Fix NPE when rotation after split dismissed

Because drag to dismissed will not call SplitDecorManager#onResized
so mShown status will be wrong. Reset some flag in release and also
add some null check to avoid NPE.

Also refine some function params and naming to avoid confuse.

Fix: 226551765
Test: follow bug repro step and check no NPE
Test: pass existing tests
Change-Id: Ife592e176ef67c5df79be0a81509531ffcbd1b39

libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitDecorManager.java

@@ -124,6 +124,9 @@ public class SplitDecorManager extends WindowlessWindowManager {
 
     /** Releases the surfaces for split decor. */
     public void release(SurfaceControl.Transaction t) {
+        if (mFadeAnimator != null && mFadeAnimator.isRunning()) {
+            mFadeAnimator.cancel();
+        }
         if (mViewHost != null) {
             mViewHost.release();
             mViewHost = null;
@@ -139,6 +142,8 @@ public class SplitDecorManager extends WindowlessWindowManager {
         mHostLeash = null;
         mIcon = null;
         mResizingIconView = null;
+        mIsResizing = false;
+        mShown = false;
     }
 
     /** Showing resizing hint. */
@@ -181,13 +186,13 @@ public class SplitDecorManager extends WindowlessWindowManager {
             if (mFadeAnimator != null && mFadeAnimator.isRunning()) {
                 mFadeAnimator.cancel();
             }
-            startFadeAnimation(show, false /* releaseLeash */);
+            startFadeAnimation(show, false /* isResized */);
             mShown = show;
         }
     }
 
     /** Stops showing resizing hint. */
-    public void onResized(Rect newBounds, SurfaceControl.Transaction t) {
+    public void onResized(SurfaceControl.Transaction t) {
         if (mResizingIconView == null) {
             return;
         }
@@ -200,7 +205,7 @@ public class SplitDecorManager extends WindowlessWindowManager {
                 mFadeAnimator.addListener(new AnimatorListenerAdapter() {
                     @Override
                     public void onAnimationEnd(Animator animation) {
-                        releaseLeash(finishT);
+                        releaseDecor(finishT);
                         finishT.apply();
                         finishT.close();
                     }
@@ -212,22 +217,25 @@ public class SplitDecorManager extends WindowlessWindowManager {
             mFadeAnimator.cancel();
         }
         if (mShown) {
-            startFadeAnimation(false /* show */, true /* releaseLeash */);
-            mShown = false;
+            startFadeAnimation(false /* show */, true /* isResized */);
         } else {
-            // Surface is hidden so release it directly.
-            releaseLeash(t);
+            // Decor surface is hidden so release it directly.
+            releaseDecor(t);
         }
     }
 
-    private void startFadeAnimation(boolean show, boolean releaseLeash) {
+    private void startFadeAnimation(boolean show, boolean isResized) {
         final SurfaceControl.Transaction animT = new SurfaceControl.Transaction();
         mFadeAnimator = ValueAnimator.ofFloat(0f, 1f);
         mFadeAnimator.setDuration(FADE_DURATION);
         mFadeAnimator.addUpdateListener(valueAnimator-> {
             final float progress = (float) valueAnimator.getAnimatedValue();
-            animT.setAlpha(mBackgroundLeash, show ? progress : 1 - progress);
-            animT.setAlpha(mIconLeash, show ? progress : 1 - progress);
+            if (mBackgroundLeash != null) {
+                animT.setAlpha(mBackgroundLeash, show ? progress : 1 - progress);
+            }
+            if (mIconLeash != null) {
+                animT.setAlpha(mIconLeash, show ? progress : 1 - progress);
+            }
             animT.apply();
         });
         mFadeAnimator.addListener(new AnimatorListenerAdapter() {
@@ -241,19 +249,25 @@ public class SplitDecorManager extends WindowlessWindowManager {
             @Override
             public void onAnimationEnd(@NonNull Animator animation) {
                 if (!show) {
-                    animT.hide(mBackgroundLeash).hide(mIconLeash).apply();
+                    if (mBackgroundLeash != null) {
+                        animT.hide(mBackgroundLeash);
+                    }
+                    if (mIconLeash != null) {
+                        animT.hide(mIconLeash);
+                    }
                 }
-                if (releaseLeash) {
-                    releaseLeash(animT);
-                    animT.apply();
+                if (isResized) {
+                    releaseDecor(animT);
                 }
+                animT.apply();
                 animT.close();
             }
         });
         mFadeAnimator.start();
     }
 
-    private void releaseLeash(SurfaceControl.Transaction t) {
+    /** Release or hide decor hint. */
+    private void releaseDecor(SurfaceControl.Transaction t) {
         if (mBackgroundLeash != null) {
             t.remove(mBackgroundLeash);
             mBackgroundLeash = null;

libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java

@@ -1072,8 +1072,8 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         mSyncQueue.queue(wct);
         mSyncQueue.runInSync(t -> {
             updateSurfaceBounds(layout, t);
-            mMainStage.onResized(getMainStageBounds(), t);
-            mSideStage.onResized(getSideStageBounds(), t);
+            mMainStage.onResized(t);
+            mSideStage.onResized(t);
         });
         mLogger.logResize(mSplitLayout.getDividerPositionAsFraction());
     }

libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java

@@ -319,9 +319,9 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
         }
     }
 
-    void onResized(Rect newBounds, SurfaceControl.Transaction t) {
+    void onResized(SurfaceControl.Transaction t) {
         if (mSplitDecorManager != null) {
-            mSplitDecorManager.onResized(newBounds, t);
+            mSplitDecorManager.onResized(t);
         }
     }