Report, QTextDocument (memory leak)

[layer]

I have some issues with simple reports that my application makes by QTextDocument, html-page (template), QPrinter and QPrintPreviewDialog. I made classes for this stuff.
But recently I was realised that I have memory leak. so I tried to find where is it.
It seems that I found out smth but don't know exactly why this happening..

I threw out spec. classes and wrote just necessary code:

QTextDocument* document;
........
// in widget's constructor
document = new QTextDocument();
........
// in widget'd destructor
delete document;
........
 
//----------------------------------------------------------------------------------------
void fmPartStatInRange::previewSelectionReport() {
    QFile file (QCoreApplication::applicationDirPath () + "/reports/statisticPartsInRange.html");
    if (!file.open (QIODevice::ReadOnly)) {
        QMessageBox::critical (this, "", tr ("Error opening report file %1").arg (file.fileName ()));
        return;
    }
    QTextStream stream (&file);
    stream.setCodec (QTextCodec::codecForName ("UTF-8"));
    document->clear();
    document->setHtml (stream.readAll ());
    file.close ();
 
//----------------------------------------------------------------------------------------
void fmPartStatInRange::print(QPrinter *printer) {
#ifdef QT_NO_PRINTER
    Q_UNUSED(printer);
#else
    document->print(printer);
#endif
}
 
//----------------------------------------------------------------------------------------
void fmPartStatInRange::printReport() {
#ifndef QT_NO_PRINTER
    QPrinter printer(QPrinter::HighResolution);
    QPrintPreviewDialog preview(&printer, this);
    connect(&preview, SIGNAL(paintRequested(QPrinter*)), SLOT(print(QPrinter*)));
    preview.exec();
#endif
}
 
//----------------------------------------------------------------------------------------
void fmPartStatInRange::createReport() {
    previewSelectionReport();
    if (document) 
        printReport();
}
//----------------------------------------------------------------------------------------

QTextDocument* document;
........
// in widget's constructor
document = new QTextDocument();
........
// in widget'd destructor
delete document;
........

//----------------------------------------------------------------------------------------
void fmPartStatInRange::previewSelectionReport() {
    QFile file (QCoreApplication::applicationDirPath () + "/reports/statisticPartsInRange.html");
    if (!file.open (QIODevice::ReadOnly)) {
        QMessageBox::critical (this, "", tr ("Error opening report file %1").arg (file.fileName ()));
        return;
    }
    QTextStream stream (&file);
    stream.setCodec (QTextCodec::codecForName ("UTF-8"));
    document->clear();
    document->setHtml (stream.readAll ());
    file.close ();

//----------------------------------------------------------------------------------------
void fmPartStatInRange::print(QPrinter *printer) {
#ifdef QT_NO_PRINTER
    Q_UNUSED(printer);
#else
    document->print(printer);
#endif
}

//----------------------------------------------------------------------------------------
void fmPartStatInRange::printReport() {
#ifndef QT_NO_PRINTER
    QPrinter printer(QPrinter::HighResolution);
    QPrintPreviewDialog preview(&printer, this);
    connect(&preview, SIGNAL(paintRequested(QPrinter*)), SLOT(print(QPrinter*)));
    preview.exec();
#endif
}

//----------------------------------------------------------------------------------------
void fmPartStatInRange::createReport() {
    previewSelectionReport();
    if (document) 
        printReport();
}
//----------------------------------------------------------------------------------------

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I execute createReport() many times and see memory leak.
But if I comment this line:

document->setHtml (stream.readAll ());

document->setHtml (stream.readAll ());

To copy to clipboard, switch view to plain text mode 

that's all ok. no memory leak.
of course in this case I don't get any sence of report only white page.

I use 4.7.3 Qt ver.
unfortunately I haven't any opportunities to check out it on new Qt ver.

so what is wrong with this code or maybe it's a bug in Qt lib?

thanks in advance!

[ChrisW67]

How do you "see memory leak"?

[layer]

in win task manager for example.

here it is 24 Mb in memory before doing smth:
memory_1.jpg

after 20 reports (35 Mb):
memory_2.jpg

and it's keep growing if we do reports...
is it normal or I didn't catch smth?