登录时颤振显示旋转器

Question

null

@override
  Widget build(BuildContext context) {
    final logo = Hero(
      tag: 'hero',
      child: CircleAvatar(
        backgroundColor: Colors.transparent,
        radius: 48.0,
        child: Image.asset('assets/images/logo.png'),
      ),
    );

    final email = TextFormField(
      controller: _usernameController,
      keyboardType: TextInputType.emailAddress,
      autofocus: false,

    //  initialValue: "[e-mail]",
      validator: _validateEmail,
      decoration: InputDecoration(
        hintText: 'Email',
        contentPadding: EdgeInsets.fromLTRB(20.0, 10.0, 20.0, 10.0),
        border: OutlineInputBorder(borderRadius: BorderRadius.circular(32.0)),
      ),
    );

    final password = TextFormField(
      autofocus: false,
      controller: _passwordController,
      obscureText: true,
      //initialValue: "12345",
      decoration: InputDecoration(
        hintText: 'Password',
        contentPadding: EdgeInsets.fromLTRB(20.0, 10.0, 20.0, 10.0),
        border: OutlineInputBorder(borderRadius: BorderRadius.circular(32.0)),
      ),
    );

    final loginButton = Padding(
      padding: EdgeInsets.only(left:16, right: 16, top: 16, bottom: 5),
      child: RaisedButton(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(24),
        ),
        onPressed: () {

        bloc.fetchLoginDetails(_usernameController.text,_passwordController.text).then((result){

            if(result != null && result is UserLoginModel){
              //Navigator.of(context).pushNamed(HomePage.tag);
              Navigator.push(context,    MaterialPageRoute(
                builder: (context) => HomePage(name: result.response.username),
              ));
            }else {
              _showDialog(result as UserLoginErrorModel);
            }


          });
        },

        padding: EdgeInsets.only(left:12, right: 12),
        color: Colors.lightBlueAccent,
        child: Text('Log In', style: TextStyle(color: Colors.white)),
      ),


    );

请注意，我试图展示一个本地旋转器。谢了！

Answer 1

创建一个新变量：

bool checkLoginFinish = false;

您的登录函数是一个异步函数。可以在“whencomplete”之后使用“then”。

bloc.fetchLoginDetails(_usernameController.text,_passwordController.text).then((result
{
.....
}).whenComplete((){
   setState(() {
      checkLoginFinish = true;
    });
});

如果checkFinish为false，则显示CircularProgressIndicator，如果不是，则不显示并转到新页面。

return checkLoginFinish ? LoginPage() : CircularProgressIndicator();