On 7 December 2016 at 01:18, Philip Schuchardt <vpica...@gmail.com> wrote: > Since QGraphicsView can only render in the main gui thread, rendering in a > separate process will prevent the blocking on the main thread. You could > even implement "big pixel" zooming. You zoom in on the visible buffer while > a back buffer is being rendered in the background by the separate process. > This approach doesn't optimize the rendering. It just prevents the main gui > thread from being blocked by the rendering. It would be great if you could > render QGraphicsScene in a non-gui thread, but as far as I can tell you > can't.
I see what you mean now, I forgot about the main gui thread restriction... So how one know if a GUI Class that is not directly related to QWIdget can be used or not outside the main gui thread? I'm thinking about classes such as QFontMetric, QPainter, QPixmap, ... and generally speaking any off-screen rendering component (inc. PDF, ...) Should the absence of the usual re-entrant note near the top of the documentation page be taken as "Main GUI thread only"? Eg: QList and QPainter have "Note: All functions in this class are reentrant.", but QPainterPath doesn't (!?!). Chris > > On Tue, Dec 6, 2016 at 4:25 AM Ulf Hermann <ulf.herm...@qt.io> wrote: >> >> Hello, >> >> I had a somewhat similar, but not quite the same problem when building the >> timeline view for the QML profiler in Qt Creator. It's currently usable with >> up to about 1 million events in the timeline and you can zoom and scroll it. >> There might be potential for further optimization. I used the Qt Quick >> SceneGraph API to directly work with OpenGL geometry. The scene graph nodes >> are built on demand and then cached and recycled when applicable. You can >> check out the result in the Qt Creator sources in src/libs/timeline. >> >> br, >> Ulf >> _______________________________________________ >> Interest mailing list >> Interest@qt-project.org >> http://lists.qt-project.org/mailman/listinfo/interest > > -- > Phi|ip > > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest > _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
