Implement repeat filtering logic in Android Embedder (flutter/engine#17509)

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

@@ -37,10 +37,46 @@ class InputConnectionAdaptor extends BaseInputConnection {
   private int mBatchCount;
   private InputMethodManager mImm;
   private final Layout mLayout;
-
   // Used to determine if Samsung-specific hacks should be applied.
   private final boolean isSamsung;
 
+  private boolean mRepeatCheckNeeded = false;
+  private TextEditingValue mLastSentTextEditngValue;
+  // Data class used to get and store the last-sent values via updateEditingState to
+  // the  framework. These are then compared against to prevent redundant messages
+  // with the same data before any valid operations were made to the contents.
+  private class TextEditingValue {
+    public int selectionStart;
+    public int selectionEnd;
+    public int composingStart;
+    public int composingEnd;
+    public String text;
+
+    public TextEditingValue(Editable editable) {
+      selectionStart = Selection.getSelectionStart(editable);
+      selectionEnd = Selection.getSelectionEnd(editable);
+      composingStart = BaseInputConnection.getComposingSpanStart(editable);
+      composingEnd = BaseInputConnection.getComposingSpanEnd(editable);
+      text = editable.toString();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (o == this) {
+        return true;
+      }
+      if (!(o instanceof TextEditingValue)) {
+        return false;
+      }
+      TextEditingValue value = (TextEditingValue) o;
+      return selectionStart == value.selectionStart
+          && selectionEnd == value.selectionEnd
+          && composingStart == value.composingStart
+          && composingEnd == value.composingEnd
+          && text.equals(value.text);
+    }
+  }
+
   @SuppressWarnings("deprecation")
   public InputConnectionAdaptor(
       View view,
@@ -76,15 +112,42 @@ class InputConnectionAdaptor extends BaseInputConnection {
     // If the IME is in the middle of a batch edit, then wait until it completes.
     if (mBatchCount > 0) return;
 
-    int selectionStart = Selection.getSelectionStart(mEditable);
-    int selectionEnd = Selection.getSelectionEnd(mEditable);
-    int composingStart = BaseInputConnection.getComposingSpanStart(mEditable);
-    int composingEnd = BaseInputConnection.getComposingSpanEnd(mEditable);
+    TextEditingValue currentValue = new TextEditingValue(mEditable);
 
-    mImm.updateSelection(mFlutterView, selectionStart, selectionEnd, composingStart, composingEnd);
+    // Return if this data has already been sent and no meaningful changes have
+    // occurred to mark this as dirty. This prevents duplicate remote updates of
+    // the same data, which can break formatters that change the length of the
+    // contents.
+    if (mRepeatCheckNeeded && currentValue.equals(mLastSentTextEditngValue)) {
+      return;
+    }
+
+    mImm.updateSelection(
+        mFlutterView,
+        currentValue.selectionStart,
+        currentValue.selectionEnd,
+        currentValue.composingStart,
+        currentValue.composingEnd);
 
     textInputChannel.updateEditingState(
-        mClient, mEditable.toString(), selectionStart, selectionEnd, composingStart, composingEnd);
+        mClient,
+        currentValue.text,
+        currentValue.selectionStart,
+        currentValue.selectionEnd,
+        currentValue.composingStart,
+        currentValue.composingEnd);
+
+    mRepeatCheckNeeded = true;
+    mLastSentTextEditngValue = currentValue;
+  }
+
+  // This should be called whenever a change could have been made to
+  // the value of mEditable, which will make any call of updateEditingState()
+  // ineligible for repeat checking as we do not want to skip sending real changes
+  // to the framework.
+  public void markDirty() {
+    // Disable updateEditngState's repeat-update check
+    mRepeatCheckNeeded = false;
   }
 
   @Override
@@ -109,7 +172,7 @@ class InputConnectionAdaptor extends BaseInputConnection {
   @Override
   public boolean commitText(CharSequence text, int newCursorPosition) {
     boolean result = super.commitText(text, newCursorPosition);
-    updateEditingState();
+    markDirty();
     return result;
   }
 
@@ -118,14 +181,21 @@ class InputConnectionAdaptor extends BaseInputConnection {
     if (Selection.getSelectionStart(mEditable) == -1) return true;
 
     boolean result = super.deleteSurroundingText(beforeLength, afterLength);
-    updateEditingState();
+    markDirty();
+    return result;
+  }
+
+  @Override
+  public boolean deleteSurroundingTextInCodePoints(int beforeLength, int afterLength) {
+    boolean result = super.deleteSurroundingTextInCodePoints(beforeLength, afterLength);
+    markDirty();
     return result;
   }
 
   @Override
   public boolean setComposingRegion(int start, int end) {
     boolean result = super.setComposingRegion(start, end);
-    updateEditingState();
+    markDirty();
     return result;
   }
 
@@ -137,7 +207,7 @@ class InputConnectionAdaptor extends BaseInputConnection {
     } else {
       result = super.setComposingText(text, newCursorPosition);
     }
-    updateEditingState();
+    markDirty();
     return result;
   }
 
@@ -159,7 +229,7 @@ class InputConnectionAdaptor extends BaseInputConnection {
       }
     }
 
-    updateEditingState();
+    markDirty();
     return result;
   }
 
@@ -173,6 +243,13 @@ class InputConnectionAdaptor extends BaseInputConnection {
     return extractedText;
   }
 
+  @Override
+  public boolean clearMetaKeyStates(int states) {
+    boolean result = super.clearMetaKeyStates(states);
+    markDirty();
+    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.
@@ -197,7 +274,7 @@ class InputConnectionAdaptor extends BaseInputConnection {
   @Override
   public boolean setSelection(int start, int end) {
     boolean result = super.setSelection(start, end);
-    updateEditingState();
+    markDirty();
     return result;
   }
 
@@ -219,6 +296,7 @@ class InputConnectionAdaptor extends BaseInputConnection {
 
   @Override
   public boolean sendKeyEvent(KeyEvent event) {
+    markDirty();
     if (event.getAction() == KeyEvent.ACTION_DOWN) {
       if (event.getKeyCode() == KeyEvent.KEYCODE_DEL) {
         int selStart = clampIndexToEditable(Selection.getSelectionStart(mEditable), mEditable);
@@ -344,6 +422,7 @@ class InputConnectionAdaptor extends BaseInputConnection {
 
   @Override
   public boolean performContextMenuAction(int id) {
+    markDirty();
     if (id == android.R.id.selectAll) {
       setSelection(0, mEditable.length());
       return true;
@@ -397,6 +476,7 @@ class InputConnectionAdaptor extends BaseInputConnection {
 
   @Override
   public boolean performEditorAction(int actionCode) {
+    markDirty();
     switch (actionCode) {
       case EditorInfo.IME_ACTION_NONE:
         textInputChannel.newline(mClient);

engine/src/flutter/shell/platform/android/io/flutter/plugin/editing/TextInputPlugin.java

@@ -322,6 +322,10 @@ public class TextInputPlugin {
     }
     // Always apply state to selection which handles updating the selection if needed.
     applyStateToSelection(state);
+    InputConnection connection = getLastInputConnection();
+    if (connection != null && connection instanceof InputConnectionAdaptor) {
+      ((InputConnectionAdaptor) connection).markDirty();
+    }
     // Use updateSelection to update imm on selection if it is not neccessary to restart.
     if (!restartAlwaysRequired && !mRestartInputPending) {
       mImm.updateSelection(

engine/src/flutter/shell/platform/android/test/io/flutter/plugin/editing/InputConnectionAdaptorTest.java

@@ -270,6 +270,49 @@ public class InputConnectionAdaptorTest {
     assertEquals(extractedText.selectionEnd, selStart);
   }
 
+  @Test
+  public void inputConnectionAdaptor_RepeatFilter() throws NullPointerException {
+    View testView = new View(RuntimeEnvironment.application);
+    FlutterJNI mockFlutterJni = mock(FlutterJNI.class);
+    DartExecutor dartExecutor = spy(new DartExecutor(mockFlutterJni, mock(AssetManager.class)));
+    int inputTargetId = 0;
+    TestTextInputChannel textInputChannel = new TestTextInputChannel(dartExecutor);
+    Editable mEditable = Editable.Factory.getInstance().newEditable("");
+    Editable spyEditable = spy(mEditable);
+    EditorInfo outAttrs = new EditorInfo();
+    outAttrs.inputType = InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_MULTI_LINE;
+
+    InputConnectionAdaptor inputConnectionAdaptor =
+        new InputConnectionAdaptor(
+            testView, inputTargetId, textInputChannel, spyEditable, outAttrs);
+
+    inputConnectionAdaptor.beginBatchEdit();
+    assertEquals(textInputChannel.updateEditingStateInvocations, 0);
+    inputConnectionAdaptor.setComposingText("I do not fear computers. I fear the lack of them.", 1);
+    assertEquals(textInputChannel.text, null);
+    assertEquals(textInputChannel.updateEditingStateInvocations, 0);
+    inputConnectionAdaptor.endBatchEdit();
+    assertEquals(textInputChannel.updateEditingStateInvocations, 1);
+    assertEquals(textInputChannel.text, "I do not fear computers. I fear the lack of them.");
+
+    inputConnectionAdaptor.beginBatchEdit();
+    assertEquals(textInputChannel.updateEditingStateInvocations, 1);
+    inputConnectionAdaptor.endBatchEdit();
+    assertEquals(textInputChannel.updateEditingStateInvocations, 1);
+
+    inputConnectionAdaptor.beginBatchEdit();
+    assertEquals(textInputChannel.text, "I do not fear computers. I fear the lack of them.");
+    assertEquals(textInputChannel.updateEditingStateInvocations, 1);
+    inputConnectionAdaptor.setSelection(3, 4);
+    assertEquals(textInputChannel.updateEditingStateInvocations, 1);
+    assertEquals(textInputChannel.selectionStart, 49);
+    assertEquals(textInputChannel.selectionEnd, 49);
+    inputConnectionAdaptor.endBatchEdit();
+    assertEquals(textInputChannel.updateEditingStateInvocations, 2);
+    assertEquals(textInputChannel.selectionStart, 3);
+    assertEquals(textInputChannel.selectionEnd, 4);
+  }
+
   private static final String SAMPLE_TEXT =
       "Lorem ipsum dolor sit amet," + "\nconsectetur adipiscing elit.";
 
@@ -285,4 +328,35 @@ public class InputConnectionAdaptorTest {
     TextInputChannel textInputChannel = mock(TextInputChannel.class);
     return new InputConnectionAdaptor(testView, client, textInputChannel, editable, null);
   }
+
+  private class TestTextInputChannel extends TextInputChannel {
+    public TestTextInputChannel(DartExecutor dartExecutor) {
+      super(dartExecutor);
+    }
+
+    public int inputClientId;
+    public String text;
+    public int selectionStart;
+    public int selectionEnd;
+    public int composingStart;
+    public int composingEnd;
+    public int updateEditingStateInvocations = 0;
+
+    @Override
+    public void updateEditingState(
+        int inputClientId,
+        String text,
+        int selectionStart,
+        int selectionEnd,
+        int composingStart,
+        int composingEnd) {
+      this.inputClientId = inputClientId;
+      this.text = text;
+      this.selectionStart = selectionStart;
+      this.selectionEnd = selectionEnd;
+      this.composingStart = composingStart;
+      this.composingEnd = composingEnd;
+      updateEditingStateInvocations++;
+    }
+  }
 }