QPainter::drawText() draws distorted text in some combinations of font size and font stretch factor

[ckagerer]

Hey,

I have a problem with QPainters drawText() method. Which I think is a Bug in Qt.

If i run the following minimal demonstration application on my Ubuntu 12.04 the drawText() produces a deformed output how you can see on the following pictures.
The Problem can also be reproduced on a Fedora 19 machine. If I run the same Application on Windows the output is like expected (same font is installed/used).

The deformation only appears on some combinations (ranges?!?) of font-size and font-stretch-factor. In such cases the is alwas a warning in stderr when closing the programm, which says:
[warning] (thread/qmutex.cpp:194) - QMutex: destroying locked mutex

I could reproduce this behavieor with Qt 5.1 and 5.0.2 and with other fonts.

Is this a Bug in Qt and has anybody a workaround for this Problem?

Screenshot Ubuntu 12.04 32Bit (Gnome Classic)
!http://up.picr.de/15492086jj.png(Ubuntu 12.04)!

Screenshot Windows 7 64Bit
!http://up.picr.de/15492087kf.png(Windows 7 64Bit)!

@
// Main.cpp
#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

return a.exec();

}
@

@
// MainWindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();

QString GetFont();

protected:
void paintEvent(QPaintEvent *ap_event);

private:
Ui::MainWindow *ui;
QFont font;
};

#endif // MAINWINDOW_H
@

@
// MainWindow.cpp
#include "MainWindow.h"
#include "ui_MainWindow.h"

#include <QPainter>

MainWindow::MainWindow( QWidget *parent ) :
QMainWindow( parent ),
ui( new Ui::MainWindow ) {
ui->setupUi( this );
}

MainWindow::~MainWindow() {
delete ui;
}

void MainWindow::paintEvent( QPaintEvent */event/ ) {
QString str( "Hello World" );
QPoint pos( 10, 10 );

QFont font( "Ubuntu Mono" );
font.setPointSize( 40 );
font.setStretch( 200 );
font.setUnderline( true );
font.setOverline( true );

QFontMetrics fm( font );
QRect boundingRect( pos, fm.size( 0, str ) );

QPainter painter( this );
painter.setPen( Qt::black );
painter.fillRect( boundingRect, Qt::lightGray );
painter.setFont( font );

// probleme here
// Warning: QMutex: destroying locked mutex
painter.drawText( boundingRect, Qt::AlignCenter, str );
}
@

[SGaist]

Hi and welcome to devnet,

I indeed sounds like a bug, did you check the "bug report system":http://bugreports.qt-project.org/issues/ ?

If nothing has been reported yet you may consider creating a new bug report

[ckagerer]

Hey,

Thank you for your help.

I've checked the bug report system already. I couldn't find any Bug which distorted the text the same way like in may case.

The Bug which comes close mine best is QTBUG-13682. But with an other form of distortion.

Therefore I will create a new bug report during the day.

[SGaist]

Don't forget to also post your new bug report here so other may follow

[ckagerer]

I just created a bug report.

"QTBUG-32991":https://bugreports.qt-project.org/browse/QTBUG-32991