insert method
Implementation
void insert(String insert) {
final text = editingValue.text;
final textSelection = editingValue.selection;
final start = textSelection.start;
final end = textSelection.end;
final newText = text.replaceRange(start, end, insert);
final textLength = insert.length;
editingValue = editingValue.copyWith(
text: newText,
selection: textSelection.copyWith(
baseOffset: textSelection.start + textLength,
extentOffset: textSelection.start + textLength,
),
composing: TextRange.empty,
);
// Request the attached client to update accordingly.
widget.embedTextInput.updateEditingValue(editingValue);
}