Better IME transition while switching app with recents (1/N)

Changes includes:
- In DC#computeImeTarget, keeps the IME target with the last window
  while swiping up to recents to prevent flickering due to IME hide
  animation on top of recents.
- Screenshot Task with IME window if IME is attatched to the app.
- Ignore hiding current IME if IME is attached to the app.

Bug: 166736352
Test: manual, test the app with focusing editor and show soft-input,
      swiping up recents and see if the task view with IME screenshot are
      shows up without flickering.

Change-Id: Ib898bc2e3a5b063fe9eaf8b07d022231dd1326a3

services/core/java/com/android/server/wm/DisplayContent.java

@@ -3374,6 +3374,14 @@ class DisplayContent extends RootDisplayArea implements WindowManagerPolicy.Disp
         mUpdateImeTarget = updateImeTarget;
         WindowState target = getWindow(mComputeImeTargetPredicate);
 
+        // Keeps the IME target with the last window while swiping up to recents to prevent
+        // flickering due to IME hide animation on top of recents.
+        // TODO(b/166736352): This logic should go away once we switch over target immediately
+        //  and do the screenshot to preserve IME on disappearing target
+        if (target != null && curTarget != null && target.isActivityTypeHome()
+                && curTarget.getInsetsState().getSource(ITYPE_IME).isVisible()) {
+            return curTarget;
+        }
 
         // Yet more tricksyness!  If this window is a "starting" window, we do actually want
         // to be on top of it, but it is not -really- where input will go. So look down below
@@ -3546,7 +3554,7 @@ class DisplayContent extends RootDisplayArea implements WindowManagerPolicy.Disp
         );
     }
 
-    private void updateImeParent() {
+    void updateImeParent() {
         final SurfaceControl newParent = computeImeParent();
         if (newParent != null) {
             getPendingTransaction().reparent(mImeWindowsContainers.mSurfaceControl, newParent);

services/core/java/com/android/server/wm/RecentsAnimationController.java

@@ -283,6 +283,20 @@ public class RecentsAnimationController implements DeathRecipient {
         public void hideCurrentInputMethod() {
             final long token = Binder.clearCallingIdentity();
             try {
+                synchronized (mService.getWindowManagerLock()) {
+                    // Make sure to update the correct IME parent in case that the IME parent may
+                    // be computed as display layer when re-layout window happens during rotation
+                    // but there is intermediate state that the bounds of task and the IME
+                    // target's activity is not the same during rotating.
+                    mDisplayContent.updateImeParent();
+
+                    // Ignore hiding IME if IME window is attached to app.
+                    // Since we would like to snapshot Task with IME window while transitioning
+                    // to recents.
+                    if (mDisplayContent.isImeAttachedToApp()) {
+                        return;
+                    }
+                }
                 final InputMethodManagerInternal inputMethodManagerInternal =
                         LocalServices.getService(InputMethodManagerInternal.class);
                 if (inputMethodManagerInternal != null) {

services/core/java/com/android/server/wm/TaskSnapshotController.java

@@ -368,7 +368,8 @@ class TaskSnapshotController {
 
         SurfaceControl[] excludeLayers;
         final WindowState imeWindow = task.getDisplayContent().mInputMethodWindow;
-        if (imeWindow != null) {
+        // Exclude IME window snapshot when IME isn't proper to attach to app.
+        if (imeWindow != null && !task.getDisplayContent().isImeAttachedToApp()) {
             excludeLayers = new SurfaceControl[1];
             excludeLayers[0] = imeWindow.getSurfaceControl();
         } else {