Retrieve QgsPalLayerSettings object from a layer

Question

A pyqgis stand-alone app labels layer features with QgsPalLayerSettings, in the same fashion as in Labelling line layer using QgsPalLayerSettings() QGIS failed, it works for me too.

How do I retrieve that pal layer object after it is "tied in" with a layer for further manipulation (enable/disable etc) or do I just define another pal layer object and writeTo that same layer again to overwrite it?

there is a fromLayer(layer) static function of the QgsPalLayerSettings class that seems to be able to get back a PalLayer object, but it looks like it is a cloned copy, I would like to just get the original pal layer object.

Answer 1

Don't think you need to define another pal object. Just use the readFromLayer() method once and then you can retrieve your labelling properties or update them.

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For example, if you want to see if the labelling properties are currently enabled/disabled or see what field is chosen, you could use:

palyr = QgsPalLayerSettings()
layer = iface.activeLayer()
palyr.readFromLayer(layer)

palyr.enabled
palyr.fieldName

Which for me printed:

>>>False
>>>u''

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If you want to overwrite the same settings, you could use:

palyr = QgsPalLayerSettings()
layer = iface.activeLayer()
palyr.readFromLayer(layer)

def update():
    palyr.writeToLayer(layer)
    layer.triggerRepaint()

palyr.enabled = True
palyr.fieldName = 'City'
update()