Dear All,
I currently get to know the Qt Model/View classes. So I went on and created a
subclass of QAbstractItemModel to provide the data for the different views in
Qt. As my structure is tree like, I followed the SimpleTreeModel example that
comes with Qt.
At first, I had some problems implementing the required functions correctly
(data, index, parent, rowCount, columnCount). So I added some output at the
top of each function. Finally I got everything to work and the data is being
displayed correctly.
However, one thing I noticed is that whenever the view changes focus or it is
resized the complete model seems to redrawn. After looking at my code checking
why this would happen I decided to put the same output at the top of every
function in the SimpleTreeModel:
it has the same result.
Reducing the number lines that get parsed in the SimpleTreeModel to two
produces this 'stacktrace' for the above mentioned case:
4x TM::columnCount QModelIndex(-1,-1,0x0,QObject(0x0) )
8x TM::headerData
TM::rowCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::columnCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::rowCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::columnCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::rowCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::index QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::rowCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::columnCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::rowCount QModelIndex(0,0,0x19e3ad0,TreeModel(0x7fff3f3aa590) )
TM::columnCount QModelIndex(0,0,0x19e3ad0,TreeModel(0x7fff3f3aa590) )
TM::columnCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::parent QModelIndex(0,0,0x19e3ad0,TreeModel(0x7fff3f3aa590) )
TM::index QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::rowCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::columnCount QModelIndex(-1,-1,0x0,QObject(0x0) )
8x TM::data QModelIndex(0,0,0x19e3ad0,TreeModel(0x7fff3f3aa590) ) 8
TM::index QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::rowCount QModelIndex(-1,-1,0x0,QObject(0x0) )
TM::columnCount QModelIndex(-1,-1,0x0,QObject(0x0) )
8x TM::data QModelIndex(0,1,0x19e3ad0,TreeModel(0x7fff3f3aa590) ) 13
8x TM::headerData
For a rather large model this seems quite some work. So my question is, is
this behaviour to be expected?
Thanks for your help
Christian
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