On Wed, 18 May 2016 15:57:04 -0300, Lisandro Damián Nicanor Pérez Meyer wrote:
> Now if I add a lot of straight lines (QGraphicsLineItem instances) > performance (number of movements seen on screen per second) varies > according the zoom. If I zoom in I get to a point in which everything is > too slow. Qt does the polygon clipping very late, so a huge amount of pointless caclulations is going on before it detects that it is not needed. IIRC the Graphics View framework isn't any better than QPainter - but I havn't checked the code quite some time. If this is still the case you need to implement your own polygon clipping before entering Qt rendering code. At least this is what I do it in the Qwt project ( qwt.sf.net ). If you need an implementation for polygon clipping you find something there too: see https://sourceforge.net/p/qwt/code/HEAD/tree/trunk/qwt/src/ qwt_clipper.cpp HTH, Uwe _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
