#include <QtGui>

class MyTextEdit : public QTextEdit {

    Q_OBJECT

public:
    
    MyTextEdit() : QTextEdit() {
        QTextCursor tc= textCursor();
        QTextCharFormat f = tc.charFormat();
        f.setVerticalAlignment(QTextCharFormat::AlignMiddle);
        tc.setCharFormat(f);
        tc.insertText("hoge");
        setTextCursor(tc);
        qDebug() << "textcarformat";
    }

protected:
    void resizeEvent(QResizeEvent * event)
    {
        valignMiddle();
        QTextEdit::resizeEvent(event);
    }

    void showEvent(QShowEvent * event)
    {
        valignMiddle();
        QTextEdit::showEvent(event);
    }


private slots:

    void valignMiddle()
    {
        int nDocHeight = (int)document()->size().height();
        if(nDocHeight == 0) return;
        int nCtrlHeight= height(); 

        QTextFrame * pFrame = document()->rootFrame();
        QTextFrameFormat frameFmt = pFrame->frameFormat();

        int nTopMargin = (int)frameFmt.topMargin();
        int nBBDocH = nDocHeight - nTopMargin;

        // compute and set appropriate frame top margin
        if(nCtrlHeight <= nBBDocH)
            nTopMargin = 2;
        else
            nTopMargin = (nCtrlHeight - nBBDocH)/2 - 2;

        frameFmt.setTopMargin(nTopMargin); // setTopMargin() to valign.

        frameFmt.setBorder(1);
        frameFmt.setBorderBrush(QColor(0xFFFFFF));
        pFrame->setFrameFormat(frameFmt); 

        //qDebug() << toHtml();
    }
};

int main(int argc, char *argv[]) {

    QApplication app(argc, argv);

    MyTextEdit edit;
    edit.show();

    return app.exec();

}

#include "main.moc"