Avoid IME restart for configChanges

Handle onConfigurationChanged() in order to prevent restarting
InputMethodService everytime. We introduce a new API attribute
"configChanges" in InputMethod(attrs.xml) which when declared
by IME, will be responsible for handling mentioned
configuration changes.

This CL re-introduces [1] with fix: Use new Configuration instance for
IMS#mLastKnownConfig and also handle followup comments.

[1] Ib94fddadb0dae648cf73a4c1642e51edebd19f50

Note: this change has no impact for devices not using DisplayAreas.

Bug: 167948419
Test: atest InputMethodServiceTest
    Manually:
      1. Patch Ie91e7a8e06b80864ef9409031e8543858552d70d to use dual
         display area.
      2. Open applications with editors on both display areas.
      3. Attach a debug point for IMS#onConfigurationChanged().
      4. Make sure IMS#resetStateForNewConfiguration() is not called
         when IME moves between these two identical DisplayAreas
    Also verify that bug 182604598 don't happen.

Change-Id: I43b6b80cdb35410554412ee1d3b0917ee3198272

1 files changed, 9 insertions, 3 deletions

diff --git a/core/java/android/inputmethodservice/InputMethodService.java b/core/java/android/inputmethodservice/InputMethodService.java
index 7e2be01feb01..bf016124da31 100644
--- a/core/java/android/inputmethodservice/InputMethodService.java
+++ b/core/java/android/inputmethodservice/InputMethodService.java
@@ -513,6 +513,7 @@ public class InputMethodService extends AbstractInputMethodService {
     private boolean mIsAutomotive;
     private Handler mHandler;
     private boolean mImeSurfaceScheduledForRemoval;
+    private ImsConfigurationTracker mConfigTracker = new ImsConfigurationTracker();
 
     /**
      * An opaque {@link Binder} token of window requesting {@link InputMethodImpl#showSoftInput}
@@ -588,12 +589,13 @@ public class InputMethodService extends AbstractInputMethodService {
         @MainThread
         @Override
         public final void initializeInternal(@NonNull IBinder token, int displayId,
-                IInputMethodPrivilegedOperations privilegedOperations) {
+                IInputMethodPrivilegedOperations privilegedOperations, int configChanges) {
             if (InputMethodPrivilegedOperationsRegistry.isRegistered(token)) {
                 Log.w(TAG, "The token has already registered, ignore this initialization.");
                 return;
             }
             Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "IMS.initializeInternal");
+            mConfigTracker.onInitialize(configChanges);
             mPrivOps.set(privilegedOperations);
             InputMethodPrivilegedOperationsRegistry.put(token, mPrivOps);
             updateInputMethodDisplay(displayId);
@@ -663,6 +665,7 @@ public class InputMethodService extends AbstractInputMethodService {
             reportFullscreenMode();
             initialize();
             onBindInput();
+            mConfigTracker.onBindInput(getResources());
             Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
         }
 
@@ -1428,10 +1431,13 @@ public class InputMethodService extends AbstractInputMethodService {
      * state: {@link #onStartInput} if input is active, and
      * {@link #onCreateInputView} and {@link #onStartInputView} and related
      * appropriate functions if the UI is displayed.
+     * <p>Starting with {@link Build.VERSION_CODES#S}, IMEs can opt into handling configuration
+     * changes themselves instead of being restarted with
+     * {@link android.R.styleable#InputMethod_configChanges}.
      */
     @Override public void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);
-        resetStateForNewConfiguration();
+        mConfigTracker.onConfigurationChanged(newConfig, this::resetStateForNewConfiguration);
     }
 
     private void resetStateForNewConfiguration() {
@@ -3181,7 +3187,7 @@ public class InputMethodService extends AbstractInputMethodService {
             requestHideSelf(InputMethodManager.HIDE_NOT_ALWAYS);
         }
     }
-    
+
     void startExtractingText(boolean inputChanged) {
         final ExtractEditText eet = mExtractEditText;
         if (eet != null && getCurrentInputStarted()