Samsung duplication bug hack-fix

shell/platform/android/io/flutter/plugin/editing/InputConnectionAdaptor.java

@@ -4,8 +4,10 @@
 
 package io.flutter.plugin.editing;
 
+import android.annotation.SuppressLint;
 import android.content.Context;
 import android.os.Build;
+import android.provider.Settings;
 import android.text.DynamicLayout;
 import android.text.Editable;
 import android.text.Layout;
@@ -17,6 +19,7 @@
 import android.view.inputmethod.CursorAnchorInfo;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputMethodManager;
+import android.view.inputmethod.InputMethodSubtype;
 import io.flutter.Log;
 import io.flutter.embedding.engine.systemchannels.TextInputChannel;
 
@@ -30,6 +33,9 @@ class InputConnectionAdaptor extends BaseInputConnection {
   private InputMethodManager mImm;
   private final Layout mLayout;
 
+  // Used to determine if Samsung-specific hacks should be applied.
+  private final boolean isSamsung;
+
   @SuppressWarnings("deprecation")
   public InputConnectionAdaptor(
       View view,
@@ -56,6 +62,8 @@ public InputConnectionAdaptor(
             0.0f,
             false);
     mImm = (InputMethodManager) view.getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
+
+    isSamsung = isSamsung();
   }
 
   // Send the current state of the editable to Flutter.
@@ -132,19 +140,64 @@ public boolean setComposingText(CharSequence text, int newCursorPosition) {
   public boolean finishComposingText() {
     boolean result = super.finishComposingText();
 
-    if (Build.VERSION.SDK_INT >= 21) {
-      // Update the keyboard with a reset/empty composing region. Critical on
-      // Samsung keyboards to prevent punctuation duplication.
-      CursorAnchorInfo.Builder builder = new CursorAnchorInfo.Builder();
-      builder.setComposingText(-1, "");
-      CursorAnchorInfo anchorInfo = builder.build();
-      mImm.updateCursorAnchorInfo(mFlutterView, anchorInfo);
+    // Apply Samsung hacks. Samsung caches composing region data strangely, causing text
+    // duplication.
+    if (isSamsung) {
+      if (Build.VERSION.SDK_INT >= 21) {
+        // Samsung keyboards don't clear the composing region on finishComposingText.
+        // Update the keyboard with a reset/empty composing region. Critical on
+        // Samsung keyboards to prevent punctuation duplication.
+        CursorAnchorInfo.Builder builder = new CursorAnchorInfo.Builder();
+        builder.setComposingText(/*composingTextStart*/ -1, /*composingText*/ "");
+        CursorAnchorInfo anchorInfo = builder.build();
+        mImm.updateCursorAnchorInfo(mFlutterView, anchorInfo);
+      }
+      // TODO(garyq): There is still a duplication case that comes from hiding+showing the keyboard.
+      // The exact behavior to cause it has so far been hard to pinpoint and it happens far more
+      // rarely than the original bug.
+
+      // Temporarily indicate to the IME that the composing region selection should be reset.
+      // The correct selection is then immediately set properly in the updateEditingState() call
+      // in this method. This is a hack to trigger Samsung keyboard's internal cache to clear.
+      // This prevents duplication on keyboard hide+show. See
+      // https://github.com/flutter/flutter/issues/31512
+      //
+      // We only do this if the proper selection will be restored later, eg, when mBatchCount is 0.
+      if (mBatchCount == 0) {
+        mImm.updateSelection(
+            mFlutterView,
+            -1, /*selStart*/
+            -1, /*selEnd*/
+            -1, /*candidatesStart*/
+            -1 /*candidatesEnd*/);
+      }
     }
 
     updateEditingState();
     return result;
   }
 
+  // Detect if the keyboard is a Samsung keyboard, where we apply Samsung-specific hacks to
+  // fix critical bugs that make the keyboard otherwise unusable. See finishComposingText() for
+  // more details.
+  @SuppressLint("NewApi") // New API guard is inline, the linter can't see it.
+  @SuppressWarnings("deprecation")
+  private boolean isSamsung() {
+    InputMethodSubtype subtype = mImm.getCurrentInputMethodSubtype();
+    // Impacted devices all shipped with Android Lollipop or newer.
+    if (subtype == null
+        || Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP
+        || !Build.MANUFACTURER.equals("samsung")) {
+      return false;
+    }
+    String keyboardName =
+        Settings.Secure.getString(
+            mFlutterView.getContext().getContentResolver(), Settings.Secure.DEFAULT_INPUT_METHOD);
+    // The Samsung keyboard is called "com.sec.android.inputmethod/.SamsungKeypad" but look
+    // for "Samsung" just in case Samsung changes the name of the keyboard.
+    return keyboardName.contains("Samsung");
+  }
+
   @Override
   public boolean setSelection(int start, int end) {
     boolean result = super.setSelection(start, end);

shell/platform/android/test/io/flutter/plugin/editing/TextInputPluginTest.java

@@ -28,6 +28,9 @@
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.platform.PlatformViewsController;
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.junit.Test;
@@ -305,9 +308,17 @@ public void inputConnection_createsActionFromEnter() throws JSONException {
 
   @Test
   public void inputConnection_finishComposingTextUpdatesIMM() throws JSONException {
+    ShadowBuild.setManufacturer("samsung");
+    InputMethodSubtype inputMethodSubtype =
+        new InputMethodSubtype(0, 0, /*locale=*/ "en", "", "", false, false);
+    Settings.Secure.putString(
+        RuntimeEnvironment.application.getContentResolver(),
+        Settings.Secure.DEFAULT_INPUT_METHOD,
+        "com.sec.android.inputmethod/.SamsungKeypad");
     TestImm testImm =
         Shadow.extract(
             RuntimeEnvironment.application.getSystemService(Context.INPUT_METHOD_SERVICE));
+    testImm.setCurrentInputMethodSubtype(inputMethodSubtype);
     FlutterJNI mockFlutterJni = mock(FlutterJNI.class);
     View testView = new View(RuntimeEnvironment.application);
     DartExecutor dartExecutor = spy(new DartExecutor(mockFlutterJni, mock(AssetManager.class)));
@@ -338,13 +349,59 @@ public void inputConnection_finishComposingTextUpdatesIMM() throws JSONException
     }
   }
 
+  @Test
+  public void inputConnection_samsungFinishComposingTextSetsSelection() throws JSONException {
+    ShadowBuild.setManufacturer("samsung");
+    InputMethodSubtype inputMethodSubtype =
+        new InputMethodSubtype(0, 0, /*locale=*/ "en", "", "", false, false);
+    Settings.Secure.putString(
+        RuntimeEnvironment.application.getContentResolver(),
+        Settings.Secure.DEFAULT_INPUT_METHOD,
+        "com.sec.android.inputmethod/.SamsungKeypad");
+    TestImm testImm =
+        Shadow.extract(
+            RuntimeEnvironment.application.getSystemService(Context.INPUT_METHOD_SERVICE));
+    testImm.setCurrentInputMethodSubtype(inputMethodSubtype);
+    FlutterJNI mockFlutterJni = mock(FlutterJNI.class);
+    View testView = new View(RuntimeEnvironment.application);
+    DartExecutor dartExecutor = spy(new DartExecutor(mockFlutterJni, mock(AssetManager.class)));
+    TextInputPlugin textInputPlugin =
+        new TextInputPlugin(testView, dartExecutor, mock(PlatformViewsController.class));
+    textInputPlugin.setTextInputClient(
+        0,
+        new TextInputChannel.Configuration(
+            false,
+            false,
+            true,
+            TextInputChannel.TextCapitalization.NONE,
+            new TextInputChannel.InputType(TextInputChannel.TextInputType.TEXT, false, false),
+            null,
+            null));
+    // There's a pending restart since we initialized the text input client. Flush that now.
+    textInputPlugin.setTextInputEditingState(
+        testView, new TextInputChannel.TextEditState("", 0, 0));
+    InputConnection connection = textInputPlugin.createInputConnection(testView, new EditorInfo());
+
+    testImm.setTrackSelection(true);
+    connection.finishComposingText();
+    testImm.setTrackSelection(false);
+
+    List<Integer> expectedSelectionValues =
+        Arrays.asList(0, 0, -1, -1, -1, -1, -1, -1, 0, 0, -1, -1);
+    assertEquals(testImm.getSelectionUpdateValues(), expectedSelectionValues);
+  }
+
   @Implements(InputMethodManager.class)
   public static class TestImm extends ShadowInputMethodManager {
     private InputMethodSubtype currentInputMethodSubtype;
     private SparseIntArray restartCounter = new SparseIntArray();
     private CursorAnchorInfo cursorAnchorInfo;
+    private ArrayList<Integer> selectionUpdateValues;
+    private boolean trackSelection = false;
 
-    public TestImm() {}
+    public TestImm() {
+      selectionUpdateValues = new ArrayList<Integer>();
+    }
 
     @Implementation
     public InputMethodSubtype getCurrentInputMethodSubtype() {
@@ -370,6 +427,28 @@ public void updateCursorAnchorInfo(View view, CursorAnchorInfo cursorAnchorInfo)
       this.cursorAnchorInfo = cursorAnchorInfo;
     }
 
+    // We simply store the values to verify later.
+    @Implementation
+    public void updateSelection(
+        View view, int selStart, int selEnd, int candidatesStart, int candidatesEnd) {
+      if (trackSelection) {
+        this.selectionUpdateValues.add(selStart);
+        this.selectionUpdateValues.add(selEnd);
+        this.selectionUpdateValues.add(candidatesStart);
+        this.selectionUpdateValues.add(candidatesEnd);
+      }
+    }
+
+    // only track values when enabled via this.
+    public void setTrackSelection(boolean val) {
+      trackSelection = val;
+    }
+
+    // Returns true if the last updateSelection call passed the following values.
+    public ArrayList<Integer> getSelectionUpdateValues() {
+      return selectionUpdateValues;
+    }
+
     public CursorAnchorInfo getLastCursorAnchorInfo() {
       return cursorAnchorInfo;
     }