[vlc-devel] [PATCH] vout: fix fullscreen race condition

[Romain Vimont]

On Tue, Apr 17, 2018 at 07:25:53PM +0300, Rémi Denis-Courmont wrote:
> > So fullscreen is and remains true
> > (resp. false) for the playlist object while it is and remains false
> > (resp. true) for the vout object.
> 
> That is by design.
> 
> Pressing F when there is no video window toggles fullscreen mode for future 
> video windows. Pressing F while there is a video window should toggle the 
> fullscreen mode of the focused window, or if none, the embedded video window.

OK, this makes sense.

> > More fundamentally, the fullscreen flag is duplicated into several
> > objects, while it represents exactly 1 state (so the variables must be
> > kept in sync, and they are/were not).
> 
> No, it does _not_ represent exactly one state. There can be any number of 
> video windows at a time, each with their independent fullscreen flag. The 
> input manager flag is *only* the initial value for future video windows.

OK, that clarifies the meaning of having several variables here. Thank
you.

> > > Meanwhile, Qt shows a fullscreen video window, and, at the same time, does
> > > not show the FSC. That is totally a bug within Qt GUI.
> > 
> > Anything using both the playlist "fullscreen" variable and the vout
> > "fullscreen" variable would have this inconsistency, since the values
> > may be different indefinitely.
> 
> If there are no video outputs, then there are no FSC to show, and thus the 
> playlist flag is irrelevant. If there are video outputs, then each of them has 
> its own fullscreen flag, and there are also no reasons to check the playlist 
> flag ever as far as the FSC is concerned.
> 
> > The fact that the Qt GUI reveals it is just a consequence.
> 
> No, the Qt GUI is just buggy.

What do you think about this alternate patch:

diff --git a/modules/gui/qt/components/controller.cpp b/modules/gui/qt/components/controller.cpp
index e10b1e4208..3b4e3bbd66 100644
--- a/modules/gui/qt/components/controller.cpp
+++ b/modules/gui/qt/components/controller.cpp
@@ -1209,9 +1209,7 @@ void FullscreenControllerWidget::setVoutList( vout_thread_t **pp_vout, int i_vou
         vout.append( p_vout );
         var_AddCallback( p_vout, "fullscreen",
                          FullscreenControllerWidget::FullscreenChanged, this );
-        /* I miss a add and fire */
-        emit fullscreenChanged( p_vout, var_InheritBool( THEPL, "fullscreen" ),
-                           var_GetInteger( p_vout, "mouse-hide-timeout" ) );
+        var_SetBool( p_vout, "fullscreen", var_InheritBool( THEPL, "fullscreen" ) );
         vlc_mutex_unlock( &lock );
     }
 }

?