Add adjust filter features to libvlc_media_player/libvlc_video

This patch exposes the adjust module to libvlc_media_player/libvlc_video
and adds a frequently requested featureset: to manipulate brightness,
contrast, gamma, saturation and hue through libvlc. The patch introduces
a new set of functions analogous to
libvlc_video_{get,set}_{marq,logo}_*, hence the use of the function set
should be self explanatory.

New Functions:

* value = libvlc_video_get_adjust_int( p_mi, option );
* libvlc_video_set_adjust_int( p_mi, option, value );
* value = libvlc_video_get_adjust_float( p_mi, option );
* libvlc_video_set_adjust_float( p_mi, option, value );

New Options:

* libvlc_adjust_Enable
* libvlc_adjust_Contrast
* libvlc_adjust_Brightness
* libvlc_adjust_Hue
* libvlc_adjust_Saturation
* libvlc_adjust_Gamma
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

include/vlc/libvlc_media_player.h

@@ -925,6 +925,58 @@ VLC_PUBLIC_API void libvlc_video_set_logo_string( libvlc_media_player_t *p_mi,
                                       unsigned option, const char *psz_value );
 
 
+/** option values for libvlc_video_{get,set}_adjust_{int,float,bool} */
+enum libvlc_video_adjust_option_t {
+    libvlc_adjust_Enable = 0,
+    libvlc_adjust_Contrast,
+    libvlc_adjust_Brightness,
+    libvlc_adjust_Hue,
+    libvlc_adjust_Saturation,
+    libvlc_adjust_Gamma,
+};
+
+/**
+ * Get integer adjust option.
+ *
+ * \param p_mi libvlc media player instance
+ * \param option adjust option to get, values of libvlc_video_adjust_option_t
+ */
+VLC_PUBLIC_API int libvlc_video_get_adjust_int( libvlc_media_player_t *p_mi,
+                                                unsigned option );
+
+/**
+ * Set adjust option as integer. Options that take a different type value
+ * are ignored.
+ * Passing libvlc_adjust_enable as option value has the side effect of
+ * starting (arg !0) or stopping (arg 0) the adjust filter.
+ *
+ * \param p_mi libvlc media player instance
+ * \param option adust option to set, values of libvlc_video_adjust_option_t
+ * \param value adjust option value
+ */
+VLC_PUBLIC_API void libvlc_video_set_adjust_int( libvlc_media_player_t *p_mi,
+                                                 unsigned option, int value );
+
+/**
+ * Get float adjust option.
+ *
+ * \param p_mi libvlc media player instance
+ * \param option adjust option to get, values of libvlc_video_adjust_option_t
+ */
+VLC_PUBLIC_API float libvlc_video_get_adjust_float( libvlc_media_player_t *p_mi,
+                                                    unsigned option );
+
+/**
+ * Set adjust option as float. Options that take a different type value
+ * are ignored.
+ *
+ * \param p_mi libvlc media player instance
+ * \param option adust option to set, values of libvlc_video_adjust_option_t
+ * \param value adjust option value
+ */
+VLC_PUBLIC_API void libvlc_video_set_adjust_float( libvlc_media_player_t *p_mi,
+                                                   unsigned option, float value );
+
 /** @} video */
 
 /** \defgroup libvlc_audio LibVLC audio controls

src/control/media_player.c

@@ -411,6 +411,12 @@ libvlc_media_player_new( libvlc_instance_t *instance )
     var_Create (mp, "logo-opacity", VLC_VAR_INTEGER | VLC_VAR_DOINHERIT);
     var_Create (mp, "logo-position", VLC_VAR_INTEGER | VLC_VAR_DOINHERIT);
 
+    var_Create (mp, "contrast", VLC_VAR_FLOAT | VLC_VAR_DOINHERIT);
+    var_Create (mp, "brightness", VLC_VAR_FLOAT | VLC_VAR_DOINHERIT);
+    var_Create (mp, "hue", VLC_VAR_INTEGER | VLC_VAR_DOINHERIT);
+    var_Create (mp, "saturation", VLC_VAR_FLOAT | VLC_VAR_DOINHERIT);
+    var_Create (mp, "gamma", VLC_VAR_FLOAT | VLC_VAR_DOINHERIT);
+
      /* Audio */
     var_Create (mp, "aout", VLC_VAR_STRING | VLC_VAR_DOINHERIT);
     var_Create (mp, "volume-muted", VLC_VAR_BOOL);

src/control/video.c

@@ -671,6 +671,46 @@ get_int( libvlc_media_player_t *p_mi, const char *restrict name,
 }
 
 
+static void
+set_float( libvlc_media_player_t *p_mi, const char *restrict name,
+            const opt_t *restrict opt, float value )
+{
+    if( !opt ) return;
+
+    if( opt->type != VLC_VAR_FLOAT )
+    {
+        libvlc_printerr( "Invalid argument to %s in %s", name, "set float" );
+        return;
+    }
+
+    var_SetFloat( p_mi, opt->name, value );
+
+    vlc_object_t *object = get_object( p_mi, name );
+    if( object )
+    {
+        var_SetFloat(object, opt->name, value );
+        vlc_object_release( object );
+    }
+}
+
+
+static float
+get_float( libvlc_media_player_t *p_mi, const char *restrict name,
+            const opt_t *restrict opt )
+{
+    if( !opt ) return 0.0;
+
+
+    if( opt->type != VLC_VAR_FLOAT )
+    {
+        libvlc_printerr( "Invalid argument to %s in %s", name, "get float" );
+        return 0.0;
+    }
+
+    return var_GetFloat( p_mi, opt->name );
+}
+
+
 static void
 set_string( libvlc_media_player_t *p_mi, const char *restrict name,
             const opt_t *restrict opt, const char *restrict psz_value )
@@ -821,3 +861,53 @@ int libvlc_video_get_logo_int( libvlc_media_player_t *p_mi,
 }
 
 
+/* adjust module support */
+
+
+static opt_t *
+adjust_option_bynumber( unsigned option )
+{
+    static const opt_t optlist[] =
+    {
+        { "adjust",               0 },
+        { "contrast",             VLC_VAR_FLOAT },
+        { "brightness",           VLC_VAR_FLOAT },
+        { "hue",                  VLC_VAR_INTEGER },
+        { "saturation",           VLC_VAR_FLOAT },
+        { "gamma",                VLC_VAR_FLOAT },
+    };
+    enum { num_opts = sizeof(optlist) / sizeof(*optlist) };
+
+    opt_t *r = option < num_opts ? optlist+option : NULL;
+    if( !r )
+        libvlc_printerr( "Unknown adjust option" );
+    return r;
+}
+
+
+void libvlc_video_set_adjust_int( libvlc_media_player_t *p_mi,
+                                  unsigned option, int value )
+{
+    set_int( p_mi, "adjust", adjust_option_bynumber(option), value );
+}
+
+
+int libvlc_video_get_adjust_int( libvlc_media_player_t *p_mi,
+                                 unsigned option )
+{
+    return get_int( p_mi, "adjust", adjust_option_bynumber(option) );
+}
+
+
+void libvlc_video_set_adjust_float( libvlc_media_player_t *p_mi,
+                                    unsigned option, float value )
+{
+    set_float( p_mi, "adjust", adjust_option_bynumber(option), value );
+}
+
+
+float libvlc_video_get_adjust_float( libvlc_media_player_t *p_mi,
+                                     unsigned option )
+{
+    return get_float( p_mi, "adjust", adjust_option_bynumber(option) );
+}

src/libvlc.sym

@@ -162,6 +162,9 @@ libvlc_set_log_verbosity
 libvlc_toggle_fullscreen
 libvlc_toggle_teletext
 libvlc_track_description_release
+libvlc_video_get_adjust_bool
+libvlc_video_get_adjust_float
+libvlc_video_get_adjust_int
 libvlc_video_get_aspect_ratio
 libvlc_video_get_chapter_description
 libvlc_video_get_crop_geometry
@@ -181,6 +184,9 @@ libvlc_video_get_track
 libvlc_video_get_track_count
 libvlc_video_get_track_description
 libvlc_video_get_width
+libvlc_video_set_adjust_bool
+libvlc_video_set_adjust_float
+libvlc_video_set_adjust_int
 libvlc_video_set_aspect_ratio
 libvlc_video_set_crop_geometry
 libvlc_video_set_deinterlace