From 41ba83089f946289c8cf032deda8794998667be4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cosmin=20B=C4=83ie=C8=99?= <cosminbaies@google.com>
Date: Tue, 13 Jun 2023 15:56:25 +0200
Subject: [PATCH] Fix IME nav bar button flickers

This fixes the back navigation button flicker in 3-button navigation
when switching IMEs, by setting it to the default (non-IME) position
when the IME switcher dialog is shown.

This also fixes the IME switcher button flicker in 3-button and gesture
navigation modes when switching IMEs.

Test: install two IMEs, open the IME and have the IME switcher icon
  visible, test switching IMEs in 3-button and gesture navigation mode
  and observe the behaviour of the navigation buttons.
Bug: 287045025
Change-Id: I9c0d521d372db8b33f4898eb25bdef1e6fc50e48
---
 .../inputmethod/InputMethodManagerService.java     | 14 ++++++++++++--
 .../inputmethod/InputMethodMenuController.java     |  8 +++++++-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
index 8c137e2eb44c4..4dbd82065a667 100644
--- a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
+++ b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
@@ -3043,7 +3043,12 @@ public final class InputMethodManagerService extends IInputMethodManager.Stub
     private boolean shouldShowImeSwitcherLocked(
             @InputMethodService.ImeWindowVisibility int visibility) {
         if (!mShowOngoingImeSwitcherForPhones) return false;
+        // When the IME switcher dialog is shown, the IME switcher button should be hidden.
         if (mMenuController.getSwitchingDialogLocked() != null) return false;
+        // When we are switching IMEs, the IME switcher button should be hidden.
+        if (!Objects.equals(getCurIdLocked(), getSelectedMethodIdLocked())) {
+            return false;
+        }
         if (mWindowManagerInternal.isKeyguardShowingAndNotOccluded()
                 && mWindowManagerInternal.isKeyguardSecure(mSettings.getCurrentUserId())) {
             return false;
@@ -3208,7 +3213,12 @@ public final class InputMethodManagerService extends IInputMethodManager.Stub
             } else {
                 vis &= ~InputMethodService.IME_VISIBLE_IMPERCEPTIBLE;
             }
-            // mImeWindowVis should be updated before calling shouldShowImeSwitcherLocked().
+            if (mMenuController.getSwitchingDialogLocked() != null
+                    || !Objects.equals(getCurIdLocked(), getSelectedMethodIdLocked())) {
+                // When the IME switcher dialog is shown, or we are switching IMEs,
+                // the back button should be in the default state (as if the IME is not shown).
+                backDisposition = InputMethodService.BACK_DISPOSITION_ADJUST_NOTHING;
+            }
             final boolean needsToShowImeSwitcher = shouldShowImeSwitcherLocked(vis);
             if (mStatusBarManagerInternal != null) {
                 mStatusBarManagerInternal.setImeWindowStatus(mCurTokenDisplayId,
@@ -5775,7 +5785,7 @@ public final class InputMethodManagerService extends IInputMethodManager.Stub
                 // input target changed, in case seeing the dialog dismiss flickering during
                 // the next focused window starting the input connection.
                 if (mLastImeTargetWindow != mCurFocusedWindow) {
-                    mMenuController.hideInputMethodMenu();
+                    mMenuController.hideInputMethodMenuLocked();
                 }
             }
         }
diff --git a/services/core/java/com/android/server/inputmethod/InputMethodMenuController.java b/services/core/java/com/android/server/inputmethod/InputMethodMenuController.java
index c212e8e3c82cc..c2ef83d066900 100644
--- a/services/core/java/com/android/server/inputmethod/InputMethodMenuController.java
+++ b/services/core/java/com/android/server/inputmethod/InputMethodMenuController.java
@@ -175,13 +175,13 @@ final class InputMethodMenuController {
                     int subtypeId = mSubtypeIds[which];
                     adapter.mCheckedItem = which;
                     adapter.notifyDataSetChanged();
-                    hideInputMethodMenu();
                     if (im != null) {
                         if (subtypeId < 0 || subtypeId >= im.getSubtypeCount()) {
                             subtypeId = NOT_A_SUBTYPE_ID;
                         }
                         mService.setInputMethodLocked(im.getId(), subtypeId);
                     }
+                    hideInputMethodMenuLocked();
                 }
             };
             mDialogBuilder.setSingleChoiceItems(adapter, checkedItem, choiceListener);
@@ -220,12 +220,18 @@ final class InputMethodMenuController {
         }
     }
 
+    /**
+     * Hides the input method switcher menu.
+     */
     void hideInputMethodMenu() {
         synchronized (ImfLock.class) {
             hideInputMethodMenuLocked();
         }
     }
 
+    /**
+     * Hides the input method switcher menu, synchronised version of {@link #hideInputMethodMenu}.
+     */
     @GuardedBy("ImfLock.class")
     void hideInputMethodMenuLocked() {
         if (DEBUG) Slog.v(TAG, "Hide switching menu");