Custom fonts in Flutter - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the first step to use a custom font in a Flutter app?

Add the font files (usually .ttf or .otf) to your project folder, typically under an assets or fonts directory.

beginner

How do you tell Flutter about your custom fonts?

You declare the font in the pubspec.yaml file under the 'fonts' section, specifying the font family name and the path to the font files.

beginner

How do you apply a custom font to a Text widget in Flutter?

Use the TextStyle class with the 'fontFamily' property set to the font family name you declared in pubspec.yaml.

intermediate

Why is it important to declare multiple font weights in your custom font setup?

Declaring multiple weights (like regular, bold) allows Flutter to use the correct font style automatically when you set fontWeight in TextStyle.

beginner

What happens if you forget to run 'flutter pub get' after adding fonts to pubspec.yaml?

Flutter won't recognize the new fonts and your app may show default fonts or errors when trying to use the custom font.

Where should you place your custom font files in a Flutter project?

A In the assets or fonts folder inside the project directory

B In the lib folder only

C Anywhere on your computer

D In the android folder only

Custom fonts should be inside your project folder, usually in assets or fonts, so Flutter can include them in the app bundle.

Which file do you edit to register custom fonts in Flutter?

A main.dart

B build.gradle

C AndroidManifest.xml

D pubspec.yaml

The pubspec.yaml file is where you declare assets and fonts for Flutter to use.

How do you specify the font family in a Text widget?

A fontFamily: 'YourFontName' in TextStyle

B font: 'YourFontName' in Text widget

C style: 'YourFontName' in Text widget

D fontName: 'YourFontName' in TextStyle

You use the fontFamily property inside TextStyle to apply a custom font.

What is the purpose of declaring multiple font weights in pubspec.yaml?

A To make fonts load faster

B To reduce app size

C To allow Flutter to use different font styles like bold or light

D To change font colors

Multiple font weights let Flutter pick the right style automatically when you use fontWeight.

What command should you run after editing pubspec.yaml to add fonts?

A flutter run

B flutter pub get

C flutter clean

D flutter build

flutter pub get downloads and registers new assets and dependencies declared in pubspec.yaml.

Explain the steps to add and use a custom font in a Flutter app.

Think about where the font files go, how Flutter knows about them, and how to apply them in code.

Why is it helpful to declare different font weights for a custom font in Flutter?

Consider how text styles like bold or light are controlled.

Practice

1. What is the first step to use a custom font in a Flutter app?

easy

A. Add the font files to the assets folder and declare them in pubspec.yaml

B. Write the font name directly in the Text widget

C. Import a font package from pub.dev

D. Use the default system font without changes

Solution

1. Step 1: Add font files to assets

   You must first place your font files (like .ttf) inside an assets folder in your project.

2. Step 2: Declare fonts in pubspec.yaml

   Next, you declare these font files under the fonts section in pubspec.yaml so Flutter knows about them.

3. Final Answer:

   Add the font files to the assets folder and declare them in pubspec.yaml -> Option A

4. Quick Check:

   Custom fonts start with assets + pubspec.yaml declaration [OK]

Hint: Always start by adding font files and declaring in pubspec.yaml [OK]

Common Mistakes:

• Skipping pubspec.yaml declaration
• Trying to use font without adding files
• Using font name without quotes in TextStyle

2. Which of the following is the correct way to specify a custom font family in a Text widget's style?

easy

A. Text('Hello', style: TextStyle(fontStyle: 'MyFont'))

B. Text('Hello', style: TextStyle(font: 'MyFont'))

C. Text('Hello', style: TextStyle(fontName: 'MyFont'))

D. Text('Hello', style: TextStyle(fontFamily: 'MyFont'))

Solution

1. Step 1: Use fontFamily property in TextStyle

   The correct property to set a font family is fontFamily, not font, fontName, or fontStyle.

2. Step 2: Apply fontFamily in Text widget

   Use TextStyle(fontFamily: 'YourFontName') inside the style parameter of Text widget.

3. Final Answer:

   Text('Hello', style: TextStyle(fontFamily: 'MyFont')) -> Option D

4. Quick Check:

   fontFamily property sets custom font [OK]

Hint: Use fontFamily property inside TextStyle for custom fonts [OK]

Common Mistakes:

• Using font instead of fontFamily
• Confusing fontStyle with fontFamily
• Omitting quotes around font family name

3. Given this pubspec.yaml snippet:

fonts:
  - family: CoolFont
    fonts:
      - asset: assets/fonts/CoolFont-Regular.ttf
      - asset: assets/fonts/CoolFont-Bold.ttf
        weight: 700

What will this code display?

Text('Hi', style: TextStyle(fontFamily: 'CoolFont', fontWeight: FontWeight.bold))

medium

A. Text 'Hi' in CoolFont Bold style

B. Text 'Hi' in default font because fontWeight is ignored

C. Error because fontWeight 700 is invalid

D. Text 'Hi' in CoolFont Regular style ignoring bold

Solution

1. Step 1: Understand fontWeight mapping

   The pubspec.yaml declares two font assets: Regular (default weight) and Bold (weight 700).

2. Step 2: TextStyle uses fontWeight.bold

   Using fontWeight: FontWeight.bold matches weight 700, so Flutter uses the Bold font file.

3. Final Answer:

   Text 'Hi' in CoolFont Bold style -> Option A

4. Quick Check:

   fontWeight matches declared font weight for bold [OK]

Hint: Match fontWeight in TextStyle to declared font weights in pubspec.yaml [OK]

Common Mistakes:

• Ignoring fontWeight and expecting bold
• Assuming fontWeight 700 is invalid
• Not declaring font weights in pubspec.yaml

4. Why does this Flutter app fail to apply the custom font?

pubspec.yaml:
fonts:
  - family: FancyFont
    fonts:
      - asset: assets/fonts/FancyFont.ttf

Dart code:
Text('Hello', style: TextStyle(fontFamily: 'FancyFontt'))

medium

A. pubspec.yaml syntax error due to missing indentation

B. Font file is missing from assets folder

C. Font family name in TextStyle does not match pubspec.yaml

D. Text widget cannot use custom fonts

Solution

1. Step 1: Check fontFamily spelling in Dart code

   The Dart code uses 'FancyFontt' but pubspec.yaml declares 'FancyFont' (extra 't').

2. Step 2: Font family names must match exactly

   Font family names are case-sensitive and must match exactly between pubspec.yaml and Dart code.

3. Final Answer:

   Font family name in TextStyle does not match pubspec.yaml -> Option C

4. Quick Check:

   Font family names must match exactly [OK]

Hint: Check spelling of fontFamily matches pubspec.yaml exactly [OK]

Common Mistakes:

• Typos in font family names
• Forgetting to run flutter pub get after changes
• Incorrect indentation in pubspec.yaml

5. You want to use two different custom fonts in your Flutter app: 'Lobster' for titles and 'OpenSans' for body text. How should you organize your pubspec.yaml and Dart code to achieve this?

hard

A. Add both font files but use only one family name in pubspec.yaml

B. Declare both fonts under fonts in pubspec.yaml with different family names, then use fontFamily: 'Lobster' or 'OpenSans' in TextStyle accordingly

C. Declare only one font in pubspec.yaml and switch fontFamily names in Dart code

D. Use system fonts for titles and custom font for body text without declaring both

Solution

1. Step 1: Declare each font family separately in pubspec.yaml

   You must list each font family with its own name and font files under the fonts section.

2. Step 2: Use fontFamily property in Dart code for each Text widget

   Apply fontFamily: 'Lobster' for titles and fontFamily: 'OpenSans' for body text in TextStyle.

3. Final Answer:

   Declare both fonts under fonts in pubspec.yaml with different family names, then use fontFamily: 'Lobster' or 'OpenSans' in TextStyle accordingly -> Option B

4. Quick Check:

   Multiple fonts need separate declarations and usage [OK]

Hint: Declare each font family separately and use fontFamily accordingly [OK]

Common Mistakes:

• Declaring only one font family for multiple fonts
• Using wrong fontFamily names in Dart code
• Not adding all font files to assets