updateEditingValue method

@override void updateEditingValue(TextEditingValue value)

Requests that this client update its editing state to the given value.

The new value is treated as user input and thus may subject to input formatting.

Implementation

@override
void updateEditingValue(TextEditingValue value) {
  if (!shouldCreateInputConnection) {
    return;
  }

  if (_sentRemoteValues.contains(value)) {
    /// There is a race condition in Flutter text input plugin where sending
    /// updates to native side too often results in broken behavior.
    /// TextInputConnection.setEditingValue is an async call to native side.
    /// For each such call native side _always_ sends an update which triggers
    /// this method (updateEditingValue) with the same value we've sent it.
    /// If multiple calls to setEditingValue happen too fast and we only
    /// track the last sent value then there is no way for us to filter out
    /// automatic callbacks from native side.
    /// Therefore we have to keep track of all values we send to the native
    /// side and when we see this same value appear here we skip it.
    /// This is fragile but it's probably the only available option.
    _sentRemoteValues.remove(value);
    return;
  }

  if (_lastKnownRemoteTextEditingValue == value) {
    // There is no difference between this value and the last known value.
    return;
  }

  // Check if only composing range changed.
  if (_lastKnownRemoteTextEditingValue!.text == value.text &&
      _lastKnownRemoteTextEditingValue!.selection == value.selection) {
    // This update only modifies composing range. Since we don't keep track
    // of composing range in Zefyr we just need to update last known value
    // here.
    // This check fixes an issue on Android when it sends
    // composing updates separately from regular changes for text and
    // selection.
    _lastKnownRemoteTextEditingValue = value;
    return;
  }

  // Note Flutter (unintentionally?) silences errors occurred during
  // text input update, so we have to report it ourselves.
  // For more details see https://github.com/flutter/flutter/issues/19191
  // TODO: remove try-catch when/if Flutter stops silencing these errors.
  try {
    final effectiveLastKnownValue = _lastKnownRemoteTextEditingValue!;
    _lastKnownRemoteTextEditingValue = value;
    final oldText = effectiveLastKnownValue.text;
    final text = value.text;
    final cursorPosition = value.selection.extentOffset;
    final diff = fastDiff(oldText, text, cursorPosition);
    _remoteValueChanged(
        diff.start, diff.deleted, diff.inserted, value.selection);
  } catch (e, trace) {
    FlutterError.reportError(FlutterErrorDetails(
      exception: e,
      stack: trace,
      library: 'Zefyr',
      context: ErrorSummary('while updating editing value'),
    ));
    rethrow;
  }
}