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Qtableview verticalheader show icon instead of numbers


  • Lifetime Qt Champion

    Always initializes all your pointers in the constructor either to something valid or NULL like in this case.

    And check for NULL for all pointer variables that are initialized to NULL each time you'll be using these variables



  • Yes, the probem caused by non initialisation of m_selectionModel pointer

    but still i have a small a problem

    when i select a row the icon show up, but when i leave the row (i can't get the icon disappear
    @if(m_selectionModel)
    {
    QModelIndexList indexList = m_selectionModel->selection().indexes();
    if(!indexList.isEmpty())
    {
    QModelIndex index = indexList.at(0);
    if(index.isValid() )
    return QPixmap("imgs/arrow.png");
    }else{
    return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);

                }
    
            }else{
                return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
            }
    

    @


  • Moderators

    @Andre: The headerDataChanged() signal doesn't get emitted with this method, correct? Thus the view won't be notified to update the headers when it's meant to?

    [quote author="advseo32" date="1375459821"]i'm not familiare with debugger[/quote]Take time to learn. It's a very valuable tool for programmers: http://qt-project.org/doc/qtcreator-2.8/creator-debugging.html



  • [quote author="SGaist" date="1375475299"]Always initializes all your pointers in the constructor either to something valid or NULL like in this case.

    And check for NULL for all pointer variables that are initialized to NULL each time you'll be using these variables[/quote]
    Ok, i got it now :)



  • bq.
    [quote author="advseo32" date="1375459821"]i'm not familiare with debugger[/quote]Take time to learn. It's a very valuable tool for programmers: http://qt-project.org/doc/qtcreator-2.8/creator-debugging.html[/quote]

    thanks JKSH, i will learn how i can use debugger



  • the icon showed randomly in vertical header

    her is my code @switch (role) {
    case Qt::DecorationRole :
    if(m_selectionModel)
    {
    QModelIndexList indexList = m_selectionModel->selection().indexes();
    if(!indexList.isEmpty())
    {
    QModelIndex index = indexList.at(0);
    if(index.isValid() )
    {
    for (int i=0;i<this->rowCount();++i)
    {
    if(i == index.row())
    return QPixmap("imgs/arrow.png");
    else
    return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
    }
    }
    }else
    return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);

            }else
                return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
    
    
            break;
        default:
            QSortFilterProxyModel::headerData(section,orientation,role);
            break;
        }@


  • [quote author="JKSH" date="1375487264"]@Andre: The headerDataChanged() signal doesn't get emitted with this method, correct? Thus the view won't be notified to update the headers when it's meant to?[/quote]

    The point of my answer was not to provide a complete, ready to use solution, but give a pointer in the right direction. Emitting the changed signal was considered as an excersise for the reader, as was properly initializing the pointer to the selection model. The code I showed was just typed in quickly directly in the forum editor...



  • i have emitted a signal to inform changes in vertical header but it won't
    compile

    and show me this error @E:\apprendreQt\gestionstock5\mytablemodel.cpp:54: erreur : passing 'const MytableModel' as 'this' argument of 'void QAbstractItemModel::headerDataChanged(Qt::Orientation, int, int)' discards qualifiers [-fpermissive]@

    @if(m_selectionModel)
    {

                QModelIndexList indexList = m_selectionModel->selection().indexes();
                if(!indexList.isEmpty())
                {
                    QModelIndex index =   indexList.at(0);
                    if(index.isValid() )
                    {
                        emit headerDataChanged(Qt::Vertical,0,this->rowCount()-1);
                        return  QPixmap("imgs/arrow.png");
    
                    }
    
                }else
                    return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
            }else
                return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);@

  • Lifetime Qt Champion

    Because you can't emit a signal from a const function



  • [quote author="SGaist" date="1375558375"]Because you can't emit a signal from a const function[/quote]
    I don't know about this, thank's, but really i haven't an idea on
    where i will place this emit



  • i have tried many ways to infrome view that the data is changed
    with out any success

    @void MytableModel::SetSelectionModel(QItemSelectionModel* selection)
    {
    m_selectionModel = selection ;
    emit headerDataChanged(Qt::Vertical,0,this->rowCount()-1);
    }
    @

    i can't emit signal in const functions !! where i can emit that signal ?


  • Lifetime Qt Champion

    Well, you want that arrow showed when you select a row, right ? In that case you need to detect that a selection has been made/changed, then tell the world that your header data has changed.



  • [quote author="SGaist" date="1375652135"]Well, you want that arrow showed when you select a row, right ? In that case you need to detect that a selection has been made/changed, then tell the world that your header data has changed.[/quote]

    Yes,

    i have use this in my main and still not working, i don't know if is the correct place @ connect(listProduitTableView->selectionModel(),
    SIGNAL(selectionChanged(QItemSelection,QItemSelection)),listProduitTableView->verticalHeader(),
    SLOT(headerDataChanged(Qt::Vertical,int,int)));@


  • Lifetime Qt Champion

    You can't connect two signals with different signatures like that. When starting the application you should have seen an error about that on the console.

    Please read the Signals and Slots chapter in Qt's documentation.



  • [quote author="SGaist" date="1375653308"]You can't connect two signals with different signatures like that. When starting the application you should have seen an error about that on the console.

    Please read the Signals and Slots chapter in Qt's documentation.[/quote]
    Yeah! the console show me an error,

    i don't know what the signature , it's the parameters ???
    if yes , how i can connect Signal selectionChanged() with cheaderDataChanged()

    i tried to get this work, but it won't work for me , i miss many many concepts in model/view programming

    @ connect(listProduitTableView->selectionModel(),SIGNAL(currentRowChanged(QModelIndex,QModelIndex)),listProduitTableView->verticalHeader(),SLOT(dataChanged(QModelIndex,QModelIndex)));
    @

    or maybe my implement is wrong, plz check it out
    her is the header file of custommodel
    @#include <QSortFilterProxyModel>
    #include <QItemSelectionModel>
    class MytableModel : public QSortFilterProxyModel
    {
    public:
    explicit MytableModel(QObject parent = 0);
    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
    QVariant data(const QModelIndex &proxyIndex, int role) const;
    void SetSelectionModel(QItemSelectionModel
    selection) ;
    private:
    QItemSelectionModel *m_selectionModel;

    };@
    her is the cpp file of custommodel

    @#include "mytablemodel.h"
    #include <QPixmap>
    MytableModel::MytableModel(QObject *parent) : QSortFilterProxyModel(parent)

    {
    m_selectionModel = 0;

    }

    QVariant MytableModel::headerData(int section, Qt::Orientation orientation, int role) const
    {
    switch (orientation) {
    case Qt::Horizontal :
    switch (role) {
    case Qt::DisplayRole :
    switch (section) {
    case 0: return "Id";break;
    case 1: return "Reference";break;
    case 2: return "Designation";break;
    case 3: return "localisation";break;
    case 4: return "Famille";break;
    case 5: return "Qte min";break;
    case 6: return "Qte max";break;
    case 7: return "Qte disponible";break;
    case 8: return "Unité";break;
    case 9: return "Prix achat";break;
    case 10: return "Prix vente";break;
    default:
    return QString("Column %1").arg(section + 1);
    break;

               }
    
            break;
        default:
            QSortFilterProxyModel::headerData(section,orientation,role);
            break;
        }
        break;
    case Qt::Vertical :
        switch (role) {
        case Qt::DecorationRole :
            if(m_selectionModel)
            {
    
                QModelIndexList indexList = m_selectionModel->selection().indexes();
                if(!indexList.isEmpty())
                {
                    QModelIndex index =   indexList.at(0);
                    if(index.isValid() )
                    {
    
                        return  QPixmap("imgs/arrow.png");
    
                    }
    
                }else
                    return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
            }else
                return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
    
            break;
        default:
            return QSortFilterProxyModel::headerData(section,orientation,role);
            break;
        }
        break;
    default:
        return QSortFilterProxyModel::headerData(section,orientation,role);
        break;
    }
    
    
    
    return QVariant();
    

    }

    QVariant MytableModel::data(const QModelIndex &proxyIndex, int role) const
    {
    if(role == Qt::TextAlignmentRole)
    return Qt::AlignCenter;
    else if (role == Qt::DisplayRole)
    return QSortFilterProxyModel::data(proxyIndex , role);

    return QVariant();
    

    }

    void MytableModel::SetSelectionModel(QItemSelectionModel* selection)
    {
    m_selectionModel = selection ;
    }
    @
    @@



  • The signature of a function consists of the return type, the parameter types and constness of the function. You're expected to do your own debugging though.


  • Lifetime Qt Champion

    To add to what Andre said, function signature is not Qt specific, it's pure C/C++.

    Please take some time to look at the "Signal & Slots chapter":http://qt-project.org/doc/qt-4.8/signalsandslots.html of the documentation as well as the examples given.



  • i tried many solutions, i'm completly lost

    i have created a slots in my proxyModel
    @void emitHeaderChangedData(QModelIndex &current,QModelIndex &prev) ;@

    her code is
    @void MytableModel::emitHeaderChangedData(QModelIndex &current, QModelIndex &prev)
    {
    int currentRow = current.row();
    int previousRow = prev.row() ;
    emit headerDataChanged(Qt::Vertical,currentRow,previousRow);
    }

    @

    and i connect the signal currentRowChanged to that slots in my constructor , but it's still not working

    @MytableModel::MytableModel(QObject *parent) : QSortFilterProxyModel(parent)

    {
    m_selectionModel = 0;
    connect(m_selectionModel,SIGNAL(currentRowChanged(QModelIndex,QModelIndex)),
    this,SLOT(emitHeaderChangedData(QModelIndex&,QModelIndex&)));

    }

    @


  • Lifetime Qt Champion

    Just a quick question, why didn't you follow Andre's suggestion and use a QIdentityProxyModel ?



  • I'm using Andre's method her is the complete code

    header file

    i create a function to emit headerDatachanged but not works,

    @void MytableModel::emitHeaderChangedData(QModelIndex &current, QModelIndex &prev)@

    and i try to use connect in my constrector, also not working

    i don't know exactly what's the best way to emit that signal

    @#ifndef MYTABLEMODEL_H
    #define MYTABLEMODEL_H

    #include <QSortFilterProxyModel>
    #include <QItemSelectionModel>
    class MytableModel : public QSortFilterProxyModel
    {
    public:
    explicit MytableModel(QObject parent = 0);
    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
    QVariant data(const QModelIndex &proxyIndex, int role) const;
    void SetSelectionModel(QItemSelectionModel
    selection) ;
    public slots:
    void emitHeaderChangedData(QModelIndex &current,QModelIndex &prev) ;
    private:
    QItemSelectionModel *m_selectionModel;

    };

    #endif // MYTABLEMODEL_H
    @

    her is mytablemodel.cpp

    @#include "mytablemodel.h"
    #include <QPixmap>
    MytableModel::MytableModel(QObject *parent) : QSortFilterProxyModel(parent)

    {
    m_selectionModel = 0;
    connect(m_selectionModel,SIGNAL(currentRowChanged(QModelIndex,QModelIndex)),m_selectionModel,SLOT(emitHeaderChangedData(QModelIndex&,QModelIndex&)));

    }

    QVariant MytableModel::headerData(int section, Qt::Orientation orientation, int role) const
    {
    switch (orientation) {
    case Qt::Horizontal :
    switch (role) {
    case Qt::DisplayRole :
    switch (section) {
    case 0: return "Id";break;
    case 1: return "Reference";break;
    case 2: return "Designation";break;
    case 3: return "localisation";break;
    case 4: return "Famille";break;
    case 5: return "Qte min";break;
    case 6: return "Qte max";break;
    case 7: return "Qte disponible";break;
    case 8: return "Unité";break;
    case 9: return "Prix achat";break;
    case 10: return "Prix vente";break;
    default:
    return QString("Column %1").arg(section + 1);
    break;
    }
    break;
    default:
    QSortFilterProxyModel::headerData(section,orientation,role);
    break;
    }
    break;
    case Qt::Vertical :
    switch (role) {
    case Qt::DecorationRole :
    if(m_selectionModel)
    {
    QModelIndexList indexList = m_selectionModel->selection().indexes();
    if(!indexList.isEmpty())
    {
    QModelIndex index = indexList.at(0);
    if(index.isValid() )
    {
    return QPixmap("imgs/arrow.png");

                    }
    
                }else
                    return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
            }else
                return QSortFilterProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
    
            break;
        default:
            return QSortFilterProxyModel::headerData(section,orientation,role);
            break;
        }
        break;
    default:
        return QSortFilterProxyModel::headerData(section,orientation,role);
        break;
    }
    
    
    
    return QVariant();
    

    }

    QVariant MytableModel::data(const QModelIndex &proxyIndex, int role) const
    {
    if(role == Qt::TextAlignmentRole)
    return Qt::AlignCenter;
    else if (role == Qt::DisplayRole)
    return QSortFilterProxyModel::data(proxyIndex , role);

    return QVariant();
    

    }

    void MytableModel::SetSelectionModel(QItemSelectionModel* selection)
    {
    m_selectionModel = selection ;
    }

    void MytableModel::emitHeaderChangedData(QModelIndex &current, QModelIndex &prev)
    {
    int currentRow = current.row();
    int previousRow = prev.row() ;
    emit headerDataChanged(Qt::Vertical,currentRow,previousRow);
    }

    @



  • In your constructor, you first set m_selectionModel to 0, meaning that it does not refer to a valid object. And on the next line, you try to connect to it anyway? You should make the connection from your SetSelectionModel method where you actually have the valid object, at line 92 of your cpp.

    Note that because you are not changing the stucture or sort order of your model, it is more efficient to use QIdentityProxyModel than QSortFilterProxyModel as your base class.



  • unfortunately, i can't get this work

    i don't know where i'm wrong @void MytableModel::SetSelectionModel(QItemSelectionModel *selection)
    {
    m_selectionModel = selection ;
    QObject::connect(m_selectionModel,SIGNAL(currentRowChanged(QModelIndex,QModelIndex)),
    this,SLOT(emitHeaderDataChanged(QModelIndex&,QModelIndex&))) ;
    }

    void MytableModel::emitHeaderDataChanged(QModelIndex &current, QModelIndex &prev)
    {
    int currentRow = current.row();
    int previousRow = prev.row() ;
    emit headerDataChanged(Qt::Vertical,currentRow,previousRow);

    }
    @



    • Why do you use QObject:: before your connect?

    • What does this call return?

    • Do you see any application output for this connect statement?

    • Where do you call SetSelectionModel? And how?

    • What exactly does not work?

    • Does emitHeaderDataChanged get called or not?



  • Why do you use QObject:: before your connect?
    

    i forgot that the macro Q_OBJECT is included

    What does this call return?
    

    what function you mean, connect ??

    Do you see any application output for this connect statement?
    

    no

    Where do you call SetSelectionModel?

    i  call it in other file , where is use my view( to get selection model)
    

    And how?

    with @myMytableModel->SetSelectionModel(myView->selectionModel());@

    What exactly does not work?
    
    when the icon ( arrow.png) showed in vertical and the selection changed  the icon stay in vertical header and never disappear
    

    witch mean, all rows have an icon "arrow.png" in their left side ( vertical header) in stead of only the selected one !!

    Does emitHeaderDataChanged get called or not?
    

    i place break point in it but it's not called



  • I see something weird in your headerData implementation:

    What you do there, is that you only check if there are selected indices. You are not checking if any of the selected indices is on the row that the current header data is requested for. So indeed: as long as you have a selected item, it should make all your vertical headers render the arrow.

    I do not get why you don't get the signal. Did you try with the selectionChanged signal from QItemSelectionModel?



  • i have modified the code , but i get an error

    @Démarrage de E:\apprendreQt\build-gestionstock5-Desktop_Qt_5_1_0_MinGW_32bit-Debug\debug\gestionstock5.exe...ASSERT failure in QList<T>::at: "index out of range", file C:\Qt\Qt5.1.0\5.1.0\mingw48_32\include/QtCore/qlist.h, line 452
    Invalid parameter passed to C runtime function.
    Invalid parameter passed to C runtime function.

    @
    i have checked with debugger to get the source of the error , it crashed
    when he execute this line

    @QModelIndex index = indexList.at(0);@ ( line 9 )

    her is headerData for vertical header @case Qt::Vertical :
    switch (role) {
    case Qt::DecorationRole :
    if(m_selectionModel)
    {
    QModelIndexList indexList = m_selectionModel->selection().indexes();
    if(!indexList.isEmpty())
    {
    QModelIndex index = indexList.at(0);
    if(index.isValid() )
    {

                        if(index.row() == section)
                            return  QPixmap("imgs/arrow.png");
                        else
                            return "**";
    
                    }
    
                }else
                    return QIdentityProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
            }else
                return QIdentityProxyModel::headerData(section,Qt::Vertical,Qt::DecorationRole);
    
            break;
        default:
            return QIdentityProxyModel::headerData(section,orientation,role);
            break;
        }
        break;@
    

    i have changed my signal to selectionChanged()
    @void MytableModel::SetSelectionModel(QItemSelectionModel *selection)
    {
    m_selectionModel = selection ;
    connect(m_selectionModel,SIGNAL(selectionChanged(QItemSelection,QItemSelection)),this,SLOT(emitHeaderDataChanged(QItemSelection,QItemSelection))) ;
    }
    @

    and her is my slot ( the program enter into slot )

    @void MytableModel::emitHeaderDataChanged(QItemSelection selected, QItemSelection deselected)
    {
    int selectedRow = selected.indexes().at(0).row() ;
    int deselectedRow = deselected.indexes().at(0).isValid() ? deselected.indexes().at(0).row() : 0 ;

    emit headerDataChanged(Qt::Vertical,selectedRow,deselectedRow);
    

    }
    @


  • Lifetime Qt Champion

    your indexList is empty and you are trying to access an element



  • [quote author="SGaist" date="1375786256"]your indexList is empty and you are trying to access an element[/quote]

    No, as there is a check for that just two lines above...



  • [quote author="SGaist" date="1375786256"]your indexList is empty and you are trying to access an element[/quote]
    i think there is a problem with connect methode

    @void MytableModel::SetSelectionModel(QItemSelectionModel *selection)
    {
    m_selectionModel = selection ;
    connect(m_selectionModel,SIGNAL(selectionChanged(QItemSelection,QItemSelection)),this,SLOT(emitHeaderDataChanged(QItemSelection,QItemSelection))) ;
    }@

    and SLOT

    @void MytableModel::emitHeaderDataChanged(QItemSelection selected, QItemSelection deselected)
    {
    int selectedRow = selected.indexes().at(0).row() ;
    int deselectedRow = deselected.indexes().at(0).isValid() ? deselected.indexes().at(0).row() : 0 ;

    emit headerDataChanged(Qt::Vertical,selectedRow,deselectedRow);
    

    }
    @

    when i delete this line @connect(m_selectionModel,SIGNAL(selectionChanged(QItemSelection,QItemSelection)),this,SLOT(emitHeaderDataChanged(QItemSelection,QItemSelection))) ;@
    from setSelectionModel(), it works perfectly :), without emitting headerDataChanged() signal

    i wish to figure out what happened


  • Lifetime Qt Champion

    [quote author="Andre" date="1375786790"]
    [quote author="SGaist" date="1375786256"]your indexList is empty and you are trying to access an element[/quote]

    No, as there is a check for that just two lines above...[/quote]

    Indeed, keyboard/brain/finger bug, I was thinking about selected/deselected.indexes() which may be empty



  • [quote author="SGaist" date="1375787169"]
    [quote author="Andre" date="1375786790"]
    [quote author="SGaist" date="1375786256"]your indexList is empty and you are trying to access an element[/quote]

    No, as there is a check for that just two lines above...[/quote]

    Indeed, keyboard/brain/finger bug, I was thinking about selected/deselected.indexes() which may be empty[/quote]

    Probably, because there is no selected row in my view at intial, so deseleted.indexs() is empty !

    sorry, if you get a difficulty to understand me ( English is not my native language)


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