configs/same70-xplained/twm4nx/defconfig: Switch to 8BPP. That is the negotiated size requested by the VNC client anyway. graphics/vnc/server/vnc_color.c: Fix an error in color conversion.

configs/same70-xplained/twm4nx/defconfig

@@ -8,8 +8,7 @@
 # CONFIG_ARCH_RAMFUNCS is not set
 # CONFIG_MMCSD_MMCSUPPORT is not set
 # CONFIG_MMCSD_SPI is not set
-# CONFIG_NXTK_DEFAULT_BORDERCOLORS is not set
-# CONFIG_NX_DISABLE_16BPP is not set
+# CONFIG_NX_DISABLE_8BPP is not set
 # CONFIG_SAMV7_UART0 is not set
 # CONFIG_SAMV7_UART2 is not set
 # CONFIG_SAMV7_UART4 is not set
@@ -60,7 +59,7 @@ CONFIG_NETDEV_STATISTICS=y
 CONFIG_NETUTILS_TELNETD=y
 CONFIG_NET_ARP_SEND=y
 CONFIG_NET_BROADCAST=y
-CONFIG_NET_ETH_PKTSIZE=1514
+CONFIG_NET_ETH_PKTSIZE=870
 CONFIG_NET_ICMP=y
 CONFIG_NET_ICMP_SOCKET=y
 CONFIG_NET_SOCKOPTS=y
@@ -79,17 +78,7 @@ CONFIG_NXTERM_CACHESIZE=32
 CONFIG_NXTERM_CURSORCHAR=95
 CONFIG_NXTERM_MXCHARS=325
 CONFIG_NXTERM_NXKBDIN=y
-CONFIG_NXTK_BORDERCOLOR1=0x5cb7
-CONFIG_NXTK_BORDERCOLOR2=0x21c9
-CONFIG_NXTK_BORDERCOLOR3=0xffdf
-CONFIG_NXWIDGETS_BPP=16
-CONFIG_NXWIDGETS_CUSTOM_EDGECOLORS=y
-CONFIG_NXWIDGETS_CUSTOM_FILLCOLORS=y
-CONFIG_NXWIDGETS_DEFAULT_BACKGROUNDCOLOR=0x9dfb
-CONFIG_NXWIDGETS_DEFAULT_HIGHLIGHTCOLOR=0xc618
-CONFIG_NXWIDGETS_DEFAULT_SELECTEDBACKGROUNDCOLOR=0xd73e
-CONFIG_NXWIDGETS_DEFAULT_SHADOWEDGECOLOR=0x21e9
-CONFIG_NXWIDGETS_DEFAULT_SHINEEDGECOLOR=0xffdf
+CONFIG_NXWIDGETS_BPP=8
 CONFIG_NXWIDGETS_SIZEOFCHAR=1
 CONFIG_NX_BLOCKING=y
 CONFIG_NX_KBD=y
@@ -132,8 +121,9 @@ CONFIG_TWM4NX_ARCHINIT=y
 CONFIG_USART1_SERIAL_CONSOLE=y
 CONFIG_USER_ENTRYPOINT="twm4nx_main"
 CONFIG_VNCSERVER=y
+CONFIG_VNCSERVER_COLORFMT_RGB8=y
 CONFIG_VNCSERVER_PRIO=120
 CONFIG_VNCSERVER_SCREENHEIGHT=600
 CONFIG_VNCSERVER_SCREENWIDTH=800
 CONFIG_VNCSERVER_UPDATER_PRIO=120
-CONFIG_VNCSERVER_UPDATE_BUFSIZE=2048
+CONFIG_VNCSERVER_UPDATE_BUFSIZE=800

graphics/vnc/server/Kconfig

@@ -112,8 +112,25 @@ config VNCSERVER_UPDATE_BUFSIZE
 		example, an update buffers of 32 pixels at 8-bits per pixel and
 		32-rows would yield a buffer size of 1024!
 
-		Ideally, this buffer should fit in one network packet to avoid
-		accessive re-assembly of partial TCP packets.
+		There is a very strong interaction with this setting and the network MTU.
+		Ideally, this buffer should fit in one network packet to avoid accessive
+		re-assembly of partial TCP packets.
+
+		REVISIT:  In fact, if the buffer does not fit in one network packet,
+		then there appears to be reliability issues in the connection.  I am
+		not sure why that is; TCP is a stream so it should not matter how
+		many packets are in a transfer.
+
+		Example:  Negotiated pixel depth = 8 BPP, window width = 800 pixels.
+		CONFIG_VNCSERVER_UPDATE_BUFSIZE needs to be the payload size (MSS)
+		of the transfer or 800 bytes.  The MTU is then:
+
+		  MSS = MTU - sizeof(IP Header) - sizeof(VNC FramebufferUpdate Header)
+
+		For IPv4, the IP Header is 20 bytes; 40 bytes for IPv6.  The
+		FramebufferUpdate header is 16 bytes so.  The desired MSS is 800 bytes
+		so MTU = 836 or 856.  For Ethernet, this is a total packet size of 870
+		bytes.
 
 config VNCSERVER_KBDENCODE
 	bool "Encode keyboard input"

graphics/vnc/server/vnc_color.c

@@ -155,7 +155,7 @@ uint8_t vnc_convert_rgb8_332(lfb_color_t rgb)
    *          RRRGGGBB
    */
 
-  return (uint8_t)(((rgb >> 8) & 0x0070)  |
+  return (uint8_t)(((rgb >> 8) & 0x00e0)  |
                    ((rgb >> 6) & 0x001c)  |
                    ((rgb >> 3) & 0x0003));
 }

graphics/vnc/server/vnc_raw.c

@@ -164,7 +164,8 @@ static size_t vnc_copy16(FAR struct vnc_session_s *session,
 
   /* Source rectangle start address (left/top)*/
 
-  srcleft = (FAR lfb_color_t *)(session->fb + RFB_STRIDE * row + RFB_BYTESPERPIXEL * col);
+  srcleft = (FAR lfb_color_t *)
+    (session->fb + RFB_STRIDE * row + RFB_BYTESPERPIXEL * col);
 
   /* Transfer each row from the source buffer into the update buffer */
 
@@ -235,7 +236,8 @@ static size_t vnc_copy32(FAR struct vnc_session_s *session,
 
   /* Source rectangle start address (left/top)*/
 
-  srcleft = (FAR lfb_color_t *)(session->fb + RFB_STRIDE * row + RFB_BYTESPERPIXEL * col);
+  srcleft = (FAR lfb_color_t *)
+    (session->fb + RFB_STRIDE * row + RFB_BYTESPERPIXEL * col);
 
   /* Transfer each row from the source buffer into the update buffer */