[Qgis-user] Convert symbology of qgis layer into PyQGIS code to define renderer

[Tudorache, Marian]

Hi,

As far as I know symbology is tight to the topology.
Here is a simple example for lines.

mlayer = qgis.utils.iface.activeLayer()
styles = {'width': '0.5', 'color': 'yellow', 'penstyle': 'solid'}
registry = qgis.core.QgsSymbolLayerV2Registry.instance()
symbol = qgis.core.QgsSymbolV2.defaultSymbol(mlayer.geometryType())
lineLayer = lineMeta.createSymbolLayer(styles)
symbol.deleteSymbolLayer(0)
symbol.appendSymbolLayer(lineLayer)
renderer = qgis.core.QgsSingleSymbolRendererV2(symbol)
mlayer.setRendererV2(renderer)
mlayer.triggerRepaint()
qgis.utils.iface.mapCanvas().refresh()

For points
styles = {'name': 'diamond', 'color': 'yellow', 'size': '2'}
pointSymbol = qgis.core.QgsMarkerSymbolV2.createSimple(styles)
mlayer.rendererV2().setSymbol(pointSymbol)
qgis.utils.iface.mapCanvas().refresh()
mlayer.triggerRepaint()

for polygons
                    symbol.setColor(QtGui.QColor("blue"))
                    registry = QgsSymbolLayerV2Registry.instance()
                    lineMeta = registry.symbolLayerMetadata("SimpleLine")
                    lineLayer = lineMeta.createSymbolLayer({'width': '0.8', 'color': 'blue', 'offset': '0', 'penstyle': 'solid'})
                    symbol.appendSymbolLayer(lineLayer)
                    symbol.setAlpha(0.2)

                    renderer = QgsRuleBasedRendererV2(symbol)
                    vLayer.setRendererV2(renderer)
                    vLayer.setLayerTransparency(0)
                    vLayer.triggerRepaint()

This when you want to have static symbols.
QGIS also gives the capability of creating dynamic symbols
-----Original Message-----
From: Qgis-user <qgis-user-bounces at lists.osgeo.org> On Behalf Of Manuel Campagnolo
Sent: June 11, 2021 7:56 AM
To: qgis-user at lists.osgeo.org
Subject: [EXT] [Qgis-user] Convert symbology of qgis layer into PyQGIS code to define renderer

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Hi

Do you know of a way of using the style of a ,say, vector layer in QGIS3 to create automatically the python code that would generate it, namely the QgsSymbol part in the code below.

Thanks


symbol1=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
symbol2=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
symbol3=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
symbol4=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())
symbol5=QgsSymbol.defaultSymbol(ifn_ppsm.geometryType())

symbol1.setColor(QColor('black'))
symbol2.setColor(QColor('gray'))
symbol3.setColor(QColor('dark green'))
symbol4.setColor(QColor('light green'))
symbol5.setColor(QColor('orange'))

cat1=QgsRendererCategory('Improdutivos', symbol1, 'Improdutivos') # category, symbol, label cat2=QgsRendererCategory('Urbano', symbol2, 'Urbano') cat3=QgsRendererCategory('Matos e Pastagens', symbol3, 'Matos e Pastagens') cat4=QgsRendererCategory('Floresta', symbol4, 'Floresta') cat5=QgsRendererCategory('Agricultura', symbol5, 'Agricultura') categories=[cat1,cat2,cat3,cat4,cat5] # list

renderer = QgsCategorizedSymbolRenderer('usosolo', categories)
ifn_ppsm.setRenderer(renderer)

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