On Thu, Oct 20, 2011 at 6:59 AM, <[email protected]> wrote: > ext [email protected] wrote on 2011-10-19: >> I don't neccessarily disagree, as having it built into the language >> seems like the obvious solution. But I don't think it is _that_ clear >> cut: - If we do not support those constraints it for anchors, but give >> items properties like minimum/maximumWidth, it would just add to the >> confusion. - Adding constraints could have a significant performance >> penalty for low end hardware. Hopefully this would be negligible if you >> don't make use of them. - Giving anchors hard constraints can impact how >> easy it is to animate certain things. Making layouts explicit makes it >> easier to determine when you are giving away control over positioning. - >> Giving anchors constraints makes them unpredictable. Who wins when you >> have conflicting min/max sizes? The largest item? Most likely by random? >> Again, I somewhat like the distinction that anchors are somewhat more >> rigid/harder and wins over layouts every time. > > As long as all anchors in QML are directional (it simply uses the property > propagation system), it does not make sense to add min/max sizes. Think about > how you can make an item stretch in Qt Quick anchor layout: Two independent > propagation paths must meet one item (e.g. one stops on the left edge, the > other stops on the right edge). This does not allow distribution of available > space to different items. (it's rather all remaining space gets allocated to > the item in "the middle") > This would most likely mean that we'd need a different syntax (\see > VisualFormatLanguage below) for anchors if we want to have proper > distribution, and each anchor should not be directed.
Yes, it would not handle space distribution or item stretching correctly, it's just a possible not-good-looking feature that could raise from the 1st approach. For a more advanced anchor layout, maybe the target is not QtQuick API but an independent layout component. What do you think? > Since Cocoa Autolayout is *very* similar to QGraphicsAnchorLayout, I have > wanted to try to make a similar "language" for QGAL. This could then be used > in Qt Quick. Unfortunately I haven't had the time yet (sometimes I wish I > could clone myself). It should be quite easy to implement, since it's a very > simple language. I think that would be a very nice feature. Would it make sense to create an AnchorLayout component to provide that? Br, Adriano _______________________________________________ Qt-qml mailing list [email protected] http://lists.qt.nokia.com/mailman/listinfo/qt-qml
