title: Vertically center text in text field in Flutter
body: <p>I'm creating a login screen with fields for username and password, but the text always seems a little bit off to the top(see image).</p>
  
  <p><a href="https://i.stack.imgur.com/UfRt3.png" rel="noreferrer">Image of the Issue</a></p>
  
  <p><a href="https://i.stack.imgur.com/mJQqT.png" rel="noreferrer">How it should look (did with Photoshop)</a></p>
  
  <p>How can i fix this?</p>
  
  <p>Here is code for the TextFormField:</p>
  
  <pre><code>new Padding(
                      padding: const EdgeInsets.symmetric(vertical: 8.0),
                      child: new TextFormField(
                        maxLines: 1,
                        controller: controller,
                        validator: (value) {
                          if (value.isEmpty) {
                            return 'Please enter username.';
                          }
                        },
                        decoration: new InputDecoration(
                            labelText: 'Username',
                            suffixIcon: new IconButton(
                              highlightColor: Colors.transparent,
                              icon: new Container(
                                  width: 36.0, child: new Icon(Icons.clear)),
                              onPressed: () {
                                controller.clear();
                              },
                              splashColor: Colors.transparent,
                            ),
                            prefixIcon: new Icon(Icons.account_circle)),
                      ),
                    ),
  </code></pre>
  
  <p>And here is my general theme code, if that helps^^</p>
  
  <pre><code>new ThemeData(
      fontFamily: 'Product Sans',
      brightness: Brightness.dark,
      buttonColor: Colors.green[300],
      accentColor: Colors.green[300],
      scaffoldBackgroundColor: Colors.blueGrey[900],
      canvasColor: Colors.blueGrey[900],
      textSelectionColor: new Color.fromRGBO(81, 107, 84, 0.8),
      bottomAppBarColor: Colors.blueGrey[800],
      primaryColor: Colors.blueGrey[900],
      indicatorColor: Colors.green[300],
      cardColor: Colors.white,
      highlightColor: Colors.green[300],
      errorColor: Colors.red[400],
      textSelectionHandleColor: Colors.green[300],
      splashColor: Colors.white10,
      buttonTheme: new ButtonThemeData(
          shape: new RoundedRectangleBorder(
              borderRadius: new BorderRadius.circular(22.0))),
      inputDecorationTheme: new InputDecorationTheme(
          contentPadding:
              new EdgeInsets.symmetric(horizontal: 10.0, vertical: 10.0),
          border: new OutlineInputBorder(
              gapPadding: 3.0,
              borderRadius: new BorderRadius.circular(22.0))),
    ),
  </code></pre>