[Sugar-devel] tracking CTRL and ALT keys in a sugar activity

[Aleksey Lim]

On Fri, Dec 17, 2010 at 05:23:03PM -0500, Erik Blankinship wrote:
> On Fri, Dec 17, 2010 at 4:52 PM, Walter Bender <walter.bender at gmail.com>wrote:
> 
> > On Fri, Dec 17, 2010 at 4:48 PM, Erik Blankinship <erikb at mediamods.com>
> > wrote:
> > > I would like to know when CTRL or ALT are being pressed in my sugar
> > > activity.  To be complete, I would need to know if they are pressed when
> > the
> > > activity regains focus (e.g. changing activities or if the focus was in a
> > > textfield).
> > >
> > > I am not sure of the right way to do this. My current thinking is to keep
> > a
> > > dictionary with CTRL_L, CTRL_R, ALT_L, and ALT_R key states which are
> > > updated on key-press and key-release events.
> > >
> > > But this model breaks as soon the application loses focus and the user
> > > releases one of those keys -- I would never know when there is a
> > mouse-up.
> > > My workaround is to clear the dictionary when the application loses
> > focus. I
> > > can also attempt to update the dictionary when there are mouse events by
> > > skimming information from these events regarding CTRL and ALT modifiers.
> > >
> > > Is this a good approach? Maybe I am missing something obvious?
> >
> > Maybe I am misunderstanding the complexity of what you are trying to
> > do...
> 
> 
> I want to change my cursor into a magicwand whenever CTRL or ALT are held
> down, and when none of them are pressed, I want to change my cursor into the
> system pointer.  I do not want someone to cheat by switching out of the
> activity with CTRL down and return with my activity thinking CTRL is still
> down.

You can use key-press-event event
http://library.gnome.org/devel/gtk/stable/GtkWidget.html#GtkWidget-key-press-event
see event.state to check what modifier was pressed
http://library.gnome.org/devel/gdk/stable/gdk-Event-Structures.html#GdkEventKey

> don't you simply check the mode mask when you get a keyboard
> > event to determine whether or not Alt or Ctrl is pressed?
> >
> 
> Thank you!  Yes, I can do that while the activity is running.  That sure
> makes things simpler while the activity has focus.
> 
> But to determine if CTRL or ALT are pressed when returning to the activity?
>  I am not sure what signal to listen to that would have the correct mode
> mask.

> _______________________________________________
> Sugar-devel mailing list
> Sugar-devel at lists.sugarlabs.org
> http://lists.sugarlabs.org/listinfo/sugar-devel


-- 
Aleksey