Folding

One of the more frequent questions that I see is how to do interesting transition effects for applications. So here's how, first of all prototype your algorithm. Here we're going to use a page folding to visualize transitions as turning of pages. So that it looks like this:

Then we figure out how to adopt it to application. The trick is how to get contents of an application without extra repaints. In Qt the contents of top-level's is buffered and there is a private but exported way of fetching that contents (not fully platform independent at the moment). The example #2 shows how to grab the contents of the window without extra repaints and copies and use it to implement the effect, so it looks like this:

The forms were taken from Kate config dialogs so they're real config pages (hence also why they're, well, not too pretty). The effect is fully animated so to get a better idea of how it looks you'll have to look at the ogg file provided here. It's also worth noting that this effect is very efficient and works smoothly with virtually 0 cpu usage.

As mentioned in the last blog, to see more examples and code for this one visit Graphics Dojo. The above mentioned examples are at the examples 2 page.

Graphics Dojo

I have been traveling and working a lot lately. I was attending Bossa Conference, which was the best organized Open Source conference I had the pleasure of attending. I got to hang out with people I normally spend very little time with like Rasterman. Raster and I had some time to sit down and talk about graphics, Qt, Evas, chickens (don't ask), him being a crab killer (again, don't ask) and just have a lot of fun. Chris explained a few things about LLVM to me. It's always fun to hang out with Marcelo as well. All around it was a great time.

I went to spend a little time with my "family" in England last week which was also just amazing.

The most important news though is that thanks to amazing work that Marius did on labs.trolltech.com I've got a Qt focused graphics corner. Being a Graphics Ninja, I've decided to call it the Graphics Dojo. The first action point was the release of some of the examples that I wrote in my spare time. You can take a look at an overview here or go directly to page 1 or page 2. There's a few ones I've never shown before, like Mario Klingemann influenced Ring of Fire.



I hope that the "Graphics Dojo" and the articles which I'll be posting on it will help everyone write better looking interfaces.

Reflections

In the spirit of my never ending "pimp your Qt application" series comes another example. This time, "how to make iTunes-like album selector". It's funny how much attention this widget got. I looked at it yesterday on one of the Macs at the office and just implemented it. I probably should make it a view for a list model but for now it's just a simple widget. It runs at perfectly smooth 60 frames per second while utilizing ~7% cpu on my 3GHz Pentium4 with NVIDIA GeForce 6600, so by no means a monster of a machine. Oh, and of course this is all done with pure Qt. Reflections are actually a vector effect, so they would work equally well for any vector based graphics (by using the same code as this example, you can reflect your svg's or even whole widgets with no problem). Mandatory screenshot:
And as with every animated example a movie (again, framerate of the screencapture does not come close to the real world performance) is available here . Finally the code is available here.

Gradient bounds

The most unfriendly thing about rendering gradients with Qt has been the fact that you had to specify gradients in coordinates of the shape they were to be rendered on. It wasn't ideal especially for all applications which included any kind of animations or were rendering large number of items because it meant that the gradient had to be individually created for each and every one of items/frames. I've fixed that two days ago by adding a coordinate-mode property to QGradient, which now accepts ObjectBoundingMode. Object bounding mode, just like in SVG, means that the gradient coordinates are percentages of bounding box of the shape that the gradient is about to fill. So all the coordinates are between 0 and 1 and Qt automatically adjusts the bounds for gradient when it's being rendered. This makes it possible to easily use QGradient's with QPalette. An example where I'm drawing a bunch of rectangles and animate them along while the gradient is set only once with (0,0, 1, 1) coordinate box (meaning starting at the topleft and ending at the bottom right corner of each rectangle).
And since it's an animation (including a widget show/hide effect) here's a movie showing it in action.

Browsers, performance and interventions

This week I beat WebKit Qt's rendering into shape. I rewrote the theming and canvas code.
It works so nicely that I'm actually pretty happy with it. The rewrite helped me fix issues with statically positioned elements (which just didn't work on a scrollview/canvas combination I did before). Due to which my blog finally looks and behaves correctly as seen on the screenshot above. That plus scrolling is about 10x faster and you never see gray areas on scrolling as you did before.
This week George Staikos has been here in Oslo to work with us on the networking code. George and I have been friends for five or six years and he has this nasty habit that forces me to start an intervention and try to get him off it. What I'm referring to is the fact that George has been Canadian for, well his entire life, and it is my professional opinion (but I'm not a doctor) that he needs to move on. I'm not sure in which culture it is customary to bring Snapple ice-tea to your friends when you come to see them but we need to change him to that because he definitely didn't bring me any this time and that's just rude.
Going back to work, I'm sure Lars will blog about the networking magic they did so I'll keep my mouth shut. Once the code they were working on will be ready (which should happen within next week or two) and we'll start using in WebKit, we'll make the transition and start using WebKit Qt based browser on a daily basis. So we're close which is pretty exciting.

We have also started optimization run for Qt 4.3. My grand plan is to make sure Qt 4.3 is 2x faster in general rendering code than Qt 4.2 was. I have a list of algorithms to shave and rewrite over the next few weeks which will be rather challenging.
By the way of performance some people noticed that Qt OpenGL in recent snapshots with Antialiasing turned on is actually slower than it was in Qt 4.2. It's because of an experiment that we're trying on. We're now using GLSL to antialias primitives. Of course it's a lot slower than the old code but produces very high quality results. I don't really like it though because the performance hit is just too big.

Core dump

Today I'm joining the rapid fire blogging squad.

• Roberto is moving back to Italy and last Wednesday was his last day at the office. Roberto is one of my best friends at Trolltech so I was incredibly bummed out by his departure. The office won't be the same place without him. Plus who will help me hack on a prototype GLSL jit engine that I wanted to do some research on? (rhetorical question, I'd only trust him with that anyway)
  Roberto is also, by far, one of the best hackers who ever worked on KDE so I'm very excited to say that Roberto and Trolltech came to an agreement by which Trolltech will sponsor Roberto for two days of the week to work on KDE.
  


• This has been a bug fixing week so I didn't have any time to work on WebKit. Last week I did manage to finish off integrating SVG into WebKit Qt
  I also played a little bit with combining native Qt application rendering from within WebKit. One can embed a whole native Qt window inside an html frame and then control the Qt application from javascript (signals, slots and properties of the window and its children are dynamically exposed). Here's a native Qt application (my transform example) rendered inside the advertisment frame on cnn.com (sorry for the depressing image).
  
  


• For the last two days I've been thinking about adding basic high dynamic range color support to Qt. QColor is already suitable for it and extending it wouldn't be a big issue. QColor's internal representation is a union of unsigned shorts. Basic HDR support requires 64bit, where every channel is a so-called, "half". Half values have 1-bit sign bit, 5 exponent bits, and 10 mantissa bits. It's a format used, among others, in OpenEXR and Cg. In fact OpenEXR project provides a C++ half implementation under a BSD-like license. Along a CIELAB colorspace support that I wanted to add to Qt for a while now, support for HDR would open a slew of new possibilities. On a silly, desktop level - imagine a desktop background the is light proportionally to the sun-light that you'd see for your currently configured timezone. On a more basic level HDR is pretty much essential for any kind of image processing/editing nowadays. I'll most likely write another blog dedicated to color-theory and things I'd like to fix/implemented in Qt that are related to it. Google returns hundred thousands of HDR images so if you'd like to see what people do with it, you won't have to look for long. One of my favorite examples is New York at night by Paulo Barcellos Jr that can be seen on fickr here.


• During lunch at Trolltech there's only one kind of yellow cheese available. Climbing to the highest-levels of good-faith and stupidity I assumed the cheese would absolutely have to be vegetarian (many cheeses is still made with natural rennet, which is taken out of lining of young cattle's stomachs). Yesterday one of the people pointed out that it most likely isn't. Today morning I called Tine, which is the biggest dairy producer in Norway (and one whose cheese Trolltech buys) to ask them about the situation. The result was, that of course, the cheese is not vegetarian. If you're a vegetarian, do not eat cheese or any products containing it while in Norway. For me the bottom line is that for the last few months I've been having non-vegetarian cheese for lunch putting me right now in levels of pissed off/disappointed that I've never been at (you know that silly questions about graphics you wanted to ask me? you might want to wait with that a few days).

Generating SVG's with Qt

I've been working on a lot of things at once over the last week but I just remembered that I never mentioned something that I should have. In the beginning of the Qt 4.3 development phase I added a class called QSvgGenerator to QtSvg. QSvgGenerator is a paint device, meaning you can open QPainter on it and yes, that's right, you'll get an SVG XML stream back that you can save to a file or manipulate.

So now you can redirect your widget/window and have a snapshot of your application dumped to SVG format... Come on that's pretty cool. The generator still needs a lot of work, especially when it comes to complex text. But here's a weird, example. I made Qt render a simple animating bezier curve, then loaded html with Qt documentation and rendered that with opacity of .75 (which is why it looks very blend) and finally redirected to a painter opened on a QSvgGenerator. As a result I get a SVG (viewed, of course with, svgviewer) looking like this:

And the full output is here. So yeah, the concept of being able to load simple html and then save it as SVG is pretty neat.

Also boolean ops on paths are now in Qt. You'll find them in QPainterPath's. Since I already had the code and Andreas asked me for it, I added QPainterPath::intersects(const QPainterPath &other) and QPainterPath::contains(const QPainterPath &other) that can be used to check whether two paths intersect or whether one path fully contains the other. I still want to do some heavy optimisations on it, but I'd like to implement "Snap Rounding of Bezier Curves" instead of trying to find the right shortcuts to use reduced-predicates for the intersection finding algorithm.

The magic of animation

Creating a decent animation, albeit a lot of fun, is quite complex. Besides being able to create the content (and therefore exhibiting basic artistic skills) one has to go through the mundane process of trying to figure out what exactly should be on every frame.

SVG, as a format, is absolutely atrocious at expressing animations. KDE 4 is moving more towards dynamic metaphors, where animations will be used to convey a lot more information. Now the question is how do we let people who inherently have no artistic skills create animations that look and behave correctly. While "look correctly" is pretty simply defined as: it's visually appealing. Then "behave correctly" has a more complex definition that will depend on many factors. We'll define a "well behaved animation" as one which simply doesn't irritate or inhibit the work flow of the users.

While the latter is mostly a challenge for usability engineers I'd like to help people create animations - quickly, with minimal amount of artistic skills and no mundane tasks. So ideally I'd like to be able to say "this is what I'm starting with" and "this is what I'd like to end up with" and see computer animate this process. The technique is known under "shape interpolation", "shape blending", "image morphing" and many other names. There was a lot of research done on this topic but so far no one used this technique to do real-time animations on desktop.

The most popular research papers related to this problem include "As-Rigid-As-Possible Shape Interpolation", "A physically based approach to 2-D shape blending" and finally "As-Rigid-As-Possible Shape Manipulation". If you haven't seen it, you definitely want to look at the last one, there's a short movie on that site showcasing some of the things one can do utilising their algorithm. Some of the examples from the above research follows:

I think that shape interpolation together with as-rigid-as-possible shape manipulation done on QPainterPath's, or whole SVG's in fact, could potentially be the answer to our animation woes. The pain, once again, is that people always work on polygons in those papers so I'd need to spend a bit of time to figure out how to mix it in with paths and inject curves into the algorithm.

Oh, and yesterday was the "World Hug Day" so if you haven't hugged anyone yet, go right ahead.

More on WebKit Qt

Two days ago Lars and I sat down and did the initial implementation of classes which will represent the public API for the Qt/KDE version of WebKit. In KHTML almost everything has been handled by KHTMLPart. We'd like to avoid having one huge object that does everything this time so we went with similar abstraction to the one present in WebCore - meaning Page/Frame distinction. The top level classes are now: QWebPage which represents (surprise - a web page) and QWebFrame which is (another shocking discovery) a frame (remember that a page can have multiple frames).

It's pretty interesting what one can do with it. Me being me (aka. weird) had to try to do something visually funky so I made our test browser have a transparent overlay progress loader that is hidden when nothing is being loaded and made the pages render in grayscale until they are fully loaded, so a loading page looks like:And before someone complains - no this won't be a default and won't even be included in WebKit by default, it's just to give people a rough idea what one can do with this framework (and yes, the filter that I did for it messes up fonts but I just didn't even bother to make it flawless) Or more precisely I wanted to make sure one can do anything. Here's another example with webpage rotated a little bit (this time without grayscale filter on it) :
So, yeah, I think you'll be able to do a lot of new and pretty exciting things with WebKit once KDE 4 hits the streets.

OpenVG

OpenVG is a royalty-free, cross-platform API that provides a low-level hardware acceleration interface for vector graphics libraries such as Flash and SVG. Or at least that's how http://www.khronos.org/openvg defines it.

The problem is that there is no Open Source implementation. And the implementation that claims to be the reference implementation is closed. It'ss a rather silly situation, especially given how important vector graphics is becoming on our desktops/mobile devices nowadays.

After this introduction I'm sure you already know that I went ahead and started an Open Source implementation of OpenVG. I did it on top of QtOpenGL. The main reason for it is that QtOpenGL, quality and speed wise (in Qt 4.3) beats everything out there - every vector graphics framework.

So, there's a git repository at:
http://gitweb.freedesktop.org/?p=users/zack/openvg.git;a=summary
there's an example included, that animates and looks like this:Gears demos are mandatory for any kinds of hardware accelerated API it seems ;) Oh, and due of all the extra features that went in Qt 4.3, Qt snapshots are currently required to compile it.

I'm not sure where this is going to go. It will largely depend on whether there's real interest in it. In general I think it'd be interesting to see KDE have a library that would allow running of OpenVG based content right on KDE. It could be potentially an incredibly powerful feature of KDE as a platform, to support the hardware accelerated vector graphics api.

More boolean ops

I've spent most of the day just playing around with different degenerate cases of boolean operations. I've recorded a short movie showing some live path merging - the one case that should be interesting to application developer is combining two simple rounded rectangles to produce a frame with, what one can easily imagine to be, a highlighted selection on the left. Note that in this case two simple rectangles are enough to produce animation of the selection rectangle on the left going up and down between the "imagined" items :)

And also I forgot a very important thing, which is that Gunnar and Eskil hooked me up with a very cool QtJambi mug. They're doing an amazing job (working on QtJambi, not giving out cups). And here's the mug (and the last I checked, the thing holding it, was me).

Set operations on paths

I'm virtually never excited about the things I have implemented. Partially because I've been working on computer graphics for quite a while and a lot of what I do comes down to doing things that I've done before for different software, or in a different scenario. Writing code while knowing exactly what problems you'll end up facing and how to solve each one of them is very mundane and it makes it hard to get excited about it once you're done. So whenever I have a little bit of time I try to sit down and implement something that hasn't been done before.

So, here's problem #1: one of my embarrassments in the Qt X11 engine is that fact that we don't do anti-aliased clipping there. So if you'll clip out a rounded rectangle in your viewport/widget it will leave out nasty jaggies on the sides. We do it correctly on Windows but not on X.

Main reason for why we haven't done it, is that Qt has this nice concept of combining clip-regions which requires basically a full fledged implementation of boolean set operations on polygons to work correctly.

And here's problem #2: in Qt we have this class called QPainterPath which is a resolution independent, geometrical representation of some rendering. We got reports from people saying it would be really great if people could use boolean set operations with QPainterPath's. And I agree. Set operations on QPainterPath's would be an incredibly powerful feature, especially for animations.

Requirements for a state of the art algorithm here would be: fast, works with all kinds of degeneracies and operates directly on paths without intermediate conversion to polygons. The issue is that none of those things is usually associated with set operations on polygons.

In 1998 a paper entitled "Efficient clipping of arbitrary polygons" was published by Günther Greiner and Kai Hormann. It's a great paper, unfortunately the algorithm doesn't handle degenerate cases at all. This November Dae Hyun Kim and Myoung-Jun Kim published a paper entitled "An Extension of Polygon Clipping To Resolve Degenerate Cases" which addressed the shortcoming of the algorithm described by Greiner. The paper was a little short on details though so I've emailed Dae Hyun Kim who was kind enough to send me the full, original version of their papers. It's a tremendous paper and I'm very grateful to Dae Hyun Kim for sending me it.

Equipped with the paper I've sat down to modify the algorithm to handle paths, which was the last of my requirements for it. The research done in both papers was dedicated to polygons, while I wanted to apply it to paths, where curves are first class citizens. The main difference between polygons and paths. for the purposes of our new algorithm. is that with polygons any two segments can intersect in at most one point, with paths two arbitrary segments can intersect each other in at most 9 points. Furthermore with paths one segment can intersect itself. That plus a few smaller issues are causes of serious woes when working with paths in computational geometry - reason why basically no one does it.

Qt does now though. And yeah, I'm very excited about it. The new algorithm deserves a research paper of its own and if I'll have some spare time I'll definitely write a little bit about it.

I really needed this. I needed to do something that was very unique from a purely mathematical/computer science perspective rather than "oh, hey i fixed this bug/implemented this feature" type of stuff to keep me motivated. A screenshot showing a path (in dark gray fill and black outline) created from an intersection (boolean "And" operation) of two paths (the dashed blue and red objects) is shown below.

The number of effects and things that can be done with boolean set operations on paths is tremendous (not even mentioning the clipping :) ). You can be sure I'll write at least a few demos to show how to do very neat effects by differently combining few very simple paths.

Blend modes and dash offsets

Draft of SVG 1.2 Full adds composition modes to SVG. Besides the typical Porter&Duff operators some additional blend modes are defined in it. Those modes are also very commonly seen in many Adobe Photoshop tutorials and people frequently asked for them in Qt. They include "screen", "multiply", "overlay", "plus", "difference", "hard and soft light" and a few less prominent ones.

We decided to implement them for 4.3. Unfortunately Gunnar said that he simply won't have time to implement them and since I consider them to be very important I sat down after work today and implemted those blend modes in Qt. So if you checkout tonight's snapshot of Qt you'll nice that QPainter has new CompositionMode's. If you looked at some of the Photoshop tutorials on the net on how to do lightning effects, now you'll be able to do them all in Qt which is rather nice.

Once I did that I decided that I'll go ahead and implement the other feature that was missing in Qt and is required by SVG which is: dash offsets for stroke. API wise to QPen and QPainterPathStroker I just added setDashOffset(qreal offset) methods which respectively set the dash offset for the rendering operations in Qt.

To play around with blend modes I took two input images - CD cover image from a band called H2O and a flare generated with Gimp, they looked as follows:

And I wrote a simple application that blends those in real time, and the results of two of the modes look as follows:

One can do a lot of really interesting things with the new blend modes.
Oh, and since I'm weird like that I just went ahead and added support for composition modes (and dash offsets of course) to QtSvg and from what I see QtSvg is currently the only open source SVG renderer supporting the extended blend modes which is a nice bonus :)

Rotations

I didn't have time or motivation lately to talk about the things I am doing but today I wanted to mention something because I think it will make your life a little more exciting (that's assuming you like adding eye-candy to your applications).

Andreas and I were talking yesterday and to my great surprise he mentioned that not everyone can do 3D math in their heads. Furthermore he insisted that some people might have a problem with using QTransform::quadToQuad method which I added as a convenience method to the QTransform class. He went as far as to say that some people might not know how to transform one quad into another in 3D space. Of course in no way do I believe him, but after a short discussions we decided that adding QTransform::rotate(qreal angle, Qt::Axis axis) method to QTransform which lets one rotate an object about any arbitrary axis (X, Y and Z) would help some people.
I'm swamped with work so Samuel took this task of me and implemented that method today.

Anyway, if you quickly need to add some nice effects to your application without feeling like doing any work just use QTransform::rotate and blow people's mind ;) A short Ogg movie showing qtransform2 (you'll of course need the latest Qt snapshot to compile it) in action is here and it looks like this:

California and Cheese

Last week I was in California with Lars. It was a pretty vicious trip. Partially caused by the fact that I abhor flying. I don't have anything against the action of flying itself, but I do have a lot against the airlines. And the fact that Snapple icetea has been taken away from me 3 times on this trip is just atrocious. First they took my Snapple when I was going from New York to San Francisco, then they took 2 more before the San Francisco, Munich flights and finally I was completely stripped when flying from Munich to Oslo. Heartbreaking.

George, Lars and I spent a little bit of time hacking on WebKit. As a result we have our changes merged in the main WebKit repository. Yesterday I've setup a new buildbot and we were able to take down the machine that was heating WildFox's apartment ;) If you're planning to checkout WebKit make sure you look at http://build.webkit.org and see whether in post-commit-linux-qt column the "compiled release" box is green, if it is everything compiles. We're going through some major changes so things break every few hours. If you want to build WebKit just do a svn checkout and follow it with ./WebKitTools/Scripts/build-webkit command, that should be enough to have WebKitQt/QtLauncher compiled and running. There's a lot of things busted at the moment because of the above mentioned changes. We'll fix them once some of the architectural changes that we need will land. Currently I'm serving as the reviewer of all the Qt code which I hope, with time, is going to change as more people gets familiar with it.

Most importantly though, I'd like to thank the person who sent me cheese. Lots of cheese. You absolutely and totally rock. If not the fact that I'm already emotionally involved with Free Software, I'd be all yours. I'm very certain you'd love to see my face when our secretary came to my office and said "your cheese is here". Although it's a perfectly valid sentence, I felt really confused and being certain I never ordered cheese in my life, was seconds away from suing Trolltech over sexual-harassment (I'm not 100% sure why, but I always wanted to do that). Oh, and Norwegian government being definitely anti-me didn't want to deliver the cheese and decided that I have to pay taxes on it. Plus in all their glorious intelligence they decided that something that is marked as "cheese" clearly needs to stay in a warm place while being kept away. Despite Norwegian customs doing their "best" it was one of the coolest gifts ever.

Resolution independence for icons

Jakub Steiner wrote an interesting blog about woes of creating resolution independent icons. It's a problem I've been thinking about during the last few days, one that has been solved, at least to some extend, already.

It was solved for fonts. Grid-fitting (aka. "font hinting") is a crucial step on the way to produce legible output at small sizes for any font. Hinting can be manual (e.g TrueType has a stack-based language for it, each glyph in the font contains its own little hint program and as a result of running that program control points for the outlines can be adjusted in any way the creator of the hints desired) or automatic (as used by FreeType). An interesting medium is described in "Example-Based Hinting of TrueType Fonts" paper, in which a method of reusing hints from one font for another are described. All in all it's a very common problem for fonts.

The iSlayer blog that Jakub mentioned makes it very clear we need it fast. His example showing how much worse his logo looks in the vector form than the as bitmap looks almost precisely like the "example of hinting" image that can be found on Wikipedia:
(The upper sample in each case is unhinted)
When talking about fonts we're just dealing with a subset of our exact problem.

In Qt, Gunnar just implemented support for non-scaling stroke, which is great. Now we need to figure out a way of doing automatic hinting for vector shapes and we'll be set.

I've always been all for manual adjustment of icons on a pixel-by-pixel basis, simply because they looked a lot better, but during the last few days I've became convinced that we can, in fact, create resolution independent icons. Or let me rephrase, not "resolution independent icons" but "icons that preserve their good looks across resolutions". We have the former, we need the latter.

I'm taking a week off and that's exactly what I'll work now.

I think manual hinting is too cumbersome and we'd need a new container format for icons to make it really work. A way of specifying a whole icon theme along hints for each icon to make them look good across different resolutions wouldn't necessarily be a bad idea. In fact that would be great, it's the problem of developing the way of storing and producing those hints that would be quite challenging. XML format (with some namespace of course) that can be embedded right in the SVG's would probably work fairly well but I'm afraid wouldn't be enough. Then there's also a question of how would we get artists to create those hints.

No, I think auto-hinting makes a lot more sense here. The research FreeType people did in that area is outstanding.

All in all, I think I can make it work =)

Oh, and if you have a SVG icon that you hand-adjusted to produce a better looking bitmap, I'd appreciate a lot if you could send me both examples via email to <my first name>@kde.org address so that I have some testcases to work with :)

WebKit and new examples

With 4.3 snapshots out I updated the list of my examples with a few new ones:
Animation along a path,

And text on a path that I mentioned in the previous blog.

And two examples showing perspective transformations here and here.

Last week I finally got a new laptop. I bought a Sony Vaio SZ340. Mainly because it came with two gpu's, and for a 13"" laptop that's a very unique feature. In general everything works ok (sleeping, cpu frequency scaling, ethernet, wifi, audio). Battery life for some reason is abysmal at around 1.5 hours even though both cores seem to be scaled correctly. I haven't had the time or motivation to figure out what's causing it though. All in all I'm pretty happy with it so far.

In completely unrelated news I became a WebKit reviewer. To answer all the questions about what does that mean for KDE I have to say that right now it doesn't mean anything. KDE is a community, in which technical decisions emerge in the process of natural selection. If we'll manage to get WebKit Qt/KDE ports working better than KHTML does right now, the transition from our own KHTML repository is going to be fluent and natural. If we won't be able to do that, then we'll still have our own version of KHTML. In my opinion, working on WebKit is, from a purely pragmatic point of view, the right thing to do. Working on new features and maintaining a web engine are very complex tasks that we can make a lot, lot simpler by sharing the burden with WebKit contributors.

Text on a path

Yesterday a rather large selection of trolls went to see Borat and while waiting for the movie to start Simon and I started talking about adding support for layouting of text on a path in Qt. I've sat down today, did the necessary math and added some extra members to QPainterPath and QBezier to make it all work. As always I wrote a short demo to illustrate what I'm talking about. I felt a little guilty tough because while I never blog about politics I see more and more people on planetkde feeling obliged to share their opinions on the world of politics. So my hard hitting politically charged statement for today is "i really like cookies". Discuss among yourselves.
With visual aids the results of it all are shown in this short Ogg Theora video file here and the screenshots look like this:


It's actually pretty neat (the code, not the fact that I like cookies). It's not yet integrated at all within the QTextDocument (also the code and not the cookies) framework but hopefully we'll be able to figure something out (both the code and the cookies) before Qt 4.3.

Expressing myself

Simon and I went for a few days to Berlin. It was a lot of fun. Being able to hang out with Ellen, Scott, Espen and Matthias is always great.
Ellen is vegetarian, so thanks to her I've eaten better in Berlin than I think I did the whole last year (granted that my frame of reference is all messed up when it comes to food, but still).
On Tuesday Scott dragged us to a free jazz concert. Simon even contemplated joining and playing along. I was busy being generally freaked out. In the middle of the thing one of the guys playing, walked away from his keyboard, lied down in the middle, on his back, hiked his legs way up in the air and started wiggling his feet. Everyone was clapping and cheering. I've learned that he was not "messed up" as I, personally thought, but was "expressing himself" which is a good thing. I'm not 100% certain how to distinguish between the two but I'm sure I can use this "expressing myself" thing to my advantage. In fact Simon and I kept expressing ourselves throughout our stay in Berlin by getting lost all the time. It's not that we had no clue where we were going - we were simply trying to show that humans, as individuals, are sometimes getting lost in this great world, but no matter how lost one gets, how smelly the subway is that took one the wrong direction or how funny the word "wurst" is, there always is Ellen waiting with some food or maybe even Snapple's... Or something along those lines. I'm still trying to work out this pretentious art thing, but I think I almost got it.
Simon and I even had a few minutes to look at WebKit. I haven't looked at it since we have done the initial port. We fixed most of the serious issues. The rendered pages should all look fine.

I still have 3 patches in WebKit's bugzilla but hopefully they'll get in soon. It feels a little weird to be writing patches, for code that I wrote, fixing my bugs in a project I've been working on for so long and not being able to commit myself. Waiting for others to review and commit my patches to my code is a little, well, silly. But I understand, they changed some style rules and are trying to keep it consistent, while my motivation to read "style guide" documents is basically zero so it's ok to have people look over the patches to make sure they match the style guide.

Right now it mostly sucks for me because I'm forced to keep a few patchsets and since a few of them are not in the main repository, I have to be reverting them to work on fixing something else and wait for them to be committed to the main repository. I think it will take me two or three days of spare-time work to get it to a point where it's more/less usable and once it's there I can comfortably leave it to George and Niko who did amazing job up till now. Plus there seems to be great interest in it from others. Personally, with my todo, I couldn't be bothered to work like I am right now - maintaining local patchsets and reverting and applying them over again, that workflow is just too painful to keep it up. I have this strange perversion where I like to commit my patches to my code myself =) But as I found out in Germany, that's not weird, that's just me expressing myself.

GLOverlay

I uploaded another wonderful Qt example to http://ktown.kde.org/~zrusin/examples. This example has been written by Trond Kjernaasen (one of the Samurai Graphics Assassins, hobbies include death metal and beating Trolltech's QA department at ping-pong). The example shows a wonderful mixing of OpenGL with Qt native rendering. You can type in any phrase, the application will try to look up the images on flicker and then display them in a very eye-candish kind of a way. The application looks like this (but remember it's all nicely animated so you want to see it on your machine).
Trond uses pbuffers to make it all work together so make sure your card supports them. Direct link to the code is here. (some people reported crashes when running on latest NVIDIA driver so watch out ;) )