[Qemu-devel] [PATCH 3/5] vnc: add lossless option

[Corentin Chary <corentincj@iksaif.net>]

The lossless option can be used to force lossless compression
by disabling all lossy encodings like gradient or jpeg.

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
---
 qemu-options.hx      |    5 +++++
 vnc-encoding-tight.c |    4 ++++
 vnc.c                |    2 ++
 vnc.h                |    2 ++
 4 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/qemu-options.hx b/qemu-options.hx
index a6928b7..81fd737 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -828,6 +828,11 @@ empty, with a @code{deny} policy. Thus no one will be allowed to
 use the VNC server until the ACLs have been loaded. This can be
 achieved using the @code{acl} monitor command.
 
+@item lossless
+
+Turn off all lossy compression methods (gradient, JPEG, ...). If this
+option is set, VNC client will only receive lossless framebuffer updates.
+
 @end table
 ETEXI
 
diff --git a/vnc-encoding-tight.c b/vnc-encoding-tight.c
index 495745e..51bb707 100644
--- a/vnc-encoding-tight.c
+++ b/vnc-encoding-tight.c
@@ -230,6 +230,10 @@ tight_detect_smooth_image(VncState *vs, int w, int h)
     int compression = vs->tight_compression;
     int quality = vs->tight_quality;
 
+    if (vs->vd->lossless) {
+        return 0;
+    }
+
     if (ds_get_bytes_per_pixel(vs->ds) == 1 ||
         vs->clientds.pf.bytes_per_pixel == 1 ||
         w < VNC_TIGHT_DETECT_MIN_WIDTH || h < VNC_TIGHT_DETECT_MIN_HEIGHT) {
diff --git a/vnc.c b/vnc.c
index 9cf38d1..e3ef315 100644
--- a/vnc.c
+++ b/vnc.c
@@ -2482,6 +2482,8 @@ int vnc_display_open(DisplayState *ds, const char *display)
 #endif
         } else if (strncmp(options, "acl", 3) == 0) {
             acl = 1;
+        } else if (strncmp(options, "lossless", 8) == 0) {
+            vs->lossless = true;
         }
     }
 
diff --git a/vnc.h b/vnc.h
index 2a9024d..cca1946 100644
--- a/vnc.h
+++ b/vnc.h
@@ -33,6 +33,7 @@
 #include "monitor.h"
 #include "audio/audio.h"
 #include <zlib.h>
+#include <stdbool.h>
 
 #include "keymaps.h"
 
@@ -111,6 +112,7 @@ struct VncDisplay
     char *display;
     char *password;
     int auth;
+    bool lossless;
 #ifdef CONFIG_VNC_TLS
     int subauth; /* Used by VeNCrypt */
     VncDisplayTLS tls;
-- 
1.7.1