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.

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

Change-Id: Iff88b768c6b06cf5cf1fe9e97ee97f8f78e6f0bd

1 files changed, 49 insertions, 3 deletions

diff --git a/core/java/android/inputmethodservice/InputMethodService.java b/core/java/android/inputmethodservice/InputMethodService.java
index 7e2be01feb01..03dd3067e64e 100644
--- a/core/java/android/inputmethodservice/InputMethodService.java
+++ b/core/java/android/inputmethodservice/InputMethodService.java
@@ -70,6 +70,7 @@ import android.compat.annotation.ChangeId;
 import android.compat.annotation.EnabledSince;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.content.Context;
+import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
 import android.content.res.Configuration;
 import android.content.res.Resources;
@@ -131,6 +132,7 @@ import android.widget.TextView;
 import android.window.WindowMetricsHelper;
 
 import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.inputmethod.IInputContentUriToken;
 import com.android.internal.inputmethod.IInputMethodPrivilegedOperations;
 import com.android.internal.inputmethod.InputMethodPrivilegedOperations;
@@ -513,6 +515,8 @@ public class InputMethodService extends AbstractInputMethodService {
     private boolean mIsAutomotive;
     private Handler mHandler;
     private boolean mImeSurfaceScheduledForRemoval;
+    private Configuration mLastKnownConfig;
+    private int mHandledConfigChanges;
 
     /**
      * An opaque {@link Binder} token of window requesting {@link InputMethodImpl#showSoftInput}
@@ -588,12 +592,14 @@ 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");
+            mHandledConfigChanges = configChanges;
             mPrivOps.set(privilegedOperations);
             InputMethodPrivilegedOperationsRegistry.put(token, mPrivOps);
             updateInputMethodDisplay(displayId);
@@ -821,6 +827,9 @@ public class InputMethodService extends AbstractInputMethodService {
                 setImeWindowStatus(mapToImeWindowStatus(), mBackDisposition);
             }
             final boolean isVisible = isInputViewShown();
+            if (isVisible && getResources() != null) {
+                mLastKnownConfig = getResources().getConfiguration();
+            }
             final boolean visibilityChanged = isVisible != wasVisible;
             if (resultReceiver != null) {
                 resultReceiver.send(visibilityChanged
@@ -1428,10 +1437,37 @@ 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();
+        if (shouldImeRestartForConfig(newConfig)) {
+            resetStateForNewConfiguration();
+        }
+    }
+
+    /**
+     * @return {@code true} if {@link InputMethodService} needs to restart to handle
+     * .{@link #onConfigurationChanged(Configuration)}
+     */
+    @VisibleForTesting
+    boolean shouldImeRestartForConfig(@NonNull Configuration newConfig) {
+        if (mLastKnownConfig == null) {
+            return true;
+        }
+        // If the new config is the same as the config this Service is already running with,
+        // then don't bother calling resetStateForNewConfiguration.
+        int diff = mLastKnownConfig.diffPublicOnly(newConfig);
+        if (diff != 0) {
+            // remove attrs not-relevant to IME service.
+            diff &= ActivityInfo.CONFIG_KEYBOARD_HIDDEN;
+            diff &= ActivityInfo.CONFIG_KEYBOARD;
+            diff &= ActivityInfo.CONFIG_NAVIGATION;
+        }
+        int unhandledDiff = (diff & ~mHandledConfigChanges);
+        return unhandledDiff != 0;
     }
 
     private void resetStateForNewConfiguration() {
@@ -3181,7 +3217,17 @@ public class InputMethodService extends AbstractInputMethodService {
             requestHideSelf(InputMethodManager.HIDE_NOT_ALWAYS);
         }
     }
-    
+
+    @VisibleForTesting
+    void setLastKnownConfig(@NonNull Configuration config) {
+        mLastKnownConfig = config;
+    }
+
+    @VisibleForTesting
+    void setHandledConfigChanges(int configChanges) {
+        mHandledConfigChanges = configChanges;
+    }
+
     void startExtractingText(boolean inputChanged) {
         final ExtractEditText eet = mExtractEditText;
         if (eet != null && getCurrentInputStarted()