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Qt-interest Archive, July 2007
Qt3 to Qt4: QTreeView change expanded decoration..?

Message 1 in thread

Hi,

I'm currently moving an application from qt3 to qt4 (4.3) and I'm trying 
to convert Q3ListView based code to QTreeView with an ItemModel and an 
ItemDelegate.

In qt3 i have code that changes an item decoration if it gets expanded 
(pseudocode, the string represents the Pixmaps):


class BookmarkLvi : public Q3ListViewItem
...

void BookmarkLvi::setOpen(bool open)
{
   if(open)
     setPixmap( 0, "openend" );
   else
     setPixmap( 0, "closed" );
}


What's the simplest way to build this with an QTreeView and an ItemModel?


I came up with the following code but I'm not very happy with it because 
i now have icon related in a delegate and the model.

Delegate:

// I'm ignoring the parameter pixmap here and simply overwrite it with
// the correct pixmap.

void drawDecoration( ... const QPixmap& pixmap ) const
{
   if( option.state & QStyle::State_Open )
     super::drawDecoration(painter,option,rect,"openend");
   else
     super::drawDecoration(painter,option,rect,"closed");
}


// unfortunately i have to return a dummy pixmap with size information
// from the model. Without it drawDecoration is not called.

Model:

QVariant BookmarkViewItemModel::data( ... )
{
...
   if( role == Qt::DecorationRole )
     return QPixmap(16,14);
...
}


Any better idea?



Martin



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