拍照开发指导

About 15 min

拍照开发指导

使用场景

使用Camera产生图片帧(拍照)。

接口说明

表 1 API列表

类名

接口名

描述

CameraKit

int32_t GetCameraIds(std::list<string> cameraList)

获取cameraId列表

CameraKit

CameraAbility& GetCameraAbility(string cameraId)

获取指定camera的能力

CameraKit

void RegisterCameraDeviceCallback(CameraDeviceCallback* callback, EventHandler* handler)

注册camera设备状态回调

CameraKit

void UnregisterCameraDeviceCallback(CameraDeviceCallback* callback)

去注册camera设备状态回调

CameraKit

void CreateCamera(string cameraId, CameraStateCallback* callback, EventHandler* handler)

创建camera实例

CameraKit

const CameraInfo GetCameraInfo(std::string cameraId);

创建cameraInfo实例

Camera

string GetCameraId()

获取cameraID

Camera

CameraConfig& GetCameraConfig()

获取camera配置信息

Camera

FrameConfig& GetFrameConfig(int32_t type)

获取捕获帧类型

Camera

void Configure(CameraConfig& config)

配置camera

Camera

void Release()

释放camera

Camera

int TriggerLoopingCapture(FrameConfig& frameConfig)

开始循环帧捕获

Camera

void StopLoopingCapture()

停止循环帧捕获

Camera

int32_t TriggerSingleCapture(FrameConfig& frameConfig)

抓图

CameraConfig

void SetFrameStateCallback(FrameStateCallback callback, EventHandler* handler);

设置帧状态回调

CameraConfig

static CameraConfig* CreateCameraConfig()

创建camera配置信息实例

CameraAbility

std::list<Size> GetSupportedSizes(int format)

根据类型获取支持输出图像尺寸大小

CameraAbility

std::list<T> GetParameterRange(uint32_t key)

获取支持的参数范围

CameraAbility

std::list<int32_t> GetSupportedAfModes() const;

获取支持的自动对焦模式列表

CameraAbility

std::list<int32_t> GetSupportedAeModes() const;

获取支持的自动曝光模式列表

CameraDevice

CameraDeviceCallback()

camera设备回调类构造函数

CameraDevice

void OnCameraStatus​(std::string cameraId, int32_t status)

camera设备状态变化时的回调

CameraStateCallback

CameraStateCallback​()

camera状态回调类构造函数

CameraStateCallback

void OnConfigured​(Camera& camera)

camera配置成功回调

CameraStateCallback

void OnConfigureFailed​(Camera& camera,int32_t errorCode)

camera配置失败回调

CameraStateCallback

void OnCreated​(Camera& camera)

camera创建成功回调

CameraStateCallback

void OnCreateFailed​(std::string cameraId,int32_t errorCode)

camera创建失败回调

CameraStateCallback

void OnReleased​(Camera& camera)

camera释放回调

FrameStateCallback

FrameStateCallback​()

帧状态回调类构造函数

FrameStateCallback

void OnFrameFinished(Camera& camera, FrameConfig& frameConfig, FrameResult& frameResult)

拍照帧完成回调

FrameStateCallback

void OnFrameError​(Camera& camera, FrameConfig& frameConfig, int32_t errorCode, FrameResult& frameResult)

拍照帧异常回调

FrameConfig

int32_t GetFrameConfigType()

获取帧配置类型

FrameConfig

std::list<OHOS::Surface> GetSurfaces()

获取帧配置的surface

FrameConfig

void AddSurface(OHOS::AGP::UISurface& surface);

添加surface

FrameConfig

void RemoveSurface(OHOS::AGP::UISurface& surface);

删除surface

FrameConfig

void GetVendorParameter(uint8_t *value, uint32_t len);

获取自定义参数

FrameConfig

void SetVendorParameter(uint8_t *value, uint32_t len);

设置自定义参数

CameraInfo

int32_t GetCameraType() const;

获取相机类型

CameraInfo

int32_t GetCameraFacingType() const;

获取相机朝向

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
        }
    };
    
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  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;
            }
        }
    };
    
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  3. 实现相机状态回调的派生类,当相机状态发生变化(配置成功/失败,创建成功/失败)时,自定义操作。

    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 {}
    };
    
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  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;
        }
    }
    
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  5. 创建Camera实例。

    EventHandler eventHdlr; // Create a thread to handle callback events
    SampleCameraStateMng CamStateMng(eventHdlr);
    
    camKit->CreateCamera(camId, CamStateMng, eventHdlr);
    
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  6. 根据步骤1步骤2步骤3中的回调设计,camera实例创建成功后会进行配置操作,主流程中app需要设计同步机制。

    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);
    }
    
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