Re: [gtk-vnc-devel] PATCH: fix keycode -> keysym conversions

[Anthony Liguori <anthony codemonkey ws>]

Daniel P. Berrange wrote:
> Since the VNC protocol only concerns itself with key up & down events, there
> is no way to provide modifier key state to the remote server. For this reason
> when converting from keycodes to keysyms prior to transmission, the client
> must *not* apply modifier state. The exception is that the shift key should
> be applied. The current code just sends the  keysym that GTK converted to
> the server. The result is that pressing 'Alt' results in the server getting
> a Alt Down, followed by  ISO_Prev_Group Up event - and so the Alt key is
> forever 'stuck' down now.
>
> This patch re-runs the keycode -> keysym conversion, masking out all the
> modifier keys except for Shift. This ensures matching key down & up events
> get sent to the server, which then applies the modifier mapping itself.
>   

Great, thanks!

Regards,

Anthony Liguori

> Dan.
>   
> ------------------------------------------------------------------------
>
> changeset:   28:233507f10a28
> user:        "Daniel P. Berrange <berrange redhat com>"
> date:        Fri Jul 06 13:42:52 2007 -0400
> summary:     Fix keycode -> keysym mapping wrt to modifiers
>
> diff -r 3c2eb84af9ae -r 233507f10a28 src/vncdisplay.c
> --- a/src/vncdisplay.c	Fri Jul 06 13:39:41 2007 -0400
> +++ b/src/vncdisplay.c	Fri Jul 06 13:42:52 2007 -0400
> @@ -310,22 +310,49 @@ static gboolean key_event(GtkWidget *wid
>  			  gpointer data G_GNUC_UNUSED)
>  {
>  	VncDisplayPrivate *priv = VNC_DISPLAY(widget)->priv;
> -	int down;
> +	guint keyval;
> +	gint group, level;
> +	GdkModifierType consumed;
>  
>  	if (priv->gvnc == NULL || !gvnc_is_connected(priv->gvnc))
>  		return TRUE;
> +
> +	/*
> +	 * Key handling in VNC is screwy. The event.keyval from GTK is
> +	 * interpreted relative to modifier state. This really messes
> +	 * up with VNC which has no concept of modifiers - it just sees
> +	 * key up *& down events - the remote end interprets modifiers
> +	 * itself. So if we interpret at the client end you can end up
> +	 * with 'Alt' key press generating Alt_L, and key release generating
> +	 * ISO_Prev_Group. This really really confuses the VNC server
> +	 * with 'Alt' getting stuck on.
> +	 *
> +	 * So we have to redo GTK's  keycode -> keyval translation
> +	 * using only the SHIFT modifier which the RFB explicitly
> +	 * requires to be interpreted at client end.
> +	 *
> +	 * Arggggh.
> +	 */
> +	gdk_keymap_translate_keyboard_state(gdk_keymap_get_default(),
> +					    key->hardware_keycode,
> +					    key->state & (GDK_SHIFT_MASK | GDK_LOCK_MASK),
> +					    key->group,
> +					    &keyval,
> +					    &group,
> +					    &level,
> +					    &consumed);
>  
>  	/* 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) {
> +		if (keyval == GDK_Control_L ||
> +		    keyval == GDK_Control_R ||
> +		    keyval == GDK_Alt_L ||
> +		    keyval == GDK_Alt_R) {
>  			/* Got a modifier, start counting presses */
> -			if (priv->last_keyval == key->keyval) {
> +			if (priv->last_keyval == keyval) {
>  				priv->last_repeat++;
>  			} else {
> -				priv->last_keyval = key->keyval;
> +				priv->last_keyval = keyval;
>  				priv->last_repeat = 1;
>  			}
>  		} else if (priv->last_keyval != 0 && priv->last_repeat >= 3) {
> @@ -336,21 +363,16 @@ static gboolean key_event(GtkWidget *wid
>  	}
>  
>  
> -	if (key->type == GDK_KEY_PRESS)
> -		down = 1;
> -	else
> -		down = 0;
> -
>  	/* Send this real event */
> -	gvnc_key_event(priv->gvnc, down, key->keyval);
> +	gvnc_key_event(priv->gvnc, key->type == GDK_KEY_PRESS ? 1 : 0, 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) {
> +		if (keyval != GDK_Control_L &&
> +		    keyval != GDK_Control_R &&
> +		    keyval != GDK_Alt_L &&
> +		    keyval != GDK_Alt_R) {
>  			/* Have a sticky key, might need a fake key up */
>  			if (priv->last_keyval != 0 &&
>  			    priv->last_repeat >= 3)
> @@ -363,8 +385,8 @@ static gboolean key_event(GtkWidget *wid
>  
>  	/* 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)))) {
> +	    ((keyval == GDK_Control_L && (key->state & GDK_MOD1_MASK)) ||
> +	     (keyval == GDK_Alt_L && (key->state & GDK_CONTROL_MASK)))) {
>  		if (priv->in_pointer_grab)
>  			do_pointer_ungrab(VNC_DISPLAY(widget));
>  		else
>
>   
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