fix(xworkspace): Fully support _NET_DESKTOP_NAMES spec (#1579)

Ref https://specifications.freedesktop.org/wm-spec/wm-spec-latest.html#idm140200472706208

Fixes #1491
Fixes #248
Closes #904

include/modules/xworkspaces.hpp

@@ -69,6 +69,7 @@ namespace modules {
     void set_desktop_urgent(xcb_window_t window);
 
     bool input(string&& cmd);
+    vector<string> get_desktop_names();
 
    private:
     static constexpr const char* DEFAULT_ICON{"icon-default"};

include/x11/ewmh.hpp

@@ -24,6 +24,7 @@ namespace ewmh_util {
   vector<position> get_desktop_viewports(int screen = 0);
   vector<string> get_desktop_names(int screen = 0);
   unsigned int get_current_desktop(int screen = 0);
+  unsigned int get_number_of_desktops(int screen = 0);
   xcb_window_t get_active_window(int screen = 0);
 
   void change_current_desktop(unsigned int desktop);

src/modules/xworkspaces.cpp

@@ -81,7 +81,7 @@ namespace modules {
     m_monitors = randr_util::get_monitors(m_connection, m_connection.root(), false);
 
     // Get desktop details
-    m_desktop_names = ewmh_util::get_desktop_names();
+    m_desktop_names = get_desktop_names();
     m_current_desktop = ewmh_util::get_current_desktop();
 
     rebuild_desktops();
@@ -97,8 +97,8 @@ namespace modules {
   void xworkspaces_module::handle(const evt::property_notify& evt) {
     if (evt->atom == m_ewmh->_NET_CLIENT_LIST) {
       rebuild_clientlist();
-    } else if (evt->atom == m_ewmh->_NET_DESKTOP_NAMES) {
+    } else if (evt->atom == m_ewmh->_NET_DESKTOP_NAMES || evt->atom == m_ewmh->_NET_NUMBER_OF_DESKTOPS) {
-      m_desktop_names = ewmh_util::get_desktop_names();
+      m_desktop_names = get_desktop_names();
       rebuild_desktops();
       rebuild_desktop_states();
     } else if (evt->atom == m_ewmh->_NET_CURRENT_DESKTOP) {
@@ -224,6 +224,22 @@ namespace modules {
     }
   }
 
+  vector<string> xworkspaces_module::get_desktop_names(){
+    vector<string> names = ewmh_util::get_desktop_names();
+    unsigned int desktops_number = ewmh_util::get_number_of_desktops();
+    if(desktops_number == names.size()) {
+      return names;
+    }
+    else if(desktops_number < names.size()) {
+      names.erase(names.begin()+desktops_number, names.end());
+      return names;
+    }
+    for (unsigned int i = names.size(); i < desktops_number + 1; i++) {
+      names.insert(names.end(), to_string(i));
+    }
+    return names;
+  }
+
   /**
    * Find window and set corresponding desktop to urgent
    */

src/x11/ewmh.cpp

@@ -77,6 +77,13 @@ namespace ewmh_util {
     return desktop;
   }
 
+  unsigned int get_number_of_desktops(int screen) {
+    auto conn = initialize().get();
+    unsigned int desktops = XCB_NONE;
+    xcb_ewmh_get_number_of_desktops_reply(conn, xcb_ewmh_get_number_of_desktops(conn, screen), &desktops, nullptr);
+    return desktops;
+  }
+
   vector<position> get_desktop_viewports(int screen) {
     auto conn = initialize().get();
     vector<position> viewports;