[LV2] Qt5 plugin UIs and libsuil

Stefan Westerfeld stefan at space.twc.de
Thu Feb 23 04:35:14 PST 2017


My SpectMorph LV2 plugin uses Qt5 for its UI. Ardour (and maybe other hosts)
uses libsuil, but since libsuil doesn't support embedding Qt5 widgets, the
plugin UI won't work. This is not only the case for SpectMorph, other Qt based
plugins like synthv1 can also be compiled against Qt5.

I've created a libsuil bug report with a Qt5/libsuil embedding implementation:


and mention that in the SpectMorph README, but in the long run it would be
better if Qt5 plugin users wouldn't need to compile their own libsuil in order
to use the plugin in Ardour.

As a last remark, I've read some earlier discussions on the list that Qt or Gtk
UIs would somehow be not nice because of issues when multiple plugin share the
same address space. And in fact loading SpectMorph Qt5 UI into qtractor linked
against Qt4 produces a crash.

But if the custom UI uses message passing (not instance access) like SpectMorph
does, libsuil (or some other hypothetical meta-LV2-support library) could
always instantiate the UIs in an extra process, which would avoid bad
interactions between different plugin UIs.

   Cu... Stefan
Stefan Westerfeld, http://space.twc.de/~stefan

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