VNC: Ignore client framebuffer updates if nothing has changed (we can does this because client requests incremental updates

graphics/vnc/server/vnc_fbdev.c

@@ -877,7 +877,7 @@ void nx_notify_rectangle(FAR NX_PLANEINFOTYPE *pinfo,
     {
       /* Queue the rectangular update */
 
-      ret = vnc_update_rectangle(session, rect);
+      ret = vnc_update_rectangle(session, rect, true);
       if (ret < 0)
         {
           gdbg("ERROR: vnc_update_rectangle failed: %d\n", ret);

graphics/vnc/server/vnc_negotiate.c

@@ -521,5 +521,6 @@ int vnc_client_pixelformat(FAR struct vnc_session_s *session,
       return -ENOSYS;
     }
 
+  session->change = true;
   return OK;
 }

graphics/vnc/server/vnc_receiver.c

@@ -176,6 +176,10 @@ int vnc_receiver(FAR struct vnc_session_s *session)
           return -errcode;
         }
 
+      /* REVISIT: This assertion sometimes fires when there is a client
+       * disconnection.
+       */
+
       DEBUGASSERT(nrecvd == 1);
 
       /* The single byte received should be the message type.  Handle the
@@ -218,7 +222,7 @@ int vnc_receiver(FAR struct vnc_session_s *session)
           case RFB_SETENCODINGS_MSG:   /* SetEncodings */
             {
               FAR struct rfb_setencodings_s *encodings;
-              uint32_t nencodings;
+              unsigned int nencodings;
 
               gvdbg("Received SetEncodings\n");
 
@@ -239,7 +243,7 @@ int vnc_receiver(FAR struct vnc_session_s *session)
                   /* Read the following encodings */
 
                   encodings  = (FAR struct rfb_setencodings_s *)session->inbuf;
-                  nencodings = rfb_getbe32(encodings->nencodings);
+                  nencodings = rfb_getbe16(encodings->nencodings);
 
                   ret = vnc_read_remainder(session,
                                            nencodings * sizeof(uint32_t),
@@ -291,7 +295,7 @@ int vnc_receiver(FAR struct vnc_session_s *session)
                   rect.pt2.x = rect.pt1.x + rfb_getbe16(update->width);
                   rect.pt2.y = rect.pt1.y + rfb_getbe16(update->height);
 
-                  ret = vnc_update_rectangle(session, &rect);
+                  ret = vnc_update_rectangle(session, &rect, false);
                   if (ret < 0)
                     {
                       gdbg("ERROR: Failed to queue update: %d\n", ret);
@@ -463,7 +467,7 @@ int vnc_client_encodings(FAR struct vnc_session_s *session,
 
   /* Loop for each client supported encoding */
 
-  nencodings = rfb_getbe32(encodings->nencodings);
+  nencodings = rfb_getbe16(encodings->nencodings);
   for (i = 0; i < nencodings; i++)
     {
       /* Get the next encoding */
@@ -475,10 +479,10 @@ int vnc_client_encodings(FAR struct vnc_session_s *session,
       if (encoding == RFB_ENCODING_RRE)
         {
           session->rre = true;
-          return OK;
         }
     }
 
+  session->change = true;
   return OK;
 }
 

graphics/vnc/server/vnc_server.h

@@ -246,14 +246,15 @@ struct vnc_session_s
   struct socket connect;       /* Connected socket */
   volatile uint8_t state;      /* See enum vnc_server_e */
   volatile uint8_t nwhupd;     /* Number of whole screen updates queued */
+  volatile bool change;        /* True: Frambebuffer data change since last whole screen update */
 
   /* Display geometry and color characteristics */
 
   uint8_t display;             /* Display number (for debug) */
   volatile uint8_t colorfmt;   /* Remote color format (See include/nuttx/fb.h) */
   volatile uint8_t bpp;        /* Remote bits per pixel */
-  volatile bool bigendian;     /* Remote expect data in big-endian format */
+  volatile bool bigendian;     /* True: Remote expect data in big-endian format */
-  volatile bool rre;           /* Remote supports RRE encoding */
+  volatile bool rre;           /* True: Remote supports RRE encoding */
   FAR uint8_t *fb;             /* Allocated local frame buffer */
 
   /* VNC client input support */
@@ -450,6 +451,7 @@ int vnc_stop_updater(FAR struct vnc_session_s *session);
  * Input Parameters:
  *   session - An instance of the session structure.
  *   rect    - The rectanglular region to be updated.
+ *   change  - True: Frame buffer data has changed
  *
  * Returned Value:
  *   Zero (OK) is returned on success; a negated errno value is returned on
@@ -458,7 +460,8 @@ int vnc_stop_updater(FAR struct vnc_session_s *session);
  ****************************************************************************/
 
 int vnc_update_rectangle(FAR struct vnc_session_s *session,
-                         FAR const struct nxgl_rect_s *rect);
+                         FAR const struct nxgl_rect_s *rect,
+                         bool change);
 
 /****************************************************************************
  * Name: vnc_receiver

graphics/vnc/server/vnc_updater.c

@@ -490,6 +490,7 @@ int vnc_stop_updater(FAR struct vnc_session_s *session)
  * Input Parameters:
  *   session - An instance of the session structure.
  *   rect    - The rectanglular region to be updated.
+ *   change  - True: Frame buffer data has changed
  *
  * Returned Value:
  *   Zero (OK) is returned on success; a negated errno value is returned on
@@ -498,7 +499,7 @@ int vnc_stop_updater(FAR struct vnc_session_s *session)
  ****************************************************************************/
 
 int vnc_update_rectangle(FAR struct vnc_session_s *session,
-                         FAR const struct nxgl_rect_s *rect)
+                         FAR const struct nxgl_rect_s *rect, bool change)
 {
   FAR struct vnc_fbupdate_s *update;
   struct nxgl_rect_s intersection;
@@ -519,20 +520,34 @@ int vnc_update_rectangle(FAR struct vnc_session_s *session,
       whupd = (memcmp(&intersection, &g_wholescreen,
                       sizeof(struct nxgl_rect_s)) == 0);
 
-      /* Ignore all updates if there is a queue whole screen update */
+      /* Ignore any client update requests if there have been no changes to
+       * the framebuffer since the last whole screen update.
+       */
 
       sched_lock();
+      if (!change && !session->change)
+        {
+          /* No.. ignore the client update.  We have nothing new to report. */
+
+          sched_unlock();
+          return OK;
+        }
+
+      /* Ignore all updates if there is a queued whole screen update */
+
       if (session->nwhupd == 0)
         {
-          /* Is this a new whole screen update */
+          /* No whole screen updates in the queue.  Is this a new whole
+           * screen update?
+           */
 
           if (whupd)
             {
+              /* Yes.. Discard all of the previously queued updates */
+
               FAR struct vnc_fbupdate_s *curr;
               FAR struct vnc_fbupdate_s *next;
 
-              /* Yes.. discard all of the previously queued updates */
-
               updvdbg("New whole screen update...\n");
 
               curr = (FAR struct vnc_fbupdate_s *)session->updqueue.head;
@@ -545,7 +560,20 @@ int vnc_update_rectangle(FAR struct vnc_session_s *session,
                   vnc_free_update(session, curr);
                 }
 
+              /* One whole screen update will be queued.  There have been
+               * no frame buffer data changes since this update was queued.
+               */
+
               session->nwhupd = 1;
+              session->change = false;
+            }
+          else
+            {
+              /* We are not updating the whole screen.  Remember if this
+               * update (OR a preceding update) was due to a data change.
+               */
+
+              session->change |= change;
             }
 
           /* Allocate an update structure... waiting if necessary */