I am trying to create this layout (avoid the erased part in blue background). Attaching my code too.

class TasksScreen extends StatelessWidget {
  const TasksScreen({
    Key ? key
  }): super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.lightBlueAccent,
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.lightBlueAccent,
        onPressed: () {},
        child: const Icon(Icons.add),
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Container(
            padding: const EdgeInsets.only(
                top: 60.0, bottom: 30.0, right: 30.0, left: 30.0),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: < Widget > [
                  const CircleAvatar(
                      backgroundColor: Colors.white,
                      child: Icon(
                        Icons.list,
                        color: Colors.lightBlueAccent,
                        size: 30.0,
                      ),
                      radius: 30.0,
                    ),
                    const SizedBox(
                        height: 10.0,
                      ),
                      const Text(
                          'TodoList',
                          style: TextStyle(
                            color: Colors.white,
                            fontWeight: FontWeight.w700,
                            fontSize: 50.0,
                          ),
                        ),
                        const Text(
                            '12 items',
                            style: TextStyle(
                              color: Colors.white,
                              fontSize: 18.0,
                            ),
                          ),
                          Expanded(
                            child: Container(
                              padding: const EdgeInsets.symmetric(horizontal: 20.0),
                                decoration: const BoxDecoration(
                                  color: Colors.white,
                                  borderRadius: BorderRadius.only(
                                    topLeft: Radius.circular(20.0),
                                    topRight: Radius.circular(20.0)),
                                ),
                            ),
                          ),
                ]),
          ),
        ],
      ));
  }
}

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

I am getting the error "RenderFlex children have non-zero flex but incoming height constraints are unbounded error". I replaced the Expanded widget with Flexible. The app builds and I get the icons and text with the floating action button but I don't get the white container area. If I keep the Expanded, I get the full light blue screen.

How can i do this?

CodePudding user response：

Do this instead! Containers are dumb, they will not know to what extend to fill up the space until you provide a width and a height!

In my case I used media query to determine the height of the container(white part)

Here is the code:

import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
class TasksScreen extends StatelessWidget {
  const TasksScreen({
    Key ? key
  }): super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        backgroundColor: Colors.lightBlueAccent,
        floatingActionButton: FloatingActionButton(
          backgroundColor: Colors.lightBlueAccent,
          onPressed: () {},
          child: const Icon(Icons.add),
        ),
        body: SingleChildScrollView(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const  SizedBox(height: 50,),
              Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: < Widget > [
                    Padding(
                      padding: const EdgeInsets.only(left:30.0),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: const[
                           CircleAvatar(
                            backgroundColor: Colors.white,
                            child: Icon(
                              Icons.list,
                              color: Colors.lightBlueAccent,
                              size: 30.0,
                            ),
                            radius: 30.0,
                          ),
                           SizedBox(
                            height: 10.0,
                          ),
                           Text(
                            'TodoList',
                            style: TextStyle(
                              color: Colors.white,
                              fontWeight: FontWeight.w700,
                              fontSize: 50.0,
                            ),
                          ),
                           Text(
                            '12 items',
                            style: TextStyle(
                              color: Colors.white,
                              fontSize: 18.0,
                            ),
                          ),
                        ],
                      ),
                    ),
                    Container(
                        height: MediaQuery.of(context).size.height,
                        decoration: const BoxDecoration(
                    color: Colors.white,
                    borderRadius: BorderRadius.only(
                        topLeft: Radius.circular(20.0),
                        topRight: Radius.circular(20.0)),
                        ),
                      ),
                  ]),
            ],
          ),
        ));
  }
}

And also I grouped the top part inside a column so that I could generalize the the paddings.

Cheers:)