title: How to move label text to top of the input text field only when I type some text
body: <p>I want to move the label text to top of the input text field only when I enter some text. Currently it is moving on top when input text field is getting focus. </p>
  
  <pre><code>Widget nameField() {
      return TextFormField(
        keyboardType: TextInputType.text,
        autofocus: false,
        textAlign: TextAlign.start,
        textInputAction: TextInputAction.done,
        controller: nameTextEditingController,
        style: TextStyle(
            color: Colors.white, fontSize: 18, fontWeight: FontWeight.w500),
        decoration: const InputDecoration(
          contentPadding: EdgeInsets.symmetric(vertical: 15),
          labelText: Strings.user_info_page_name_placeholder,
          labelStyle: TextStyle(
              color: Colors.grey, fontSize: 18, fontWeight: FontWeight.w500),
          focusedBorder: OutlineInputBorder(
              borderSide: BorderSide(color: Colors.transparent, width: 1)),
        ),
      );
    }
  
  </code></pre>