On 10/18/2012 11:08 AM, Bache-Wiig Jens wrote: >> Maybe as a best effort we could introduce a different render hint, >> asking QPainter to treat cosmetic pens as geometric, would be a better >> solution for Morten's high-dpi use case. Then it would be opt-in instead >> of opt-out, and no existing applications would be affected. Turning on >> high-dpi mode could be documented to also set the render hint. > ... >> In summary (or TL;DR), my new proposal would be to just make >> QPainter::NonCosmeticDefaultPen work as advertised, and have it be set >> by default when high-dpi mode is enabled. This way there would be >> minimal breakage of existing code. Thoughts? > > > No I don't think this would work. That way we will get the obscure > scalability issues that Uwe mentioned but it would only happen on retina > capable computers so it can become even harder to discover.
True, the fact that applications that are tested and working on non-retina suddenly break on retina will cause confusing behavior even for applications written from scratch with Qt 5. Assuming we have as a goal that applications should work in high-dpi mode without any testing or modifications being needed. Morten, is that the case? > The original proposal doesn't really have these problems though. We already > set the render hint NonCosmeticPenByDefault on GraphicsView to avoid > inconsistent scalability issues there and keep style code working when being > scaled. That's why I figured that setting it for high-dpi would make sense as well, but at least in the QGraphicsView case you wouldn't get any surprises since it's always set. Having a potentially breaking behavior depend on whether high-dpi is enabled or not might not be a good idea after all... > I think we should extend this behavior to QPainter in general by only > initialising QPen to 1 instead of 0. We keeping the explicit 0-pen working as > before. In addition, we introduce a CosmeticPenByDefault render hint that > Qwt can set on its painter to make all pens cosmetic by default. (not just > 0-pen) Though the Qt4PainterRenderHint could still explicitly give only 0 pen > cosmetic properties. I'm not sure Qwt actually _wants_ all pens to be cosmetic by default. For > 0 width pens it must already have had explicit calls to setCosmetic(true), so it's really only the default-constructed QPens that would be an issue. So I don't see how CosmeticPenByDefault would be needed in addition to Qt4CompatiblePainting. -- Samuel _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
