How to turn off this annoying feature of QColumnView?

[jwieland]

Hi all,

I use a QStandardItemModel coupled with QColumnView to display a list of simple hierarchal tree structure. My view has 2 columns, rows on the second columns are children of a item on first column. When user select a item/row on column 1, children of that item/row will be displayed on second column. Now here comes the annoying behavior of the QColumnView: although my list has only 2 columns, whenever user click on an item of the second column, it automatically rolls further to the third column on the right (which is empty).

How do I disable this annoyed feature so that even if user click on a row in second column, the view does not automatically roll horizontally?

Thank you for all your help.

[wysota]

Try reimplementing QColumnView::createColumn() and returning 0. But in general it might be easier for you to substitute the column view with two list views. After all, the column view is for something different...

[jwieland]

Thanks Wysota. That what I will do (using 2 lists). BTW, Could you elaborate on what QColumnView is intended for?

[wysota]

It's a widget originating on Mac for showing filesystem contents. The final column is meant to show a preview of a node (file) chosen in the previous column.

[LarryERamey]

I attempted to do exactly this....and it dies on me.

namespace systemoutliner
{
  class MyColumnView : public QColumnView
  {
 
    Q_OBJECT
 
    public:
 
    MyColumnView(QWidget* parent=NULL);
    ~MyColumnView();
    protected:
    virtual QAbstractItemView * createColumn ( const QModelIndex & index );
 
  };
}
 
 
namespace systemoutliner
{
  MyColumnView::MyColumnView(QWidget* parent):
    QColumnView(parent)
  {
  }
  MyColumnView::~MyColumnView()
  {
  }
 
  QAbstractItemView* MyColumnView::createColumn ( const QModelIndex &)
  {
    return NULL;
  }
}

namespace systemoutliner
{
  class MyColumnView : public QColumnView
  {
    
    Q_OBJECT
    
    public:
    
    MyColumnView(QWidget* parent=NULL);
    ~MyColumnView();
    protected:
    virtual QAbstractItemView * createColumn ( const QModelIndex & index );
    
  };
}


namespace systemoutliner
{
  MyColumnView::MyColumnView(QWidget* parent):
    QColumnView(parent)
  {
  }
  MyColumnView::~MyColumnView()
  {
  }

  QAbstractItemView* MyColumnView::createColumn ( const QModelIndex &)
  {
    return NULL;
  }
}

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And when I try to connect a Model to this view I get this error:

QObject::connect: Cannot connect (null)::clicked(QModelIndex) to systemoutliner::MyColumnView::_q_clicked(QModelInd ex)
QObject::connect: Cannot connect (null)::activated(QModelIndex) to systemoutliner::MyColumnView::activated(QModelInde x)
QObject::connect: Cannot connect (null)::clicked(QModelIndex) to systemoutliner::MyColumnView::clicked(QModelIndex)
QObject::connect: Cannot connect (null)::doubleClicked(QModelIndex) to systemoutliner::MyColumnView::doubleClicked(QModel Index)
QObject::connect: Cannot connect (null)::entered(QModelIndex) to systemoutliner::MyColumnView::entered(QModelIndex)
QObject::connect: Cannot connect (null):ressed(QModelIndex) to systemoutliner::MyColumnView:ressed(QModelIndex)




Any ideas?

[tbscope]

Your code doesn't show where these connections are made.

[LarryERamey]

sorry...

MyColumnView *columnView =  new MyColumnView();
    //QColumnView* columnView = new QColumnView();
ColumnModel *columnModel = new ColumnModel(inspectorGadget);
columnView->setFocusPolicy(Qt::NoFocus);
columnView->setModel(columnModel);

MyColumnView *columnView =  new MyColumnView();
    //QColumnView* columnView = new QColumnView();
ColumnModel *columnModel = new ColumnModel(inspectorGadget);
columnView->setFocusPolicy(Qt::NoFocus);
columnView->setModel(columnModel);

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Line 5 explodes.....

ColumnModel is my own QAbstractModel class, but it works just fine with the default QColumnview.

Thanks,
Larry

[ChrisW67]

You still don't show where these connect() calls are being made. The error messages are coming from using a null pointer as the first argument to the connect() calls listed.

[LarryERamey]

well.... I didn't write the connect calls that are failing? I'm inheriting from a QAbsractItemModel and I'm overloading a QColumnView.

None of those pointers are NULL in the debugger when I make that setModel call so I am a bit puzzled. I guess I'll have to compile the Qt libs debug so I can step into them and see where is exploding.

[wysota]

You are returning a null pointer from QColumnView::createColumn() reimplementation so no wonder you get such messages. You have to return a widget there. You can hide it afterwards if you don't want it but it has to be there.

[LarryERamey]

Ahhh.....

That is a bummer since your original suggestion was to return a 0. I have opened the QColumnView.cpp and yeah, its pretty obvious that returning a NULL in that function is going to blow up the world.....

I'm looking right now, but does anyone have a quick suggestion to turn off the preview column in QColumnView?

[wysota]

I have given you a suggestion already. Hide the column.