[Qgis-developer] Need help with Plugin button behavior connected to SIGNAL("selectionChanged()")

[Alexandre Neto]

Hello all,

I'm updating the Multipart split
plugin<http://plugins.qgis.org/plugins/splitmultipart/> to
make it work with the 2.0 API.

Has I have successfully updated the plugin to make it work in 2.0, I would
like to improve it's button behavior to work like the rest of the advanced
editing toolbar. I am able to enable and disable it if the current layer is
editable.

Now I'm trying to get the same behavior if there are selected features. I
have made it work, but QGIS starts to get really slow... I found out that's
because lots of connections are being created to
SIGNAL("selectionChanged()").

Can someone please, point me in the right direction, or tell me where can I
find some code example doing this?

Thank you very much,

Alexandre Neto

Part of the code bellow:

def initGui(self):
        # Create action that will start plugin configuration
        self.action = QAction(
            QIcon(":/plugins/splitmultipart/icon.svg"),
            QCoreApplication.translate('Multipart split', u"Split Selected
Multipart features"), self.iface.mainWindow())
        self.action.setEnabled(False)

        # connect to signals for button behavior
        QObject.connect(self.action, SIGNAL("triggered()"), self.run)
        QObject.connect(self.iface,
SIGNAL("currentLayerChanged(QgsMapLayer*)"), self.toggle)
        #QObject.connect(self.iface, SIGNAL("selectionChanged(QgsMapLayer
*)"), self.toggle)

        # Add toolbar button and menu item
        self.iface.advancedDigitizeToolBar().addAction(self.action)
        self.iface.editMenu().addAction(self.action)

    def toggle(self):
        mc = self.canvas
        layer = mc.currentLayer()

        # Decide whether the plugin button is enable or disable
        if layer <> None:
            # set enable
            if layer.isEditable():

QObject.connect(layer,SIGNAL("editingStopped()"),self.toggle)
                QObject.connect(layer, SIGNAL("selectionChanged()"),
self.toggle)

QObject.disconnect(layer,SIGNAL("editingStarted()"),self.toggle)
                self.iface.messageBar().pushMessage("Debug"," Connect
SIGNAL(selectionChanged()",0)
                if layer.selectedFeatureCount() > 0:
                    self.action.setEnabled(True)
                else:
                    self.action.setEnabled(False)

            # set disable
            else:
                self.action.setEnabled(False)

QObject.connect(layer,SIGNAL("editingStarted()"),self.toggle)

QObject.disconnect(layer,SIGNAL("editingStopped()"),self.toggle)
                QObject.disconnect(layer, SIGNAL("selectionChanged()"),
self.toggle)
                self.iface.messageBar().pushMessage("Debug"," Disconnect
SIGNAL(selectionChanged()",0)
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