digiKam Developer Documentation
Professional Photo Management with the Power of Open Source
Loading...
Searching...
No Matches
Digikam::WorkerObject Class Reference
+ Inheritance diagram for Digikam::WorkerObject:

Public Types

enum  DeactivatingMode { FlushSignals , KeepSignals , PhaseOut }
 
enum  State { Inactive , Scheduled , Running , Deactivating }
 

Public Slots

void deactivate (DeactivatingMode mode=FlushSignals)
 Quits execution of this worker object.
 
void schedule ()
 Starts execution of this worker object: The object is moved to a thread and an event loop started, so that queued signals will be received.
 

Signals

void finished ()
 
void started ()
 

Public Member Functions

 WorkerObject ()
 Deriving from a worker object allows you to execute your slots in a thread.
 
bool connectAndSchedule (const QObject *sender, const char *signal, const char *method, Qt::ConnectionType type=Qt::AutoConnection) const
 You must normally call schedule() to ensure that the object is active when you send a signal with work data.
 
QThread::Priority priority () const
 
void setPriority (QThread::Priority priority)
 Sets the priority for this dynamic thread.
 
State state () const
 
void wait ()
 

Static Public Member Functions

static bool connectAndSchedule (const QObject *sender, const char *signal, const WorkerObject *receiver, const char *method, Qt::ConnectionType type=Qt::AutoConnection)
 
static bool disconnectAndSchedule (const QObject *sender, const char *signal, const WorkerObject *receiver, const char *method)
 

Protected Member Functions

virtual void aboutToDeactivate ()
 Called from deactivate(), typically from a different thread than the worker thread, possibly the UI thread.
 
virtual void aboutToQuitLoop ()
 Called from within thread's event loop to quit processing.
 
void addRunnable (WorkerObjectRunnable *loop)
 
bool event (QEvent *e) override
 
void removeRunnable (WorkerObjectRunnable *loop)
 
void run ()
 
void setEventLoop (QEventLoop *loop)
 
void shutDown ()
 If you are deleting data in your destructor which is accessed from the thread, do one of the following from your destructor to guarantee a safe shutdown: 1) Call this method 2) Call stop() and wait(), knowing that nothing will call start() anymore after this 3) Be sure the thread will never be running at destruction.
 
void transitionToInactive ()
 
bool transitionToRunning ()
 

Friends

class ThreadManager
 
class WorkerObjectRunnable
 

Member Enumeration Documentation

◆ DeactivatingMode

Enumerator
FlushSignals 

Already sent signals are cleared.

KeepSignals 

The thread is stopped, but already sent signals remain in the queue.

PhaseOut 

The thread is stopped when all signals emitted until now have been processed.

Constructor & Destructor Documentation

◆ WorkerObject()

Digikam::WorkerObject::WorkerObject ( )
explicit

Implement any slots and connect signals just as usual. Call schedule() before or when signals are emitted. The object will have moved to a thread when the signals are received by the slots. Call deactivate() to stop computation. Note that without calling schedule(), no signal will ever be processed. You can use the connectAndSchedule convenience connection to avoid having to call schedule() directly. Note that you cannot make this QObject the child of another QObject. Please check if you need to call shutDown from your destructor (see below).

Member Function Documentation

◆ aboutToDeactivate()

void Digikam::WorkerObject::aboutToDeactivate ( )
protectedvirtual

You can stop any extra controlled threads here. Immediately afterwards, an event will be sent to the working thread which will cause the event loop to quit. (aboutToQuitLoop())

◆ aboutToQuitLoop()

void Digikam::WorkerObject::aboutToQuitLoop ( )
protectedvirtual

Quit any blocking operation. Immediately afterwards, the event loop will be quit.

◆ connectAndSchedule()

bool Digikam::WorkerObject::connectAndSchedule ( const QObject *  sender,
const char *  signal,
const char *  method,
Qt::ConnectionType  type = Qt::AutoConnection 
) const

Instead, you can use these connect() methods when connecting your signal to this object, the signal that carries work data. Then the object will be scheduled each time you emit the signal.

◆ deactivate

void Digikam::WorkerObject::deactivate ( DeactivatingMode  mode = FlushSignals)
slot

If mode is FlushSignals, all already emitted signals will be cleared. If mode is KeepSignals, already emitted signals are not cleared and will be kept in the event queue until destruction or schedule() is called. If mode is PhaseOut, already emitted signals will be processed and the thread quit immediately afterwards.

◆ setPriority()

void Digikam::WorkerObject::setPriority ( QThread::Priority  priority)

Can be set anytime. If the thread is currently not running, the priority will be set when it is run next time. When you set QThread::InheritPriority (default), the priority is not changed but inherited from the thread pool.

◆ shutDown()

void Digikam::WorkerObject::shutDown ( )
protected
Note
This irrevocably stops this object.
It is not sufficient that your parent class does this. Calling this method, or providing one of the above mentioned equivalent guarantees, must be done by every single last class in the hierarchy with an implemented destructor deleting data. (the base class destructor is always called after the derived class)