Changing centroid marker to font marker using PyQGIS

Question

I'm trying to get a "P" font marker in the middle of my polygon layer. So far, I've managed to make a simple centroid marker (the basic one) appear on my polygons.

The code doesn't bug, but it doesn't change the simple marker to a font marker.

Here's the code, does anyone know what I am missing?

colorpark = QtGui.QColor(88, 88, 88, 255)
symbo_park = QgsSimpleFillSymbolLayer(color=colorpark, strokeColor=colorpark, strokeWidth=0)
parking_l93.renderer().symbol().changeSymbolLayer(0, symbo_park)
parking_l93.triggerRepaint()

symbol_parkcent = QgsCentroidFillSymbolLayer.create()
parking_l93.renderer().symbol().appendSymbolLayer(symbol_parkcent)
colorP = QtGui.QColor(255, 255, 255, 255) 
symbolparkP = QgsFontMarkerSymbolLayer(fontFamily='Arial Black', chr='P', pointSize=2, color=colorP)      
parking_L93.renderer().symbol().changeSymbolLayer(0, symbolparkP)                
parking_l93.triggerRepaint()

Answer 1

The QgsFontMarkerSymbolLayer must be added as a subSymbol to your QgsCentroidFillSymbolLayer.

I just needed to add 4 lines to your code to obtain something like this :

Here is the lines I added :

symbol_parkcent = QgsCentroidFillSymbolLayer.create()
# Make the centroid transparent
symbol_parkcent.setColor(QColor("transparent"))
#
colorP = QtGui.QColor(255, 255, 255, 255) 
symbolparkP = QgsFontMarkerSymbolLayer(fontFamily='Arial Black', chr='P', pointSize=2, color=colorP)      
# Add the Font Marker as subsymbol
marker_symbol = QgsMarkerSymbol()
marker_symbol.changeSymbolLayer(0, symbolparkP)
symbol_parkcent.setSubSymbol(marker_symbol)
#
parking_l93.renderer().symbol().appendSymbolLayer(symbol_parkcent)
parking_l93.triggerRepaint()

By using appendSymbolLayer I added your QgsFontMarkerSymbolLayer to your QgsSimpleFillSymbolLayer If you only want the QgsFontMarkerSymbolLayer you need to use parking_l93.renderer().symbol().changeSymbolLayer(0, symbol_parkcent)