[Qt-interest] Adding multiple checkboxes to a QTreeView with QFileSystemModel

[Sven Grunewaldt]

Hey Andre,

thanks for your reply. I tried creating a proxy model but after some
days of fiddling around I have to give up, I don't know how to code this
properly...

I uploaded my current source code to http://pastebin.ca/1900964
Maybe someone can look into it and give me directions.

What my code should do: Prepend three columns containing the text
"Checkbox N" to the existing columns.

Sadly it has several problems:
- only the first column of the source model is shown after my three columns
- there are no more children to the items

Maybe this really can't be done... then I'd "recreate" QFileSystemModel
with a completely new QAbstractItemModel. Though I think that a a proxy
model would be a better way...

Regards,
Sven Grunewaldt

Am 12.07.2010 21:37, schrieb Andre Somers:
> Op 12-7-2010 14:57, Sven Grunewaldt schreef:
>> Hi,
>>
>> I need multiple (currently 3, maybe more in the future) Checkboxes in
>> front of the first column in a QTreeView. The view is populated by a
>> QFileSystemModel.
>>
>> All the examples I can find are about adding ONE checkbox which can be
>> achieved by setting the checkable-flag or so. Sadly this doesn't work
>> for more than one checkbox...
>>
>> I tried QItemDelegate but I don't understand how I should use a delegate
>> to add multiple checkboxes in ONE column, I guess this class is not made
>> for stuff like this.
>> After that I tried subclassing QFileSystemModel and implementing my own
>> data() function which calls the parent function when the column is
>> higher than 0, but this leads to access violations and other funny stuff...
>>
>> How can I achieve this? I'm at a total loss right now...
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>>
>>    
> You have two issues to address: the first is to actually show the check 
> boxes, but you will also have to think about how you are going to store 
> the check state.
> 
> The ultimate solution depends on your exact needs. Would it be 
> acceptable for you to have the checkboxes in separate columns? Or do you 
> need them all in the first column?
> If separate columns are acceptable, then I think I would prefer using a 
> method where you use a proxy model to add columns to an existing model, 
> and keep track of the checkstate of each of the items. That would be the 
> simplest option by far.
> 
> However, if you do need to have all three checkboxes in the same column, 
> you have no option than to use a delegate. Drawing the checkboxes can be 
> done using the methods supplied by QStyle. Look at how 
> QStyledItemDelegate is implemented for inspiration. It is not trivial! 
> You also need to take care to handle mouse clicks on the items 
> (QAbstractItemDelegate provides a method for this), as well as think of 
> a way to store the state of the items.
> 
> André
> 
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