[Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down

[Chunyan Liu <cyliu@suse.com>]

Using xen tools 'xl vncviewer' with tigervnc (default on SLE-12),
found that: the display of the guest is unexpected while keep
pressing a key. We expect the same character multiple times, but
it prints only one time. This happens on a PV guest in text mode.

After debugging, found that tigervnc sends repeated key down events
in this case, to differentiate from user pressing the same key many
times. Vnc server only prints the character when it finally receives
key up event.

To solve this issue, this patch tries to add additional key up event
before the next repeated key down event (if the key is not a control
key).

Signed-off-by: Chunyan Liu <cyliu@suse.com>
---
 ui/vnc.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/ui/vnc.c b/ui/vnc.c
index f8d9b7d..a265378 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -1659,6 +1659,25 @@ static void do_key_event(VncState *vs, int down, int keycode, int sym)
         if (down)
             vs->modifiers_state[keycode] ^= 1;
         break;
+    default:
+        if (qemu_console_is_graphic(NULL)) {
+            /* record key 'down' info. Some client like tigervnc
+             * will send key down repeatedly if user pressing a
+             * a key for long time. In this case, we should add
+             * additional key up event before repeated key down,
+             * so that it can display the key multiple times.
+             */
+            if (down) {
+                if (vs->modifiers_state[keycode]) {
+                    /* add a key up event */
+                    do_key_event(vs, 0, keycode, sym);
+                }
+                vs->modifiers_state[keycode] = 1;
+            } else {
+                vs->modifiers_state[keycode] = 0;
+            }
+        }
+        break;
     }
 
     /* Turn off the lock state sync logic if the client support the led
-- 
1.8.4.5