MediaQuery for responsiveness in Flutter

Introduction

MediaQuery helps your app adjust its layout based on the screen size and orientation. This makes your app look good on all devices.

You want your app to look good on phones and tablets.

You need to change font size or button size depending on screen width.

You want to switch layout when the device is in landscape or portrait mode.

You want to get the device's screen height or width to position widgets.

You want to make sure your app works well on small or large screens.

Syntax

Flutter

MediaQuery.of(context).size.width
MediaQuery.of(context).size.height
MediaQuery.of(context).orientation

Use MediaQuery.of(context) inside a widget's build method.

size gives screen width and height in logical pixels.

Examples

Get the screen width to adjust widget size.

Flutter

double screenWidth = MediaQuery.of(context).size.width;

Get the screen height to position widgets vertically.

Flutter

double screenHeight = MediaQuery.of(context).size.height;

Check if device is in portrait or landscape mode.

Flutter

Orientation orientation = MediaQuery.of(context).orientation;

Sample App

This app shows a blue box that changes height based on device orientation. It also displays the screen width, height, and orientation inside the box.

Flutter

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: const Text('MediaQuery Example')),
        body: const ResponsiveBox(),
      ),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    double width = MediaQuery.of(context).size.width;
    double height = MediaQuery.of(context).size.height;
    Orientation orientation = MediaQuery.of(context).orientation;

    return Center(
      child: Container(
        width: width * 0.8,
        height: orientation == Orientation.portrait ? height * 0.3 : height * 0.6,
        color: Colors.blue,
        child: Center(
          child: Text(
            'Width: ${width.toStringAsFixed(0)}\nHeight: ${height.toStringAsFixed(0)}\nOrientation: ${orientation.name}',
            style: const TextStyle(color: Colors.white, fontSize: 18),
            textAlign: TextAlign.center,
          ),
        ),
      ),
    );
  }
}

Important Notes

Always call MediaQuery.of(context) inside the build method or where context is valid.

Use orientation.name to get 'portrait' or 'landscape' as a string.

Logical pixels are device-independent pixels, so your UI scales well on different screens.

Summary

MediaQuery helps your app adapt to different screen sizes and orientations.

Use MediaQuery.of(context).size to get screen width and height.

Use MediaQuery.of(context).orientation to check if device is portrait or landscape.

Practice

1. What does MediaQuery.of(context).size provide in a Flutter app?

easy

A. The list of installed fonts

B. The current theme colors

C. The width and height of the device screen

D. The app's current state

Solution

1. Step 1: Understand MediaQuery size property

   MediaQuery.of(context).size returns the screen's width and height as a Size object.

2. Step 2: Differentiate from other properties

   Theme colors, fonts, and app state are unrelated to MediaQuery size.

3. Final Answer:

   The width and height of the device screen -> Option C

4. Quick Check:

   MediaQuery size = screen dimensions [OK]

Hint: MediaQuery size always means screen width and height [OK]

Common Mistakes:

• Confusing size with theme or app state
• Thinking it returns orientation
• Assuming it gives device model info

2. Which of the following is the correct syntax to get the device orientation using MediaQuery?

easy

A. MediaQuery.orientation(context)

B. MediaQuery.of(context).orientation

C. MediaQuery.getOrientation(context)

D. MediaQuery.context.orientation

Solution

1. Step 1: Recall correct MediaQuery syntax

   The correct way is MediaQuery.of(context).orientation to access orientation.

2. Step 2: Eliminate incorrect options

   Other options use invalid method names or wrong property access.

3. Final Answer:

   MediaQuery.of(context).orientation -> Option B

4. Quick Check:

   Use .of(context) to access MediaQuery properties [OK]

Hint: Always use MediaQuery.of(context) to access properties [OK]

Common Mistakes:

• Omitting .of(context)
• Using wrong method names
• Accessing properties directly on MediaQuery

3. Given this Flutter code snippet:

final size = MediaQuery.of(context).size;
final width = size.width;
final height = size.height;

print('Width: $width, Height: $height');

What will this print if the device screen is 360 pixels wide and 640 pixels tall?

medium

A. Width: 360, Height: 640

B. Width: 0, Height: 0

C. Width: 640, Height: 360

D. Width: null, Height: null

Solution

1. Step 1: Understand MediaQuery size values

   MediaQuery.of(context).size.width gives screen width (360), height gives screen height (640).

2. Step 2: Match printed output

   The print statement outputs width first then height, so it prints "Width: 360, Height: 640".

3. Final Answer:

   Width: 360, Height: 640 -> Option A

4. Quick Check:

   Width = 360, Height = 640 [OK]

Hint: Width is first, height is second in MediaQuery size [OK]

Common Mistakes:

• Swapping width and height values
• Assuming zero or null values
• Confusing print output format

4. This Flutter code tries to get screen width but causes an error:

double width = MediaQuery.size.width;

What is the main problem?

medium

A. MediaQuery.size.width should be MediaQuery.width.size

B. Width should be an int, not double

C. MediaQuery.size needs a BuildContext parameter

D. MediaQuery.size is not a valid property; .of(context) is missing

Solution

1. Step 1: Check MediaQuery usage

   MediaQuery properties require calling .of(context) to access size.

2. Step 2: Identify missing .of(context)

   The code misses .of(context), so MediaQuery.size is invalid.

3. Final Answer:

   MediaQuery.size is not a valid property; .of(context) is missing -> Option D

4. Quick Check:

   Always use MediaQuery.of(context) [OK]

Hint: Always call MediaQuery.of(context) before properties [OK]

Common Mistakes:

• Forgetting .of(context)
• Confusing property order
• Wrong data type assumptions

5. You want to build a widget that shows a different layout depending on device orientation. Which Flutter code snippet correctly uses MediaQuery to check orientation?

hard

A. if (MediaQuery.of(context).orientation == Orientation.portrait) { return PortraitWidget(); } else { return LandscapeWidget(); }

B. if (MediaQuery.orientation(context) == 'portrait') { return PortraitWidget(); } else { return LandscapeWidget(); }

C. if (MediaQuery.of(context).size.width > MediaQuery.of(context).size.height) { return PortraitWidget(); } else { return LandscapeWidget(); }

D. if (MediaQuery.of(context).orientation == 'landscape') { return PortraitWidget(); } else { return LandscapeWidget(); }

Solution

1. Step 1: Use correct orientation check

   MediaQuery.of(context).orientation returns an enum Orientation.portrait or Orientation.landscape.

2. Step 2: Verify correct comparison and widget return

   if (MediaQuery.of(context).orientation == Orientation.portrait) { return PortraitWidget(); } else { return LandscapeWidget(); } compares orientation to Orientation.portrait correctly and returns widgets accordingly.

3. Step 3: Eliminate wrong options

   if (MediaQuery.orientation(context) == 'portrait') { return PortraitWidget(); } else { return LandscapeWidget(); } uses wrong syntax, C compares sizes incorrectly, D reverses widget logic.

4. Final Answer:

   if (MediaQuery.of(context).orientation == Orientation.portrait) { return PortraitWidget(); } else { return LandscapeWidget(); } -> Option A

5. Quick Check:

   Compare orientation enum, not strings or sizes [OK]

Hint: Compare orientation to Orientation.portrait or .landscape [OK]

Common Mistakes:

• Comparing orientation to strings
• Using size to guess orientation
• Reversing widget logic