Latest Postings by Michael
How to customize your view with delegates
The usual way in Qt, when an item view wants to render itself, is to ask the item model for everything, layout, style and the actual data. Storing view-specific layout information in the model itself means that views and models can always only exist in a 1:1 relationship. The logical conclusion: If you need to share a model between different views, you will probably have to add proxy models for each view. I wasn't satisfied with that idea, so I continued to research QStyledItemDelegates. They ...
Fragile API and invalid iterators
For the Miniature project I sometimes need to iterate over all graphics items in a QGraphicsScene, or more precisely, all items of a specific parent item, the chess board itself. For that, I use the QGraphicsItem::childItems() API. However, when used with STL-style iterators you have to be careful, since value types of that form can easily break the iterator idiom:
for (QList<QGraphicsItem *>::iterator iter = parent_item->childItems().begin();
iter != parent_item->childItems().end();
++iter)
{
...
About delegates and cell renderers - data formatting in Qt
Warning: the following blog post has a rant-to-usefulness ratio of 3:1.
Last week I needed to perform some data formatting on Qt list view. From reading the documentation alone I could not find a satisfying answer. When asking on IRC the answer was to use proxy models. This would have worked, but having two models for one view can create all kind of correspondence problems (think of sorting etc.). And there is [this ...
First Miniature .debs sighted!
Thanks to Mathias, Miniature is now suitable for debian packaging. He also uploaded a first test balloon which at least allows you to move pieces around. Feedback is of course more than welcome.
Personally I wish the board's cell size could have been made bigger, but 60x60 pixels is already the upper limit. It is now up to us ...
Qt 4.6 for Maemo: It works!
Today at work, David King kindly informed me that there was some new Qt package in extras-devel. This could only mean one thing - I immediately fired up my scratchbox environment and installed the packages, trying to confirm that this new version would run with Qlom. And in fact, it was surprisingly painless. Thanks to autotroll, a simple QT_PATH env variable did all the magic, hooray! ...
Miniature - it moves!
How it begun
Wt - a Qt-ish web toolkit written in C++
First of all, C++ for web apps doesn't necessarily make it easier to write them. Compared to other solutions (let's say Django) you'll end up writing a lot more code. And you have to be very very careful with memory leaks.
But that isn't the point. The main advantage of this framework is how close it is to desktop applications. Porting your Qt desktop application to the web is certainly easier with Wt than with any other solution, as you keep most of the widget API and also the signal and slots paradigm (which should allow to port the ...
Show me your home screen!
To me the empty home screen* of the N900 looked like an invitation, so I tried to fill it up with useless stuff as quickly as possible. The home screen configuration menu offers app launchers (shortcuts), bookmarks, widgets and contacts. Let's go through all four options in detail:
- Shortcuts: I almost always have some tasks running in the background so launching an application would usually take three to four finger touches. Therefore the app launchers are extremely helpful to ...
Computer chess and the N900
My first chess computer
Years ago, when I was thoroughly fascinated by chess, I always wanted a portable chess computer. When I finally got one (a Novag Piccolo, for the odd chance someone else had the same device) I'd take it with me whenever possible. It got worn out quickly, moving the small plastic figures required more and more pressure to make the computer acknowledge my moves. For each move you first had to "touch" the figure you wanted to move. The computer would beep ...
Who wants my feedback for the Maemo6-Qt tech preview?
During the Maemo Summit there were several talks about the upcoming Maemo 6 platform and also about the transition from GTK+/Hildon to Qt. One of them - the "(Introduction to the) Harmattan UI framework" also mentioned where to get the code for the Maemo 6 UI Framework from. So I went there and cloned the two available repos (tech preview of the framework ...
Why Squeak is not the answer, part 2
Error handling (or god forbid, exception handling) is one of the weak parts in Squeak. A great deal of course comes from its dynamically typed nature. However, the greater impact probably comes from the utter lack of guard clauses in most core librares I've seen so far: Objects will happily accept any kind of parameter and continue to wrack havoc on them until the debugger, at some later point (IF we are lucky), stops the travesty.
Let's move on to BitBlits, where the lack of parameter checking and the absence of proper initialization quickly crashes your VM. Why use BitBlits at all? Because Morphics are crap. More precisely, they feature:
- poor performance (I guess all the redrawing with overlapping Morphic instances doesn't come for free),
- a hideously complex class hierarchy
- undocumented models (say, the model ...
Why Squeak is not the answer
For some time now I've been busy with Squeak. It's nice to get a chance to work with Smalltalk which is one of the most consistent languages I've ever seen. This probably doesn't mean much - I haven't seen that many languages yet. Of course consistency comes with a price but I can appreciate the idea. And yes, I think "Everything is an object" and Garbage Collection are great concepts. The fomer ...
First steps with Qt
I started to look into Qt with the help of "Foundations of Qt Development" by Johan Thelin. As with its counter-part it shares the decent text and the sometimes not-so-convincing examples. Perhaps code examples from a book should generally be maintained like a real project (including bugtracker, mailing list/forum and public repository), since that allows the examples to improve over time.
...
U2 line overhaul
One of the oldest Berlin U-Bahn lines, the U2, gets overhauled. It feels strange, now that the bridge at Schönhauser Allee/Bornholmer Strasse is missing. Hopefully the new one won't look too modern since I really like the Magistratsschirm (neudeutsch: "U-Bahn-Viadukt", bleh).
Goodbye Energie Cottbus
Since the Taschenorakel has become a football newsticker I thought I chime in with my feelings. Energie Cottbus might not deserve being in the premier league, as some would say (I certainly disagree). But at least they fight! Now with the 0:3 against the FCN in the first part of the relegation duel it doesn't look too bright. And I had ...
