[Spice-devel] [spice-gtk v2] mouse: Fix pointer grabbing in server mode

[Christophe Fergeau]

On Tue, Aug 09, 2016 at 10:33:05AM -0400, Frediano Ziglio wrote:
> > 
> > Trying to click on spice-gtk window while in server mode should result
> > in a pointer grab. This is currently failing, with the cursor wrapping
> > to the top left corner of the window instead without being grabbed.
> > 
> > This is caused by our use of gtk_event_box_set_above_child(),
> > when clicking on the SpiceWidget, the grab is implicitly taken by
> > the window which is above the event box (which is an internal
> > GtkEventBox input-only GdkWindow). Then when we call gdk_pointer_grab()
> > on the GtkEventBox::window, we get a grab-broken event indicating the
> > grab was transferred from the internal input-only window to
> > GtkEventBox::window (see gtk+ bug
> > https://bugzilla.gnome.org/show_bug.cgi?id=769635#c2 for a detailed
> > explanation).
> > 
> > This commit ignores grab-broken events when the GdkWindow who got the
> > grab corresponds to the one we called gdk_pointer_grab() on.
> > An alternative would be to call gdk_pointer_grab() on the GdkWindow
> > which received the button-press-event, but the call chain between
> > button_event() and the eventual gdk_pointer_grab() call, so it would be
> > not so elegant to pass the correct GdkWindow all the way.
> > ---
> > Changes since v1:
> > 
> > Rework commit log/code comment following garnacho's input in the gtk+ bug. No
> > code change.
> > 
> > 
> >  src/spice-widget.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/src/spice-widget.c b/src/spice-widget.c
> > index 7c1c756..de10736 100644
> > --- a/src/spice-widget.c
> > +++ b/src/spice-widget.c
> > @@ -462,8 +462,19 @@ static GdkCursor* get_blank_cursor(void)
> >  static gboolean grab_broken(SpiceDisplay *self, GdkEventGrabBroken *event,
> >                              gpointer user_data G_GNUC_UNUSED)
> >  {
> > +    GdkWindow *window = gtk_widget_get_window(GTK_WIDGET(self));
> >      SPICE_DEBUG("%s (implicit: %d, keyboard: %d)", __FUNCTION__,
> >                  event->implicit, event->keyboard);
> > +    SPICE_DEBUG("%s (SpiceDisplay::GdkWindow %p, event->grab_window: %p)",
> > +                __FUNCTION__, window, event->grab_window);
> > +    if (window == event->grab_window) {
> > +        /* ignore grab-broken event moving the grab to GtkEventBox::window
> > +         * (from GtkEventBox::event_window) as we initially called
> > +         * gdk_pointer_grab() on GtkEventBox::window, see
> > +         * https://bugzilla.gnome.org/show_bug.cgi?id=769635
> > +         */
> > +        return false;
> 
> s/false/FALSE/ ??
> Not a big deal.

This function ends with a 'return false;' so I kept things consistent. I
think spice-gtk uses both forms.


> 
> > +    }
> >  
> >      if (event->keyboard) {
> >          try_keyboard_ungrab(self);
> 
> Acked-by: Frediano Ziglio <fziglio at redhat.com>
> 
> (I think Victor one is still valid too).
> 

Yup, definitely, I resent so that the new wording/spelling can be checked :)

Christophe
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