Add support for %nwin% in xworkspaces label (#2329)

%nwin% tells the number of windows in a workspace

CHANGELOG.md

@@ -70,6 +70,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `internal/network`: `interface-type` may be used in place of `interface` to
   automatically select a network interface
   ([`#2025`](https://github.com/polybar/polybar/pull/2025))
+- `internal/xworkspaces`: `%nwin%` can be used to display the number of open
+  windows per workspace
+  ([`#604`](https://github.com/polybar/polybar/issues/604))
 
 ### Changed
 - Slight changes to the value ranges the different ramp levels are responsible

include/modules/xworkspaces.hpp

@@ -99,6 +99,7 @@ namespace modules {
      * Maps an xcb window to its desktop number
      */
     map<xcb_window_t, unsigned int> m_clients;
+    map<unsigned int, unsigned int> m_windows;
     vector<unique_ptr<viewport>> m_viewports;
     map<desktop_state, label_t> m_labels;
     label_t m_monitorlabel;

src/modules/xworkspaces.cpp

@@ -144,9 +144,11 @@ namespace modules {
 
     // rebuild entire mapping of clients to desktops
     m_clients.clear();
+    m_windows.clear();
     for (auto&& client : newclients) {
       auto desk = ewmh_util::get_desktop_from_window(client);
       m_clients[client] = desk;
+      m_windows[desk]++;
     }
 
     rebuild_urgent_hints();
@@ -270,6 +272,7 @@ namespace modules {
         d->label->reset_tokens();
         d->label->replace_token("%index%", to_string(d->index + 1));
         d->label->replace_token("%name%", m_desktop_names[d->index]);
+        d->label->replace_token("%nwin%", to_string(m_windows[d->index]));
         d->label->replace_token("%icon%", m_icons->get(m_desktop_names[d->index], DEFAULT_ICON)->get());
       }
     }