labeling.py

        if isinstance(self.mEditor, ClassificationSchemeComboBox):
            cs = self.mEditor.classificationScheme()
            if isinstance(cs, ClassificationScheme) and len(cs) > 0:
                i = cs.classIndexFromValue(value)
                self.mEditor.setCurrentIndex(max(i, 0))
        elif isinstance(self.mEditor, QLineEdit):
            if value in [QVariant(), None]:
                self.mEditor.setText(None)
            else:
                self.mEditor.setText(str(value))


class LabelShortcutWidgetFactory(QgsEditorWidgetFactory):

    def __init__(self, name:str):

        super(LabelShortcutWidgetFactory, self).__init__(name)

        self.mConfigurations = {}


    def name(self)->str:
        return 'EOTSV Label Shortcut'

    def configWidget(self, layer:QgsVectorLayer, fieldIdx:int, parent=QWidget)->LabelShortcutEditorConfigWidget:
        """
        Returns a SpectralProfileEditorConfigWidget
        :param layer: QgsVectorLayer
        :param fieldIdx: int
        :param parent: QWidget
        :return: SpectralProfileEditorConfigWidget
        """

        w = LabelShortcutEditorConfigWidget(layer, fieldIdx, parent)
        key = self.configKey(layer, fieldIdx)
        w.setConfig(self.readConfig(key))
        w.changed.connect(lambda : self.writeConfig(key, w.config()))
        return w

    def configKey(self, layer:QgsVectorLayer, fieldIdx:int):
        """
        Returns a tuple to be used as dictionary key to identify a layer field configuration.
        :param layer: QgsVectorLayer
        :param fieldIdx: int
        :return: (str, int)
        """
        return (layer.id(), fieldIdx)

    def create(self, layer:QgsVectorLayer, fieldIdx:int, editor:QWidget, parent:QWidget)->LabelShortcutEditorWidgetWrapper:
        """
        Create a ClassificationSchemeEditorWidgetWrapper
        :param layer: QgsVectorLayer
        :param fieldIdx: int
        :param editor: QWidget
        :param parent: QWidget
        :return: ClassificationSchemeEditorWidgetWrapper
        """
        w = LabelShortcutEditorWidgetWrapper(layer, fieldIdx, editor, parent)
        return w

    def writeConfig(self, key:tuple, config:dict):
        """
        :param key: tuple (str, int), as created with .configKey(layer, fieldIdx)
        :param config: dict with config values
        """
        self.mConfigurations[key] = config

    def readConfig(self, key:tuple):
        """
        :param key: tuple (str, int), as created with .configKey(layer, fieldIdx)
        :return: {}
        """
        if key in self.mConfigurations.keys():
            conf = self.mConfigurations[key]
        else:
            #return the very default configuration
            conf = {}
        return conf

    def fieldScore(self, vl:QgsVectorLayer, fieldIdx:int)->int:
        """
        This method allows disabling this editor widget type for a certain field.
        0: not supported: none String fields
        5: maybe support String fields with length <= 400
        20: specialized support: String fields with length > 400

        :param vl: QgsVectorLayer
        :param fieldIdx: int
        :return: int
        """
        #log(' fieldScore()')
        if fieldIdx < 0:
            return 0
        field = vl.fields().at(fieldIdx)
        assert isinstance(field, QgsField)
        if field.type() in [QVariant.String, QVariant.Int]:
            return 5
        else:
            return 0 # no support

    def supportsField(self, vl:QgsVectorLayer, idx:int)->True:
        """
        :param vl: vectorlayers
        :param idx:
        :return: bool
        """
        field = vl.fields().at(idx)
        if isinstance(field, QgsField) and field.type() in [QVariant.Int, QVariant.String]:
            return True
        return False




EDITOR_WIDGET_REGISTRY_KEY = 'EOTSV_Labeling'
labelEditorWidgetFactory = None
def registerLabelShortcutEditorWidget():
    reg = QgsGui.editorWidgetRegistry()
    if not EDITOR_WIDGET_REGISTRY_KEY in reg.factories().keys():
        labelEditorWidgetFactory = LabelShortcutWidgetFactory(EDITOR_WIDGET_REGISTRY_KEY)
        reg.registerWidget(EDITOR_WIDGET_REGISTRY_KEY, labelEditorWidgetFactory)
    else:
        labelEditorWidgetFactory = reg.factories()[EDITOR_WIDGET_REGISTRY_KEY]