SDL_EVENT_QUIT when no window nor tray

SDL_HINT_QUIT_ON_LAST_WINDOW_CLOSE will not fire if there are active tray icons. This impacts only applications that create tray icons, and that at least one icon outlives the last visible top-level window. SDL_EVENT_QUIT will fire when the last active tray is destroyed if there are no active windows.

src/events/SDL_windowevents.c

@@ -24,7 +24,7 @@
 
 #include "SDL_events_c.h"
 #include "SDL_mouse_c.h"
-
+#include "../tray/SDL_tray_utils.h"
 
 static bool SDLCALL RemoveSupercededWindowEvents(void *userdata, SDL_Event *event)
 {
@@ -247,7 +247,7 @@ bool SDL_SendWindowEvent(SDL_Window *window, SDL_EventType windowevent, int data
         break;
     }
 
-    if (windowevent == SDL_EVENT_WINDOW_CLOSE_REQUESTED && !window->parent) {
+    if (windowevent == SDL_EVENT_WINDOW_CLOSE_REQUESTED && !window->parent && SDL_HasNoActiveTrays()) {
         int toplevel_count = 0;
         SDL_Window *n;
         for (n = SDL_GetVideoDevice()->windows; n; n = n->next) {

src/tray/SDL_tray_utils.c

@@ -0,0 +1,62 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#include "../video/SDL_sysvideo.h"
+#include "../events/SDL_events_c.h"
+
+static int active_trays = 0;
+
+extern void SDL_IncrementTrayCount(void)
+{
+    if (++active_trays < 1) {
+        SDL_Log("Active tray count corrupted (%d < 1), this is a bug. The app may close or fail to close unexpectedly.", active_trays);
+    }
+}
+
+extern void SDL_DecrementTrayCount(void)
+{
+    int toplevel_count = 0;
+    SDL_Window *n;
+
+    if (--active_trays < 0) {
+        SDL_Log("Active tray count corrupted (%d < 0), this is a bug. The app may close or fail to close unexpectedly.", active_trays);
+    }
+
+    if (!SDL_GetHintBoolean(SDL_HINT_QUIT_ON_LAST_WINDOW_CLOSE, true)) {
+        return;
+    }
+
+    for (n = SDL_GetVideoDevice()->windows; n; n = n->next) {
+        if (!n->parent && !(n->flags & SDL_WINDOW_HIDDEN)) {
+            ++toplevel_count;
+        }
+    }
+
+    if (toplevel_count < 1) {
+        SDL_SendQuit();
+    }
+}
+
+extern bool SDL_HasNoActiveTrays(void)
+{
+    return active_trays < 1;
+}

src/tray/SDL_tray_utils.h

@@ -0,0 +1,25 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+extern void SDL_IncrementTrayCount(void);
+extern void SDL_DecrementTrayCount(void);
+extern bool SDL_HasNoActiveTrays(void);

src/tray/cocoa/SDL_tray.m

@@ -25,6 +25,7 @@
 
 #include <Cocoa/Cocoa.h>
 
+#include "../SDL_tray_utils.h"
 #include "../../video/SDL_surface_c.h"
 
 /* applicationDockMenu */
@@ -158,6 +159,8 @@ SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
     }
 
 skip_putting_an_icon:
+    SDL_IncrementTrayCount();
+
     return tray;
 }
 
@@ -445,6 +448,8 @@ void SDL_DestroyTray(SDL_Tray *tray)
     }
 
     SDL_free(tray);
+
+    SDL_DecrementTrayCount();
 }
 
 #endif // SDL_PLATFORM_MACOS

src/tray/dummy/SDL_tray.c

@@ -23,6 +23,8 @@
 
 #ifndef SDL_PLATFORM_MACOS
 
+#include "../SDL_tray_utils.h"
+
 SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 {
     SDL_Unsupported();

src/tray/unix/SDL_tray.c

@@ -21,6 +21,8 @@
 
 #include "SDL_internal.h"
 
+#include "../SDL_tray_utils.h"
+
 #include <dlfcn.h>
 
 /* getpid() */
@@ -52,6 +54,7 @@ typedef enum
     G_CONNECT_SWAPPED = 1 << 1
 } GConnectFlags;
 gulong (*g_signal_connect_data)(gpointer instance, const gchar *detailed_signal, GCallback c_handler, gpointer data, GClosureNotify destroy_data, GConnectFlags connect_flags);
+void (*g_object_unref)(gpointer object);
 
 #define g_signal_connect(instance, detailed_signal, c_handler, data) \
     g_signal_connect_data ((instance), (detailed_signal), (c_handler), (data), NULL, (GConnectFlags) 0)
@@ -237,6 +240,7 @@ static bool init_gtk(void)
     gtk_widget_get_sensitive = dlsym(libgtk, "gtk_widget_get_sensitive");
 
     g_signal_connect_data = dlsym(libgdk, "g_signal_connect_data");
+    g_object_unref = dlsym(libgdk, "g_object_unref");
 
     app_indicator_new = dlsym(libappindicator, "app_indicator_new");
     app_indicator_set_status = dlsym(libappindicator, "app_indicator_set_status");
@@ -257,6 +261,7 @@ static bool init_gtk(void)
         !gtk_menu_shell_insert ||
         !gtk_widget_destroy ||
         !g_signal_connect_data ||
+        !g_object_unref ||
         !app_indicator_new ||
         !app_indicator_set_status ||
         !app_indicator_set_icon ||
@@ -394,6 +399,8 @@ SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 
     app_indicator_set_status(tray->indicator, APP_INDICATOR_STATUS_ACTIVE);
 
+    SDL_IncrementTrayCount();
+
     return tray;
 }
 
@@ -660,5 +667,9 @@ void SDL_DestroyTray(SDL_Tray *tray)
         SDL_RemovePath(tray->icon_path);
     }
 
+    g_object_unref(tray->indicator);
+
     SDL_free(tray);
+
+    SDL_DecrementTrayCount();
 }

src/tray/windows/SDL_tray.c

@@ -21,7 +21,9 @@
 
 #include "SDL_internal.h"
 
+#include "../SDL_tray_utils.h"
 #include "../../core/windows/SDL_windows.h"
+
 #include <windowsx.h>
 #include <shellapi.h>
 #include <stdlib.h> /* FIXME: for mbstowcs_s, wcslen */
@@ -228,6 +230,8 @@ SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 
     SetWindowLongPtr(tray->hwnd, GWLP_USERDATA, (LONG_PTR) tray);
 
+    SDL_IncrementTrayCount();
+
     return tray;
 }
 
@@ -568,4 +572,6 @@ void SDL_DestroyTray(SDL_Tray *tray)
     }
 
     SDL_free(tray);
+
+    SDL_DecrementTrayCount();
 }