Custom Fonts using Support Library

Google announced native custom font support at I/O 2017. With Support Library 26, the feature was backported to API 14 — fonts work as first-class resources rather than raw assets bundled in the APK. The library also introduced downloadable fonts: fonts served on demand from a provider (Google Play Services for Google Fonts), shared across applications, and never bundled at build time.

There are three approaches: fonts as resources, downloadable fonts via XML, and downloadable fonts requested programmatically. Here's how each works.

## Fonts as a Resource

Android Studio 3.0 adds a font directory under res/. Drop a .ttf or .otf file there and reference it directly in XML:

<android.support.v7.widget.AppCompatButton    android:id="@+id/action_xml"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_marginBottom="8dp"    android:text="@string/label_xml"    android:textSize="16sp"    app:fontFamily="@font/ubuntu_bold"/>

To load it programmatically:

Typeface typeface = getResources().getFont(R.font.ubuntu_bold);

### Font Families

Group related weights and styles into a single font family XML:

<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:android="http://schemas.android.com/apk/res/android">
    <font
        android:font="@font/open_sans"
        android:fontStyle="normal"
        android:fontWeight="400"/>
    <font
        android:font="@font/open_sans_italic"
        android:fontStyle="italic"
        android:fontWeight="400"/>
</font-family>

### App-wide Font via Theme

Apply a font to your entire app by setting android:fontFamily in the theme:

<resources>    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">        <item name="colorPrimary">@color/colorPrimary</item>        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>        <item name="colorAccent">@color/colorAccent</item>        <item name="android:fontFamily">@font/open_sans</item>    </style></resources>

## Downloadable Fonts

Instead of bundling fonts in the APK, downloadable fonts are fetched from a Font Provider at runtime. Multiple apps sharing the same font download it only once, saving storage and data.

### Selecting via Android Studio

The easiest path is through the layout editor: click the fontFamily attribute, choose "More Fonts...", and Android Studio sets up the XML automatically.

### XML Configuration

To set one up manually, create a font family XML pointing at the provider:

<?xml version="1.0" encoding="utf-8"?>
<font-family
    xmlns:app="http://schemas.android.com/apk/res-auto"
    app:fontProviderAuthority="com.google.android.gms.fonts"
    app:fontProviderPackage="com.google.android.gms"
    app:fontProviderQuery="Open Sans"
    app:fontProviderCerts="@array/com_google_android_gms_fonts_certs">
</font-family>

### Certificate Configuration

Android Studio populates these automatically when you use the font picker. The structure:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <array name="com_google_android_gms_fonts_certs">
        <item>@array/com_google_android_gms_fonts_certs_dev</item>
        <item>@array/com_google_android_gms_fonts_certs_prod</item>
    </array>
    <string-array name="com_google_android_gms_fonts_certs_dev">
        <item><!-- dev cert --></item>
    </string-array>
    <string-array name="com_google_android_gms_fonts_certs_prod">
        <item><!-- prod cert --></item>
    </string-array>
</resources>

## Preloading Fonts

By default fonts download synchronously when their containing layout inflates. Declaring them in the manifest tells the system to fetch them in the background before your app launches:

### Declare the font array

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <array name="preloaded_fonts" translatable="false">
        <item>@font/open_sans</item>
        <item>@font/open_sans_bold</item>
        <item>@font/open_sans_light</item>
    </array>
</resources>

### Reference it in the manifest

<application>
    ...
    <meta-data
        android:name="preloaded_fonts"
        android:resource="@array/preloaded_fonts" />
</application>

You can also control the fetch strategy per font family:

<font-family
    ...
    app:fontProviderFetchStrategy="async"
    app:fontProviderFetchTimeout="500">
</font-family>

## Programmatic Font Requests

For dynamic font loading at runtime, use FontsContractCompat:

class MainActivity : AppCompatActivity() {    private var regular: AppCompatTextView? = null    private val certificate = R.array.com_google_android_gms_fonts_certs    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_labels_no_fonts)        regular = findViewById(R.id.tv_regular)        val sansRegularRequest = FontRequest(            PROVIDER_AUTHORITY,            PROVIDER_PACKAGE,            "Open Sans",            certificate        )        val sansRegularCallback = object : FontsContractCompat.FontRequestCallback() {            override fun onTypefaceRetrieved(typeface: Typeface?) {                regular!!.typeface = typeface            }            override fun onTypefaceRequestFailed(reason: Int) {                // handle failure — reason is an error code constant            }        }        FontsContractCompat.requestFont(this, sansRegularRequest, sansRegularCallback, Handler())    }    companion object {        private val PROVIDER_PACKAGE = "com.google.android.gms"        private val PROVIDER_AUTHORITY = "$PROVIDER_PACKAGE.fonts"    }}

## Result

This was a meaningful upgrade from the old approach of bundling font files as raw assets and loading them manually through Typeface.createFromAsset():

Fonts as resources and downloadable fonts make the old approach unnecessary for almost every use case.

The full source is on GitHub.