harmony 鸿蒙拍照开发指导

2022-08-09
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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

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.
    }
};

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;
        }
    }
};

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 {}
};

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;
    }
}

创建Camera实例。

EventHandler eventHdlr; // Create a thread to handle callback events.
SampleCameraStateMng CamStateMng(eventHdlr);


camKit->CreateCamera(camId, CamStateMng, eventHdlr);

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);
}