Class: QgsFeedback

class qgis.core.QgsFeedback(parent: QObject = None)

Bases: PyQt5.QtCore.QObject

Construct a feedback object

Base class for feedback objects to be used for cancellation of something running in a worker thread. The class may be used as is or it may be subclassed for extended functionality for a particular operation (e.g. report progress or pass some data for preview).

When cancel() is called, the internal code has two options to check for cancellation state: - if the worker thread uses an event loop (e.g. for network communication), the code can make a queued connection to canceled() signal and handle the cancellation in its slot. - if the worker thread does not use an event loop, it can poll isCanceled() method regularly to see if the operation should be canceled.

The class is meant to be created and destroyed in the main thread.

For map rendering, the object may be created in constructor of a QgsMapLayerRenderer subclass and available with QgsMapLayerRenderer.feedback() method. When a map rendering job gets canceled, the cancel() method is called on the feedback object of all layers.

New in version 3.0.

Parameters

parent

cancel(self)

Tells the internal routines that the current operation should be canceled. This should be run by the main thread

canceled

Internal routines can connect to this signal if they use event loop [signal]

childEvent()
connectNotify()
customEvent()
disconnectNotify()
isCanceled(self) → bool

Tells whether the operation has been canceled already

Return type

bool

isSignalConnected()
progress(self) → float

Returns the current progress reported by the feedback object. Depending on how the feedback object is used progress reporting may not be supported. The returned value is in percentage and ranges from 0-100.

See also

setProgress()

New in version 3.0.

Return type

float

progressChanged

Emitted when the feedback object reports a progress change. Depending on how the feedback object is used progress reporting may not be supported. The progress argument is in percentage and ranges from 0-100.

See also

setProgress()

See also

progress()

New in version 3.0: [signal]

Parameters

progress (float) –

receivers()
sender()
senderSignalIndex()
setProgress(self, progress: float)

Sets the current progress for the feedback object. The progress argument is in percentage and valid values range from 0-100.

See also

progress()

New in version 3.0.

Parameters

progress (float) –

timerEvent()