Den 15. feb. 2012 08:38, skrev ext gunnar.sle...@nokia.com: > For some time we have wanted to unify the behavior of qreal on desktop and > embedded. Currently, qreal is defined to be double on desktop and to a float > on embedded. > > The reasons for unifying are: > > - Using "double" is pure waste for a lot of use cases. QRectF, QPointF, > QPainter, QPolygonF, OpenGL, QMouseEvent, QTouchEvent, to name a few. None of > these require the precision offered by double precision floating point. > > - Predictable behavior on across desktop and device. In the past we have > had a few cases where things fell apart when run on embedded because the > reduced precision. These were fixed, but they would have been immediately > caught during development if they were the same. > > - For specific use cases were higher precision floats are required, double > can still be used. Both inside and outside the Qt libraries. > > Our initial idea was to change "qreal" to "double" to avoid any potential > regression but the impact on size combined with the fact that the added > precision is almost never needed changed our minds > (https://bugreports.qt-project.org/browse/QTBUG-23758) > > The only questionable use case is geolocation. We know for a fact that floats > have limitations in this area and both Qt3D and QtLocation make use of > QVector[2|3|4]D and QMatrix4x4 which will now be a float. However, this is no > worse (for device) than it already is, so any use case that fails and needs > work will now be found early in the development cycle as opposed to during > device testing. > > Unless there are any objections that I have not yet covered, I will go ahead > with this change. > > cheers, > Gunnar
Great. This would allow us to get rid of various hacks for qreal in the meta-type system as well. Kent _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
