I am converting several Plugins from QGIS 3 and I am struggling heavily with symbology and labeling. The straightforwart QGIS 2 approach seems to be totally gone. I found some help here:

Reading and setting label settings in PyQGIS 3?

But I can't figure out how to set the label-size to map Units, the QGIS2 approach was:

layer_loaded.setCustomProperty("labeling/fontFamily", "Arial")
layer_loaded.setCustomProperty("labeling/fontSize", "100")
layer_loaded.setCustomProperty("labeling/fontSizeInMapUnits", "true")

The new approach seems to be

layer_settings  = QgsPalLayerSettings()
text_format = QgsTextFormat()

text_format.setFont(QFont("Arial", 10))
text_format.setSizeMapUnitScale(True) <-- wants a "QgsMapUnitScale"


layer_settings = QgsVectorLayerSimpleLabeling(layer_settings)

Is this the right approach?


You need to call


(see https://qgis.org/pyqgis/3.2/core/Text/QgsTextFormat.html#qgis.core.QgsTextFormat.setSizeUnit)

  • Thanks, works like a charm and improved my unterstanding of the documentation. (So text_format.setSizeMapUnitScale(QgsMapUnitScale) was completely unnecessary.) – AndreasK Nov 9 '18 at 8:45
  • Yes, that's only necessary to set the map unit size limits. – ndawson Nov 9 '18 at 19:21

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