introduced i3 command for changing the hidden state and the mode of i3bar

The hidden_state and mode of each i3bar instance can now be controlled from within i3.
Therefore, two new i3 command were introduced:
    _
    bar hidden_state show|hide|toggle [<bar_id>]

    show: always show the bar
    hide: normal hide mode
    toggle: toggle between show and hide (individually for each bar)
    _
    bar mode dock|hide|invisible|toggle [<bar_id>]

    hide,dock: like before
    invisible: always keep the bar hidden
    toggle: toggle between dock and hide (individually for each bar)

This patch introduces a hidden_state ("hidden_state hide|show") in the
barconfig, which indicates the current hidden_state of each i3bar
instance. It only affects the bar when in hide mode. Additionally, a new
invisible mode was introduced. In order to change the hidden_state or
mode of the bar from i3, a barconfig-update event was introduced, for
which a bar can subscribe and the bar then gets notified about the
currently set hidden_state and mode in its barconfig.

For convenience, an id field ("id <bar_id>") was added to the barconfig, where one can
set the desired id for the corresponding bar. If the id is not specified, i3 will
deterministically choose an id; otherwise, with the previous random approach for finding
a new id, which is actually not shared with i3bar, as it would determine its id on
startup, the event-subscription would be destroyed on reload. Still, this issue remains
when manually changing the bar_id in the config and then reloading.

fixes #833, #651

include/commands.h

@@ -265,4 +265,10 @@ void cmd_scratchpad_show(I3_CMD);
  */
 void cmd_rename_workspace(I3_CMD, char *old_name, char *new_name);
 
+/**
+ * Implementation of 'bar (hidden_state hide|show|toggle)|(mode dock|hide|invisible|toggle) [<bar_id>]'
+ *
+ */
+void cmd_bar(I3_CMD, char *bar_type, char *bar_value, char *bar_id);
+
 #endif

include/config.h

@@ -199,6 +199,9 @@ struct Config {
         /* just ignore the popup, that is, don’t map it */
         PDF_IGNORE = 2,
     } popup_during_fullscreen;
+
+    /* The number of currently parsed barconfigs */
+    int number_barconfigs;
 };
 
 /**
@@ -226,8 +229,11 @@ struct Barconfig {
      * root window! */
     char *socket_path;
 
-    /** Bar display mode (hide unless modifier is pressed or show in dock mode) */
-    enum { M_DOCK = 0, M_HIDE = 1 } mode;
+    /** Bar display mode (hide unless modifier is pressed or show in dock mode or always hide in invisible mode) */
+    enum { M_DOCK = 0, M_HIDE = 1, M_INVISIBLE = 2 } mode;
+
+    /* The current hidden_state of the bar, which indicates whether it is hidden or shown */
+    enum { S_HIDE = 0, S_SHOW = 1 } hidden_state;
 
     /** Bar modifier (to show bar when in hide mode). */
     enum {
@@ -323,6 +329,12 @@ void grab_all_keys(xcb_connection_t *conn, bool bind_mode_switch);
  */
 void switch_mode(const char *new_mode);
 
+/**
+ * Sends the current bar configuration as an event to all barconfig_update listeners.
+ * This update mechnism currently only includes the hidden_state and the mode in the config.
+ *
+ */void update_barconfig();
+
 /**
  * Returns a pointer to the Binding with the specified modifiers and keycode
  * or NULL if no such binding exists.

include/config_directives.h

@@ -62,6 +62,8 @@ CFGFUN(mode_binding, const char *bindtype, const char *modifiers, const char *ke
 
 CFGFUN(bar_font, const char *font);
 CFGFUN(bar_mode, const char *mode);
+CFGFUN(bar_hidden_state, const char *hidden_state);
+CFGFUN(bar_id, const char *bar_id);
 CFGFUN(bar_output, const char *output);
 CFGFUN(bar_verbose, const char *verbose);
 CFGFUN(bar_modifier, const char *modifier);

include/i3/ipc.h

@@ -99,4 +99,7 @@ typedef struct i3_ipc_header {
 /* The window event will be triggered upon window changes */
 #define I3_IPC_EVENT_WINDOW                     (I3_IPC_EVENT_MASK | 3)
 
+/** Bar config update will be triggered to update the bar config */
+#define I3_IPC_EVENT_BARCONFIG_UPDATE           (I3_IPC_EVENT_MASK | 4)
+
 #endif