fix: black screen resume / pause (#2400)

client/android/src/org/amnezia/vpn/AmneziaActivity.kt

@@ -343,12 +343,22 @@ class AmneziaActivity : QtActivity() {
         resumeHandler.removeCallbacksAndMessages(null)
         openFileDeliveryScheduled = false
         Log.d(TAG, "Pause Amnezia activity")
+        // Notify Qt to stop rendering before the EGL surface is disconnected
+        mainScope.launch {
+            qtInitialized.await()
+            QtAndroidController.onActivityPaused()
+        }
     }
 
     override fun onResume() {
         super.onResume()
         isActivityResumed = true
         Log.d(TAG, "Resume Amnezia activity")
+        // Notify Qt to resume rendering after surface reconnects
+        mainScope.launch {
+            qtInitialized.await()
+            QtAndroidController.onActivityResumed()
+        }
 
         if (pendingOpenFileUri != null && !openFileDeliveryScheduled) {
             val uri = pendingOpenFileUri!!

client/android/src/org/amnezia/vpn/qt/QtAndroidController.kt

@@ -31,4 +31,7 @@ object QtAndroidController {
 
     external fun onImeInsetsChanged(heightDp: Int)
     external fun onSystemBarsInsetsChanged(navBarHeightDp: Int, statusBarHeightDp: Int)
+
+    external fun onActivityPaused()
+    external fun onActivityResumed()
 }

client/platforms/android/android_controller.cpp

@@ -101,7 +101,9 @@ bool AndroidController::initialize()
         {"onAuthResult", "(Z)V", reinterpret_cast<void *>(onAuthResult)},
         {"decodeQrCode", "(Ljava/lang/String;)Z", reinterpret_cast<bool *>(decodeQrCode)},
         {"onImeInsetsChanged", "(I)V", reinterpret_cast<void *>(onImeInsetsChanged)},
-        {"onSystemBarsInsetsChanged", "(II)V", reinterpret_cast<void *>(onSystemBarsInsetsChanged)}
+        {"onSystemBarsInsetsChanged", "(II)V", reinterpret_cast<void *>(onSystemBarsInsetsChanged)},
+        {"onActivityPaused", "()V", reinterpret_cast<void *>(onActivityPaused)},
+        {"onActivityResumed", "()V", reinterpret_cast<void *>(onActivityResumed)}
     };
 
     QJniEnvironment env;
@@ -558,3 +560,22 @@ void AndroidController::onSystemBarsInsetsChanged(JNIEnv *env, jobject thiz, jin
     emit AndroidController::instance()->systemBarsInsetsChanged(navBarHeightDp, statusBarHeightDp);
 }
 
+// static
+void AndroidController::onActivityPaused(JNIEnv *env, jobject thiz)
+{
+    Q_UNUSED(env);
+    Q_UNUSED(thiz);
+
+    emit AndroidController::instance()->activityPaused();
+}
+
+// static
+void AndroidController::onActivityResumed(JNIEnv *env, jobject thiz)
+{
+    Q_UNUSED(env);
+    Q_UNUSED(thiz);
+
+    emit AndroidController::instance()->activityResumed();
+}
+
+

client/platforms/android/android_controller.h

@@ -75,6 +75,8 @@ signals:
     void authenticationResult(bool result);
     void imeInsetsChanged(int heightDp);
     void systemBarsInsetsChanged(int navBarHeightDp, int statusBarHeightDp);
+    void activityPaused();
+    void activityResumed();
 
 private:
     bool isWaitingStatus = true;
@@ -105,6 +107,8 @@ private:
     static bool decodeQrCode(JNIEnv *env, jobject thiz, jstring data);
     static void onImeInsetsChanged(JNIEnv *env, jobject thiz, jint heightDp);
     static void onSystemBarsInsetsChanged(JNIEnv *env, jobject thiz, jint navBarHeightDp, jint statusBarHeightDp);
+    static void onActivityPaused(JNIEnv *env, jobject thiz);
+    static void onActivityResumed(JNIEnv *env, jobject thiz);
 
     template <typename Ret, typename ...Args>
     static auto callActivityMethod(const char *methodName, const char *signature, Args &&...args);

client/ui/controllers/settingsController.cpp

@@ -45,6 +45,8 @@ SettingsController::SettingsController(const QSharedPointer<ServersModel> &serve
         emit safeAreaBottomMarginChanged();
         emit safeAreaTopMarginChanged();
     });
+    connect(AndroidController::instance(), &AndroidController::activityPaused, this, &SettingsController::activityPaused);
+    connect(AndroidController::instance(), &AndroidController::activityResumed, this, &SettingsController::activityResumed);
 #endif
 
     m_isDevModeEnabled = m_settings->isDevGatewayEnv();

client/ui/controllers/settingsController.h

@@ -141,6 +141,9 @@ signals:
     void safeAreaTopMarginChanged();
     void safeAreaBottomMarginChanged();
 
+    void activityPaused();
+    void activityResumed();
+
     void isHomeAdLabelVisibleChanged(bool visible);
     void startMinimizedChanged();
 

client/ui/qml/main2.qml

@@ -23,17 +23,25 @@ Window  {
                 if (Qt.application.state === Qt.ApplicationActive) {
                     root.visible = true
                     refreshTimer.restart()
-                } else if (Qt.application.state === Qt.ApplicationSuspended) {
-                    // Hide window to stop the Qt render loop and prevent
-                    // eglSwapBuffers from being called on a lost EGL context.
-                    // NOTE: Do NOT hide on ApplicationInactive — that fires on any
-                    // focus change (IME, notifications) and would blank the screen.
-                    root.visible = false
                 }
             }
         }
     }
 
+    // Hide the window immediately when Android Activity.onPause() fires so that
+    // Qt's render loop stops before the EGL surface is disconnected.  This
+    // prevents "QRhiGles2: Failed to make context current" and the resulting
+    // black screen that appears after swiping home and returning.
+    Connections {
+        target: SettingsController
+        function onActivityPaused() {
+            if (Qt.platform.os === "android") root.visible = false
+        }
+        function onActivityResumed() {
+            if (Qt.platform.os === "android") root.visible = true
+        }
+    }
+
     Timer {
         id: refreshTimer
         interval: 150