Resources in Compose

Jetpack Compose can access the resources defined in your Android project. This document explains some of the APIs Compose offers to do so.

Resources are the additional files and static content that your code uses, such as bitmaps, layout definitions, user interface strings, animation instructions, and more. If you're not familiar with resources in Android, check out the App resources overview guide.

Strings

The most common type of resource are your Strings. Use the stringResource API to retrieve a string statically defined in your XML resources.

// In the res/values/strings.xml file
// <string name="compose">Jetpack Compose</string>

// In your Compose code
Text(
    text = stringResource(R.string.compose)
)

stringResource also works with positional formatting.

// In the res/values/strings.xml file
// <string name="congratulate">Happy %1$s %2$d</string>

// In your Compose code
Text(
    text = stringResource(R.string.congratulate, "New Year", 2021)
)

String plurals

Compose doesn't offer a direct method to retrieve String plurals yet. However, you can use the traditional approach with the getQuantityString method of the Resources class. To access Resources from the current Context, use the LocalContext composition local. Read more about Composition locals in the Interoperability documentation.

// In the res/strings.xml file
// <plurals name="runtime_format">
//    <item quantity="one">%1$d minute</item>
//    <item quantity="other">%1$d minutes</item>
// </plurals>

// In your Compose code
val resources = LocalContext.current.resources

Text(
    text = resources.getQuantityString(
        R.plurals.runtime_format, quantity, quantity
    )
)

Dimensions

Similarly, use the dimensionResource API to get dimensions from a resource XML file.

// In the res/values/dimens.xml file
// <dimen name="padding_small">8dp</dimen>

// In your Compose code
val smallPadding = dimensionResource(R.dimen.padding_small)
Text(
    text = "...",
    modifier = Modifier.padding(smallPadding)
)

Colors

If you're adopting Compose incrementally in your app, use the colorResource API to get colors from a resource XML file.

// In the res/colors.xml file
// <color name="colorGrey">#757575</color>

// In your Compose code
Divider(color = colorResource(R.color.colorGrey))

colorResource works as expected with static colors, but it flattens color state list resources.

Warning: Prefer colors from the theme rather than hard-coded colors. Even though it's possible to access colors using the colorResource function, it's recommended that the colors of your app are defined in a MaterialTheme which can be accessed from your composables like MaterialTheme.colors.primary. Learn more about this in the Theming in Compose documentation.

Vector assets and image resources

Use the painterResource API to load either vector drawables or rasterized asset formats like PNGs. You don't need to know the type of the drawable, simply use painterResource in Image composables or paint modifiers.

// Files in res/drawable folders. For example:
// - res/drawable-nodpi/ic_logo.xml
// - res/drawable-xxhdpi/ic_logo.png

// In your Compose code
Icon(
    painter = painterResource(id = R.drawable.ic_logo),
    contentDescription = null // decorative element
)

painterResource decodes and parses the content of the resource on the main thread.

Note: Unlike Context.getDrawable, painterResource can only load BitmapDrawable and VectorDrawable platform Drawable types.

Animated Vector Drawables

Use the animatedVectorResource API to load an animated vector drawable XML. The method returns an AnimatedImageVector instance. In order to display the animated image, use the painterFor method to create a Painter that can be used in Image and Icon composables. The boolean atEnd parameter of the painterFor method indicates whether the image should be drawn at the end of all the animations. If used with a mutable state, changes to this value trigger the corresponding animation.

// Files in res/drawable folders. For example:
// - res/drawable/animated_vector.xml

// In your Compose code
val image = animatedVectorResource(id = R.drawable.animated_vector)
val atEnd by remember { mutableStateOf(false) }
Icon(
    painter = image.painterFor(atEnd = atEnd),
    contentDescription = null // decorative element
)

Icons

Jetpack Compose comes with the Icons object that is the entry point for using Material Icons in Compose. There are five distinct icon themes: Filled, Outlined, Rounded, TwoTone, and Sharp. Each theme contains the same icons, but with a distinct visual style. You should typically choose one theme and use it across your application for consistency.

To draw an icon, you can use the Icon composable which applies tint and provides layout size matching the icon.

import androidx.compose.material.Icon

Icon(Icons.Rounded.Menu, contentDescription = "Localized description")

Some of the most commonly used icons are available as part of the androidx.compose.material dependency. To use any of the other Material icons, add the material-icons-extended dependency to the build.gradle file.

dependencies {
  ...
  implementation "androidx.compose.material:material-icons-extended:$compose_version"
}

Note: Icons maintain the same names defined by Material, but with their snake_case name converted to PascalCase. For example, add_alarm becomes AddAlarm. Icons that start with a number, such as 360, are prefixed with _, becoming _360.

Warning: material-icons-extended is a large library and can affect your APK size. For that reason, consider using R8/Proguard in production builds to remove the resources that aren't used. Furthermore due to the large size, your project's build time and Android Studio's previews loading time could increase during development. On the other hand, material-icons-extended lets you iterate more rapidly through quick access to the latest versions of all icons. You can also use this library to copy the source code of the icon to have a fixed copy in your app, or alternatively, import the icons using Android Studio's Import vector asset feature.

Fonts

To use fonts in Compose, download and bundle the font files directly in your APKs by placing them in the res/font folder.

Note: Downloadable fonts are not yet supported in Compose.

Load each font using the Font API and create a FontFamily with them that you can use in TextStyle instances to create your own Typography. The following is code taken from the Crane compose sample and its Typography.kt file.

// Define and load the fonts of the app
private val light = Font(R.font.raleway_light, FontWeight.W300)
private val regular = Font(R.font.raleway_regular, FontWeight.W400)
private val medium = Font(R.font.raleway_medium, FontWeight.W500)
private val semibold = Font(R.font.raleway_semibold, FontWeight.W600)

// Create a font family to use in TextStyles
private val craneFontFamily = FontFamily(light, regular, medium, semibold)

// Use the font family to define a custom typography
val craneTypography = Typography(
    defaultFontFamily = craneFontFamily,
    /* ... */
)

// Pass the typography to a MaterialTheme that will create a theme using
// that typography in the part of the UI hierarchy where this theme is used
@Composable
fun CraneTheme(content: @Composable () -> Unit) {
    MaterialTheme(typography = craneTypography) {
        content()
    }
}

Learn more about typography in the Theming in Compose documentation.