vnc: tight: add JPEG and gradient subencoding with smooth image detection

Add gradient filter and JPEG compression with an heuristic to detect how
lossy the comppression will be. This code has been adapted from
libvncserver/tight.c.

JPEG support can be enabled/disabled at compile time with --enable-vnc-jpeg
and --disable-vnc-jpeg.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/vnc.h b/vnc.h
index 7b64cf730b..2a9024d1cc 100644
--- a/vnc.h
+++ b/vnc.h
@@ -176,6 +176,10 @@ struct VncState
     Buffer tight;
     Buffer tight_tmp;
     Buffer tight_zlib;
+    Buffer tight_gradient;
+#ifdef CONFIG_VNC_JPEG
+    Buffer tight_jpeg;
+#endif
     int tight_levels[4];
     z_stream tight_stream[4];