'notify' signal handler

[Robert Park <rbpark exolucere ca>]

Hi guys,

I have a question that should hopefully be unrelated to the pygobject
introspection problem that is still ongoing ;-)

My application provides a crosshair that displays directly at map
center, and a text label that displays the map center coordinates.
Obviously, these two items need to be updated frequently to stay
accurate (if the stage changes it's size due to a user resize event, I
need to reposition the crosshair, and if the user moves the map view,
I need to update the coordinates).

Up until now, I have naively been connecting to the 'paint' signal to
do both of these things, since that seemed like the only way to update
as frequently as possible, and there were never any problems. However,
today I learned about the 'notify' signal (which was quite well hidden
in the documentation), and I thought it would be a good way to reduce
the number of calls to my signal handlers without letting the display
go stale.

So, for starters, this worked like a charm:

        self.stage.connect('notify::height', self.position_crosshair)
        self.stage.connect('notify::width',  self.position_crosshair)

It had exactly the intended result. The crosshair only updates it's
position when it needs to, and not "constantly all the time always."

The problem I'm having is with my latitude/longitude label. This
mostly works as expected:

        self.map_view.connect('notify::latitude',  self.display_coords)
        self.map_view.connect('notify::longitude', self.display_coords)

But the precision is terrible! If I do one long click+drag on the map,
the signal fires every 100m or so, but it's actually possible to make
a series of short drags to move a great distance before the signal
fires. I was able to move almost an entire kilometer before it fired,
just by moving in very small increments.

Playing with this a bit, I realize that the same problem existed
before when I was connected to the 'paint' signal handler, I just
didn't notice it then. The label was updating with a furious
frequency, but it was just setting the same imprecise value over and
over until a minimum threshhold of movement was achieved.

What gives? Ideally I'd like my label to be very precise and update
with precise coordinates after every mouse movement, no matter how
subtle.

Thanks guys.

-- 
http://exolucere.ca