feat(xkeyboard): Switch layout group on click

When serveral layout groups are defined for the keyboard
they can be cycled when clicking on the module.

   For example:

   $ setxkbmap -layout us,sv,fr

Ref #84

include/modules/xkeyboard.hpp

@@ -25,6 +25,10 @@ namespace modules {
     void teardown();
     void update();
     bool build(builder* builder, const string& tag) const;
+    bool handle_event(string cmd);
+    bool receive_events() const {
+      return true;
+    }
 
    protected:
     bool query_keyboard();
@@ -39,6 +43,8 @@ namespace modules {
     static constexpr const char* TAG_LABEL_INDICATOR{"<label-indicator>"};
     static constexpr const char* FORMAT_DEFAULT{"<label-layout> <label-indicator>"};
 
+    static constexpr const char* EVENT_SWITCH{"xkeyboard/switch"};
+
     connection& m_connection;
     event_timer m_xkbnotify{};
     unique_ptr<keyboard> m_keyboard;

include/x11/xkb.hpp

@@ -72,6 +72,7 @@ class keyboard {
   const string group_name(size_t index = 0) const;
   const string layout_name(size_t index = 0) const;
   const string indicator_name(const indicator::type&) const;
+  size_t size() const;
 
  private:
   vector<layout> layouts;
@@ -82,6 +83,7 @@ class keyboard {
 namespace xkb_util {
   static constexpr const char* LAYOUT_SYMBOL_BLACKLIST{";group;inet;pc;"};
 
+  void switch_layout(connection& conn, xcb_xkb_device_spec_t device, uint8_t index);
   uint8_t get_current_group(connection& conn, xcb_xkb_device_spec_t device);
   vector<keyboard::layout> get_layouts(connection& conn, xcb_xkb_device_spec_t device);
   map<keyboard::indicator::type, keyboard::indicator> get_indicators(connection& conn, xcb_xkb_device_spec_t device);

src/components/bar.cpp

@@ -478,7 +478,6 @@ void bar::handle(const evt::button_press& evt) {
   }
 
   std::lock_guard<std::mutex> guard(m_mutex, std::adopt_lock);
-
   if (m_buttonpress.deny(evt->time)) {
     return m_log.trace_x("bar: Ignoring button press (throttled)...");
   }

src/components/controller.cpp

@@ -262,6 +262,8 @@ void controller::wait_for_eventloop() {
 }
 
 bool controller::on(const sig_ev::process_update& evt) {
+  bool force{evt.data()->flag};
+
   if (!m_bar) {
     return false;
   }

src/modules/xkeyboard.cpp

@@ -99,6 +99,8 @@ namespace modules {
    * Map format tags to content
    */
   bool xkeyboard_module::build(builder* builder, const string& tag) const {
+    builder->cmd(mousebtn::LEFT, EVENT_SWITCH);
+
     if (tag == TAG_LABEL_LAYOUT) {
       builder->node(m_layout);
     } else if (tag == TAG_LABEL_INDICATOR) {
@@ -114,6 +116,31 @@ namespace modules {
       return false;
     }
 
+    builder->cmd_close();
+
+    return true;
+  }
+
+  /**
+   * Handle input command
+   */
+  bool xkeyboard_module::handle_event(string cmd) {
+    if (cmd.compare(0, strlen(EVENT_SWITCH), EVENT_SWITCH) != 0) {
+      return false;
+    }
+
+    size_t current_group{m_keyboard->current() + 1UL};
+
+    if (current_group >= m_keyboard->size()) {
+      current_group = 0;
+    }
+
+    printf("%zu\n", current_group);
+
+    xkb_util::switch_layout(m_connection, XCB_XKB_ID_USE_CORE_KBD, current_group);
+    m_keyboard->current(current_group);
+    m_connection.flush();
+
     return true;
   }
 

src/x11/xkb.cpp

@@ -7,7 +7,7 @@
 POLYBAR_NS
 
 /**
- * Get indicator name
+ * Get next layout index
  */
 const keyboard::indicator& keyboard::get(const indicator::type& i) const {
   return indicators.at(i);
@@ -70,7 +70,19 @@ const string keyboard::indicator_name(const indicator::type& i) const {
   return indicators.at(i).name;
 }
 
+size_t keyboard::size() const {
+  return layouts.size();
+}
+
 namespace xkb_util {
+  /**
+   * Get current group number
+   */
+  void switch_layout(connection& conn, xcb_xkb_device_spec_t device, uint8_t index) {
+    xcb_xkb_latch_lock_state(conn, device, 0, 0, true, index, 0, 0, 0);
+    xcb_flush(conn);
+  }
+
   /**
    * Get current group number
    */