events: Let arbitrary signals to simulate iOS/Android backgrounding events.

This lets you build a custom embedded device that roughly offers the "this
process is going to the background NOW" semantics of SDL on a mobile device.

CMakeLists.txt

@@ -341,6 +341,8 @@ set_option(VIDEO_VIVANTE       "Use Vivante EGL video driver" ${UNIX_SYS})
 dep_option(VIDEO_VULKAN        "Enable Vulkan support" ON "ANDROID OR APPLE OR LINUX OR WINDOWS" OFF)
 set_option(VIDEO_KMSDRM        "Use KMS DRM video driver" ${UNIX_SYS})
 dep_option(KMSDRM_SHARED       "Dynamically load KMS DRM support" ON "VIDEO_KMSDRM" OFF)
+option_string(BACKGROUNDING_SIGNAL "number to use for magic backgrounding signal or 'OFF'" "OFF")
+option_string(FOREGROUNDING_SIGNAL "number to use for magic foregrounding signal or 'OFF'" "OFF")
 
 # TODO: We should (should we?) respect cmake's ${BUILD_SHARED_LIBS} flag here
 # The options below are for compatibility to configure's default behaviour.
@@ -384,6 +386,14 @@ else()
 endif()
 set(HAVE_ASSERTIONS ${ASSERTIONS})
 
+if(NOT BACKGROUNDING_SIGNAL STREQUAL "OFF")
+  add_definitions("-DSDL_BACKGROUNDING_SIGNAL=${BACKGROUNDING_SIGNAL}")
+endif()
+
+if(NOT FOREGROUNDING_SIGNAL STREQUAL "OFF")
+  add_definitions("-DSDL_FOREGROUNDING_SIGNAL=${FOREGROUNDING_SIGNAL}")
+endif()
+
 # Compiler option evaluation
 if(USE_GCC OR USE_CLANG)
   # Check for -Wall first, so later things can override pieces of it.

configure

@@ -870,6 +870,8 @@ enable_sdl_dlopen
 enable_hidapi
 enable_clock_gettime
 enable_rpath
+enable_backgrounding_signal
+enable_foregrounding_signal
 enable_render_d3d
 '
       ac_precious_vars='build_alias
@@ -1627,6 +1629,12 @@ Optional Features:
   --enable-clock_gettime  use clock_gettime() instead of gettimeofday() on
                           UNIX [[default=yes]]
   --enable-rpath          use an rpath when linking SDL [[default=yes]]
+  --enable-backgrounding-signal
+                          number to use for magic backgrounding signal or 'no'
+                          [[default=no]]
+  --enable-foregrounding-signal
+                          number to use for magic foregrounding signal or 'no'
+                          [[default=no]]
   --enable-render-d3d     enable the Direct3D render driver [[default=yes]]
 
 Optional Packages:
@@ -23947,8 +23955,37 @@ fi
 
 }
 
+CheckEventSignals()
+{
+    # Check whether --enable-backgrounding-signal was given.
+if test "${enable_backgrounding_signal+set}" = set; then :
+  enableval=$enable_backgrounding_signal;
+else
+  enable_backgrounding_signal=no
+fi
+
+    if test x$enable_backgrounding_signal != xno; then
+        EXTRA_CFLAGS="$EXTRA_CFLAGS -DSDL_BACKGROUNDING_SIGNAL=$enable_backgrounding_signal"
+    fi
+
+    # Check whether --enable-foregrounding-signal was given.
+if test "${enable_foregrounding_signal+set}" = set; then :
+  enableval=$enable_foregrounding_signal;
+else
+  enable_foregrounding_signal=no
+fi
+
+    if test x$enable_foregrounding_signal != xno; then
+        EXTRA_CFLAGS="$EXTRA_CFLAGS -DSDL_FOREGROUNDING_SIGNAL=$enable_foregrounding_signal"
+    fi
+}
+
+
+
 CheckWarnAll
 
+CheckEventSignals
+
 case "$host" in
     *-*-linux*|*-*-uclinux*|*-*-gnu*|*-*-k*bsd*-gnu|*-*-bsdi*|*-*-freebsd*|*-*-dragonfly*|*-*-netbsd*|*-*-openbsd*|*-*-sysv5*|*-*-solaris*|*-*-hpux*|*-*-aix*|*-*-minix*|*-*-nto*)
         case "$host" in

configure.in

@@ -3344,9 +3344,34 @@ AC_HELP_STRING([--enable-rpath], [use an rpath when linking SDL [[default=yes]]]
                   , enable_rpath=yes)
 }
 
+dnl Check if we want to use custom signals to fake iOS/Android's backgrounding
+dnl  events. These could be useful if you're building a custom embedded
+dnl  environment, etc, but most people don't need this.
+CheckEventSignals()
+{
+    AC_ARG_ENABLE(backgrounding-signal,
+AC_HELP_STRING([--enable-backgrounding-signal], [number to use for magic backgrounding signal or 'no' [[default=no]]]),
+                  , enable_backgrounding_signal=no)
+    if test x$enable_backgrounding_signal != xno; then
+        EXTRA_CFLAGS="$EXTRA_CFLAGS -DSDL_BACKGROUNDING_SIGNAL=$enable_backgrounding_signal"
+    fi
+
+    AC_ARG_ENABLE(foregrounding-signal,
+AC_HELP_STRING([--enable-foregrounding-signal], [number to use for magic foregrounding signal or 'no' [[default=no]]]),
+                  , enable_foregrounding_signal=no)
+    if test x$enable_foregrounding_signal != xno; then
+        EXTRA_CFLAGS="$EXTRA_CFLAGS -DSDL_FOREGROUNDING_SIGNAL=$enable_foregrounding_signal"
+    fi
+}
+
+
+
 dnl Do this on all platforms, before everything else (other things might want to override it).
 CheckWarnAll
 
+dnl Do this for every platform, but for some it doesn't mean anything, but better to catch it here anyhow.
+CheckEventSignals
+
 dnl Set up the configuration based on the host platform!
 case "$host" in
     *-*-linux*|*-*-uclinux*|*-*-gnu*|*-*-k*bsd*-gnu|*-*-bsdi*|*-*-freebsd*|*-*-dragonfly*|*-*-netbsd*|*-*-openbsd*|*-*-sysv5*|*-*-solaris*|*-*-hpux*|*-*-aix*|*-*-minix*|*-*-nto*)
@@ -3923,7 +3948,7 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         CheckDummyVideo
         CheckInputEvents
         CheckPTHREAD
-        
+
         # Set up files for the timer library
         if test x$enable_timers = xyes; then
             AC_DEFINE(SDL_TIMER_UNIX, 1, [ ])

src/events/SDL_events.c

@@ -689,7 +689,7 @@ SDL_PumpEvents(void)
     }
 #endif
 
-    SDL_SendPendingQuit();  /* in case we had a signal handler fire, etc. */
+    SDL_SendPendingSignalEvents();  /* in case we had a signal handler fire, etc. */
 }
 
 /* Public functions */

src/events/SDL_events_c.h

@@ -52,7 +52,7 @@ extern int SDL_SendQuit(void);
 extern int SDL_EventsInit(void);
 extern void SDL_EventsQuit(void);
 
-extern void SDL_SendPendingQuit(void);
+extern void SDL_SendPendingSignalEvents(void);
 
 #endif /* SDL_events_c_h_ */
 

src/events/SDL_quit.c

@@ -34,6 +34,14 @@
 static SDL_bool disable_signals = SDL_FALSE;
 static SDL_bool send_quit_pending = SDL_FALSE;
 
+#ifdef SDL_BACKGROUNDING_SIGNAL
+static SDL_bool send_backgrounding_pending = SDL_FALSE;
+#endif
+
+#ifdef SDL_FOREGROUNDING_SIGNAL
+static SDL_bool send_foregrounding_pending = SDL_FALSE;
+#endif
+
 #ifdef HAVE_SIGNAL_H
 static void
 SDL_HandleSIG(int sig)
@@ -43,46 +51,81 @@ SDL_HandleSIG(int sig)
 
     /* Send a quit event next time the event loop pumps. */
     /* We can't send it in signal handler; malloc() might be interrupted! */
-    send_quit_pending = SDL_TRUE;
+    if ((sig == SIGINT) || (sig == SIGTERM)) {
+        send_quit_pending = SDL_TRUE;
+    }
+
+    #ifdef SDL_BACKGROUNDING_SIGNAL
+    else if (sig == SDL_BACKGROUNDING_SIGNAL) {
+        send_backgrounding_pending = SDL_TRUE;
+    }
+    #endif
+
+    #ifdef SDL_FOREGROUNDING_SIGNAL
+    else if (sig == SDL_FOREGROUNDING_SIGNAL) {
+        send_foregrounding_pending = SDL_TRUE;
+    }
+    #endif
 }
 #endif /* HAVE_SIGNAL_H */
 
-/* Public functions */
-static int
-SDL_QuitInit_Internal(void)
+static void
+SDL_EventSignal_Init(const int sig)
 {
 #ifdef HAVE_SIGACTION
     struct sigaction action;
-    sigaction(SIGINT, NULL, &action);
+
+    sigaction(sig, NULL, &action);
 #ifdef HAVE_SA_SIGACTION
     if ( action.sa_handler == SIG_DFL && (void (*)(int))action.sa_sigaction == SIG_DFL ) {
 #else
     if ( action.sa_handler == SIG_DFL ) {
 #endif
         action.sa_handler = SDL_HandleSIG;
-        sigaction(SIGINT, &action, NULL);
+        sigaction(sig, &action, NULL);
+    }
+#elif HAVE_SIGNAL_H
+    void (*ohandler) (int) = signal(sig, SDL_HandleSIG);
+    if (ohandler != SIG_DFL) {
+        signal(sig, ohandler);
     }
-    sigaction(SIGTERM, NULL, &action);
-
-#ifdef HAVE_SA_SIGACTION
-    if ( action.sa_handler == SIG_DFL && (void (*)(int))action.sa_sigaction == SIG_DFL ) {
-#else
-    if ( action.sa_handler == SIG_DFL ) {
 #endif
-        action.sa_handler = SDL_HandleSIG;
-        sigaction(SIGTERM, &action, NULL);
+}
+
+static void
+SDL_EventSignal_Quit(const int sig)
+{
+#ifdef HAVE_SIGACTION
+    struct sigaction action;
+    sigaction(sig, NULL, &action);
+    if ( action.sa_handler == SDL_HandleSIG ) {
+        action.sa_handler = SIG_DFL;
+        sigaction(sig, &action, NULL);
     }
 #elif HAVE_SIGNAL_H
-    void (*ohandler) (int);
+    void (*ohandler) (int) = signal(sig, SIG_DFL);
+    if (ohandler != SDL_HandleSIG) {
+        signal(sig, ohandler);
+    }
+#endif /* HAVE_SIGNAL_H */
+}
 
+/* Public functions */
+static int
+SDL_QuitInit_Internal(void)
+{
     /* Both SIGINT and SIGTERM are translated into quit interrupts */
-    ohandler = signal(SIGINT, SDL_HandleSIG);
-    if (ohandler != SIG_DFL)
-        signal(SIGINT, ohandler);
-    ohandler = signal(SIGTERM, SDL_HandleSIG);
-    if (ohandler != SIG_DFL)
-        signal(SIGTERM, ohandler);
-#endif /* HAVE_SIGNAL_H */
+    /* and SDL can be built to simulate iOS/Android semantics with arbitrary signals. */
+    SDL_EventSignal_Init(SIGINT);
+    SDL_EventSignal_Init(SIGTERM);
+
+    #ifdef SDL_BACKGROUNDING_SIGNAL
+    SDL_EventSignal_Init(SDL_BACKGROUNDING_SIGNAL);
+    #endif
+
+    #ifdef SDL_FOREGROUNDING_SIGNAL
+    SDL_EventSignal_Init(SDL_FOREGROUNDING_SIGNAL);
+    #endif
 
     /* That's it! */
     return 0;
@@ -100,28 +143,16 @@ SDL_QuitInit(void)
 static void
 SDL_QuitQuit_Internal(void)
 {
-#ifdef HAVE_SIGACTION
-    struct sigaction action;
-    sigaction(SIGINT, NULL, &action);
-    if ( action.sa_handler == SDL_HandleSIG ) {
-        action.sa_handler = SIG_DFL;
-        sigaction(SIGINT, &action, NULL);
-    }
-    sigaction(SIGTERM, NULL, &action);
-    if ( action.sa_handler == SDL_HandleSIG ) {
-        action.sa_handler = SIG_DFL;
-        sigaction(SIGTERM, &action, NULL);
-    }
-#elif HAVE_SIGNAL_H
-    void (*ohandler) (int);
-
-    ohandler = signal(SIGINT, SIG_DFL);
-    if (ohandler != SDL_HandleSIG)
-        signal(SIGINT, ohandler);
-    ohandler = signal(SIGTERM, SIG_DFL);
-    if (ohandler != SDL_HandleSIG)
-        signal(SIGTERM, ohandler);
-#endif /* HAVE_SIGNAL_H */
+    SDL_EventSignal_Quit(SIGINT);
+    SDL_EventSignal_Quit(SIGTERM);
+
+    #ifdef SDL_BACKGROUNDING_SIGNAL
+    SDL_EventSignal_Quit(SDL_BACKGROUNDING_SIGNAL);
+    #endif
+
+    #ifdef SDL_FOREGROUNDING_SIGNAL
+    SDL_EventSignal_Quit(SDL_FOREGROUNDING_SIGNAL);
+    #endif
 }
 
 void
@@ -141,12 +172,26 @@ SDL_SendQuit(void)
 }
 
 void
-SDL_SendPendingQuit(void)
+SDL_SendPendingSignalEvents(void)
 {
     if (send_quit_pending) {
         SDL_SendQuit();
         SDL_assert(!send_quit_pending);
     }
+
+    #ifdef SDL_BACKGROUNDING_SIGNAL
+    if (send_backgrounding_pending) {
+        send_backgrounding_pending = SDL_FALSE;
+        SDL_OnApplicationWillResignActive();
+    }
+    #endif
+
+    #ifdef SDL_FOREGROUNDING_SIGNAL
+    if (send_foregrounding_pending) {
+        send_foregrounding_pending = SDL_FALSE;
+        SDL_OnApplicationDidBecomeActive();
+    }
+    #endif
 }
 
 /* vi: set ts=4 sw=4 expandtab: */