The situation: In Qt I have to get some data ready in an application but it doesn't all need to be ready at the start so I want to get some to begin with and then continue getting the rest in the background without freezing the UI. Also I need to be able to stop this data getting for when I want to run a high precision timer with high accuracy.
First attempted solution: Subclassing QThread (though this is not recommended, see http://labs.qt.nokia.com/2010/06/17/youre-doing-it-wrong/).
Basically in this case, i make the run method of a QThread subclass do a little piece of the data processing. There are 2 disadvantages to this method, firstly, it has a large overhead creating a whole thread and secondly you also have to implement your own pause and resume functions as QThread does not come with these.
The used solution: Write a slot that performs a single part of the data processing, connect it to the timeout() slot of a QTimer and then call QTimer->start(0) where the 0 is a special value to QTimer indicating that it should only fire when the application is idle (see http://doc.trolltech.com/4.6/qtimer.html#interval-prop). This method also makes pausing and resuming very very simple as to pause you just need to call QTimer->stop() and then to start again call QTimer->start(0).
This solution works ridiculously well in my application and the ease of pausing and resuming really is a treat.