QgsDxfExport not exporting all features of a layer

Question

I have a simple script to export a layer to a dxf file:

layer = iface.activeLayer()
dxf = QgsDxfExport()
dxfPath = os.path.realpath("C:/abc/test.dxf")
extent = QgsRectangle()
dxflayers = []

dxflayer = dxf.DxfLayer(layer, -1)
dxflayers.append(dxflayer)
extent.combineExtentWith(layer.extent())
extent = extent.buffered(100) # To include features close to edge of extent

dxf.setDestinationCrs(layer.crs())
dxf.addLayers(dxflayers)
dxf.setExtent(extent)
f = QFile(dxfPath)
f.open(QIODevice.ReadWrite)
dxf.writeToFile(f, "utf-8")
f.close()

# Load new file to Qgis
iface.mainWindow().blockSignals(True)
newLayer = QgsVectorLayer(dxfPath, "DXF", "ogr")
iface.mainWindow().blockSignals(False)
dxfGroup = QgsLayerTreeGroup("New DXF", True)
QgsProject.instance().layerTreeRoot().addChildNode(dxfGroup)
newLayer.setCrs(layer.crs())
allLayers = newLayer.dataProvider().subLayers()
for lay in allLayers:
    geomType = lay.split(
        QgsDataProvider.SUBLAYER_SEPARATOR
    )[3]
    uri = f"{dxfPath}|layername=entities|geometrytype={geomType}"
    layerName = f"DXF - {geomType}"
    iface.mainWindow().blockSignals(True)
    l = QgsVectorLayer(uri, layerName, "ogr")
    iface.mainWindow().blockSignals(False)
    l.setCrs(layer.crs())
    QgsProject.instance().addMapLayer(l, False)
    dxfGroup.addLayer(l)

But since Qgis 3.6 i have a problem that not all features are exported. I think it's the commit dxf export: don't label invisible features (fixes #19604) that cause this problem.

My layer is a shapefile with a rule based style and only some of the rules are visible on the map, but i want to export all features when i create the dxf.

How can i change the behavior of the QgsDxfExport() to include all features?

I don't want to change the style on the layer because i don't know if it's saved or not.

Answer 1

The only way I see is to;

1. Copy the current style/renderer
2. Change it to a new simple one
3. Then restore after DxfExporter is done.

In QgsMapLayerStyleManager it's possible to do "setOverrideStyle" if you already have another style added. I haven't found any way to create a new simple style and add it to the QgsMapLayerStyleManager.

But it's possible to make a child class from DxfLayer and add your own "setOverrideStyle" functions, like this:

class MyDxfLayer(QgsDxfExport.DxfLayer):
    def __init__(self, vectorLayer, attributeIndex):
        super(MyDxfLayer, self).__init__(vectorLayer, attributeIndex)
        self.layer = vectorLayer
        self.attributeIndex = attributeIndex
        self.renderer = None

    def setOverrideStyle(self):
        from qgis.core import QgsFeatureRenderer
        self.renderer = self.layer.renderer().clone()
        newRenderer = QgsFeatureRenderer.defaultRenderer(
            self.layer.geometryType()
        )
        self.layer.setRenderer(newRenderer)

    def restoreOverrideStyle(self):
        if self.renderer is None:
            return
        self.layer.setRenderer(self.renderer)
        self.renderer = None

Then change the line:

dxflayer = dxf.DxfLayer(layer, 4)

to:

dxflayer = MyDxfLayer(layer, 4)
dxflayer.setOverrideStyle()

and after dxf.writeToFile(f, "utf-8") restore the previous style

for l in dxflayers:
    l.restoreOverrideStyle()

In this way QGis 3.6 export all feature of a layer to your DXF file