拍照开发指导

• 使用场景
• 接口说明
• 约束与限制
• 开发步骤

使用场景

使用Camera产生图片帧（拍照）。

接口说明

表 1 API列表

约束与限制

无。

开发步骤

1. 实现设备状态回调的派生类，用户在设备状态发生变更（如新插入相机设备/相机掉线）时，自定义操作。

   class SampleCameraDeviceCallback : public CameraDeviceCallback {
       void OnCameraStatus(std::string cameraId, int32_t status) override
       {
           //do something when camera is available/unavailable
       }
   };
   

2. 实现帧事件回调的派生类，这里在拿到帧数据以后将其转存为文件。

   static void SampleSaveCapture(const char *p, uint32_t size)
   {
       cout << "Start saving picture" << endl;
       struct timeval tv;
       gettimeofday(&tv, NULL);
       struct tm *ltm = localtime(&tv.tv_sec);
       if (ltm != nullptr) {
           ostringstream ss("Capture_");
           ss << "Capture" << ltm->tm_hour << "-" << ltm->tm_min << "-" << ltm->tm_sec << ".jpg";
   
           ofstream pic("/sdcard/" + ss.str(), ofstream::out | ofstream::trunc);
           cout << "write " << size << " bytes" << endl;
           pic.write(p, size);
           cout << "Saving picture end" << endl;
       }
   }
   
   class TestFrameStateCallback : public FrameStateCallback {
       void OnFrameFinished(Camera &camera, FrameConfig &fc, FrameResult &result) override
       {
           cout << "Receive frame complete inform." << endl;
           if (fc.GetFrameConfigType() == FRAME_CONFIG_CAPTURE) {
               cout << "Capture frame received." << endl;
               list<Surface *> surfaceList = fc.GetSurfaces();
               for (Surface *surface : surfaceList) {
                   SurfaceBuffer *buffer = surface->AcquireBuffer();
                   if (buffer != nullptr) {
                       char *virtAddr = static_cast<char *>(buffer->GetVirAddr());
                       if (virtAddr != nullptr) {
                           SampleSaveCapture(virtAddr, buffer->GetSize());
                       }
                       surface->ReleaseBuffer(buffer);
                   }
                   delete surface;
               }
               delete &fc;
           }
       }
   };
   

3. 实现相机状态回调的派生类，自定义相机状态发生变化（配置成功/失败，创建成功/失败)时的操作。

   class SampleCameraStateMng : public CameraStateCallback {
   public:
       SampleCameraStateMng() = delete;
       SampleCameraStateMng(EventHandler &eventHdlr) : eventHdlr_(eventHdlr) {}
       ~SampleCameraStateMng()
       {
           if (recordFd_ != -1) {
               close(recordFd_);
           }
       }
       void OnCreated(Camera &c) override
       {
           cout << "Sample recv OnCreate camera." << endl;
           auto config = CameraConfig::CreateCameraConfig();
           config->SetFrameStateCallback(&fsCb_, &eventHdlr_);
           c.Configure(*config);
           cam_ = &c;
       }
       void OnCreateFailed(const std::string cameraId, int32_t errorCode) override {}
       void OnReleased(Camera &c) override {}
   };
   

4. 创建CameraKit，用于创建和获取camera信息。

   CameraKit *camKit = CameraKit::GetInstance();
   list<string> camList = camKit->GetCameraIds();
   string camId;
   for (auto &cam : camList) {
       cout << "camera name:" << cam << endl;
       const CameraAbility *ability = camKit->GetCameraAbility(cam);
       /* find camera which fits user's ability */
       list<CameraPicSize> sizeList = ability->GetSupportedSizes(0);
       if (find(sizeList.begin(), sizeList.end(), CAM_PIC_1080P) != sizeList.end()) {
           camId = cam;
           break;
       }
   }
   

5. 创建Camera实例。

   EventHandler eventHdlr; // Create a thread to handle callback events
   SampleCameraStateMng CamStateMng(eventHdlr);
   
   camKit->CreateCamera(camId, CamStateMng, eventHdlr);
   

6. 根据步骤1、步骤2、步骤3中的回调设计，同步等待 OnCreated 回调拿到 cam_ 之后，进行相关操作。

   void OnCreated(Camera &c) override
   {
       cout << "Sample recv OnCreate camera." << endl;
       auto config = CameraConfig::CreateCameraConfig();
       config->SetFrameStateCallback(&fsCb_, &eventHdlr_);
       c.Configure(*config);
       cam_ = &c;
   }
   
   void Capture()
   {
       if (cam_ == nullptr) {
           cout << "Camera is not ready." << endl;
           return;
       }
       FrameConfig *fc = new FrameConfig(FRAME_CONFIG_CAPTURE);
       Surface *surface = Surface::CreateSurface();
       if (surface == nullptr) {
           delete fc;
           return;
       }
       surface->SetWidthAndHeight(1920, 1080); /* 1920:width,1080:height */
       fc->AddSurface(*surface);
       cam_->TriggerSingleCapture(*fc);
   }