vnc: tight add PNG encoding

Introduce a new encoding: VNC_ENCODING_TIGHT_PNG [1] (-269) with a new
tight filter VNC_TIGHT_PNG (0x0A). When the client tells it supports the Tight PNG
encoding, the server will use tight, but will always send encoding pixels using
PNG instead of zlib. If the client also told it support JPEG, then the server can
send JPEG, because PNG will only be used in the cases zlib was used in normal tight.

This encoding was introduced to speed up HTML5 based VNC clients like noVNC [2], but
can also be used on devices like iPhone where PNG can be rendered in hardware.

[1] http://wiki.qemu.org/VNC_Tight_PNG
[2] http://github.com/kanaka/noVNC/

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/configure b/configure
index 33e98a4993..59e9385b70 100755
--- a/configure
+++ b/configure
@@ -269,6 +269,7 @@ vde=""
 vnc_tls=""
 vnc_sasl=""
 vnc_jpeg=""
+vnc_png=""
 xen=""
 linux_aio=""
 attr=""
@@ -580,6 +581,10 @@ for opt do
   ;;
   --enable-vnc-jpeg) vnc_jpeg="yes"
   ;;
+  --disable-vnc-png) vnc_png="no"
+  ;;
+  --enable-vnc-png) vnc_png="yes"
+  ;;
   --disable-slirp) slirp="no"
   ;;
   --disable-uuid) uuid="no"
@@ -832,6 +837,8 @@ echo "  --disable-vnc-sasl       disable SASL encryption for VNC server"
 echo "  --enable-vnc-sasl        enable SASL encryption for VNC server"
 echo "  --disable-vnc-jpeg       disable JPEG lossy compression for VNC server"
 echo "  --enable-vnc-jpeg        enable JPEG lossy compression for VNC server"
+echo "  --disable-vnc-png        disable PNG compression for VNC server"
+echo "  --enable-vnc-png         enable PNG compression for VNC server"
 echo "  --disable-curses         disable curses output"
 echo "  --enable-curses          enable curses output"
 echo "  --disable-curl           disable curl connectivity"
@@ -1274,6 +1281,31 @@ EOF
 fi
 
 ##########################################
+# VNC PNG detection
+if test "$vnc_png" = "yes" ; then
+cat > $TMPC <<EOF
+//#include <stdio.h>
+#include <png.h>
+int main(void) {
+    png_structp png_ptr;
+    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+    return 0;
+}
+EOF
+    vnc_png_cflags=""
+    vnc_png_libs="-lpng"
+  if compile_prog "$vnc_png_cflags" "$vnc_png_libs" ; then
+    vnc_png=yes
+    libs_softmmu="$vnc_png_libs $libs_softmmu"
+  else
+    if test "$vnc_png" = "yes" ; then
+      feature_not_found "vnc-png"
+    fi
+    vnc_png=no
+  fi
+fi
+
+##########################################
 # fnmatch() probe, used for ACL routines
 fnmatch="no"
 cat > $TMPC << EOF
@@ -2123,6 +2155,7 @@ echo "Mixer emulation   $mixemu"
 echo "VNC TLS support   $vnc_tls"
 echo "VNC SASL support  $vnc_sasl"
 echo "VNC JPEG support  $vnc_jpeg"
+echo "VNC PNG support   $vnc_png"
 if test -n "$sparc_cpu"; then
     echo "Target Sparc Arch $sparc_cpu"
 fi
@@ -2264,6 +2297,10 @@ if test "$vnc_jpeg" = "yes" ; then
   echo "CONFIG_VNC_JPEG=y" >> $config_host_mak
   echo "VNC_JPEG_CFLAGS=$vnc_jpeg_cflags" >> $config_host_mak
 fi
+if test "$vnc_png" = "yes" ; then
+  echo "CONFIG_VNC_PNG=y" >> $config_host_mak
+  echo "VNC_PNG_CFLAGS=$vnc_png_cflags" >> $config_host_mak
+fi
 if test "$fnmatch" = "yes" ; then
   echo "CONFIG_FNMATCH=y" >> $config_host_mak
 fi