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Thread: QT + OpenGL + OpenCV + GStreamer (Access violation)

  1. 2nd June 2013, 19:43 #1
    Elijah Muhammad
    Elijah Muhammad is offline Beginner
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    Default QT + OpenGL + OpenCV + GStreamer (Access violation)

    Hello, I'm developing application that uses GStreamer to take video from device then do processing with OpenCV and as GUI framework I use QT.

    So... This app works on Linux well. But when I try to build it on Windows I got exception in QPainter constructor.

    First-chance exception at 0x630373cc (QtOpenGLd4.dll) in guitool.exe: 0xC0000005: Access violation reading location 0xcdcdcdd5.
    Unhandled exception at 0x630373cc (QtOpenGLd4.dll) in guitool.exe: 0xC0000005: Access violation reading location 0xcdcdcdd5.

    Qt Code: 
    1. QtOpenGLd4.dll!QScopedPointer<QGLFramebufferObjectPrivate,QScopedPointerDeleter<QGLFramebufferObjectPrivate> >::operator->()  Line 112 + 0x3 bytes	C++
    2.  	QtOpenGLd4.dll!QGLFBOGLPaintDevice::context()  Line 376 + 0xe bytes	C++
    3.  	QtOpenGLd4.dll!QGLPaintDevice::beginPaint()  Line 86 + 0xd bytes	C++
    4.  	QtOpenGLd4.dll!QOpenGLPaintEngine::begin(QPaintDevice * pdev)  Line 1259	C++
    5.  	QtGuid4.dll!QPainter::begin(QPaintDevice * pd)  Line 1881 + 0x1d bytes	C++
    6.  	QtGuid4.dll!QPainter::QPainter(QPaintDevice * pd)  Line 1508	C++
    7.  	guitool.exe!WVideo::paintGL()  Line 63 + 0x10 bytes	C++
    8.  	QtOpenGLd4.dll!QGLWidget::glDraw()  Line 4627	C++
    9.  	QtOpenGLd4.dll!QGLWidget::paintEvent(QPaintEvent * __formal)  Line 4425	C++
    10.  	QtGuid4.dll!QWidget::event(QEvent * event)  Line 8518	C++
    11.  	QtOpenGLd4.dll!QGLWidget::event(QEvent * e)  Line 4408	C++
    12.  	QtGuid4.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e)  Line 4557 + 0x11 bytes	C++
    13.  	QtGuid4.dll!QApplication::notify(QObject * receiver, QEvent * e)  Line 4522 + 0x10 bytes	C++
    14.  	QtCored4.dll!QCoreApplication::notifyInternal(QObject * receiver, QEvent * event)  Line 915 + 0x15 bytes	C++
    15.  	QtCored4.dll!QCoreApplication::sendSpontaneousEvent(QObject * receiver, QEvent * event)  Line 234 + 0x38 bytes	C++
    16.  	QtGuid4.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev, const QRegion & rgn, const QPoint & offset, int flags, QPainter * sharedPainter, QWidgetBackingStore * backingStore)  Line 5594 + 0xe bytes	C++
    17.  	QtGuid4.dll!QWidgetPrivate::repaint_sys(const QRegion & rgn)  Line 1659	C++
    18.  	QtGuid4.dll!QWidgetPrivate::syncBackingStore()  Line 1890	C++
    19.  	QtGuid4.dll!QWidget::event(QEvent * event)  Line 8665	C++
    20.  	QtOpenGLd4.dll!QGLWidget::event(QEvent * e)  Line 4408	C++
    21.  	QtGuid4.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e)  Line 4557 + 0x11 bytes	C++
    22.  	QtGuid4.dll!QApplication::notify(QObject * receiver, QEvent * e)  Line 4522 + 0x10 bytes	C++
    23.  	QtCored4.dll!QCoreApplication::notifyInternal(QObject * receiver, QEvent * event)  Line 915 + 0x15 bytes	C++
    24.  	QtCored4.dll!QCoreApplication::sendEvent(QObject * receiver, QEvent * event)  Line 231 + 0x39 bytes	C++
    25.  	QtCored4.dll!QCoreApplicationPrivate::sendPostedEvents(QObject * receiver, int event_type, QThreadData * data)  Line 1539 + 0xd bytes	C++
    26.  	QtCored4.dll!qt_internal_proc(HWND__ * hwnd, unsigned int message, unsigned int wp, long lp)  Line 496 + 0x10 bytes	C++
    27.  	user32.dll!7e368734() 	
    28.  	[Frames below may be incorrect and/or missing, no symbols loaded for user32.dll]	
    29.  	user32.dll!7e368816() 	
    30.  	user32.dll!7e3689cd() 	
    31.  	user32.dll!7e368a10() 	
    32.  	QtCored4.dll!QEventDispatcherWin32::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags)  Line 810	C++
    33.  	QtGuid4.dll!QGuiEventDispatcherWin32::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags)  Line 1204 + 0x15 bytes	C++
    34.  	QtCored4.dll!QEventLoop::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags)  Line 150	C++
    35.  	QtCored4.dll!QEventLoop::exec(QFlags<enum QEventLoop::ProcessEventsFlag> flags)  Line 204 + 0x2d bytes	C++
    36.  	QtCored4.dll!QCoreApplication::exec()  Line 1187 + 0x15 bytes	C++
    37.  	QtGuid4.dll!QApplication::exec()  Line 3819	C++
    38.  	guitool.exe!main(int argc, char * * argv)  Line 19 + 0x6 bytes	C++
    39.  	guitool.exe!WinMain(HINSTANCE__ * instance, HINSTANCE__ * prevInstance, char * __formal, int cmdShow)  Line 131 + 0x12 bytes	C++
    40.  	guitool.exe!__tmainCRTStartup()  Line 547 + 0x2c bytes	C
    41.  	guitool.exe!WinMainCRTStartup()  Line 371	C
    42.  	kernel32.dll!7c817077()
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    this is the drawing code with GL initialization:

    Qt Code: 
    2. GLuint commands;
    3.  
    4. void WVideo::init(int w, int h)
    5. {
    6.  
    7.   im_width = w;
    8.   im_height = h;
    9.  
    10.   glDeleteLists(commands, 1);
    11.   if (fbo){ 
    12. 	  delete fbo; 
    13.   }
    14.   fbo = new QGLFramebufferObject(w, h);
    15.  
    16.   commands = glGenLists(1);
    17.   glNewList(commands, GL_COMPILE);
    18.   glBegin(GL_QUADS);
    19.   glTexCoord2d(    1,         1);
    20.   glVertex2d(        w-1,     h-1);
    21.   glTexCoord2d(    0,         1);
    22.   glVertex2d(        0,         h-1);
    23.   glTexCoord2d(    0,         0);
    24.   glVertex2d(        0,         0);
    25.   glTexCoord2d(    1,         0);
    26.   glVertex2d(        w-1,     0);
    27.  
    28.   glEnd();
    29.   glEndList();
    30.  
    31.   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    32.   glMatrixMode(GL_PROJECTION);
    33.   glLoadIdentity();
    34.   glViewport(0, 0, w, h);
    35.   glOrtho(0.0, w-1, 0.0, h, -0.01, 0.0);
    36. }
    37.  
    38. void WVideo::paintGL()
    39. {
    40.   mutex.lock();
    41.  
    42.   //if (!fbo) { init(800, 600); }
    43.   if (!fbo) { init(704, 576); }
    44.  
    45.   if (img){
    46.     QPainter fbo_painter(fbo);
    47.     fbo_painter.drawImage(QRect(0, 0, im_width, im_height), *img );
    48.     fbo_painter.end();
    49.   }
    50.  
    51.   glMatrixMode(GL_MODELVIEW);
    52.   glLoadIdentity();
    53.   glEnable(GL_TEXTURE_2D);
    54.  
    55.   glPushMatrix();
    56.   glColor3d(255, 255, 255);
    57.   glCallList(commands);
    58.   glPopMatrix();
    59.   mutex.unlock();
    60. }
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  2. 3rd June 2013, 07:24 #2
    ChrisW67
    ChrisW67 is offline Guru
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    Default Re: QT + OpenGL + OpenCV + GStreamer (Access violation)

    Do you initialise fbo to zero in the constructor, or are you assuming it will start out life as zero?
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