Send IPC window events for focus and title changes

This patch fixes ticket #1168 to extend the window IPC event mechanism
to send IPC events for window focus and title changes. The newly added
window events use the same format as the already established "new"
event.

Specifically this patch:

* Moves the ipc_send_window_event() function from src/manage.c into
  src/ipc.c and adds an argument for the change property of the event
* Updates src/manage.c to use the new function signature. To ensure
  that the "new" event does not send the same event data as the
  "focus" event, setting focus now happens after the "new" event
  has been sent
* Adds IPC focus event notification to src/x.c. To workaround a problem
  during window close when accessing the window name, a function has been
  added to query whether a window is actually attached to its parent. To
  avoid obsolete focus notification, a new field has been added to keep
  track of the focus without any interference by the click handling
* Adds IPC title event notification to src/handlers.c. To avoid
  obsolete title notification, a function has been added to determine
  whether a window title has actually changed
* Updates the IPC documentation to include the new events
* Updates testcases/t/205-ipc-windows.t to include the "focus" event
  in order to ensure the correct event sequence
* Adds two new unit tests, b/testcases/t/219-ipc-window-focus.t and
  b/testcases/t/220-ipc-window-title.t to ensure proper "focus" and
 "title" events

docs/ipc

@@ -1,7 +1,7 @@
 IPC interface (interprocess communication)
 ==========================================
 Michael Stapelberg <michael@i3wm.org>
-October 2012
+February 2014
 
 This document describes how to interface with i3 from a separate process. This
 is useful for example to remote-control i3 (to write test cases for example) or
@@ -632,7 +632,8 @@ mode (2)::
 	Sent whenever i3 changes its binding mode.
 window (3)::
 	Sent when a client's window is successfully reparented (that is when i3
-	has finished fitting it into a container).
+	has finished fitting it into a container), when a window received input
+	focus or when a window title has been updated.
 barconfig_update (4)::
     Sent when the hidden_state or mode field in the barconfig of any bar
     instance was updated.
@@ -712,14 +713,14 @@ mode is simply named default.
 === window event
 
 This event consists of a single serialized map containing a property
-+change (string)+ which currently can indicate only that a new window
++change (string)+ which indicates the type of the change ("focus", "new",
-has been successfully reparented (the value will be "new").
+"title").
 
 Additionally a +container (object)+ field will be present, which consists
-of the window's parent container. Be aware that the container will hold
+of the window's parent container. Be aware that for the "new" event, the
-the initial name of the newly reparented window (e.g. if you run urxvt
+container will hold the initial name of the newly reparented window (e.g.
-with a shell that changes the title, you will still at this point get the
+if you run urxvt with a shell that changes the title, you will still at
-window title as "urxvt").
+this point get the window title as "urxvt").
 
 *Example:*
 ---------------------------

include/ipc.h

@@ -87,3 +87,9 @@ void dump_node(yajl_gen gen, Con *con, bool inplace_restart);
  * respectively.
  */
 void ipc_send_workspace_focus_event(Con *current, Con *old);
+
+/**
+ * For the window events we send, along the usual "change" field,
+ * also the window container, in "container".
+ */
+void ipc_send_window_event(const char *property, Con *con);

src/handlers.c

@@ -528,6 +528,17 @@ static void handle_destroy_notify_event(xcb_destroy_notify_event_t *event) {
     handle_unmap_notify_event(&unmap);
 }
 
+static bool window_name_changed(i3Window *window, char *old_name) {
+    if ((old_name == NULL) && (window->name == NULL))
+        return false;
+
+    /* Either the old or the new one is NULL, but not both. */
+    if ((old_name == NULL) ^ (window->name == NULL))
+        return true;
+
+    return (strcmp(old_name, i3string_as_utf8(window->name)) != 0);
+}
+
 /*
  * Called when a window changes its title
  *
@@ -538,10 +549,17 @@ static bool handle_windowname_change(void *data, xcb_connection_t *conn, uint8_t
     if ((con = con_by_window_id(window)) == NULL || con->window == NULL)
         return false;
 
+    char *old_name = (con->window->name != NULL ? sstrdup(i3string_as_utf8(con->window->name)) : NULL);
+
     window_update_name(con->window, prop, false);
 
     x_push_changes(croot);
 
+    if (window_name_changed(con->window, old_name))
+        ipc_send_window_event("title", con);
+
+    FREE(old_name);
+
     return true;
 }
 
@@ -556,10 +574,17 @@ static bool handle_windowname_change_legacy(void *data, xcb_connection_t *conn,
     if ((con = con_by_window_id(window)) == NULL || con->window == NULL)
         return false;
 
+    char *old_name = (con->window->name != NULL ? sstrdup(i3string_as_utf8(con->window->name)) : NULL);
+
     window_update_name_legacy(con->window, prop, false);
 
     x_push_changes(croot);
 
+    if (window_name_changed(con->window, old_name))
+        ipc_send_window_event("title", con);
+
+    FREE(old_name);
+
     return true;
 }
 

src/ipc.c

@@ -1056,3 +1056,32 @@ void ipc_send_workspace_focus_event(Con *current, Con *old) {
     y(free);
     setlocale(LC_NUMERIC, "");
 }
+
+/**
+ * For the window events we send, along the usual "change" field,
+ * also the window container, in "container".
+ */
+void ipc_send_window_event(const char *property, Con *con) {
+    DLOG("Issue IPC window %s event for X11 window 0x%08x\n", property, con->window->id);
+
+    setlocale(LC_NUMERIC, "C");
+    yajl_gen gen = ygenalloc();
+
+    y(map_open);
+
+    ystr("change");
+    ystr(property);
+
+    ystr("container");
+    dump_node(gen, con, false);
+
+    y(map_close);
+
+    const unsigned char *payload;
+    ylength length;
+    y(get_buf, &payload, &length);
+
+    ipc_send_event("window", I3_IPC_EVENT_WINDOW, (const char *)payload);
+    y(free);
+    setlocale(LC_NUMERIC, "");
+}

src/manage.c

@@ -75,35 +75,6 @@ void restore_geometry(void) {
     xcb_aux_sync(conn);
 }
 
-/*
- * The following function sends a new window event, which consists
- * of fields "change" and "container", the latter containing a dump
- * of the window's container.
- *
- */
-static void ipc_send_window_new_event(Con *con) {
-    setlocale(LC_NUMERIC, "C");
-    yajl_gen gen = ygenalloc();
-
-    y(map_open);
-
-    ystr("change");
-    ystr("new");
-
-    ystr("container");
-    dump_node(gen, con, false);
-
-    y(map_close);
-
-    const unsigned char *payload;
-    ylength length;
-    y(get_buf, &payload, &length);
-
-    ipc_send_event("window", I3_IPC_EVENT_WINDOW, (const char *)payload);
-    y(free);
-    setlocale(LC_NUMERIC, "");
-}
-
 /*
  * Do some sanity checks and then reparent the window.
  *
@@ -360,6 +331,8 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
 
     FREE(state_reply);
 
+    bool set_focus = false;
+
     if (fs == NULL) {
         DLOG("Not in fullscreen mode, focusing\n");
         if (!cwindow->dock) {
@@ -371,7 +344,7 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
 
             if (workspace_is_visible(ws) && current_output == target_output) {
                 if (!match || !match->restart_mode) {
-                    con_focus(nc);
+                    set_focus = true;
                 } else DLOG("not focusing, matched with restart_mode == true\n");
             } else DLOG("workspace not visible, not focusing\n");
         } else DLOG("dock, not focusing\n");
@@ -421,7 +394,7 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
                    transient_win->transient_for != XCB_NONE) {
                 if (transient_win->transient_for == fs->window->id) {
                     LOG("This floating window belongs to the fullscreen window (popup_during_fullscreen == smart)\n");
-                    con_focus(nc);
+                    set_focus = true;
                     break;
                 }
                 Con *next_transient = con_by_window_id(transient_win->transient_for);
@@ -500,7 +473,14 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
     tree_render();
 
     /* Send an event about window creation */
-    ipc_send_window_new_event(nc);
+    ipc_send_window_event("new", nc);
+
+    /* Defer setting focus after the 'new' event has been sent to ensure the
+     * proper window event sequence. */
+    if (set_focus) {
+        con_focus(nc);
+        tree_render();
+    }
 
     /* Windows might get managed with the urgency hint already set (Pidgin is
      * known to do that), so check for that and handle the hint accordingly.

src/x.c

@@ -15,6 +15,11 @@
 /* Stores the X11 window ID of the currently focused window */
 xcb_window_t focused_id = XCB_NONE;
 
+/* Because 'focused_id' might be reset to force input focus (after click to
+ * raise), we separately keep track of the X11 window ID to be able to always
+ * tell whether the focused window actually changed. */
+static xcb_window_t last_focused = XCB_NONE;
+
 /* The bottom-to-top window stack of all windows which are managed by i3.
  * Used for x_get_window_stack(). */
 static xcb_window_t *btt_stack;
@@ -232,7 +237,7 @@ void x_con_kill(Con *con) {
     free(state);
 
     /* Invalidate focused_id to correctly focus new windows with the same ID */
-    focused_id = XCB_NONE;
+    focused_id = last_focused = XCB_NONE;
 }
 
 /*
@@ -848,6 +853,24 @@ static void x_push_node_unmaps(Con *con) {
         x_push_node_unmaps(current);
 }
 
+/*
+ * Returns true if the given container is currently attached to its parent.
+ *
+ * TODO: Remove once #1185 has been fixed
+ */
+static bool is_con_attached(Con *con) {
+    if (con->parent == NULL)
+        return false;
+
+    Con *current;
+    TAILQ_FOREACH(current, &(con->parent->nodes_head), nodes) {
+        if (current == con)
+            return true;
+    }
+
+    return false;
+}
+
 /*
  * Pushes all changes (state of each node, see x_push_node() and the window
  * stack) to X11.
@@ -972,6 +995,9 @@ void x_push_changes(Con *con) {
                 send_take_focus(to_focus);
                 set_focus = !focused->window->doesnt_accept_focus;
                 DLOG("set_focus = %d\n", set_focus);
+
+                if (!set_focus && to_focus != last_focused && is_con_attached(focused))
+                   ipc_send_window_event("focus", focused);
             }
 
             if (set_focus) {
@@ -990,9 +1016,12 @@ void x_push_changes(Con *con) {
                 }
 
                 ewmh_update_active_window(to_focus);
+
+                if (to_focus != XCB_NONE && to_focus != last_focused && focused->window != NULL && is_con_attached(focused))
+                   ipc_send_window_event("focus", focused);
             }
 
-            focused_id = to_focus;
+            focused_id = last_focused = to_focus;
         }
     }
 

testcases/t/205-ipc-windows.t

@@ -30,19 +30,31 @@ $i3->connect()->recv;
 # Events
 
 my $new = AnyEvent->condvar;
+my $focus = AnyEvent->condvar;
 $i3->subscribe({
     window => sub {
         my ($event) = @_;
-        $new->send($event->{change} eq 'new');
+        if ($event->{change} eq 'new') {
+            $new->send($event);
+        } elsif ($event->{change} eq 'focus') {
+            $focus->send($event);
+        }
     }
 })->recv;
 
 open_window;
 
 my $t;
-$t = AnyEvent->timer(after => 0.5, cb => sub { $new->send(0); });
+$t = AnyEvent->timer(
+    after => 0.5,
+    cb => sub {
+        $new->send(0);
+        $focus->send(0);
+    }
+);
 
-ok($new->recv, 'Window "new" event received');
+is($new->recv->{container}->{focused}, 0, 'Window "new" event received');
+is($focus->recv->{container}->{focused}, 1, 'Window "focus" event received');
 
 }
 

testcases/t/219-ipc-window-focus.t

@@ -0,0 +1,94 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • http://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • http://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • http://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+
+use i3test;
+
+SKIP: {
+
+    skip "AnyEvent::I3 too old (need >= 0.15)", 1 if $AnyEvent::I3::VERSION < 0.15;
+
+my $i3 = i3(get_socket_path());
+$i3->connect()->recv;
+
+################################
+# Window focus event
+################################
+
+cmd 'split h';
+
+my $win0 = open_window;
+my $win1 = open_window;
+my $win2 = open_window;
+
+my $focus = AnyEvent->condvar;
+
+$i3->subscribe({
+    window => sub {
+        my ($event) = @_;
+        $focus->send($event);
+    }
+})->recv;
+
+my $t;
+$t = AnyEvent->timer(
+    after => 0.5,
+    cb => sub {
+        $focus->send(0);
+    }
+);
+
+# ensure the rightmost window contains input focus
+$i3->command('[id="' . $win2->id . '"] focus')->recv;
+is($x->input_focus, $win2->id, "Window 2 focused");
+
+cmd 'focus left';
+my $event = $focus->recv;
+is($event->{change}, 'focus', 'Focus event received');
+is($focus->recv->{container}->{name}, 'Window 1', 'Window 1 focused');
+
+$focus = AnyEvent->condvar;
+cmd 'focus left';
+$event = $focus->recv;
+is($event->{change}, 'focus', 'Focus event received');
+is($event->{container}->{name}, 'Window 0', 'Window 0 focused');
+
+$focus = AnyEvent->condvar;
+cmd 'focus right';
+$event = $focus->recv;
+is($event->{change}, 'focus', 'Focus event received');
+is($event->{container}->{name}, 'Window 1', 'Window 1 focused');
+
+$focus = AnyEvent->condvar;
+cmd 'focus right';
+$event = $focus->recv;
+is($event->{change}, 'focus', 'Focus event received');
+is($event->{container}->{name}, 'Window 2', 'Window 2 focused');
+
+$focus = AnyEvent->condvar;
+cmd 'focus right';
+$event = $focus->recv;
+is($event->{change}, 'focus', 'Focus event received');
+is($event->{container}->{name}, 'Window 0', 'Window 0 focused');
+
+$focus = AnyEvent->condvar;
+cmd 'focus left';
+$event = $focus->recv;
+is($event->{change}, 'focus', 'Focus event received');
+is($event->{container}->{name}, 'Window 2', 'Window 2 focused');
+
+}
+
+done_testing;

testcases/t/220-ipc-window-title.t

@@ -0,0 +1,57 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • http://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • http://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • http://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+
+use i3test;
+
+SKIP: {
+
+    skip "AnyEvent::I3 too old (need >= 0.15)", 1 if $AnyEvent::I3::VERSION < 0.15;
+
+my $i3 = i3(get_socket_path());
+$i3->connect()->recv;
+
+################################
+# Window title event
+################################
+
+my $window = open_window(name => 'Window 0');
+
+my $title = AnyEvent->condvar;
+
+$i3->subscribe({
+    window => sub {
+        my ($event) = @_;
+        $title->send($event);
+    }
+})->recv;
+
+$window->name('New Window Title');
+
+my $t;
+$t = AnyEvent->timer(
+    after => 0.5,
+    cb => sub {
+        $title->send(0);
+    }
+);
+
+my $event = $title->recv;
+is($event->{change}, 'title', 'Window title change event received');
+is($event->{container}->{name}, 'New Window Title', 'Window title changed');
+
+}
+
+done_testing;