# [ardour-dev] Ahhhh-dour....mmmmm

Wed Oct 27 11:03:18 PDT 2004

On Tue, Oct 26, 2004 at 05:12:13PM -0400, Paul Davis wrote:

> i think you're not understanding how something like the canvas
> works. we (the application) doesn't track every mouse motion and
> figure out where we are - the canvas generates enter/leave events for
> us, along with many other events all bound to a particular canvas
> item. we don't generally see any events until they are associated with
> a canvas item, and that association relies on the canvas' own notion
> of "close".

When the user clicks anywhere in the canvas, I assume it delivers an
event (or callback or whatever) that contains the x,y coordinates
of the click (probably relative to the canvas origin). You need that
in order to put new things on it at that place for example, and I'd
be surprised if that were impossible.
The code also knows where it last put the PH line. So all information
required to work out how close to the PH someone has clicked should be

\begin{benign-rant-mode}
This sort of thing is trivial when you use X directly. If it gets
more difficult with a toolset, then I wonder what the toolset's use is.
\end{benign-rant-mode}

--
FA