PyQGIS Documentation - Linfiniti Geo Blog

PyQGIS Documentation, Release 1.4
def keyActionF7(self):
QMessageBox.information(self.iface.mainWindow(),"Ok", "You pressed F7")
12.5.2 How to toggle Layers (work around)
Note: from QGIS 1.5 there is QgsLegendInterface class that allows some manipulation with list of layers within
legend.
As there is currently no method to directly access the layers in the legend, here is a workaround how to toggle the
layers using layer transparency:
def toggleLayer(self, lyrNr):
lyr = self.iface.mapCanvas().layer(lyrNr)
if lyr:
cTran = lyr.getTransparency()
lyr.setTransparency(0 if cTran > 100 else 255)
self.iface.mapCanvas().refresh()
The method requires the layer number (0 being the top most) and can be called by:
self.toggleLayer(3)
12.5.3 How to access attribute table of selected features
def changeValue(self, value):
layer = self.iface.activeLayer()
if(layer):
nF = layer.selectedFeatureCount()
if (nF > 0):
layer.startEditing()
ob = layer.selectedFeaturesIds()
b = QVariant(value)
if (nF > 1):
for i in ob:
layer.changeAttributeValue(int(i),1,b) # 1 being the second column
else:
layer.changeAttributeValue(int(ob[0]),1,b) # 1 being the second column
layer.commitChanges()
else:
QMessageBox.critical(self.iface.mainWindow(),"Error", "Please select at least one feature from
else:
QMessageBox.critical(self.iface.mainWindow(),"Error","Please select a layer")
The method requires the one parameter (the new value for the attribute field of the selected feature(s)) and can be
called by:
self.changeValue(50)
12.5.4 How to debug a plugin using PDB
First add this code in the spot where you would like to debug:
12.5. Code Snippets 41