QGLWidget bug

[jacek]

I have installed openSUSE in VMWare with Qt 4.3.1. First time I think that there was no bugs... But if you will drag, resize, click, move mouse (use application) you will have segmentation fault error...

I've tried resizing, clicking and moving the window, but it didn't crash.

QImage::detach() /home/wizard/qt-x11-opensource-src-4.3.1/src/gui/image/qimage.cpp:1320 0xb788f144
6 QPainter::begin() /home/wizard/qt-x11-opensource-src-4.3.1/src/gui/painting/qpainter.cpp:1301 0xb78daeff

Hmm... these two methods are always present in the backtrace. What happens if you change the code this way:

painter.fillRect(0, 0, 50, 50, QColor(qrand()));
painter.end(); // <-------
 
emit ImageReady(MyImage);

painter.fillRect(0, 0, 50, 50, QColor(qrand()));
painter.end(); // <-------

emit ImageReady(MyImage);

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?

[Wizard]

What happens if you change the code this way:

painter.fillRect(0, 0, 50, 50, QColor(qrand()));
painter.end(); // <-------
 
emit ImageReady(MyImage);

painter.fillRect(0, 0, 50, 50, QColor(qrand()));
painter.end(); // <-------

emit ImageReady(MyImage);

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?

The same bug. First, QPainter::end() was called automatically. Second, bug is near OpenGL, because after changing inheritance to QWidget all works...

[spud]

This looks like a bug to me.
It seems qt_gl_clean_cache() isn't reentrant since it accessess the
static QGLTextureCache *qt_tex_cache(qgl.cpp) without trying to protect it with a mutex. They don't even use the QGLOBALSTATIC macro. You should submit a bug report.

[Wizard]

May be they don't use it for performance reasons? I send bug report to Trolltech...
Thanks for advice )

[Wizard]

I've designed some workaround for this bug ) Just half an hour was enough...