[Interest] Replacing QIcon with QImage in a existing model, how can i do that?

Mark markg85 at gmail.com
Sat Nov 24 22:43:54 CET 2012


I'm working on a model structure where i have a file overview. Now
files can mean images as well and in the background there is a process
running that looks up the images and makes thumbnails from it.

So by default i show a QIcon because creating the thumbnail could take
a while on big folders and that would slow everything down in the
model if i where to add it directly. When the thumbnail is created it
should replace the current QIcon.

How i'm fetching the index is like this:
QModelIndex modelIndex = index(row, 0);

Yes, 0 for the column. And i'm guessing that's where i do things
wrong. The roles look as follows:
    QHash<int, QByteArray>roleNames;
    roleNames[Qt::DecorationRole] = "decoration";
    roleNames[Thumbnail]                = "Thumbnail";

Now i was expecting this to work:
setData(modelIndex, _my_qimage_thumbnail_, Thumbnail);

Sadly that doesn't work. setData will just return false. So what am i
doing wrong here? Is the index build up wrongly? Or do i need to do
some different role stuff?

Oddly, getting the data (The current QIcon) does work in the same fashion:
data(index, Thumbnail);

That works just fine so that leads me to think that the index is fine..

Any help would be very much appreciated.
Btw. this is Qt 4.8.3, not 5.0.


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