# Photographing ## When to Use Use the camera module APIs to capture frames \(photographing\). ## Available APIs **Table 1** APIs for photographing

Class

Function

Description

CameraKit

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

Obtains IDs of cameras that are currently available.

CameraKit

CameraAbility& GetCameraAbility(string cameraId)

Obtains the camera capability

CameraKit

void RegisterCameraDeviceCallback(CameraDeviceCallback* callback, EventHandler* handler)

Registers a camera callback for camera status changes.

CameraKit

void UnregisterCameraDeviceCallback(CameraDeviceCallback* callback)

Unregisters a camera callback.

CameraKit

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

Creates a Camera instance.

Camera

string GetCameraId()

Obtains the camera ID.

Camera

CameraConfig& GetCameraConfig()

Obtains the camera configuration.

Camera

FrameConfig& GetFrameConfig(int32_t type)

Obtains the frame configuration.

Camera

void Configure(CameraConfig& config)

Configures the camera using the CameraConfig object.

Camera

void Release()

Releases the Camera object and associated resources.

Camera

int TriggerLoopingCapture(FrameConfig& frameConfig)

Starts looping-frame capture.

Camera

void StopLoopingCapture()

Stops looping-frame capture.

Camera

int32_t TriggerSingleCapture(FrameConfig& frameConfig)

Starts single-frame capture.

CameraConfig

void SetFrameStateCallback(FrameStateCallback* callback, EventHandler* handler);

Sets a frame state callback to respond to state changes.

CameraConfig

static CameraConfig* CreateCameraConfig()

Creates a CameraConfig instance.

CameraAbility

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

Obtains the supported image sizes for a specified image format.

CameraAbility

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

Obtains the parameter value range based on a specified parameter key.

CameraDevice

CameraDeviceCallback()

A constructor used to create a CameraDeviceCallback instance.

CameraDevice

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

Called when the camera device status changes.

CameraStateCallback

CameraStateCallback​()

A constructor used to create a CameraStateCallback instance.

CameraStateCallback

void OnConfigured​(Camera& camera)

Called when the camera is configured.

CameraStateCallback

void OnConfigureFailed​(Camera& camera,int32_t errorCode)

Called when the camera fails to be configured.

CameraStateCallback

void OnCreated​(Camera& camera)

Called when the camera is successfully created.

CameraStateCallback

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

Called when the camera fails to be created.

CameraStateCallback

void OnReleased​(Camera& camera)

Called when the camera is released.

FrameStateCallback

FrameStateCallback​()

A constructor used to create a FrameStateCallback instance.

FrameStateCallback

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

Called when the frame capture is completed.

FrameStateCallback

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

Called when the frame capture fails.

FrameConfig

int32_t GetFrameConfigType()

Obtains the frame configuration type.

FrameConfig

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

Obtains a list of surface objects (shared memories).

FrameConfig

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

Adds a surface.

FrameConfig

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

Removes a surface.
## Limitations and Constraints None ## How to Develop 1. Extend the **CameraDeviceCallback** class and call **OnCameraStatus** to customize operations when the camera device changes, for example, when a camera becomes available or unavailable. ``` class SampleCameraDeviceCallback : public CameraDeviceCallback { void OnCameraStatus(std::string cameraId, int32_t status) override { // Do something when camera is available or unavailable. } }; ``` 2. Extend the **FrameStateCallback** class. After obtaining the frame data, save the data as a file. ``` 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 surfaceList = fc.GetSurfaces(); for (Surface *surface : surfaceList) { SurfaceBuffer *buffer = surface->AcquireBuffer(); if (buffer != nullptr) { char *virtAddr = static_cast(buffer->GetVirAddr()); if (virtAddr != nullptr) { SampleSaveCapture(virtAddr, buffer->GetSize()); } surface->ReleaseBuffer(buffer); } delete surface; } delete &fc; } } }; ``` 3. Extend the **CameraStateCallback** class and customize operations when the camera state changes \(configuration successful or failed, and creation successful or failed\). ``` 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. Create a **CameraKit** instance to set and obtain camera information. ``` CameraKit *camKit = CameraKit::GetInstance(); list camList = camKit->GetCameraIds(); string camId; for (auto &cam : camList) { cout << "camera name:" << cam << endl; const CameraAbility *ability = camKit->GetCameraAbility(cam); /* Find the camera that fits your ability. */ list sizeList = ability->GetSupportedSizes(0); if (find(sizeList.begin(), sizeList.end(), CAM_PIC_1080P) != sizeList.end()) { camId = cam; break; } } ``` 5. Create a **Camera** instance. ``` EventHandler eventHdlr; // Create a thread to handle callback events. SampleCameraStateMng CamStateMng(eventHdlr); camKit->CreateCamera(camId, CamStateMng, eventHdlr); ``` 6. Based on the callback design in steps 1 to 3, perform related operations until the **OnCreated** callback obtains **cam\_**. ``` 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); } ```