Class: QgsTaskManager¶

Task manager for managing a set of long-running QgsTask tasks.

This class can be created directly, or accessed via QgsApplication.taskManager().

Class Hierarchy¶

Base classes¶

QObject

class qgis.core.QgsTaskManager[source]¶

Bases: QObject

__init__(parent: QObject | None = None)

Constructor for QgsTaskManager.

Parameters:: parent (Optional[QObject] = None) – parent QObject

class TaskDefinition¶

Bases: object

Definition of a task for inclusion in the manager.

dependentTasks: QgsTaskList¶

task: QgsTask¶

activeTasks(self) → List[QgsTask]¶

Returns a list of the active (queued or running) tasks.

See also

countActiveTasks()

Return type:: List[QgsTask]

addTask(self, task: QgsTask | None, priority: int = 0) → int[source]¶

Adds a task to the manager. Ownership of the task is transferred to the manager, and the task manager will be responsible for starting the task. The priority argument can be used to control the run queue’s order of execution, with larger numbers taking precedence over lower priority numbers.

Returns:: unique task ID, or 0 if task could not be added

addTask(self, task: QgsTaskManager.TaskDefinition, priority: int = 0) -> int Adds a task to the manager, using a full task definition (including dependency handling). Ownership of the task is transferred to the manager, and the task manager will be responsible for starting the task. The priority argument can be used to control the run queue’s order of execution, with larger numbers taking precedence over lower priority numbers.

Return type:

int

Returns:

unique task ID, or 0 if task could not be added

Parameters:

task (Optional[QgsTask])
priority (int = 0)

signal allTasksFinished[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

cancelAll(self)[source]¶: Instructs all tasks tracked by the manager to terminate. Individual tasks may take some time to cancel, or may totally ignore this instruction. Calling this does not block but will instead signal the tasks to cancel and then return immediately.

count(self) → int[source]¶

Returns the number of tasks tracked by the manager.

Return type:: int

countActiveTasks(self, includeHidden: bool = True) → int[source]¶

Returns the number of active (queued or running) tasks.

The includeHidden argument dictates whether hidden tasks should be shown.

See also

activeTasks()

See also

countActiveTasksChanged()

Parameters:: includeHidden (bool = True)
Return type:: int

signal countActiveTasksChanged[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

dependenciesSatisfied(self, taskId: int) → bool[source]¶

Returns True if all dependencies for the specified task are satisfied

Parameters:: taskId (int)
Return type:: bool

dependentLayers(self, taskId: int) → List[QgsMapLayer]¶

Returns a list of layers on which as task is dependent. The task will automatically be canceled if any of these layers are about to be removed.

Parameters:: taskId (int) – task ID
Return type:: List[QgsMapLayer]
Returns:: list of layers

See also

tasksDependentOnLayer()

signal finalTaskProgressChanged[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

signal progressChanged[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

signal statusChanged[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

task(self, id: int) → QgsTask | None[source]¶

Returns the task with matching ID.

Parameters:: id (int) – task ID
Return type:: Optional[QgsTask]
Returns:: task if found, or None

signal taskAboutToBeDeleted[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

signal taskAdded[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

taskId(self, task: QgsTask | None) → int[source]¶

Returns the unique task ID corresponding to a task managed by the class.

Parameters:: task (Optional[QgsTask]) – task to find
Return type:: int
Returns:: task ID, or -1 if task not found

signal taskTriggered[source]¶

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

tasks(self) → List[QgsTask]¶

Returns all tasks tracked by the manager.

Return type:: List[QgsTask]

tasksDependentOnLayer(self, layer: QgsMapLayer | None) → List[QgsTask]¶

Returns a list of tasks which depend on a layer.

See also

dependentLayers()

Parameters:: layer (Optional[QgsMapLayer])
Return type:: List[QgsTask]

threadPool(self) → QThreadPool | None[source]¶

Returns the threadpool utilized by the task manager.

Added in version 3.34.

Return type:: Optional[QThreadPool]

triggerTask(self, task: QgsTask | None)[source]¶

Triggers a task, e.g. as a result of a GUI interaction.

See also

taskTriggered()

Parameters:: task (Optional[QgsTask])