16.2. Partes de código

Esta seção apresenta trechos de código para facilitar o desenvolvimento de complementos.

16.2.1. Como chamar um método por um atalho de teclas

No complemento, adicione à initGui()

self.key_action = QAction("Test Plugin", self.iface.mainWindow())
self.iface.registerMainWindowAction(self.key_action, "Ctrl+I")  # action triggered by Ctrl+I
self.iface.addPluginToMenu("&Test plugins", self.key_action)

A unload() adicione


O método chamado quando CTRL+I é pressionado

def key_action_triggered(self):
  QMessageBox.information(self.iface.mainWindow(),"Ok", "You pressed Ctrl+I")

16.2.2. Como alternar Camadas

Há uma API para acessar camadas na legenda. Aqui está um exemplo que alterna a visibilidade da camada ativa

root = QgsProject.instance().layerTreeRoot()
node = root.findLayer(iface.activeLayer().id())
new_state = Qt.Checked if node.isVisible() == Qt.Unchecked else Qt.Unchecked

16.2.3. Como acessar a tabela de atributos das feições selecionadas

 1def change_value(value):
 2    """Change the value in the second column for all selected features.
 4    :param value: The new value.
 5    """
 6    layer = iface.activeLayer()
 7    if layer:
 8        count_selected = layer.selectedFeatureCount()
 9        if count_selected > 0:
10            layer.startEditing()
11            id_features = layer.selectedFeatureIds()
12            for i in id_features:
13                layer.changeAttributeValue(i, 1, value) # 1 being the second column
14            layer.commitChanges()
15        else:
16            iface.messageBar().pushCritical("Error",
17                "Please select at least one feature from current layer")
18    else:
19        iface.messageBar().pushCritical("Error", "Please select a layer")
21# The method requires one parameter (the new value for the second
22# field of the selected feature(s)) and can be called by

16.2.4. Interface for plugin in the options dialog

You can add a custom plugin options tab to Settings ► Options. This is preferable over adding a specific main menu entry for your plugin’s options, as it keeps all of the QGIS application settings and plugin settings in a single place which is easy for users to discover and navigate.

The following snippet will just add a new blank tab for the plugin’s settings, ready for you to populate with all the options and settings specific to your plugin. You can split the following classes into different files. In this example, we are adding two classes into the main mainPlugin.py file.

 1class MyPluginOptionsFactory(QgsOptionsWidgetFactory):
 3    def __init__(self):
 4        super().__init__()
 6    def icon(self):
 7        return QIcon('icons/my_plugin_icon.svg')
 9    def createWidget(self, parent):
10        return ConfigOptionsPage(parent)
13class ConfigOptionsPage(QgsOptionsPageWidget):
15    def __init__(self, parent):
16        super().__init__(parent)
17        layout = QHBoxLayout()
18        layout.setContentsMargins(0, 0, 0, 0)
19        self.setLayout(layout)

Finally we are adding the imports and modifying the __init__ function:

 1from qgis.PyQt.QtWidgets import QHBoxLayout
 2from qgis.gui import QgsOptionsWidgetFactory, QgsOptionsPageWidget
 5class MyPlugin:
 6    """QGIS Plugin Implementation."""
 8    def __init__(self, iface):
 9        """Constructor.
11        :param iface: An interface instance that will be passed to this class
12            which provides the hook by which you can manipulate the QGIS
13            application at run time.
14        :type iface: QgsInterface
15        """
16        # Save reference to the QGIS interface
17        self.iface = iface
20    def initGui(self):
21        self.options_factory = MyPluginOptionsFactory()
22        self.options_factory.setTitle(self.tr('My Plugin'))
23        iface.registerOptionsWidgetFactory(self.options_factory)
25    def unload(self):
26        iface.unregisterOptionsWidgetFactory(self.options_factory)


Add custom tabs to a vector layer properties dialog

You can apply a similar logic to add the plugin custom option to the layer properties dialog using the classes QgsMapLayerConfigWidgetFactory and QgsMapLayerConfigWidget.