Subject: [linux-audio-dev] Some thoughts on a LADSPA GUI
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Thu Nov 16 2000 - 16:24:20 EET
Hi all,
I've been reading the previous discussions on this over the last few
days, these are my thoughts on what I would like to see. All IMHO of
course, and I am repeating the discussion to some degree:
1. Easy pixmap based construction of basic GUI elements.
2. Seperation of GUI stuff from DSP stuff (in the filesystem at least).
3. Implementation of graphical output.
1 and 2 are dealt with quite well via pdb's XML format (as in
quasimodo?), however 3 is a bit harder, something simple, like a
compressor's gain reduction meter can be done in the same way, (with a
set of pixmaps related to an output control value) but something more
complicated, like a transfer function display, or an FFT
display (either 3D or x, y and colour) is tricky. When you add control
points to a transfer function it gets even harder.
Just dealing with the XML+pixmaps thing for the moment, it would be nice
to have all the pixmaps and the XML (along with a thubmnail maybe) sotored
in a directory together, eg. plugin_foo.so -> plugin_foo_gui_simple/ +
plugin_foo_gui_advanced/ for example. I think being able to offer
multimple GUI's per plugin is important.
It strikes me that you could implement a transfer function display in XML
by giving a pixamp background, an x,y offset, a plot colour and a
reference to an array of ints (say) to render, but this seems a little
special-casey, and in the end you're going to need some way to render
bitmaps live.
Is something like GD just too slow? i.e. using a bitmap drawing library
to draw the osicoscope output/whatever, and then passing a pointer to
the bitmap back to the host. This still dosen't give you interaction
though, I guess you would need to add callbacks, etc., which is just
gettting into a whole world of pain. You would have a way of producing
arbitarly complex displays without having to do X things though.
Comments welcome,
Steve
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