fix(android): nested fragment disappears on parent fragment removal (#6677)

tns-core-modules/ui/frame/fragment.android.ts

@@ -1,7 +1,7 @@
 import { AndroidFragmentCallbacks, setFragmentCallbacks, setFragmentClass } from "./frame";
 
 @JavaProxy("com.tns.FragmentClass")
-class FragmentClass extends android.support.v4.app.Fragment {
+class FragmentClass extends org.nativescript.widgets.FragmentBase {
     // This field is updated in the frame module upon `new` (although hacky this eases the Fragment->callbacks association a lot)
     private _callbacks: AndroidFragmentCallbacks;
     
@@ -15,8 +15,7 @@ class FragmentClass extends android.support.v4.app.Fragment {
     }
 
     public onCreateAnimator(transit: number, enter: boolean, nextAnim: number): android.animation.Animator {
-        let result = this._callbacks.onCreateAnimator(this, transit, enter, nextAnim, super.onCreateAnimator);
+        return this._callbacks.onCreateAnimator(this, transit, enter, nextAnim, super.onCreateAnimator);
-        return result;
     }
 
     public onStop(): void {

tns-core-modules/ui/frame/fragment.transitions.android.ts

@@ -86,7 +86,20 @@ export function _setAndroidFragmentTransitions(
         name = navigationTransition.name ? navigationTransition.name.toLowerCase() : "";
     }
 
-    let useLollipopTransition = name && (name.indexOf("slide") === 0 || name === "fade" || name === "explode") && sdkVersion() >= 21;
+    let useLollipopTransition = !!(name && (name.indexOf("slide") === 0 || name === "fade" || name === "explode") && sdkVersion() >= 21);
+    // [nested frames / fragments] force disable lollipop transitions in case nested fragments 
+    // are detected as applying dummy animator to the nested fragment with the same duration as 
+    // the exit animator of the removing parent fragment as a workaround for 
+    // https://code.google.com/p/android/issues/detail?id=55228 works only if custom animations are
+    // used
+    // NOTE: this effectively means you cannot use Explode transition in nested frames scenarios as
+    // we have implementations only for slide, fade, and flip
+    if (currentFragment && 
+        currentFragment.getChildFragmentManager() &&
+        currentFragment.getChildFragmentManager().getFragments().toArray().length > 0) {
+        useLollipopTransition = false;
+    }
+    
     if (!animated) {
         name = "none";
     } else if (transition) {

tns-core-modules/ui/frame/frame-common.ts

@@ -457,8 +457,8 @@ export class FrameBase extends CustomLayoutView implements FrameDefinition {
     }
 
     public _onRootViewReset(): void {
-        this._removeFromFrameStack();
         super._onRootViewReset();
+        this._removeFromFrameStack();
     }
 
     get _childrenCount(): number {

tns-core-modules/ui/frame/frame.android.ts

@@ -209,8 +209,12 @@ export class Frame extends FrameBase {
     }
 
     public _onRootViewReset(): void {
-        this.disposeCurrentFragment();
         super._onRootViewReset();
+
+        // call this AFTER the super call to ensure descendants apply their rootview-reset logic first
+        // i.e. in a scenario with nested frames / frame with tabview let the descendandt cleanup the inner
+        // fragments first, and then cleanup the parent fragments
+        this.disposeCurrentFragment();
     }
 
     onUnloaded() {
@@ -223,11 +227,6 @@ export class Frame extends FrameBase {
     }
 
     private disposeCurrentFragment(): void {
-        // when interacting with nested fragments it seems Android is smart enough
-        // to automatically remove child fragments when parent fragment is removed;
-        // however, we must add a fragment.isAdded() guard as our logic will try to 
-        // explicitly remove the already removed child fragment causing an 
-        // IllegalStateException: Fragment has not been attached yet.
         if (!this._currentEntry ||
             !this._currentEntry.fragment ||
             !this._currentEntry.fragment.isAdded()) {
@@ -742,7 +741,13 @@ class FragmentCallbacksImplementation implements AndroidFragmentCallbacks {
     }
 
     @profile
-    public onCreateAnimator(fragment: android.support.v4.app.Fragment, transit: number, enter: boolean, nextAnim: number, superFunc: Function): android.animation.Animator {
+    public onCreateAnimator(fragment: org.nativescript.widgets.FragmentBase, transit: number, enter: boolean, nextAnim: number, superFunc: Function): android.animation.Animator {
+        // HACK: FragmentBase class MUST handle removing nested fragment scenario to workaround
+        // https://code.google.com/p/android/issues/detail?id=55228
+        if (!enter && fragment.getRemovingParentFragment()) {
+            return superFunc.call(fragment, transit, enter, nextAnim);
+        }
+
         let nextAnimString: string;
         switch (nextAnim) {
             case AnimationType.enterFakeResourceId: nextAnimString = "enter"; break;

tns-core-modules/ui/tab-view/tab-view.android.ts

@@ -45,7 +45,7 @@ function initializeNativeClasses() {
         return;
     }
 
-    class TabFragmentImplementation extends android.support.v4.app.Fragment {
+    class TabFragmentImplementation extends org.nativescript.widgets.FragmentBase {
         private tab: TabView;
         private index: number;
 
@@ -55,7 +55,6 @@ function initializeNativeClasses() {
         }
 
         static newInstance(tabId: number, index: number): TabFragmentImplementation {
-
             const args = new android.os.Bundle();
             args.putInt(TABID, tabId);
             args.putInt(INDEX, index);
@@ -79,10 +78,6 @@ function initializeNativeClasses() {
 
             return tabItem.view.nativeViewProtected;
         }
-
-        public onDestroyView() {
-            super.onDestroyView();
-        }
     }
 
     const POSITION_UNCHANGED = -1;
@@ -560,8 +555,13 @@ export class TabView extends TabViewBase {
     }
 
     public _onRootViewReset(): void {
-        this.disposeCurrentFragments();
         super._onRootViewReset();
+        
+        // call this AFTER the super call to ensure descendants apply their rootview-reset logic first
+        // i.e. in a scenario with tab frames let the frames cleanup their fragments first, and then
+        // cleanup the tab fragments to avoid
+        // android.content.res.Resources$NotFoundException: Unable to find resource ID #0xfffffff6
+        this.disposeCurrentFragments();
     }
 
     private disposeCurrentFragments(): void {

tns-platform-declarations/android/org.nativescript.widgets.d.ts

@@ -164,6 +164,12 @@
                 public verticalAlignment: VerticalAlignment;
             }
 
+            export class FragmentBase extends android.support.v4.app.Fragment {
+                constructor();
+
+                public getRemovingParentFragment(): android.support.v4.app.Fragment;
+            }
+
             export enum Stretch {
                 none,
                 aspectFill,