Fixed bug 4580 - Android 8: immersive fullscreen notification causes flickering between fullscreen and non-fullscreen and app is unresponsive

Sylvain 2019-04-18 21:22:59 UTC

Changes:
- SDL_WINDOWEVENT_FOCUS_GAINED and SDL_WINDOWEVENT_FOCUS_LOST are sent when the java method onWindowFocusChanged() is called.

- If we have support for MultiWindow (eg API >= 24), SDL event loop is blocked/un-blocked (or simply egl-backed-up or not), when java onStart()/onStop() are called.

- If not, this behaves like now, SDL event loop is blocked/un-blocked when onPause()/onResume() are called.

So if we have two app on screen and switch from one to the other, only FOCUS events are sent (and onPause()/onResume() are called but empty. onStart()/onStop() are not called).
The SDL app, un-focused, would still continue to run and display frames (currently the App would be displayed, but paused).
Like a video player app or a chronometer that would still be refreshed, even if the window hasn't the focus.
It should work also on ChromeBooks (not tested), with two apps opened at the same time.


I am not sure this fix Dan's issue. Because focus lost event triggers Minimize function (which BTW is not provided on android).
https://hg.libsdl.org/SDL/file/bb41b3635c34/src/video/SDL_video.c#l2653
https://hg.libsdl.org/SDL/file/bb41b3635c34/src/video/SDL_video.c#l2634

So, in addition, it would need to add by default SDL_HINT_VIDEO_MINIMIZE_ON_FOCUS_LOSS to 0.
So that the lost focus event doesn't try to minimize the window. And this should fix also the issue.

android-project/app/src/main/java/org/libsdl/app/SDLActivity.java

@@ -38,6 +38,7 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
     private static final String TAG = "SDL";
 
     public static boolean mIsResumedCalled, mHasFocus;
+    public static final boolean mHasMultiWindow = (Build.VERSION.SDK_INT >= 24);
 
     // Cursor types
     private static final int SDL_SYSTEM_CURSOR_NONE = -1;
@@ -274,16 +275,12 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
         }
     }
 
-    // Events
+    protected void pauseNativeThread() {
-    @Override
-    protected void onPause() {
-        Log.v(TAG, "onPause()");
-        super.onPause();
         mNextNativeState = NativeState.PAUSED;
         mIsResumedCalled = false;
 
         if (SDLActivity.mBrokenLibraries) {
-           return;
+            return;
         }
 
         if (mHIDDeviceManager != null) {
@@ -293,10 +290,7 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
         SDLActivity.handleNativeState();
     }
 
-    @Override
+    protected void resumeNativeThread() {
-    protected void onResume() {
-        Log.v(TAG, "onResume()");
-        super.onResume();
         mNextNativeState = NativeState.RESUMED;
         mIsResumedCalled = true;
 
@@ -311,6 +305,43 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
         SDLActivity.handleNativeState();
     }
 
+    // Events
+    @Override
+    protected void onPause() {
+        Log.v(TAG, "onPause()");
+        super.onPause();
+        if (!mHasMultiWindow) {
+            pauseNativeThread();
+        }
+    }
+
+    @Override
+    protected void onResume() {
+        Log.v(TAG, "onResume()");
+        super.onResume();
+        if (!mHasMultiWindow) {
+            resumeNativeThread();
+        }
+    }
+
+    @Override
+    protected void onStop() {
+        Log.v(TAG, "onStop()");
+        super.onStop();
+        if (mHasMultiWindow) {
+            pauseNativeThread();
+        }
+    }
+
+    @Override
+    protected void onStart() {
+        Log.v(TAG, "onStart()");
+        super.onStart();
+        if (mHasMultiWindow) {
+            resumeNativeThread();
+        }
+    }
+
     public static int getCurrentOrientation() {
         final Context context = SDLActivity.getContext();
         final Display display = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
@@ -347,15 +378,21 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
            return;
         }
 
-        SDLActivity.mHasFocus = hasFocus;
+        mHasFocus = hasFocus;
         if (hasFocus) {
            mNextNativeState = NativeState.RESUMED;
            SDLActivity.getMotionListener().reclaimRelativeMouseModeIfNeeded();
-        } else {
-           mNextNativeState = NativeState.PAUSED;
-        }
 
-        SDLActivity.handleNativeState();
+           SDLActivity.handleNativeState();
+           nativeFocusChanged(true);
+
+        } else {
+           nativeFocusChanged(false);
+           if (!mHasMultiWindow) {
+               mNextNativeState = NativeState.PAUSED;
+               SDLActivity.handleNativeState();
+           }
+        }
     }
 
     @Override
@@ -719,6 +756,7 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
     public static native void nativeQuit();
     public static native void nativePause();
     public static native void nativeResume();
+    public static native void nativeFocusChanged(boolean hasFocus);
     public static native void onNativeDropFile(String filename);
     public static native void nativeSetScreenResolution(int surfaceWidth, int surfaceHeight, int deviceWidth, int deviceHeight, int format, float rate);
     public static native void onNativeResize();

src/core/android/SDL_android.c

@@ -131,6 +131,9 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativePause)(
 JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeResume)(
         JNIEnv *env, jclass cls);
 
+JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeFocusChanged)(
+        JNIEnv *env, jclass cls, jboolean hasFocus);
+
 JNIEXPORT jstring JNICALL SDL_JAVA_INTERFACE(nativeGetHint)(
         JNIEnv *env, jclass cls,
         jstring name);
@@ -1034,7 +1037,6 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativePause)(
     __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativePause()");
 
     if (Android_Window) {
-        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_FOCUS_LOST, 0, 0);
         SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_MINIMIZED, 0, 0);
         SDL_SendAppEvent(SDL_APP_WILLENTERBACKGROUND);
         SDL_SendAppEvent(SDL_APP_DIDENTERBACKGROUND);
@@ -1060,7 +1062,6 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeResume)(
     if (Android_Window) {
         SDL_SendAppEvent(SDL_APP_WILLENTERFOREGROUND);
         SDL_SendAppEvent(SDL_APP_DIDENTERFOREGROUND);
-        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_FOCUS_GAINED, 0, 0);
         SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_RESTORED, 0, 0);
     }
 
@@ -1073,6 +1074,19 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeResume)(
     SDL_UnlockMutex(Android_ActivityMutex);
 }
 
+JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeFocusChanged)(
+                                    JNIEnv *env, jclass cls, jboolean hasFocus)
+{
+    SDL_LockMutex(Android_ActivityMutex);
+
+    if (Android_Window) {
+        __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativeFocusChanged()");
+        SDL_SendWindowEvent(Android_Window, (hasFocus ? SDL_WINDOWEVENT_FOCUS_GAINED : SDL_WINDOWEVENT_FOCUS_LOST), 0, 0);
+    } 
+
+    SDL_UnlockMutex(Android_ActivityMutex);
+}
+
 JNIEXPORT void JNICALL SDL_JAVA_INTERFACE_INPUT_CONNECTION(nativeCommitText)(
                                     JNIEnv *env, jclass cls,
                                     jstring text, jint newCursorPosition)