harmony 鸿蒙Photographing Development
Photographing Development
When to Use
Use the camera module APIs to capture frames (photographing).
Available APIs
Table 1 APIs for photographing
Class | API | 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 a CameraConfig instance. |
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 successfully. |
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 created successfully. |
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. |
FrameConfig | void AddSurface(OHOS::AGP::UISurface& surface); | Adds a surface. |
FrameConfig | void RemoveSurface(OHOS::AGP::UISurface& surface); | Removes a surface. |
Constraints
None
How to Develop
- Implement 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/unavailable
}
};
- Implement 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<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;
}
}
};
- Implement 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 {}
};
- Create a CameraKit instance to set and obtain camera information.
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;
}
}
- Create a Camera instance.
EventHandler eventHdlr; // Create a thread to handle callback events
SampleCameraStateMng CamStateMng(eventHdlr);
camKit->CreateCamera(camId, CamStateMng, eventHdlr);
- Based on the callback design in steps 1, 2, and 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);
}
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