feat: new 'background/foreground` events for app

On android `suspend/resume` was not doing what was expected.
in particular it was called while showing dialogs

packages/core/application/application-common.ts

@@ -22,6 +22,8 @@ export function hasLaunched(): boolean {
 export const launchEvent = 'launch';
 export const suspendEvent = 'suspend';
 export const displayedEvent = 'displayed';
+export const backgroundEvent = 'background';
+export const foregroundEvent = 'foreground';
 export const resumeEvent = 'resume';
 export const exitEvent = 'exit';
 export const lowMemoryEvent = 'lowMemory';

packages/core/application/index.android.ts

@@ -43,6 +43,7 @@ export class AndroidApplication extends Observable implements AndroidApplication
 	private _orientation: 'portrait' | 'landscape' | 'unknown';
 	private _systemAppearance: 'light' | 'dark';
 	public paused: boolean;
+	public backgrounded: boolean;
 	public nativeApp: android.app.Application;
 	public context: android.content.Context;
 	public foregroundActivity: androidx.appcompat.app.AppCompatActivity;
@@ -334,6 +335,9 @@ function initLifecycleCallbacks() {
 		rootView.getViewTreeObserver().addOnGlobalLayoutListener(global.onGlobalLayoutListener);
 	});
 
+
+	let activitiesStarted = 0;
+
 	const lifecycleCallbacks = new android.app.Application.ActivityLifecycleCallbacks(<any>{
 		onActivityCreated: <any>profile('onActivityCreated', function (activity: androidx.appcompat.app.AppCompatActivity, savedInstanceState: android.os.Bundle) {
 			if (!androidApp.foregroundActivity) {
@@ -374,7 +378,7 @@ function initLifecycleCallbacks() {
 			if ((<any>activity).isNativeScriptActivity) {
 				androidApp.paused = true;
 				appCommon.notify(<ApplicationEventData>{
-					eventName: appCommon.suspendEvent,
+					eventName: appCommon.backgroundEvent,
 					object: androidApp,
 					android: activity,
 				});
@@ -407,6 +411,15 @@ function initLifecycleCallbacks() {
 		}),
 
 		onActivityStarted: <any>profile('onActivityStarted', function (activity: androidx.appcompat.app.AppCompatActivity) {
+			activitiesStarted++;
+			if (activitiesStarted === 1) {
+				androidApp.backgrounded = true;
+				appCommon.notify(<ApplicationEventData>{
+					eventName: appCommon.foregroundEvent,
+					object: androidApp,
+					android: activity,
+				});
+			}
 			androidApp.notify(<AndroidActivityEventData>{
 				eventName: ActivityStarted,
 				object: androidApp,
@@ -415,6 +428,15 @@ function initLifecycleCallbacks() {
 		}),
 
 		onActivityStopped: <any>profile('onActivityStopped', function (activity: androidx.appcompat.app.AppCompatActivity) {
+			activitiesStarted--;
+			if (activitiesStarted === 0) {
+				androidApp.backgrounded = true;
+				appCommon.notify(<ApplicationEventData>{
+					eventName: appCommon.backgroundEvent,
+					object: androidApp,
+					android: activity,
+				});
+			}
 			androidApp.notify(<AndroidActivityEventData>{
 				eventName: ActivityStopped,
 				object: androidApp,

packages/core/application/index.d.ts

@@ -34,6 +34,16 @@ export const suspendEvent: string;
  */
 export const resumeEvent: string;
 
+/**
+ * String value used when hooking to foreground event.
+ */
+export const foregroundEvent: string;
+
+/**
+ * String value used when hooking to background event.
+ */
+export const backgroundEvent: string;
+
 /**
  * String value used when hooking to exit event.
  */
@@ -503,6 +513,11 @@ export class AndroidApplication extends Observable {
 	 */
 	paused: boolean;
 
+	/**
+	 * True if the main application activity is in background, false otherwise.
+	 */
+	backgrounded: boolean;
+
 	/**
 	 * Initialized the android-specific application object with the native android.app.Application instance.
 	 * This is useful when creating custom application types.

packages/core/application/index.ios.ts

@@ -4,7 +4,7 @@ import { ApplicationEventData, CssChangedEventData, LaunchEventData, LoadAppCSSE
 
 // TODO: explain why we need to this or remov it
 // Use requires to ensure order of imports is maintained
-const { displayedEvent, exitEvent, getCssFileName, launchEvent, livesync, lowMemoryEvent, notify, on, orientationChanged, orientationChangedEvent, resumeEvent, setApplication, suspendEvent, systemAppearanceChanged, systemAppearanceChangedEvent } = require('./application-common');
+const { backgroundEvent, displayedEvent, exitEvent, foregroundEvent, getCssFileName, launchEvent, livesync, lowMemoryEvent, notify, on, orientationChanged, orientationChangedEvent, resumeEvent, setApplication, suspendEvent, systemAppearanceChanged, systemAppearanceChangedEvent } = require('./application-common');
 // First reexport so that app module is initialized.
 export * from './application-common';
 
@@ -220,6 +220,7 @@ export class iOSApplication implements iOSApplicationDefinition {
 		const ios = UIApplication.sharedApplication;
 		const object = this;
 		notify(<ApplicationEventData>{ eventName: resumeEvent, object, ios });
+		notify(<ApplicationEventData>{ eventName: foregroundEvent, object, ios });
 		const rootView = this._rootView;
 		if (rootView && !rootView.isLoaded) {
 			rootView.callLoaded();
@@ -227,11 +228,10 @@ export class iOSApplication implements iOSApplicationDefinition {
 	}
 
 	private didEnterBackground(notification: NSNotification) {
-		notify(<ApplicationEventData>{
+		const ios = UIApplication.sharedApplication;
-			eventName: suspendEvent,
+		const object = this;
-			object: this,
+		notify(<ApplicationEventData>{ eventName: suspendEvent, object, ios });
-			ios: UIApplication.sharedApplication,
+		notify(<ApplicationEventData>{ eventName: backgroundEvent, object, ios });
-		});
 		const rootView = this._rootView;
 		if (rootView && rootView.isLoaded) {
 			rootView.callUnloaded();