Re: [gtk-vnc-devel] PATCH: sticky modifier keys

[Anthony Liguori <anthony codemonkey ws>]

Daniel P. Berrange wrote:
> Even with the use of a keyboard grab, there are certain key combinations
> that are completely ungrabbable using regular GTK / X libraries. The prime
> examples are  Ctrl-Alt-Backspace, and  Ctrl+Alt+Fn.  This isn't a problem
> for traditional VNC servers, but when talking to a virtualed guest OS, then
> you do need a way to send these combos to the guest OS.
>
> This patch adds the 'sticky modifiers' concept currently used in virt-manager
> Basically, if a Ctrl or Alt key is pressed 3 times in a row, then it is
> treated as sticky until the next non-modifier key is released. This allows
> you to type  'Ctrl Ctrl Ctrl Alt+F1'  to send 'Ctrl+Alt+F1' to the guest.
> This is off by default.
>   

Hrm, I don't like this very much.  I'd prefer a sendkey like abstraction 
and then virt-manager could implement "stick modifiers" if it was desired.

I think a much more common way of addressing this problem will be to 
have a menu entry allowing certain combinations to be sent.  The big 
usability problem with sticky modifiers is that if a user mistypes, 
something really bad could happen (like restarting X).

Regards,

Anthony Liguori

> Dan.
>   
> ------------------------------------------------------------------------
>
> changeset:   27:3c2eb84af9ae
> user:        "Daniel P. Berrange <berrange redhat com>"
> date:        Fri Jul 06 13:39:41 2007 -0400
> summary:     Added support for 'sticky' modifier keys
>
> diff -r 06fb3b1e2320 -r 3c2eb84af9ae examples/gvncviewer.c
> --- a/examples/gvncviewer.c	Fri Jul 06 11:40:33 2007 -0400
> +++ b/examples/gvncviewer.c	Fri Jul 06 13:39:41 2007 -0400
> @@ -124,6 +124,7 @@ int main(int argc, char **argv)
>  	vnc_display_set_keyboard_grab(VNC_DISPLAY(vnc), TRUE);
>  	vnc_display_set_pointer_grab(VNC_DISPLAY(vnc), TRUE);
>  	//vnc_display_set_pointer_local(VNC_DISPLAY(vnc), TRUE);
> +	vnc_display_set_sticky_modifiers(VNC_DISPLAY(vnc), TRUE);
>  	vnc_display_open_name(VNC_DISPLAY(vnc), argv[1], argv[2]);
>  
>  	gtk_signal_connect(GTK_OBJECT(window), "delete-event",
> diff -r 06fb3b1e2320 -r 3c2eb84af9ae examples/gvncviewer.py
> --- a/examples/gvncviewer.py	Fri Jul 06 11:40:33 2007 -0400
> +++ b/examples/gvncviewer.py	Fri Jul 06 13:39:41 2007 -0400
> @@ -70,6 +70,7 @@ v.set_pointer_grab(True)
>  v.set_pointer_grab(True)
>  v.set_keyboard_grab(True)
>  #v.set_pointer_local(True)
> +v.set_sticky_modifiers(True)
>  
>  if len(sys.argv) == 4:
>      v.set_credential(gtkvnc.CREDENTIAL_PASSWORD, sys.argv[3])
> diff -r 06fb3b1e2320 -r 3c2eb84af9ae src/libgtk-vnc_sym.version
> --- a/src/libgtk-vnc_sym.version	Fri Jul 06 11:40:33 2007 -0400
> +++ b/src/libgtk-vnc_sym.version	Fri Jul 06 13:39:41 2007 -0400
> @@ -18,6 +18,7 @@
>      vnc_display_set_pointer_local;
>      vnc_display_set_pointer_grab;
>      vnc_display_set_keyboard_grab;
> +    vnc_display_set_sticky_modifiers;
>  
>      vnc_display_get_width;
>      vnc_display_get_height;
> diff -r 06fb3b1e2320 -r 3c2eb84af9ae src/vncdisplay.c
> --- a/src/vncdisplay.c	Fri Jul 06 11:40:33 2007 -0400
> +++ b/src/vncdisplay.c	Fri Jul 06 13:39:41 2007 -0400
> @@ -36,6 +36,9 @@ struct _VncDisplayPrivate
>  	struct coroutine coroutine;
>  	struct gvnc *gvnc;
>  
> +	guint last_keyval;
> +	guint last_repeat;
> +
>  	gboolean in_pointer_grab;
>  	gboolean in_keyboard_grab;
>  
> @@ -49,6 +52,7 @@ struct _VncDisplayPrivate
>  	gboolean grab_pointer;
>  	gboolean grab_keyboard;
>  	gboolean local_pointer;
> +	gboolean sticky_modifiers;
>  };
>  
>  /* Signals */
> @@ -308,16 +312,56 @@ static gboolean key_event(GtkWidget *wid
>  	VncDisplayPrivate *priv = VNC_DISPLAY(widget)->priv;
>  	int down;
>  
> -	if (priv->gvnc == NULL)
> -		return TRUE;
> -	
> +	if (priv->gvnc == NULL || !gvnc_is_connected(priv->gvnc))
> +		return TRUE;
> +
> +	/* Sticky key down processing */
> +	if (key->type == GDK_KEY_PRESS && priv->sticky_modifiers) {
> +		if (key->keyval == GDK_Control_L ||
> +		    key->keyval == GDK_Control_R ||
> +		    key->keyval == GDK_Alt_L ||
> +		    key->keyval == GDK_Alt_R) {
> +			/* Got a modifier, start counting presses */
> +			if (priv->last_keyval == key->keyval) {
> +				priv->last_repeat++;
> +			} else {
> +				priv->last_keyval = key->keyval;
> +				priv->last_repeat = 1;
> +			}
> +		} else if (priv->last_keyval != 0 && priv->last_repeat >= 3) {
> +			/* Got a non-modifier & a sticky key was active, so
> +			 * send a fake key down event */
> +			gvnc_key_event(priv->gvnc, 1, priv->last_keyval);
> +		}
> +	}
> +
> +
>  	if (key->type == GDK_KEY_PRESS)
>  		down = 1;
>  	else
>  		down = 0;
>  
> +	/* Send this real event */
>  	gvnc_key_event(priv->gvnc, down, key->keyval);
>  
> +	/* Sticky key up processing */
> +	if (key->type == GDK_KEY_RELEASE && priv->sticky_modifiers) {
> +		/* If non-modifier need some sticky key processing */
> +		if (key->keyval != GDK_Control_L &&
> +		    key->keyval != GDK_Control_R &&
> +		    key->keyval != GDK_Alt_L &&
> +		    key->keyval != GDK_Alt_R) {
> +			/* Have a sticky key, might need a fake key up */
> +			if (priv->last_keyval != 0 &&
> +			    priv->last_repeat >= 3)
> +				gvnc_key_event(priv->gvnc, 0, priv->last_keyval);
> +
> +			/* Clear sticky key if any non-modifier was released */
> +			priv->last_keyval = 0;
> +		}
> +	}
> +
> +	/* Release pointer grab with Ctrl+Alt */
>  	if (key->type == GDK_KEY_PRESS &&
>  	    ((key->keyval == GDK_Control_L && (key->state & GDK_MOD1_MASK)) ||
>  	     (key->keyval == GDK_Alt_L && (key->state & GDK_CONTROL_MASK)))) {
> @@ -840,6 +884,11 @@ void vnc_display_set_keyboard_grab(VncDi
>  		do_keyboard_ungrab(obj);
>  }
>  
> +void vnc_display_set_sticky_modifiers(VncDisplay *obj, gboolean enable)
> +{
> +	obj->priv->sticky_modifiers = enable;
> +}
> +
>  
>  GType vnc_display_get_type(void)
>  {
> diff -r 06fb3b1e2320 -r 3c2eb84af9ae src/vncdisplay.h
> --- a/src/vncdisplay.h	Fri Jul 06 11:40:33 2007 -0400
> +++ b/src/vncdisplay.h	Fri Jul 06 13:39:41 2007 -0400
> @@ -78,6 +78,7 @@ void		vnc_display_set_pointer_local(VncD
>  void		vnc_display_set_pointer_local(VncDisplay *obj, gboolean enable);
>  void		vnc_display_set_pointer_grab(VncDisplay *obj, gboolean enable);
>  void		vnc_display_set_keyboard_grab(VncDisplay *obj, gboolean enable);
> +void		vnc_display_set_sticky_modifiers(VncDisplay *obj, gboolean enable);
>  
>  GdkPixbuf *     vnc_display_get_pixbuf(VncDisplay *obj);
>  
>
>   
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