x11: Handle external fullscreen toggles

Some window managers let you change the fullscreen state of any window
using a key combination. For example, on XFWM you can use Alt+F11 and
on Compiz you can configure a key combination with the
"Extra WM actions" plugin.

With this change mpv will handle these fullscreen state changes. So, if
you enter into fullscreen mode using the WM's shortcut and then you use
mpv's fullscreen toggle, you will get back into window mode.

Merges PR #2081.

Signed-off-by: wm4 <wm4@nowhere>

2 files changed, 44 insertions, 1 deletions

diff --git a/player/command.c b/player/command.c
index cc6a41946c..c4fe75dd25 100644
--- a/player/command.c
+++ b/player/command.c
@@ -3550,7 +3550,7 @@ static const char *const *const mp_event_property_change[] = {
       "demuxer-cache-duration", "demuxer-cache-idle", "paused-for-cache",
       "demuxer-cache-time"),
     E(MP_EVENT_WIN_RESIZE, "window-scale"),
-    E(MP_EVENT_WIN_STATE, "window-minimized", "display-names", "display-fps"),
+    E(MP_EVENT_WIN_STATE, "window-minimized", "display-names", "display-fps", "fullscreen"),
 };
 #undef E
 
diff --git a/video/out/x11_common.c b/video/out/x11_common.c
index 439db6a606..0584cf6a0b 100644
--- a/video/out/x11_common.c
+++ b/video/out/x11_common.c
@@ -135,6 +135,8 @@ static void vo_x11_selectinput_witherr(struct vo *vo, Display *display,
 static void vo_x11_setlayer(struct vo *vo, bool ontop);
 static void vo_x11_xembed_handle_message(struct vo *vo, XClientMessageEvent *ce);
 static void vo_x11_xembed_send_message(struct vo_x11_state *x11, long m[4]);
+static void vo_x11_move_resize(struct vo *vo, bool move, bool resize,
+                               struct mp_rect rc);
 
 #define XA(x11, s) (XInternAtom((x11)->display, # s, False))
 #define XAs(x11, s) XInternAtom((x11)->display, s, False)
@@ -889,6 +891,46 @@ static int get_mods(unsigned int state)
     return modifiers;
 }
 
+static void vo_x11_check_net_wm_state_fullscreen_change(struct vo *vo)
+{
+    struct vo_x11_state *x11 = vo->x11;
+
+    if (x11->wm_type & vo_wm_FULLSCREEN) {
+        int num_elems;
+        long *elems = x11_get_property(x11, x11->window, XA(x11, _NET_WM_STATE),
+                                       XA_ATOM, 32, &num_elems);
+        int is_fullscreen = 0;
+        if (elems) {
+            Atom fullscreen_prop = XA(x11, _NET_WM_STATE_FULLSCREEN);
+            for (int n = 0; n < num_elems; n++) {
+                if (elems[n] == fullscreen_prop) {
+                    is_fullscreen = 1;
+                    break;
+                }
+            }
+            XFree(elems);
+        }
+
+        if ((vo->opts->fullscreen && !is_fullscreen) ||
+            (!vo->opts->fullscreen && is_fullscreen))
+        {
+            vo->opts->fullscreen = is_fullscreen;
+            x11->fs = is_fullscreen;
+
+            if (!is_fullscreen && (x11->pos_changed_during_fs ||
+                                   x11->size_changed_during_fs))
+            {
+                vo_x11_move_resize(vo, x11->pos_changed_during_fs,
+                                       x11->size_changed_during_fs,
+                                       x11->nofsrc);
+            }
+            
+            x11->size_changed_during_fs = false;
+            x11->pos_changed_during_fs = false;
+        }
+    }
+}
+
 int vo_x11_check_events(struct vo *vo)
 {
     struct vo_x11_state *x11 = vo->x11;
@@ -1028,6 +1070,7 @@ int vo_x11_check_events(struct vo *vo)
                 }
             } else if (Event.xproperty.atom == XA(x11, _NET_WM_STATE)) {
                 x11->pending_vo_events |= VO_EVENT_WIN_STATE;
+                vo_x11_check_net_wm_state_fullscreen_change(vo);
             } else if (Event.xproperty.atom == x11->icc_profile_property) {
                 x11->pending_vo_events |= VO_EVENT_ICC_PROFILE_CHANGED;
             }