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

[Alexandre Neto]

Denis,

You were right, using selectionChanged on mapCanvas worked just fine.

Thanks!

Alexandre Neto


this worked just great. I guess I had been in the right direction before,
but some how lost it.

On Thu, Aug 22, 2013 at 1:37 PM, Denis Rouzaud <denis.rouzaud at gmail.com>wrote:

>  Hi Alexandre,
>
> Why don't you use selectionChanged on mapCanvas?
>
You have a line commented, I suppose this was it.
>
Mainly, I suppose the problem is that you never disconnect you layer from
> the signals since you always call the method for the current layer....so
> the previous current is never disconnected....
>
> Hope this helps,
>
> Cheers,
>
> Denis
>
>
>
> On 08/22/2013 02:11 PM, Alexandre Neto wrote:
>
>  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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>
>
>
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