title: Text field not taking values immediately after 1 tap in flutter. What is the problem?
body: <p>So I have <em><strong>auto-calculated text fields</strong></em> in flutter. Here it's <code>code</code>:</p>
  <pre><code>enum UnitType {
    meter,
    centimeter,
    feet,
  }
  
  class Units extends StatelessWidget {
    Units({Key? key}) : super(key: key);
    final TextEditingController _feetController =
        TextEditingController(text: '0');
    final TextEditingController _centimeterController =
        TextEditingController(text: '0');
    final TextEditingController _meterController =
        TextEditingController(text: '0');
  
    void _convertUnit(UnitType type) {
      double? ft = double.tryParse(_feetController.value.text) ?? 0;
      double? cm = double.tryParse(_centimeterController.value.text) ?? 0;
      double? m = double.tryParse(_meterController.value.text) ?? 0;
  
      switch (type) {
        case UnitType.feet:
          _meterController.text = (ft / 3.281).toStringAsFixed(2);
          _centimeterController.text = (ft * 30.48).toStringAsFixed(2);
          break;
        case UnitType.meter:
          _centimeterController.text = (m * 100).toStringAsFixed(2);
          _feetController.text = (m * 3.281).toStringAsFixed(2);
          break;
        case UnitType.centimeter:
          _meterController.text = (cm / 100).toStringAsFixed(2);
          _feetController.text = (cm / 30.48).toStringAsFixed(2);
          break;
      }
    }
  </code></pre>
  <p>I am having a problem though, I cannot immediately start putting values in the text fields, I need to press twice and then delete the Zeros '0', and then I can put some values. After a single tap it's not taking any input. What possibly can the problem be?</p>
  <p>Here's a <code>code</code> of a <code>TextFormFeild</code>:</p>
  <pre><code>@override
    Widget build(BuildContext context) {
      return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            NeumorphicText(
              &quot;Feet&quot;,
              style: NeumorphicStyle(
                color: HexColor(&quot;fcba03&quot;),
                intensity: 0.9,
                depth: 0.5,
              ),
              textStyle: NeumorphicTextStyle(
                fontSize: MediaQuery.of(context).size.height / 31,
                fontFamily: GoogleFonts.trykker().fontFamily,
              ),
            ),
            Neumorphic(
              style: NeumorphicStyle(
                color: HexColor(&quot;E19D4D&quot;),
                depth: -3,
              ),
              child: SizedBox(
                width: MediaQuery.of(context).size.width / 2,
                child: TextFormField(
                  textAlign: TextAlign.center,
                  style: GoogleFonts.tauri(
                    fontWeight: FontWeight.bold,
                    fontSize: MediaQuery.of(context).size.height / 30,
                    color: Colors.white,
                  ),
                  controller: _feetController,
                  keyboardType: TextInputType.number,
                  onChanged: (_) =&gt; _convertUnit(UnitType.feet),
                  decoration: const InputDecoration(
                    border: InputBorder.none,
                  ),
                  inputFormatters: [
                    LengthLimitingTextInputFormatter(5),
                  ],
                ),
              ),
            ),
  </code></pre>