tcl/tk is just doing what it's told, which is to send mouse movement
notifications over the socket to Pd.
For each mouse motion message Pd receives from the GUI, it does a full loop
over all the objects in the canvas to find out who was clicked. In edit mode,
it can do up to two full loops if you did a "select all". (See
canvas_findhitbox in g_editor.c). I'm assuming those are the most labor
intensive parts of moving the mouse in Pd, but I haven't actually done any
profiling.
Additionally, each iteration of the loop calls a getrectfn for the object being
inspected. Typically that function just spits back the last values stored for
the object's bbox. But if a single GUI external happens to do something oddly
inefficient in that function, it is doing it every mouse motion message.
If these calculations + dsp graph calculation don't finish in the time it takes
to compute a block, you'll get a dropout. And of course if you got a dropout,
and you continue moving the mouse, you'll probably continue getting dropouts.
On the other hand, tk will put off redrawing the canvas until it has free time
to do so. Thus redrawing may come regularly, sporadically, or in some
unfortunate cases with Pd -rt, never. The fact that tk happily stops drawing
at all when the core Pd process has realtime scheduling should tell you that tk
is usually not the culprit in dropouts.
It's unclear what the solution should be. If one removed all the
widgetbehavior from "core" and put it in a separate "gui" process, then the
patch author no longer has easy access to the visual diagram data. (Easy as in
deterministic behavior when querying object positions or bboxes in a chain of
objects that compute in zero logical time.) On the other hand, I think the GUI
could just send a message telling Pd which object was actually clicked. (But
keep all the getrect and hitbox functionality around so that if the user needs
to fetch that data programmatically they can do so.)
-Jonathan
On Friday, June 27, 2014 5:50 AM, Billy Stiltner via Pd-list
<[email protected]> wrote:
i think it has something to do with tcl and the mouse
On Thu, Jun 19, 2014 at 5:55 PM, Simon Iten via Pd-list <[email protected]>
wrote:
i was Not clear i guess. I mean it never worked properly. A lot of dropouts and
lock ups.
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