Responsive layout patterns in Flutter - Mini App: Build & Ship

Build: Responsive Layout Demo

This screen shows a responsive layout that changes based on screen width. On small screens, it stacks items vertically. On larger screens, it arranges items horizontally.

Target UI

Responsive Layout Demo

+-------------------------+
| Item 1                  |
|-------------------------|
| Item 2                  |
|-------------------------|
| Item 3                  |
+-------------------------+  (small screen stacked)

+---------------------------------------+
| Item 1 | Item 2 | Item 3              |  (large screen horizontal)
+---------------------------------------+

Use MediaQuery to detect screen width

If width < 600 pixels, show items stacked vertically

If width >= 600 pixels, show items arranged horizontally

Each item is a colored box with centered text: 'Item 1', 'Item 2', 'Item 3'

Use Flutter widgets only

Make sure layout adapts when screen size changes

Starter Code

Flutter

import 'package:flutter/material.dart';

class ResponsiveLayoutDemo extends StatelessWidget {
  const ResponsiveLayoutDemo({super.key});

  @override
  Widget build(BuildContext context) {
    // TODO: Add responsive layout code here
    return Scaffold(
      appBar: AppBar(title: const Text('Responsive Layout Demo')),
      body: Center(
        child: Text('Replace this with responsive layout'),
      ),
    );
  }
}

Task 1

Task 2

Task 3

Task 4

Solution

Flutter

import 'package:flutter/material.dart';

class ResponsiveLayoutDemo extends StatelessWidget {
  const ResponsiveLayoutDemo({super.key});

  @override
  Widget build(BuildContext context) {
    final double screenWidth = MediaQuery.of(context).size.width;
    final bool isSmallScreen = screenWidth < 600;

    Widget item(String text, Color color) {
      return Container(
        width: 100,
        height: 100,
        color: color,
        alignment: Alignment.center,
        margin: const EdgeInsets.all(8),
        child: Text(text, style: const TextStyle(color: Colors.white, fontSize: 18)),
      );
    }

    return Scaffold(
      appBar: AppBar(title: const Text('Responsive Layout Demo')),
      body: Center(
        child: isSmallScreen
            ? Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  item('Item 1', Colors.blue),
                  item('Item 2', Colors.green),
                  item('Item 3', Colors.orange),
                ],
              )
            : Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  item('Item 1', Colors.blue),
                  item('Item 2', Colors.green),
                  item('Item 3', Colors.orange),
                ],
              ),
      ),
    );
  }
}

We use MediaQuery.of(context).size.width to find the screen width. If the width is less than 600 pixels, we show the items stacked vertically using a Column. Otherwise, we arrange them horizontally using a Row. Each item is a colored box with centered white text. This way, the layout changes automatically when the screen size changes, making it responsive.

Final Result

Completed Screen

Responsive Layout Demo

+-------------------------+
|       Item 1            |
|-------------------------|
|       Item 2            |
|-------------------------|
|       Item 3            |
+-------------------------+  (small screen stacked)

+---------------------------------------+
| Item 1 | Item 2 | Item 3              |  (large screen horizontal)
+---------------------------------------+

When the user resizes the screen or rotates the device, the layout changes between vertical and horizontal automatically.

Each colored box displays its label centered in white text.

Stretch Goal

Add a toggle button in the AppBar to switch between vertical and horizontal layout manually.

💡 Hint

Use a StatefulWidget and a boolean state variable to control layout direction. Update the layout based on this variable instead of screen width.

Practice

1. What is the main purpose of using responsive layout patterns in Flutter apps?

easy

A. To make the app look good on different screen sizes

B. To add animations to the app

C. To improve app performance by caching data

D. To change the app's theme colors automatically

Solution

1. Step 1: Understand responsive layout meaning

   Responsive layouts adjust UI to fit various screen sizes and orientations.

2. Step 2: Identify the main goal

   The goal is to ensure the app looks good and works well on phones, tablets, and other devices.

3. Final Answer:

   To make the app look good on different screen sizes -> Option A

4. Quick Check:

   Responsive layout = good appearance on all screens [OK]

Hint: Responsive means adapting UI to screen size [OK]

Common Mistakes:

• Confusing responsive layout with animations
• Thinking it improves performance directly
• Mixing it with theme or color changes

2. Which Flutter widget helps you get the current screen size inside its builder function?

easy

A. Container

B. MediaQuery

C. LayoutBuilder

D. Scaffold

Solution

1. Step 1: Recall widgets for screen size

   MediaQuery provides screen info globally, but LayoutBuilder gives constraints inside its builder.

2. Step 2: Identify widget with builder function

   LayoutBuilder has a builder that provides BoxConstraints with maxWidth and maxHeight.

3. Final Answer:

   LayoutBuilder -> Option C

4. Quick Check:

   LayoutBuilder = widget with builder for size [OK]

Hint: LayoutBuilder uses builder with constraints [OK]

Common Mistakes:

• Choosing MediaQuery which is not a builder widget
• Picking Container or Scaffold which don't provide size info
• Confusing MediaQuery and LayoutBuilder roles

3. Given this Flutter code snippet, what widget will be shown on a screen width of 500 pixels?

LayoutBuilder(
  builder: (context, constraints) {
    if (constraints.maxWidth > 600) {
      return Text('Large Screen');
    } else {
      return Text('Small Screen');
    }
  },
)

medium

A. Text widget showing 'Small Screen'

B. Text widget showing 'Large Screen'

C. An error because maxWidth is not accessible

D. Empty container with no text

Solution

1. Step 1: Check the condition with maxWidth

   The code checks if maxWidth > 600 to show 'Large Screen'.

2. Step 2: Compare given width 500 with 600

   Since 500 is less than 600, the else branch runs, showing 'Small Screen'.

3. Final Answer:

   Text widget showing 'Small Screen' -> Option A

4. Quick Check:

   500 < 600 means 'Small Screen' shown [OK]

Hint: Compare maxWidth to 600 to pick text [OK]

Common Mistakes:

• Assuming 500 is greater than 600
• Thinking maxWidth is not accessible
• Ignoring else branch

4. What is wrong with this Flutter code for responsive layout?

LayoutBuilder(
  builder: (context, constraints) {
    if (constraints.maxWidth < 600) {
      return Row(children: [Text('A'), Text('B')]);
    } else {
      return Column(children: [Text('A'), Text('B')]);
    }
  },
)

medium

A. Row and Column are used incorrectly for screen sizes

B. Using Row for small screens may cause overflow horizontally

C. No error; code works fine for responsive layout

D. Missing MediaQuery to get screen size

Solution

1. Step 1: Analyze layout for small screens

   For small screens, a Row with two Text widgets may overflow horizontally.

2. Step 2: Understand overflow risk

   Row arranges children horizontally, which can cause overflow if width is limited.

3. Step 3: Check other options

   MediaQuery is not required here; LayoutBuilder provides constraints. Using Column on large screens is fine.

4. Final Answer:

   Using Row for small screens may cause overflow horizontally -> Option B

5. Quick Check:

   Row on narrow screen risks overflow [OK]

Hint: Row on narrow screen can overflow horizontally [OK]

Common Mistakes:

• Thinking code has no error
• Believing MediaQuery is mandatory here
• Confusing Row and Column usage

5. You want to create a responsive Flutter layout that shows a vertical list on narrow screens and a grid with 3 columns on wide screens. Which approach is best?

hard

A. Use a fixed Container size and ignore screen width

B. Use MediaQuery to get screen height and switch between ListView and GridView

C. Always use GridView with 3 columns regardless of screen size

D. Use LayoutBuilder to check maxWidth and return ListView or GridView accordingly

Solution

1. Step 1: Decide how to detect screen width

   LayoutBuilder provides maxWidth constraints inside builder, ideal for responsive layout.

2. Step 2: Choose widgets based on width

   Return ListView for narrow screens and GridView with 3 columns for wide screens.

3. Step 3: Evaluate other options

   MediaQuery height is not relevant; fixed Container ignores responsiveness; always GridView ignores narrow screens.

4. Final Answer:

   Use LayoutBuilder to check maxWidth and return ListView or GridView accordingly -> Option D

5. Quick Check:

   LayoutBuilder + conditional widgets = responsive layout [OK]

Hint: Use LayoutBuilder to switch layouts by width [OK]

Common Mistakes:

• Using screen height instead of width
• Ignoring responsiveness by fixed sizes
• Always using one layout without condition