Proxy for the QFileSystemModel

Code:

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#include <QtCore>
#include <QtGui>
 
class busyProxy : public QSortFilterProxyModel
{
    Q_OBJECT
public:
    explicit busyProxy(QObject *parent = 0) : QSortFilterProxyModel(parent) {}
 
    bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const
    {
        QModelIndex index = sourceModel()->index(source_row, 0, source_parent);        
        QString const &text = sourceModel()->data(index).toString();
        //the folder "very big" contains a lot of jpg, and I only want
        //to show one of it which name "kkk0.jpg"        
        if(text == "kkk0.jpg" || text == "kkk1000.jpg" || text == "kkk10.jpg") return true;
 
        if(text == "very big") return true;              
 
        return false;
    }
 
    bool lessThan(const QModelIndex &left, const QModelIndex &right) const
     {
         QString const leftString = sourceModel()->data(left).toString();
         QString const rightString = sourceModel()->data(right).toString();
 
         qDebug() << leftString << ", " << rightString;
 
         return leftString > rightString;
     }
};
 
//Do nothing, only want to compare with the busyProxy
class lazyProxy : public QSortFilterProxyModel
{
    Q_OBJECT
public:
    explicit lazyProxy(QObject *parent = 0) : QSortFilterProxyModel(parent) {}
};
 
class testProxyFiles : public QWidget
{
public:
    testProxyFiles()
    {
        QFileSystemModel *model = new QFileSystemModel(this);
 
        lazyProxy *lazyPro = new lazyProxy(this);
        lazyPro->setSourceModel(model);
 
        QTableView *sourceView = new QTableView(this);
        sourceView->setModel(lazyPro);
        QString const rootPath = "E:/file_test/very big";
        sourceView->setRootIndex(lazyPro->mapFromSource(model->setRootPath(rootPath)));
 
        QTableView *proxyView = new QTableView(this);
        busyProxy *busyPro = new busyProxy(this);
        busyPro->setSourceModel(model);
        proxyView->setModel(busyPro);
        proxyView->setRootIndex(busyPro->mapFromSource(model->setRootPath(rootPath)));
 
        QHBoxLayout *layout = new QHBoxLayout(this);
        layout->addWidget(sourceView);
        layout->addWidget(proxyView);
 
        setLayout(layout);
    }    
};
 
 
inline int proxyFiles(QApplication &app)
{
    testProxyFiles proxy;
    proxy.show();
 
    return app.exec();
}
 
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
 
  proxyFiles(app);  
 
  return 0;
}

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I have several questions :
1 : On line 16~18, do I have other solution to filter out the item of the QFileSystemModel?
The QFileSystemModel would navigate the root first, if I don't return true when the text
equal to "very big", the proxy wouldn't navigate the files inside "very big"

2 : when I show the item by busyProxy or lazyProxy, the indexes on the leftside are weird, how could
I edit them?When I set the QFileSystemModel as the model of QtableView, the indexes looks fine.

3 : the lessThan function never print anything, but why?

4 : Do you have any easy examples for the proxy of QFileSystemModel? I can't find a topic
talk about how to design a proxy for QFileSystemModel

Thanks a lot

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Added after 14 minutes:

Besides, how could I ask the view to display all of the drives(win7)?

Code:

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sourceView->setRootIndex(lazyPro->mapFromSource(model->setRootPath(rootPath)));

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What kind of path should I set at the "setRootPath" function?Thanks