QgsMapCanvas object is not callable (Ubuntu with, Eclipse, Python & QGIS 2.0)

Question

I'm basically borrowing the code for picking up a coordinate from a mouse click from this answer :

How to programatically check for a mouse click in QGIS

However in a stand alone application I do not have access to iface, so am instead calling the class with :

tool = PointTool(self.map_canvas()) 
self.map_canvas().setMapTool(tool)

Intellisense finds the map_canvas ok and it compiles, but I am getting a run time error:

'QgsMapCanvas' object not callable

Any ideas why?

Answer 1

You don't mention if you're doing it, but as you're writing a standalone application, you need to create a Map Canvas by yourself, in this way:

self.map_canvas = QgsMapCanvas()

Then you can set the map tool using self.map_canvas:

tool = PointTool( self.map_canvas ) 
self.map_canvas.setMapTool( tool )

---

Why not to write the parenthesis in self.map_canvas?

Because you already have instantiated the QgsMapCanvas class, it's now an object and you don't call objects, you call methods or functions, such as iface.mapCanvas() (here you call a function of iface that returns the QGIS map canvas) or QgsMapCanvas() (here you call the constructor of the class, which is still a method).