By Andreas Aardal Hanssen

Graphics View improvements

Published Tuesday February 27th, 2007 | 21 Comments on Graphics View improvements
Posted in Graphics Items, Graphics View, Labs, Qt

We’re in the process of closing up the features for 4.3, and I’ve had a little run-down of what’s changed in Graphics View. In general, you will notice that the graphics run faster, (especially for complex polygons,) collisions are absolutely precise, the rubberband looks 100x better… I think most of our Graphics View followers will […]

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Untransformable QGraphicsItem tags / labels

Published Sunday January 21st, 2007 | 2 Comments on Untransformable QGraphicsItem tags / labels
Posted in Graphics Items, Graphics View, Labs

Last summer, while we were finishing up 4.2, there was a great deal of activity on the mailing lists we set up for the 4.2 technical preview (http://lists.trolltech.com/). Some people kept on asking for support for “untransformable” items, that is, special QGraphicsItem items that don’t follow the parent’s or view’s transformations. Like the text labels […]

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Hands on QGraphicsScene’s index

Published Monday December 18th, 2006 | 3 Comments on Hands on QGraphicsScene’s index
Posted in Graphics Items, Graphics View, KDE, Labs, Qt, Qtopia

Some people have asked if they can have more explicit control over how QGraphicsScene’s index works. If you’ve got concrete suggestions, please post comments to this post, or send us an email, or post a suggestion through our public feedback form. Some suggestions we’ve got so far are: setting the depth of the tree, forcing […]

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Interact with volatile graphics items

Published Friday December 15th, 2006 | 2 Comments on Interact with volatile graphics items
Posted in Graphics Items, Graphics View, KDE, Labs, Qt

I hacked together some code today for interacting with a QGraphicsItem while its transformation changes. The problem? QGraphicsItem’s events are always delivered in local coordinates, and operations in response to such events that change item’s transformation (scale it, or move it, or shear it) will leave its local coordinates intact, but might change its relative […]

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Has anyone seen QDirIterator?

Published Thursday December 14th, 2006 | 2 Comments on Has anyone seen QDirIterator?
Posted in KDE, Qt, Qtopia

Recently QDirIterator showed up in the Qt 4.3 snapshots. Doesn’t have that many bells and whistles, but it’s a pretty useful tool. Here’s how to use it: QDirIterator it(“testDir/”); while (it.hasNext()) { qDebug() < < it.next(); // "testDir/." // "testDir/.." // "testDir/directory" // "testDir/file.txt" // "testDir/otherFile.txt" // "testDir/otherDirectory" // "testDir/symlink" // ... } It provides […]

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Zoom-and-rotate on mouseover effect in Graphics View

Published Thursday November 30th, 2006 | 3 Comments on Zoom-and-rotate on mouseover effect in Graphics View
Posted in Graphics Items, Graphics View, Labs, Qt

Have you seen flash-interfaces with controls that grow and twist when you move your mouse over them? Here’s how to do that in Graphics View. I was so surprised at how easy it was that I thought I’d share it. Here’s a screenshot, just so you know what I’m talking about: I’ll do this in […]

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Graphics View Gem: Item Obscurity

Published Thursday September 14th, 2006 | Comments Off on Graphics View Gem: Item Obscurity
Posted in Graphics Items, Graphics View, KDE, Labs, Qt

During this summer of pre-4.2 testing, we got many feature requests from you all, customers and Open Source’rs, and I’d like to pull out one of the things we decided to implement as a result of this. Item obscurity: being able to determine whether an item is obscured, or not. The idea is that any […]

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Behavioral changes in QIODevice in Qt 4.2

Published Monday September 11th, 2006 | Comments Off on Behavioral changes in QIODevice in Qt 4.2
Posted in KDE, Qt

Some people think QFile in Qt 4 is slow[*]. Compared to Qt 3, the noticable difference lies in QIODevice::getChar(), and to some extent, QIODevice::putChar(). But there’s good news: With Qt 4.2, we’ve managed to improve QIODevice’s performance by 4-5x when reading small blocks at a time, especially so for getChar() :-). So something has changed […]

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4 million items, is it really possible?

Published Wednesday August 30th, 2006 | 1 Comment on 4 million items, is it really possible?
Posted in Graphics Items, Graphics View, KDE, Labs, Qt

Someone asked me if it was truly possible to do 4 million items in real time using Graphics View. I challenge you to see for yourselves. Download one of the latest snapshots for Qt 4.2 (one with the 40000 Chips demo in it) – and apply this patch to increase the number of items. It’s […]

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