[Qt-interest] Segment fault when updating OpenGL QGLWidget from thread ?

[Samuel Rødal]

Ed Sutton wrote:
> How can I synchronize thread access to my GUI window?
> 
>  
> 
> 1 - I have a thread receiving video data over the network.
> 
> 2 - When a frame is complete it makes a callback to my QGLWidget derived 
> class’s frame handler  - a static method that gets passed the instance 
> of the class.
> 
> 3 – The segment fault appears to be triggered when calling 
> glClearColor(),before it gets to the end and calls QWidget::update()
> 
> 4 – The segment fault occurs after I select a new video channel in my 
> GUI and the changedChannel slot handler has been called.
> 
>  
> 
> My figure I need a mutex in my frame handler.  However, according to my 
> debug print statements the main window’s changedChannel slot handler 
> appears to have already completed before the segment fault occurs.  I am 
> a Qt / Linux newbie and realize I may be doing this all wrong.
> 
>  
> 
> Thanks in advance for sharing your experience and any tips or direction. 
> 
>  
> 
> -Ed

You shouldn't necessarily have to use a QMutex, sending the image data 
for the frame over as a QVector / QImage using signals and slots might 
be sufficient.

--
Samuel