how change size QTextDocument in qt

MainWindow::MainWindow(QString path)
{
    QPalette* palette = new QPalette();
   // palette->setBrush(QPalette::Background,*(new QBrush(*(new QPixmap(path+"/res/background.jpg")))));
    setPalette(*palette);
    setWindowTitle("Alzekr");
    resize(1024,819);
    //QLabel *qlabel=createLabel();
    QTextDocument *textDocument=new QTextDocument;
    QVBoxLayout *vbox=new QVBoxLayout;
    //-------------------------------------------------------------------------------------
    QTextEdit *editor = new QTextEdit;

        QTextDocument *document = new QTextDocument(editor);
        QTextCursor cursor(document);

        QImage image(64, 64, QImage::Format_RGB32);
        image.fill(qRgb(255, 160, 128));

    //! [Adding a resource]
        document->addResource(QTextDocument::ImageResource,
            QUrl("mydata://image.png"), QVariant(image));

        document->setPageSize(QSize(100,200));
    //! [Adding a resource]

    //! [Inserting an image with a cursor]
        QTextImageFormat imageFormat;
        imageFormat.setName("mydata://image.png");
        cursor.insertImage(imageFormat);
    //! [Inserting an image with a cursor]

        cursor.insertBlock();
        cursor.insertText("Code less. Create more.");

        editor->document()->setPageSize( QSizeF( 100, 200 ) );
        document->setTextWidth(200);
        QSize size = document->size().toSize();
        size.setWidth(200);
        size.setHeight(200);
        editor->setDocument(document);
    //! [Inserting an image using HTML]
        editor->append("<img src=\"mydata://image.png\" />");
    //-------------------------------------------------------------------------------------
    vbox->addWidget(editor);
    setLayout(vbox);
}