On 7 April 2017 at 19:41, Jean-Michaël Celerier <jeanmichael.celer...@gmail.com> wrote: > In my experience setting a GL viewport makes everything much less snappy (at > least on linux & os x, did not test on windows). > > Here is a video of my software with GL viewport: https://vid.me/kjRe > And without: https://vid.me/e2vu > > As you can see (as far as one can see in such a video), when I move the > object with the GL viewport there is a visible lag between the position of > the cursor and the position of the object ; much less when there is only > software rendering. > The experience is even worse on macOS, but maybe because of the performance > cost of retina. > I also tried porting the main view to QtQuick 2 but it is roughly the same > "laggy" performance.
My experience with QGraphicsView and GL viewport is that it can actually slow down the rendering. This is especially true when you have lot of small static items (by a lot i mean 1K+). After lot of trial, i decided that _in my case_, there was no point using GL viewport, it gave me more problems than benefits. Big QPainterPath with OpenGL will cause trouble as well, i use to get every now and then warning messages like 'QPainterPath size is greater than 32K pixels!' and a black viewport... The QGraphicsView Framework is a nice piece of software, but it takes lot of time to discover its quirks and limitations. QGraphicsPathItem has serious problems as well when used in a scene where you have to deal with small sizes (eg, better use a QGraphicsScene 'resolution' of 1.0 than 1E-6. QPainterPath uses QPointF but doesn't scale well, it is still a screen/pixel primitive. Chris > > > Best > ------- > Jean-Michaël Celerier > http://www.jcelerier.name > > > On Fri, Apr 7, 2017 at 7:04 AM, Thiago Macieira <thiago.macie...@intel.com> > wrote: >> >> Em quinta-feira, 6 de abril de 2017, às 19:38:36 PDT, Patrick Stinson >> escreveu: >> > Without stripping down my code into a runnable example, is setTransform >> > considered to be too slow for 60Hz frame-rate updates from touch events? >> > If >> > so, is there a better way to smoothly zoom and pan the graphics view? >> >> QGraphicsView is not architected correctly for smooth 60 fps. >> >> At least try to set a QOpenGLWidget as your viewport. It might help. >> >> -- >> Thiago Macieira - thiago.macieira (AT) intel.com >> Software Architect - Intel Open Source Technology Center >> >> _______________________________________________ >> 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 > _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
