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Widgets On The Canvas Integrated

Published on Thursday November 22, 2007 by Andreas Aardal Hanssen in Labs Qt Graphics Items Graphics View KDE | Comments

The day has finally arrived. We are proud to announce that we have now integrated our development branch for the Widgets On The Canvas project into Qt/main, or what will become Qt 4.4. You have already seen a random selection of screenshots and feature rundowns in previous blogs, but now it's all in your hands to try and enjoy. It should appear in tonight's snapshots.

I'd like to thank Jan-Arve, Bjørn Erik, Jo, Benjamin, Jasmin, Girish, Lars, and everyone else who has helped us with rowing this boat ashore. It was a beast, but we seem to have managed to tame it. Now, we'd all like for you to play around with this API, and let us know what you think.

Graphics View now provides a brand new layout and widget API. It's similar to the way QWidget works, and should be familiar for most of you right away. The purpose of this API is mainly so you can write layout-aware items, but it also means you now have a richer base class for your items. Because QGraphicsWidget inherits from QObject, it allows declaring signals and slots and manages event delivery just like any widget in Qt. Like QWidget it also provides a palette, a font, layout directions and a style.

Graphics View doesn't provide its own widgets like QLineEdit and QComboBox - instead, you can embed existing widgets (indeed, any custom widget that you have written yourself) into the scene by calling QGraphicsScene::addWidget(). If you also pass the Qt::Window flag, your widgets will even get window decorations similar to QMdiSubWindow. You can move, resize, rotate and scale your widgets, or combine widgets and items to generate fancy overlay or transition effects.

There are still a few remaining issues to solve. For one, Graphics View automatically embeds popups of embedded widgets. So if you embed a combobox, its popup will also appear as an embedded popup inside the scene. And QMenuBar's menus also also embedded. We aim to make this feature work 100% for 4.4, but currently it doesn't work properly (in particular, modality and mouse grabs are missing). Also, there's the well-known Mac OS X styling problem. We still haven't found a perfect solution for this, so for now, if you use Mac style for Graphics View, embedded widgets will look a bit chunky when transformed. And finally, because this is all brand new API, we expect some bugs to appear in this pre-alpha phase, and hope to iron them out based on your feedback. But hey - Widgets on Graphics View! How about it??? ;-)

PS: The members of the WOC project are all present and listening on qt4-preview-feedback@trolltech.com (also available through nntp.trolltech.com). Now is the time that you can help hone Widgets on Canvas to be just as great as we all want it to be. So enjoy! We're eagerly awaiting your feedback.

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