On Sat, Sep 22, 2012 at 9:15 PM, Josiah Bryan <josiahbr...@gmail.com> wrote: > Subclass QWidget::paintEvent(QPaintEvent*) > (http://doc.qt.digia.com/4.6/qwidget.html#paintEvent) and do your own > painting of the widget. See the Analog Clock example > (http://doc.qt.digia.com/4.7-snapshot/widgets-analogclock.html) for an > example on how to draw the contents of the widget. > > If you're wanting to do per-pixel work - the easiest (only?) way is via a > QImage - there is no direct per pixel access to video memory. The closest > thing you'll get to direct-pixel access of video memory is to use a > QGLWidget and implement pixel shaders. > > On Sat, Sep 22, 2012 at 3:00 PM, Mark <mark...@gmail.com> wrote: >> >> Hi, >> >> I know one can manipulate pixel data in a QImage using the bits() >> function, but how can i do the same for a QWidget? >> I want to play with a high performance line drawing algorithm [1] so i >> guess it's not very optimal to do the following: >> - draw in a QImage >> - put that image in the qwidget >> - further drawing in the QImage >> - put it on the QWidget again >> - ... and so on ... >> >> In this case i'm guessing that the QImage mapping to a QWidget would >> be the most costly one hence i'd like to prevent that altogether and >> "just" manipulate the QWidget pixel data directly. >> So how do i do that? >> >> Cheers, >> Mark >> >> [1] http://free.pages.at/easyfilter/bresenham.html >> _______________________________________________ >> Interest mailing list >> Interest@qt-project.org >> http://lists.qt-project.org/mailman/listinfo/interest
Thank you for your reply :) Though that is sadly not going to work. Remember, i want to test out another line drawing algorithm.. not the one from QPainter. QGLWidget and pixel shaders is also not an option. I first want to do this in software, not hardware/opengl. I could really use some way to get the widget pixel data... _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
