From 53ce154a2e446e82815034cb65a81b6784a767f5 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 12 Oct 2014 18:27:43 +0300
Subject: [PATCH] Deal with the activity being recreated during process
 lifetime

This can happen if e.g. screen orientation changes.
---
 source/core/android/main.cpp       |  6 +++++-
 source/core/android/mainthread.cpp | 22 ++++++++++++++++------
 source/core/android/mainthread.h   |  2 ++
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/source/core/android/main.cpp b/source/core/android/main.cpp
index 2101563..a71d92f 100644
--- a/source/core/android/main.cpp
+++ b/source/core/android/main.cpp
@@ -2,6 +2,10 @@
 
 extern "C" void ANativeActivity_onCreate(ANativeActivity *activity, void * /*saved_state*/, size_t /*state_size*/)
 {
-	Msp::Android::MainThread *thread = new Msp::Android::MainThread(activity);
+	static Msp::Android::MainThread *thread = 0;
+	if(thread)
+		thread->attach_to_activity(activity);
+	else
+		thread = new Msp::Android::MainThread(activity);
 	thread->wait_for_app_created();
 }
diff --git a/source/core/android/mainthread.cpp b/source/core/android/mainthread.cpp
index e07c837..1e5fc11 100644
--- a/source/core/android/mainthread.cpp
+++ b/source/core/android/mainthread.cpp
@@ -10,19 +10,23 @@ namespace Msp {
 namespace Android {
 
 MainThread::MainThread(ANativeActivity *a):
-	activity(a),
 	starting_up(true)
 {
+	attach_to_activity(a);
+	startup_mutex.lock();
+	launch();
+}
+
+void MainThread::attach_to_activity(ANativeActivity *a)
+{
+	activity = a;
+	activity->callbacks->onDestroy = &activity_destroyed;
 	activity->callbacks->onNativeWindowCreated = &native_window_created;
 	activity->callbacks->onNativeWindowResized = &native_window_resized;
 	activity->callbacks->onNativeWindowDestroyed = &native_window_destroyed;
 	activity->callbacks->onInputQueueCreated = &input_queue_created;
 	activity->callbacks->onInputQueueDestroyed = &input_queue_destroyed;
 	activity->instance = this;
-
-	startup_mutex.lock();
-
-	launch();
 }
 
 void MainThread::wait_for_app_created()
@@ -48,7 +52,8 @@ void MainThread::main()
 	Msp::Android::ErrorLogger err_logger;
 	Msp::Application::run(1, argv, this, &app_created);
 	free(appname);
-	ANativeActivity_finish(activity);
+	if(activity)
+		ANativeActivity_finish(activity);
 }
 
 void MainThread::app_created(void *data)
@@ -56,6 +61,11 @@ void MainThread::app_created(void *data)
 	reinterpret_cast<MainThread *>(data)->resume_startup();
 }
 
+void MainThread::activity_destroyed(ANativeActivity *activity)
+{
+	reinterpret_cast<MainThread *>(activity->instance)->activity = 0;
+}
+
 void MainThread::native_window_created(ANativeActivity *activity, ANativeWindow *window)
 {
 	reinterpret_cast<MainThread *>(activity->instance)->signal_native_window_created.emit(window);
diff --git a/source/core/android/mainthread.h b/source/core/android/mainthread.h
index 0330352..68da6c4 100644
--- a/source/core/android/mainthread.h
+++ b/source/core/android/mainthread.h
@@ -26,6 +26,7 @@ private:
 public:
 	MainThread(ANativeActivity *);
 
+	void attach_to_activity(ANativeActivity *);
 	bool is_starting_up() const { return starting_up; }
 	void wait_for_app_created();
 	void resume_startup();
@@ -34,6 +35,7 @@ private:
 	virtual void main();
 
 	static void app_created(void *);
+	static void activity_destroyed(ANativeActivity *);
 	static void native_window_created(ANativeActivity *, ANativeWindow *);
 	static void native_window_resized(ANativeActivity *, ANativeWindow *);
 	static void native_window_destroyed(ANativeActivity *, ANativeWindow *);
-- 
2.43.0