@ -537,6 +556,7 @@
         const targetUid = packet.data?.targetUid;
         if (typeof targetUid === 'number') {
           screenShareOwnerUid.value = targetUid;
+          console.log('[屏幕共享] 收到开始投屏消息:', { targetUid, calculatedActualUid: calculateScreenActualUid(targetUid) });
           Toast.info?.(`用户 ${targetUid} 开始投屏`);
         }
         break;
@@ -545,6 +565,7 @@
         const targetUid = packet.data?.targetUid;
         if (typeof targetUid === 'number') {
           screenShareOwnerUid.value = null;
+          console.log('[屏幕共享] 收到停止投屏消息:', { targetUid });
           Toast.info?.(`用户 ${targetUid} 停止投屏`);
         }
         break;