qgissnapping
I am trying to use the "Delete part" tool on a shapefile. While I am starting to use it, an error message shows up : "Could not snap segment. Have you set the tolerance in Settings > Project Properties > General?". I tried to set different tolerances in the snapping options, the error still shows up and I can't delete any part of my polygon.
How to fix that?
I use QGis 1.8.0-Lisboa and Windows 7.
Thanks
The select tool has a "Select by Rectangle" option. (There are also freehand/polygon options if that would be more appropriate.)
The node tool is for digitizing. I don't think that's what you want to do here.
Then, right-click on the layer in layer list and use "Save selection as ...". This will create a new file with the features you selected. (You can chose from many different formats.) Afterwards, load the file into the same old or a new project.
I seem to have found the problem. In QGIS all layers were initially activated for the Snapping. First I disable any snapping operations. Subsequently, the Snapping is enabled for a few layers.
for item in QgsMapLayerRegistry.instance().mapLayers().values():
QgsProject.instance().setSnapSettingsForLayer(item.id(), False, 2, 0, 2, True)
fieldLayer = mapUtils.getLayerByName(agroInstance.dictData['lpisid'])
backgroundLpisLayer = mapUtils.getLayerByName('LPISe')
if checked:
# Convenience function to set snap settings per layer.
# it defines the snapping options:
# id : the id of your layer, True : to enable the layer snapping, 2 : options (2: vertex+segment), 0: type of unit on map, 2 : tolerance, true : avoidIntersection)
QgsProject.instance().setSnapSettingsForLayer(layerA.id(), True, 2, 0, 2, True)
QgsProject.instance().setSnapSettingsForLayer(layerB.id(), True, 2, 0, 2, True)
The variable 'checked' checks whether a toggle button has been pressed. With this unsightly way I can turn the snapping on and off.
Best Answer
Thanks. I fixed my problem. I had set the snapping unit in map units, I found the right setting for my shapefile in pixels.