ui/vnc: disable adaptive update calculations if not needed

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/vnc.c

diff --git a/ui/vnc.c b/ui/vnc.c
index 25e4380..9c84b3e 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -3150,7 +3150,9 @@
             acl = 1;
 #endif
         } else if (strncmp(options, "lossy", 5) == 0) {
+#ifdef CONFIG_VNC_JPEG
             vs->lossy = true;
+#endif
         } else if (strncmp(options, "non-adaptive", 12) == 0) {
             vs->non_adaptive = true;
         } else if (strncmp(options, "share=", 6) == 0) {
@@ -3167,6 +3169,13 @@
         }
     }
 
+    /* adaptive updates are only used with tight encoding and
+     * if lossy updates are enabled so we can disable all the
+     * calculations otherwise */
+    if (!vs->lossy) {
+        vs->non_adaptive = true;
+    }
+
 #ifdef CONFIG_VNC_TLS
     if (acl && x509 && vs->tls.x509verify) {
         if (!(vs->tls.acl = qemu_acl_init("vnc.x509dname"))) {