# 3\_4-云课堂场景-PPT

* [1 功能概述](#_1-功能概述)
* [2 初始化](#_2-初始化)
* [3 播放](#_3-播放)
* [4 代理回调处理](#_4-代理回调处理)
* [5 浮窗](#_5-浮窗)

#### 1 功能概述

云课堂场景PPT是直播同步讲师端PPT信息、回放历史PPT信息，该功能是在`PLVLCMediaAreaView`中实现，集成[7\_5 核心common-PPT](https://git.polyv.net/help-center/document-center/-/blob/master/live/ios/7_5-核心common-PPT/README.md)中`PLVPPTView`来实现的功能。

#### 2 初始化

```objective-c
PLVLCMediaAreaView.m

- (PLVPPTView *)pptView{
    if (!_pptView && self.channelType != PLVChannelTypeAlone) {
        _pptView = [[PLVPPTView alloc] init];
        _pptView.delegate = self;
        _pptView.backgroudImageView.image = [self getImageWithName:@"plvlc_media_ppt_placeholder"];
    }
    return _pptView;
}
```

#### 3 播放

```objective-c
PLVLCMediaAreaView.m

- (void)setupModule{
    /// 注意：懒加载过程中(即Getter)，已增加判断，若场景不匹配，将创建失败并返回nil
    if (self.videoType == PLVChannelVideoType_Live) { // 视频类型为 直播
        /// 直播 模块
				/// ...
         
        /// PPT模块
        [self.floatView displayExternalView:self.pptView]; /// 无直播时的默认状态，是‘PPT画面’位于副屏(悬浮小窗)
        
    }else if (self.videoType == PLVChannelVideoType_Playback){ // 视频类型为 直播回放
        /// 直播回放 模块
				/// ...
		        
        /// PPT模块
        [self.floatView displayExternalView:self.pptView]; /// 默认状态，是‘PPT画面’位于副屏(悬浮小窗)
        [self.floatView showFloatView:YES userOperat:NO];
        [self.pptView pptStart:[PLVRoomDataManager sharedManager].roomData.vid];
        
    }
}

/// 播放器 ‘SEI信息’ 发生改变
- (void)playerPresenter:(PLVPlayerPresenter *)playerPresenter seiDidChange:(long)timeStamp newTimeStamp:(long)newTimeStamp{
    [self.pptView setSEIDataWithNewTimestamp:newTimeStamp];
}
```

#### 4 代理回调处理

实现`PLVPPTViewDelegate`代理方法，代码如下：

```objective-c
PLVLCMediaAreaView.m

- (unsigned int)plvPPTViewGetPPTRefreshDelayTime:(PLVPPTView *)pptView{
    return self.inRTCRoom ? 0 : 5000;
}

/// PPT视图 PPT位置需切换
- (void)plvPPTView:(PLVPPTView *)pptView changePPTPosition:(BOOL)pptToMain{
    if (self.videoType == PLVChannelVideoType_Live){ // 视频类型为 直播
        /// 仅在 非观看RTC场景下 执行 (观看RTC场景下，由 PLVLCLinkMicAreaView 自行处理)
        if (self.inRTCRoom == NO) {
            if (pptToMain != self.pptOnMainSite) {
                [self.floatView triggerViewExchangeEvent];
            }
        }
    } else if (self.videoType == PLVChannelVideoType_Playback) { // 视频类型为 直播回放
        if (pptToMain != self.pptOnMainSite) {
            [self.floatView triggerViewExchangeEvent];
        }
    }
}

/// [回放场景] PPT视图 需要获取视频播放器的当前播放时间点
- (NSTimeInterval)plvPPTViewGetPlayerCurrentTime:(PLVPPTView *)pptView{
    return self.playerPresenter.currentPlaybackTime * 1000;
}
```

#### 5 浮窗

云课堂场景中播放器和PPT分别在主屏（房间顶部显示区域`PLVLCMediaAreaView`）和浮窗`PLVLCMediaFloatView`中，点击浮窗时播放器和PPT互换位置的功能；

浮窗`PLVLCMediaFloatView`对象在`PLVLCMediaAreaView`中初始化并持有，显示是添加`PLVLCCloudClassViewController`的view上显示的。

具体代码可查看Demo中`PLVLCCloudClassViewController.m`和`PLVLCMediaAreaView.m`


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