Fixed bug 1293 - [Android] Support Pause/Resume

Gabriel Jacobo 2011-12-23 12:55:11 PST

The attached files provide some improvement over the current handling of
pause/resume in Android.
- I disabled the exit(status) instruction in SDL_main as that makes the entire
app instead of the SDL thread exit (while not needed for pause/resume it is
needed for Live Wallpapers, an SDLActivity for which I'll upload in a separate
bug).
- Added nativePause and nativeResume which basically just mark the window as
visible/hidden, something that the end user needs to take into consideration
(ideally pausing the event loop).

Also, this arrangement creates a new GL context when needed, which at least in
my test system is every time you go away from the app and come back to it. So,
this means that the textures need to be generated again after resuming (a
problem the end user didn't have before because the app exited completely when
it should've been pausing). I'd like to know if there's a standard way of
letting the user know that the GL context has changed and that he needs to
refresh his textures, or if this is out of the scope of the library and each
user handles it in their own way (I don't know how/if this same thing is
handled in  the iPhone backend, but it would be wise to try to imitate that).

Gabriel Jacobo 2011-12-23 12:57:10 PST
Also, in the SDLActivity the EGL handling code is moved up to the Activity from
the Surface code, as I think it is possible (in theory) that the surface is
destroyed temporarily while the context remains alive (though in practice in my
test system this is not the case)

src/core/android/SDL_android.cpp

@@ -167,6 +167,26 @@ extern "C" void Java_org_libsdl_app_SDLActivity_nativeQuit(
     SDL_SendQuit();
 }
 
+// Pause
+extern "C" void Java_org_libsdl_app_SDLActivity_nativePause(
+                                    JNIEnv* env, jclass cls)
+{
+    if (Android_Window) {
+        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_HIDDEN, 0, 0);
+        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_FOCUS_LOST, 0, 0);
+    }
+}
+
+// Resume
+extern "C" void Java_org_libsdl_app_SDLActivity_nativeResume(
+                                    JNIEnv* env, jclass cls)
+{
+    if (Android_Window) {
+        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_SHOWN, 0, 0);
+        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_FOCUS_GAINED, 0, 0);
+    }
+}
+
 extern "C" void Java_org_libsdl_app_SDLActivity_nativeRunAudioThread(
                                     JNIEnv* env, jclass cls)
 {

src/main/android/SDL_android_main.cpp

@@ -33,8 +33,8 @@ extern "C" void Java_org_libsdl_app_SDLActivity_nativeInit(JNIEnv* env, jclass c
     argv[1] = NULL;
     status = SDL_main(1, argv);
 
-    /* We exit here for consistency with other platforms. */
-    exit(status);
+    /* Do not issue an exit or the whole application will terminate instead of just the SDL thread */
+    //exit(status);
 }
 
 #endif /* __ANDROID__ */