Class: QgsMapRendererCustomPainterJob

Job implementation that renders everything sequentially using a custom painter.

Also supports synchronous rendering in main thread for cases when rendering in background is not an option because of some technical limitations (e.g. printing to printer on some platforms).

Class Hierarchy

Base classes

QgsMapRendererAbstractCustomPainterJob	Abstract base class for map renderer jobs which use custom painters.
QgsMapRendererJob	Abstract base class for map rendering implementations.
QObject

Methods

labelingHasNonDefaultCompositionModes
prepare	Prepares the job for rendering synchronously in a background thread.
preparePainter
renderPrepared	Render a pre-prepared job.
renderSynchronously	Render the map synchronously in this thread.
waitForFinishedWithEventLoop	Wait for the job to be finished - and keep the thread's event loop running while waiting.

class qgis.core.QgsMapRendererCustomPainterJob

Bases: QgsMapRendererAbstractCustomPainterJob

labelingHasNonDefaultCompositionModes()

prepare(self)

Prepares the job for rendering synchronously in a background thread.

Must be called from the main thread.

This is an alternative to ordinary API (using start() + waiting for finished() signal), and an alternative to renderSynchronously() (which should only ever be called from the main thread).

See also

renderPrepared()

Added in version 3.10.

preparePainter()

renderPrepared(self)

Render a pre-prepared job. Can be safely called in a background thread.

Must be preceded by a call to prepare()

This is an alternative to ordinary API (using start() + waiting for finished() signal), and an alternative to renderSynchronously() (which should only ever be called from the main thread).

Added in version 3.10.

renderSynchronously(self)

Render the map synchronously in this thread. The function does not return until the map is completely rendered.

This is an alternative to ordinary API (using start() + waiting for finished() signal). Users are discouraged to use this method unless they have a strong reason for doing it. The synchronous rendering blocks the main thread, making the application unresponsive. Also, it is not possible to cancel rendering while it is in progress.

waitForFinishedWithEventLoop(self, flags: QEventLoop.ProcessEventsFlags | QEventLoop.ProcessEventsFlag = QEventLoop.AllEvents)

Wait for the job to be finished - and keep the thread’s event loop running while waiting.

With a call to waitForFinished(), the waiting is done with a synchronization primitive and does not involve processing of messages. That may cause issues to code which requires some events to be handled in the main thread. Some plugins hooking into the rendering pipeline may require this in order to work properly - for example, OpenLayers plugin which uses a QWebPage in the main thread.

Ideally the “wait for finished” method should not be used at all. The code triggering rendering should not need to actively wait for rendering to finish.

Parameters:

flags (Union[QEventLoop.ProcessEventsFlags, QEventLoop.ProcessEventsFlag] = QEventLoop.AllEvents)