get the Widgets' tree of an application

Question

It's a well-known fact that Qt uses a "parent-child relationship" to link widgets together. In order to maintain a (C++)Qt5 application, I'm searching for a tool able to somehow describe these relationships, something like :

  QMainApplication
  |
  \----->QMainWindow
         |
         \----->QSplitter(as CentralWidget)
                |
                \--->QTextEdit
                \--->QTextEdit

It may be a function which could be launched from the code with the QApplication as a parameter; it may be too an external tool able to analyse the code.

Does such a function/tool exist ?

Answer 1

There are few solutions:

In Qt Designer there is widget which do something similar.

But you can use this class to see relationship:

ObjectTreeModel.h

#ifndef OBJECTTREEMODEL_H
#define OBJECTTREEMODEL_H

#include <QAbstractItemModel>

class ObjectTreeModel : public QAbstractItemModel
{
    Q_OBJECT
public:
    ObjectTreeModel( QObject *root, QObject *parent = 0 )
    {
        m_root = root;
    }

    QVariant data( const QModelIndex &index, int role ) const;
    QVariant headerData( int section, Qt::Orientation orientation,
    int role = Qt::DisplayRole ) const;
    int rowCount( const QModelIndex &parent = QModelIndex() ) const;
    int columnCount( const QModelIndex &parent = QModelIndex() ) const;
    QModelIndex index( int row, int column,
    const QModelIndex &parent = QModelIndex() ) const;
    QModelIndex parent( const QModelIndex &index ) const;
private:
    QObject *m_root;
};

#endif // OBJECTTREEMODEL_H

*.cpp

#include "objecttreemodel.h"



QVariant ObjectTreeModel::headerData(int section, Qt::Orientation orientation, int role ) const
    {
         if( role != Qt::DisplayRole || orientation != Qt::Horizontal )
            return QVariant();
         switch( section )
        {
            case 0:
                return QString( "Object" );
            case 1:
                return QString( "Class" );
            default:
                return QVariant();
        }
    }

QModelIndex ObjectTreeModel::index(int row, int column,const QModelIndex &parent ) const
{
    QObject *parentObject;
    if( !parent.isValid() )
        parentObject = m_root;
    else
        parentObject = static_cast<QObject*>( parent.internalPointer() );
    if( row >= 0 && row < parentObject->children().count() )
        return createIndex( row, column, parentObject->children().at( row ) );
    else
        return QModelIndex();
}

int ObjectTreeModel::rowCount(const QModelIndex &parent ) const
{
    QObject *parentObject;
    if( !parent.isValid() )
        parentObject = m_root;
    else
        parentObject = static_cast<QObject*>( parent.internalPointer() );
    return parentObject->children().count();
}
int ObjectTreeModel::columnCount(const QModelIndex &parent ) const
{
    return 2;
} 

QVariant ObjectTreeModel::data( const QModelIndex &index, int role) const
{
    if( !index.isValid() )
        return QVariant();
    if( role == Qt::DisplayRole )
    {
    switch( index.column() )
    {
        case 0:
            return static_cast<QObject*>( index.internalPointer() )->objectName();
        case 1:
            return static_cast<QObject*>( index.internalPointer() )->metaObject()->className();
        default:
            break;
    }
    }
return QVariant();
}

QModelIndex ObjectTreeModel::parent(const QModelIndex &index) const
{
    if( !index.isValid() )
        return QModelIndex();
    QObject *indexObject = static_cast<QObject*>( index.internalPointer() );
    QObject *parentObject = indexObject->parent();
    if( parentObject == m_root )
        return QModelIndex();
    QObject *grandParentObject = parentObject->parent();
    return createIndex( grandParentObject->children().indexOf( parentObject ),0, parentObject );
}

Usage(in main.cpp):

#include "objecttreemodel.h"
//...
MainWindow w;
w.show();
ObjectTreeModel *model = new ObjectTreeModel(&w);
QTreeView tree;
tree.setModel(model);
tree.show();

Result: