[mythtv-commits] Ticket #8952: mythfrontend UI sometimes never paints itself

[MythTV]

#8952: mythfrontend UI sometimes never paints itself
---------------------------------------------+------------------------------
 Reporter:  danielk                          |           Owner:  stuartm   
     Type:  defect                           |          Status:  assigned  
 Priority:  blocker                          |       Milestone:  0.25      
Component:  MythTV - User Interface Library  |         Version:  Trunk Head
 Severity:  medium                           |      Resolution:            
 Keywords:                                   |   Ticket locked:  0         
---------------------------------------------+------------------------------

Comment (by john.p.harvey@…):

 I am fairly certain that QT has a bug that is shown if the code follows
 this sequence
 widget->Update()
 widget->setUpdatedEnabled(false)
 qApp->ProcessEvents();
 widget->setUpdatesEnabled(true)

 What happens is that in update the backingstore is marked as dirty & sends
 an UpdateRequest event
 this is processed in ProcessEvents but discarded because updates are
 disabled.
 Any further calls to Update() add to the dirty region but because it is
 already dirty dont send an UpdateRequest event.

 At startup (in mythtv_setup) we receive 2 events, while blocked looking
 for the backed ,the updateRequest & the X11 Expose event. neither get
 processed. By changing setUpdatesEnabled() to
 d->paintwin()->setUpdatesEnabled() the expose event on mythmainwindow is
 processed and causes a repaint of it and all its children hence avoiding
 this problem at that time, but that is not a good solution.

 If the system call done from myth_system is quick enough then
 processEvents wont be called so this is more likely to show up on slower
 systems.

 I have a hunch of a workaround which i will test later today and post a
 patch for if succesful.

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/8952#comment:17>
MythTV <http://www.mythtv.org/>
MythTV Media Center