Subject: Re: [linux-audio-dev] proposed initial DTD for LADSPA-gui-xml
From: Benno Senoner (sbenno_AT_gardena.net)
Date: Tue Nov 28 2000 - 01:51:35 EET
> >
> >Well, it means an extra control output, doesn't it? Or can I bind a
> >slider and a value-display to an input control? If so, Yay!
>
> You can bind as many control elements as you wish to the same port. My
> implementation will ensure that they are all updated as the values are
> changed *using one of the widgets*. LADSPA has no provisions for
> plugins notifying the host of changes to the port value, and I have no
> idea exactly how we'll do this other than a roughly 1/screen_hz idle
> loop that updates the screen displays to match the current value.
Paul, does you code currently check if the port value has
really changed between two updates ?
I'm thinking about something like:
while(1) {
sleep n msecs
for each widget {
if(widget->port->value != widget->port->old_value) widget->update();
}
}
This should scale quite nicely even if there are many widgets on the screen,
since most of time you are only doing a few numeric comparisons.
(knowing Paul, I guess that his code already does this :-) )
Next topic:
pixmap based slider movement:
in your previous mail you said you do not use moving sliders, but you use
a set of fixed pixmaps.
Assume that one want large faders which move with single pixel precision.
Ok, what if the fader is 200 pixel in height ?
That means that we would need almost 200 pixmaps , right ?
What if there are 30-50 of these on the screen,
does this cause problems in terms of display performance ?
I tried xmms and it seems to use lots of pixmaps: it is _REALLY_ slow
(PII400 + Matrox G400 + XF 3.3) when dragging the window around or when firing
up a few instances of the app.
Are my fears that the GUI will get sluggish when the screen is full of racks
packed with sliders, displays , knobs etc unfounded ?
thanks for infos.
Benno.
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