By Samuel

Widgets enter the third dimension: WolfenQt

Published Tuesday December 2nd, 2008
40 Comments on Widgets enter the third dimension: WolfenQt
Posted in Graphics Dojo, Graphics Items, Graphics View, KDE, Labs, Qt, Qt Concurrent, Qt Script, WebKit

Some people have been asking how to embed Qt painted content (and especially Qt widgets) in a 3d scene. As I’ve been wanting to do this ever since we added QTransform supporting fully projective transformations, I sat down and wrote a small example demonstrating these capabilities. With no further delay, I present WolfenQt: Here’s a

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Translucent widgets on X11

Published Tuesday September 23rd, 2008
9 Comments on Translucent widgets on X11
Posted in Graphics Dojo, KDE

When running an X11 compositing manager it’s possible to have translucent widgets by using 32 bit visuals, also known as ARGB visuals. We don’t use these visuals by default in Qt because we’ve seen some driver issues which cause buggy rendering and widgets containing garbage pixels when first being shown, as well as generic slow-downs

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Subpixel antialiasing on X11

Published Monday September 1st, 2008
3 Comments on Subpixel antialiasing on X11
Posted in KDE, Qt

The last week I looked at some issues regarding Qt’s font rendering on X11, triggered by some bug reports comparing Qt 4’s font rendering to Qt 3’s and GTK’s font rendering, specifically when subpixel antialiasing is enabled. When rendering fonts with subpixel antialiasing Qt asks Freetype to render into an alpha mask that is three

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Old school effect: the radial blur

Published Friday August 1st, 2008
2 Comments on Old school effect: the radial blur
Posted in Graphics Dojo, Qt

For this episode of the graphics dojo I’ve implemented the classic radial blur effect. The core radial blur effect is implemented with per-pixel manipulation, which Qt lets us do quite elegantly using the QImage class. The final dojo example uses the radial blur effect in combination with scrolling text drawn using QPainter to create a nice visual impression. Below is a screenshot of the effect as well as a recording: Radial blur movie capture As usual, the source code is available from the

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Accelerate your widgets with OpenGL

Published Friday June 27th, 2008
11 Comments on Accelerate your widgets with OpenGL
Posted in Graphics Dojo, Graphics Items, Graphics View, Qt

To breathe some new life into the graphics dojo, here’s an example of how to put widgets on top of an OpenGL scene using QGraphicsView. By leveraging the synergy (tounge in cheek) of the OpenGL module and graphics view’s in 4.4 new widget capabilities, the long lacking feature of putting widgets in OpenGL becomes possible.

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Rasterizing dragons

Published Friday August 31st, 2007
7 Comments on Rasterizing dragons
Posted in Qt

I’ve been working on a new rasterizer to replace the Freetype rasterizer for aliased painting in the raster paint engine, which is used on Windows and when rendering to a QImage. The new rasterizer is scheduled to be part of Qt 4.4, and is already available in the snapshots. The performance of rasterizing various paths with QRasterizer compared to the Freetype rasterizer can bee seen in the following figure: And the same results in table form:

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