feat(xwindow): New module "xwindow"

Add module to display title of active window.
Requires WM with support for the _NET_ACTIVE_WINDOW hint.

Ref #84

README.md

@@ -34,6 +34,7 @@ problems by [creating an issue ticket](https://github.com/jaagr/lemonbuddy/issue
 The main purpose of **Lemonbuddy** is to help users create awesome status bars.
 It has built-in functionality to generate content for the most commonly used widgets, such as:
 
+- Window title
 - Playback controls and status display for [MPD](https://www.musicpd.org/) using [libmpdclient](https://www.musicpd.org/libs/libmpdclient/)
 - [ALSA](http://www.alsa-project.org/main/index.php/Main_Page) volume controls
 - Workspace and desktop panel for [bspwm](https://github.com/baskerville/bspwm) and [i3](https://github.com/i3/i3)

examples/CMakeLists.txt

@@ -3,7 +3,7 @@
 #
 
 set(MODULES_LEFT "bspwm i3 mpd")
-set(MODULES_CENTER "")
+set(MODULES_CENTER "xwindow")
 set(MODULES_RIGHT "backlight volume memory cpu wlan eth battery temperature date powermenu")
 
 # Strip disabled modules {{{

examples/config

@@ -41,7 +41,7 @@ font-1 = unifont:size=6:heavy;-2
 font-2 = siji:pixelsize=10;0
 
 modules-left = bspwm i3 mpd
-modules-center = 
+modules-center = xwindow
 modules-right = backlight volume memory cpu wlan eth battery temperature date powermenu
 
 tray-position = right
@@ -52,6 +52,12 @@ tray-padding = 4
 ;wm-restack = bspwm
 
 
+[module/xwindow]
+type = internal/xwindow
+label = %title%
+label-maxlen = 30
+
+
 [module/filesystem]
 type = internal/fs
 interval = 25

examples/config.cmake

@@ -52,6 +52,12 @@ tray-padding = 4
 ;wm-restack = bspwm
 
 
+[module/xwindow]
+type = internal/xwindow
+label = %title%
+label-maxlen = 30
+
+
 [module/filesystem]
 type = internal/fs
 interval = 25

include/drawtypes/label.hpp

@@ -52,6 +52,7 @@ namespace drawtypes {
     operator bool();
     label_t clone();
     void reset_tokens();
+    bool has_token(string token);
     void replace_token(string token, string replacement);
     void replace_defined_values(const label_t& label);
     void copy_undefined(const label_t& label);

include/modules/xbacklight.hpp

@@ -32,6 +32,7 @@ namespace modules {
     using static_module::static_module;
 
     void setup();
+    void teardown();
     void handle(const evt::randr_notify& evt);
     void update();
     string get_output();

include/modules/xwindow.hpp

@@ -0,0 +1,92 @@
+#pragma once
+
+#include <bitset>
+
+#include "components/config.hpp"
+#include "drawtypes/label.hpp"
+#include "modules/meta.hpp"
+#include "x11/connection.hpp"
+#include "x11/ewmh.hpp"
+#include "x11/icccm.hpp"
+#include "x11/window.hpp"
+
+LEMONBUDDY_NS
+
+namespace modules {
+  /**
+   * Wrapper used to update the event mask of the
+   * currently active to enable title tracking
+   */
+  class active_window {
+   public:
+    explicit active_window(xcb_window_t win)
+        : m_connection(configure_connection().create<decltype(m_connection)>()), m_window(m_connection, win) {
+      try {
+        m_window.change_event_mask(XCB_EVENT_MASK_PROPERTY_CHANGE);
+      } catch (const xpp::x::error::window& err) {
+      }
+    }
+
+    ~active_window() {
+      try {
+        m_window.change_event_mask(XCB_EVENT_MASK_NO_EVENT);
+      } catch (const xpp::x::error::window& err) {
+      }
+    }
+
+    /**
+     * Check if current window matches passed value
+     */
+    bool match(const xcb_window_t win) const {
+      return m_window == win;
+    }
+
+    /**
+     * Get the title by returning the first non-empty value of:
+     *  _NET_WM_VISIBLE_NAME
+     *  _NET_WM_NAME
+     */
+    string title(xcb_ewmh_connection_t* ewmh) {
+      string title;
+
+      if (!(title = ewmh_util::get_visible_name(ewmh, m_window)).empty()) {
+        return title;
+      } else if (!(title = icccm_util::get_wm_name(m_connection, m_window)).empty()) {
+        return title;
+      } else {
+        return "";
+      }
+    }
+
+   private:
+    connection& m_connection;
+    window m_window{m_connection};
+  };
+
+  /**
+   * Module used to display information about the
+   * currently active X window.
+   */
+  class xwindow_module : public static_module<xwindow_module>, public xpp::event::sink<evt::property_notify> {
+   public:
+    using static_module::static_module;
+
+    void setup();
+    void teardown();
+    void handle(const evt::property_notify& evt);
+    void update();
+    string get_output();
+    bool build(builder* builder, string tag) const;
+
+   private:
+    static constexpr auto TAG_LABEL = "<label>";
+
+    xcb_ewmh_connection_t m_ewmh;
+    xcb_timestamp_t m_timestamp;
+    unique_ptr<active_window> m_active;
+
+    label_t m_label;
+  };
+}
+
+LEMONBUDDY_NS_END

include/utils/memory.hpp

@@ -20,6 +20,9 @@ namespace memory_util {
   inline auto countof(T& p) {
     return sizeof(p) / sizeof(p[0]);
   }
+
+  template <typename T>
+  using malloc_ptr_t = shared_ptr<T>;
 }
 
 LEMONBUDDY_NS_END

include/x11/atoms.hpp

@@ -8,10 +8,14 @@ struct cached_atom {
   xcb_atom_t* atom;
 };
 
-extern cached_atom ATOMS[29];
+extern cached_atom ATOMS[33];
 
+extern xcb_atom_t _NET_SUPPORTED;
+extern xcb_atom_t _NET_CURRENT_DESKTOP;
+extern xcb_atom_t _NET_ACTIVE_WINDOW;
 extern xcb_atom_t _NET_WM_NAME;
 extern xcb_atom_t _NET_WM_DESKTOP;
+extern xcb_atom_t _NET_WM_VISIBLE_NAME;
 extern xcb_atom_t _NET_WM_WINDOW_TYPE;
 extern xcb_atom_t _NET_WM_WINDOW_TYPE_DOCK;
 extern xcb_atom_t _NET_WM_WINDOW_TYPE_NORMAL;

include/x11/ewmh.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <xcb/xcb_ewmh.h>
+
+#include "common.hpp"
+#include "x11/connection.hpp"
+
+LEMONBUDDY_NS
+
+namespace ewmh_util {
+  bool setup(connection& conn, xcb_ewmh_connection_t* dst);
+  bool supports(xcb_ewmh_connection_t* ewmh, xcb_atom_t atom);
+
+  xcb_window_t get_active_window(xcb_ewmh_connection_t* conn);
+
+  string get_visible_name(xcb_ewmh_connection_t* conn, xcb_window_t win);
+  string get_icon_name(xcb_ewmh_connection_t* conn, xcb_window_t win);
+  string get_reply_string(xcb_ewmh_get_utf8_strings_reply_t* reply);
+}
+
+LEMONBUDDY_NS_END

include/x11/icccm.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <xcb/xcb_icccm.h>
+
+#include "common.hpp"
+#include "x11/connection.hpp"
+
+LEMONBUDDY_NS
+
+namespace icccm_util {
+  string get_wm_name(xcb_connection_t* conn, xcb_window_t win);
+  string get_reply_string(xcb_icccm_get_text_property_reply_t* reply);
+}
+
+LEMONBUDDY_NS_END

include/x11/window.hpp

@@ -12,11 +12,19 @@ class window : public xpp::window<connection_t&> {
  public:
   using xpp::window<connection_t&>::window;
 
-  explicit window(connection_t& conn) : xpp::window<connection_t&>(conn, conn.generate_id()) {}
+  explicit window(connection_t& conn) : xpp::window<connection_t&>(conn, XCB_NONE) {}
+
+  window& operator=(const xcb_window_t win) {
+    *this = window{connection(), win};
+    return *this;
+  }
 
   window create_checked(
       int16_t x, int16_t y, uint16_t w, uint16_t h, uint32_t mask = 0, const xcb_params_cw_t* p = nullptr);
 
+  window change_event_mask(uint32_t mask);
+  window ensure_event_mask(uint32_t event);
+
   window reconfigure_geom(uint16_t w, uint16_t h, int16_t x = 0, int16_t y = 0);
   window reconfigure_pos(int16_t x, int16_t y);
   window reconfigure_struts(uint16_t w, uint16_t h, int16_t x, bool bottom = false);

src/components/bar.cpp

@@ -722,7 +722,7 @@ void bar::set_wmhints() {
   wm_util::set_wmstate(m_connection, m_window, {_NET_WM_STATE_STICKY, _NET_WM_STATE_ABOVE});
 
   m_log.trace("bar: Set _NET_WM_DESKTOP");
-  wm_util::set_wmdesktop(m_connection, m_window, -1u);
+  wm_util::set_wmdesktop(m_connection, m_window, 0xFFFFFFFF);
 
   m_log.trace("bar: Set _NET_WM_PID");
   wm_util::set_wmpid(m_connection, m_window, getpid());

src/components/controller.cpp

@@ -18,6 +18,7 @@
 #include "modules/text.hpp"
 #include "modules/unsupported.hpp"
 #include "modules/xbacklight.hpp"
+#include "modules/xwindow.hpp"
 
 #include "components/bar.hpp"
 #include "components/config.hpp"
@@ -358,8 +359,6 @@ void controller::bootstrap_modules() {
           module.reset(new counter_module(bar, m_log, m_conf, module_name));
         else if (type == "internal/backlight")
           module.reset(new backlight_module(bar, m_log, m_conf, module_name));
-        else if (type == "internal/xbacklight")
-          module.reset(new xbacklight_module(bar, m_log, m_conf, module_name));
         else if (type == "internal/battery")
           module.reset(new battery_module(bar, m_log, m_conf, module_name));
         else if (type == "internal/bspwm")
@@ -382,6 +381,10 @@ void controller::bootstrap_modules() {
           module.reset(new network_module(bar, m_log, m_conf, module_name));
         else if (type == "internal/temperature")
           module.reset(new temperature_module(bar, m_log, m_conf, module_name));
+        else if (type == "internal/xbacklight")
+          module.reset(new xbacklight_module(bar, m_log, m_conf, module_name));
+        else if (type == "internal/xwindow")
+          module.reset(new xwindow_module(bar, m_log, m_conf, module_name));
         else if (type == "custom/text")
           module.reset(new text_module(bar, m_log, m_conf, module_name));
         else if (type == "custom/script")

src/drawtypes/label.cpp

@@ -20,6 +20,10 @@ namespace drawtypes {
     m_tokenized = m_text;
   }
 
+  bool label::has_token(string token) {
+    return m_text.find(token) != string::npos;
+  }
+
   void label::replace_token(string token, string replacement) {
     m_tokenized = string_util::replace_all(m_tokenized, token, replacement);
   }

src/modules/xbacklight.cpp

@@ -61,6 +61,13 @@ namespace modules {
     update();
   }
 
+  /**
+   * Disconnect from the event registry
+   */
+  void xbacklight_module::teardown() {
+    m_connection.detach_sink(this, 1);
+  }
+
   /**
    * Handler for XCB_RANDR_NOTIFY events
    */

src/modules/xwindow.cpp

@@ -0,0 +1,123 @@
+#include "modules/xwindow.hpp"
+#include "x11/atoms.hpp"
+#include "x11/graphics.hpp"
+
+LEMONBUDDY_NS
+
+namespace modules {
+  /**
+   * Bootstrap the module
+   */
+  void xwindow_module::setup() {
+    connection& conn{configure_connection().create<decltype(conn)>()};
+
+    // Initialize ewmh atoms
+    if (!ewmh_util::setup(conn, &m_ewmh)) {
+      throw module_error("Failed to initialize ewmh atoms");
+    }
+
+    // Check if the WM supports _NET_ACTIVE_WINDOW
+    if (!ewmh_util::supports(&m_ewmh, _NET_ACTIVE_WINDOW)) {
+      throw module_error("The WM does not list _NET_ACTIVE_WINDOW as a supported hint");
+    }
+
+    // Add formats and elements
+    m_formatter->add(DEFAULT_FORMAT, TAG_LABEL, {TAG_LABEL});
+
+    if (m_formatter->has(TAG_LABEL)) {
+      m_label = load_optional_label(m_conf, name(), TAG_LABEL, "%title%");
+    }
+
+    // No need to setup X components if we can't show the title
+    if (!m_label || !m_label->has_token("%title%")) {
+      return;
+    }
+
+    // Make sure we get notified when root properties change
+    window root{conn, conn.root()};
+    root.ensure_event_mask(XCB_EVENT_MASK_PROPERTY_CHANGE);
+
+    // Connect with the event registry
+    conn.attach_sink(this, 1);
+
+    // Trigger the initial draw event
+    update();
+  }
+
+  /**
+   * Disconnect from the event registry
+   */
+  void xwindow_module::teardown() {
+    connection& conn{configure_connection().create<decltype(conn)>()};
+    conn.detach_sink(this, 1);
+  }
+
+  /**
+   * Handler for XCB_PROPERTY_NOTIFY events
+   */
+  void xwindow_module::handle(const evt::property_notify& evt) {
+    if (evt->time <= m_timestamp) {
+      return;
+    } else if (evt->atom == _NET_ACTIVE_WINDOW) {
+      update();
+    } else if (evt->atom == _NET_CURRENT_DESKTOP) {
+      update();
+    } else if (evt->atom == _NET_WM_VISIBLE_NAME) {
+      update();
+    } else if (evt->atom == _NET_WM_NAME) {
+      update();
+    } else {
+      return;
+    }
+
+    m_timestamp = evt->time;
+  }
+
+  /**
+   * Update the currently active window and query its title
+   */
+  void xwindow_module::update() {
+    xcb_window_t win{ewmh_util::get_active_window(&m_ewmh)};
+    string title;
+
+    if (m_active && m_active->match(win)) {
+      title = m_active->title(&m_ewmh);
+    } else if (win != XCB_NONE) {
+      m_active = make_unique<active_window>(win);
+      title = m_active->title(&m_ewmh);
+    } else {
+      m_active.reset();
+    }
+
+    if (m_label) {
+      m_label->reset_tokens();
+      m_label->replace_token("%title%", title);
+    }
+
+    // Emit notification to trigger redraw
+    broadcast();
+  }
+
+  /**
+   * Generate the module output
+   */
+  string xwindow_module::get_output() {
+    m_builder->node(static_module::get_output());
+    return m_builder->flush();
+  }
+
+  /**
+   * Output content as defined in the config
+   */
+  bool xwindow_module::build(builder* builder, string tag) const {
+    if (tag == TAG_LABEL) {
+      builder->node(m_label);
+    } else {
+      return false;
+    }
+
+    return true;
+  }
+}
+
+LEMONBUDDY_NS_END

src/x11/atoms.cpp

@@ -3,8 +3,12 @@
 #include <xcb/xcb.h>
 #include <xcb/xcb_atom.h>
 
+xcb_atom_t _NET_SUPPORTED;
+xcb_atom_t _NET_CURRENT_DESKTOP;
+xcb_atom_t _NET_ACTIVE_WINDOW;
 xcb_atom_t _NET_WM_NAME;
 xcb_atom_t _NET_WM_DESKTOP;
+xcb_atom_t _NET_WM_VISIBLE_NAME;
 xcb_atom_t _NET_WM_WINDOW_TYPE;
 xcb_atom_t _NET_WM_WINDOW_TYPE_DOCK;
 xcb_atom_t _NET_WM_WINDOW_TYPE_NORMAL;
@@ -34,9 +38,13 @@ xcb_atom_t _XSETROOT_ID;
 xcb_atom_t ESETROOT_PMAP_ID;
 
 // clang-format off
-cached_atom ATOMS[29] = {
+cached_atom ATOMS[33] = {
+  {"_NET_SUPPORTED", sizeof("_NET_SUPPORTED") - 1, &_NET_SUPPORTED},
+  {"_NET_CURRENT_DESKTOP", sizeof("_NET_CURRENT_DESKTOP") - 1, &_NET_CURRENT_DESKTOP},
+  {"_NET_ACTIVE_WINDOW", sizeof("_NET_ACTIVE_WINDOW") - 1, &_NET_ACTIVE_WINDOW},
   {"_NET_WM_NAME", sizeof("_NET_WM_NAME") - 1, &_NET_WM_NAME},
   {"_NET_WM_DESKTOP", sizeof("_NET_WM_DESKTOP") - 1, &_NET_WM_DESKTOP},
+  {"_NET_WM_VISIBLE_NAME", sizeof("_NET_WM_VISIBLE_NAME") - 1, &_NET_WM_VISIBLE_NAME},
   {"_NET_WM_WINDOW_TYPE", sizeof("_NET_WM_WINDOW_TYPE") - 1, &_NET_WM_WINDOW_TYPE},
   {"_NET_WM_WINDOW_TYPE_DOCK", sizeof("_NET_WM_WINDOW_TYPE_DOCK") - 1, &_NET_WM_WINDOW_TYPE_DOCK},
   {"_NET_WM_WINDOW_TYPE_NORMAL", sizeof("_NET_WM_WINDOW_TYPE_NORMAL") - 1, &_NET_WM_WINDOW_TYPE_NORMAL},

src/x11/ewmh.cpp

@@ -0,0 +1,64 @@
+#include "x11/ewmh.hpp"
+
+LEMONBUDDY_NS
+
+namespace ewmh_util {
+  bool setup(connection& conn, xcb_ewmh_connection_t* dst) {
+    return xcb_ewmh_init_atoms_replies(dst, xcb_ewmh_init_atoms(conn, dst), nullptr);
+  }
+
+  bool supports(xcb_ewmh_connection_t* ewmh, xcb_atom_t atom) {
+    bool supports{false};
+
+    xcb_ewmh_get_atoms_reply_t reply;
+    reply.atoms = nullptr;
+
+    if (!xcb_ewmh_get_supported_reply(ewmh, xcb_ewmh_get_supported(ewmh, 0), &reply, nullptr)) {
+      return false;
+    }
+
+    for (size_t n = 0; n < reply.atoms_len; ++n) {
+      if (reply.atoms[n] == atom) {
+        supports = true;
+        break;
+      }
+    }
+
+    if (reply.atoms != nullptr) {
+      xcb_ewmh_get_atoms_reply_wipe(&reply);
+    }
+
+    return supports;
+  }
+
+  xcb_window_t get_active_window(xcb_ewmh_connection_t* conn) {
+    xcb_window_t win{XCB_NONE};
+    xcb_ewmh_get_active_window_reply(conn, xcb_ewmh_get_active_window(conn, 0), &win, nullptr);
+    return win;
+  }
+
+  string get_visible_name(xcb_ewmh_connection_t* conn, xcb_window_t win) {
+    xcb_ewmh_get_utf8_strings_reply_t utf8_reply;
+    if (!xcb_ewmh_get_wm_visible_name_reply(conn, xcb_ewmh_get_wm_visible_name(conn, win), &utf8_reply, nullptr))
+      return "";
+    return get_reply_string(&utf8_reply);
+  }
+
+  string get_icon_name(xcb_ewmh_connection_t* conn, xcb_window_t win) {
+    xcb_ewmh_get_utf8_strings_reply_t utf8_reply;
+    if (!xcb_ewmh_get_wm_icon_name_reply(conn, xcb_ewmh_get_wm_icon_name(conn, win), &utf8_reply, nullptr))
+      return "";
+    return get_reply_string(&utf8_reply);
+  }
+
+  string get_reply_string(xcb_ewmh_get_utf8_strings_reply_t* reply) {
+    if (reply == nullptr || !reply->strings_len)
+      return "";
+    char buffer[BUFSIZ]{'\0'};
+    strncpy(buffer, reply->strings, reply->strings_len);
+    xcb_ewmh_get_utf8_strings_reply_wipe(reply);
+    return buffer;
+  }
+}
+
+LEMONBUDDY_NS_END

src/x11/icccm.cpp

@@ -0,0 +1,23 @@
+#include "x11/icccm.hpp"
+
+LEMONBUDDY_NS
+
+namespace icccm_util {
+  string get_wm_name(xcb_connection_t* conn, xcb_window_t win) {
+    xcb_icccm_get_text_property_reply_t reply;
+    if (!xcb_icccm_get_wm_name_reply(conn, xcb_icccm_get_wm_name(conn, win), &reply, nullptr))
+      return "";
+    return get_reply_string(&reply);
+  }
+
+  string get_reply_string(xcb_icccm_get_text_property_reply_t* reply) {
+    if (reply->name == nullptr || !reply->name_len)
+      return "";
+    char buffer[BUFSIZ]{'\0'};
+    strncpy(buffer, reply->name, reply->name_len);
+    xcb_icccm_get_text_property_reply_wipe(reply);
+    return buffer;
+  }
+}
+
+LEMONBUDDY_NS_END

src/x11/window.cpp

@@ -9,20 +9,49 @@
 
 LEMONBUDDY_NS
 
+/**
+ * Create window and check for errors
+ */
 window window::create_checked(int16_t x, int16_t y, uint16_t w, uint16_t h, uint32_t mask, const xcb_params_cw_t* p) {
+  auto conn = connection();
+
   if (*this == XCB_NONE) {
-    resource(connection(), connection().generate_id());
+    *this = conn.generate_id();
   }
 
-  auto root{connection().screen()->root};
+  auto root{conn.screen()->root};
   auto copy{XCB_COPY_FROM_PARENT};
   uint32_t values[16]{0};
   xutils::pack_values(mask, p, values);
-  connection().create_window_checked(copy, *this, root, x, y, w, h, 0, copy, copy, mask, values);
+  conn.create_window_checked(copy, *this, root, x, y, w, h, 0, copy, copy, mask, values);
 
   return *this;
 }
 
+/**
+ * Change the window event mask
+ */
+window window::change_event_mask(uint32_t mask) {
+  change_attributes_checked(XCB_CW_EVENT_MASK, &mask);
+  return *this;
+}
+
+/**
+ * Add given event to the event mask unless already added
+ */
+window window::ensure_event_mask(uint32_t event) {
+  auto attributes = get_attributes();
+
+  if ((attributes->your_event_mask & event) != event) {
+    change_event_mask(attributes->your_event_mask | event);
+  }
+
+  return *this;
+}
+
+/**
+ * Reconfigure the window geometry
+ */
 window window::reconfigure_geom(uint16_t w, uint16_t h, int16_t x, int16_t y) {
   uint32_t mask{0};
   uint32_t values[7]{0};
@@ -34,11 +63,14 @@ window window::reconfigure_geom(uint16_t w, uint16_t h, int16_t x, int16_t y) {
   XCB_AUX_ADD_PARAM(&mask, &params, y, y);
 
   xutils::pack_values(mask, &params, values);
-  connection().configure_window_checked(*this, mask, values);
+  configure_checked(mask, values);
 
   return *this;
 }
 
+/**
+ * Reconfigure the window position
+ */
 window window::reconfigure_pos(int16_t x, int16_t y) {
   uint32_t mask{0};
   uint32_t values[2]{0};
@@ -48,11 +80,14 @@ window window::reconfigure_pos(int16_t x, int16_t y) {
   XCB_AUX_ADD_PARAM(&mask, &params, y, y);
 
   xutils::pack_values(mask, &params, values);
-  connection().configure_window_checked(*this, mask, values);
+  configure_checked(mask, values);
 
   return *this;
 }
 
+/**
+ * Reconfigure the windows ewmh strut
+ */
 window window::reconfigure_struts(uint16_t w, uint16_t h, int16_t x, bool bottom) {
   auto& conn = connection();
 
@@ -75,10 +110,14 @@ window window::reconfigure_struts(uint16_t w, uint16_t h, int16_t x, bool bottom
   return *this;
 }
 
+/**
+ * Trigger redraw by toggling visibility state
+ */
 void window::redraw() {
-  xutils::visibility_notify(connection(), *this, XCB_VISIBILITY_FULLY_OBSCURED);
+  auto conn = connection();
-  xutils::visibility_notify(connection(), *this, XCB_VISIBILITY_UNOBSCURED);
+  xutils::visibility_notify(conn, *this, XCB_VISIBILITY_FULLY_OBSCURED);
-  connection().flush();
+  xutils::visibility_notify(conn, *this, XCB_VISIBILITY_UNOBSCURED);
+  conn.flush();
 }
 
 LEMONBUDDY_NS_END