Expo Docs MCP Server

--- title: Build a screen description: In this tutorial, learn how to use components such as React Native's Pressable and Expo Image to build a screen. hasVideoLink: true --- In this chapter, we'll create the first screen of the StickerSmash app. The screen above displays an image and two buttons. The app user can select an image using one of the two buttons. The first button allows the user to select an image from their device. The second button allows the user to continue with a default image provided by the app. Once the user selects an image, they can add a sticker to it. So, let's start creating this screen. --- ## Break down the screen Before we build this screen by writing code, let's break it down into some essential elements. There are two essential elements: - There is a large image displayed at the center of the screen - There are two buttons in the bottom half of the screen The first button contains multiple components. The parent element provides a yellow border, and contains an icon and text components inside a row. Now that we've broken down the UI into smaller chunks, we're ready to start coding. ## Display the image We'll use `expo-image` library to display the image in the app. It provides a cross-platform `<Image>` component to load and render an image. Stop the development server by pressing <kbd>Ctrl</kbd> + <kbd>c</kbd> in the terminal. Then, install the `expo-image` library: The [`npx expo install`](/more/expo-cli/#installation) command will install the library and add it to the project's dependencies in **package.json**. The Image component takes the source of an image as its value. The source can be either a [static asset](https://reactnative.dev/docs/images#static-image-resources) or a URL. For example, the source required from **assets/images** directory is static. It can also come from [Network](https://reactnative.dev/docs/images#network-images) as a `uri` property. To use the Image component in **app/(tabs)/index.tsx** file: 1. Import `Image` from the `expo-image` library. 2. Create a `PlaceholderImage` variable to use **assets/images/background-image.png** file as the `source` prop on the `Image` component. {/* prettier-ignore */} ```tsx app/(tabs)/index.tsx|collapseHeight=380 /* @tutinfo Import the <CODE>Image</CODE> component. */ import { Image } from 'expo-image'; /* @end */ /* @tutinfo Import the image from the "assets/images/" directory. Since this picture is a static resource, you have to reference it using <CODE>require</CODE>. */ const PlaceholderImage = require('@/assets/images/background-image.png'); /* @end */ return ( <View style={styles.container}> /* @tutinfo Wrap the <CODE>Image</CODE> component inside a container. Also, add the image component to display the placeholder image. */ <View style={styles.imageContainer}> </View> /* @end */ </View> ); } const styles = StyleSheet.create({ container: { flex: 1, backgroundColor: '#25292e', /* @tutinfo Modify container styles to remove <CODE>justifyContent</CODE> property. */ alignItems: 'center', /* @end */ }, /* @tutinfo Add styles for the image container and image. */ imageContainer: { flex: 1, }, image: { width: 320, height: 440, borderRadius: 18, }, /* @end */ }); ``` ## Divide components into files Let's divide the code into multiple files as we add more components to this screen. Throughout this tutorial, we'll use the components directory to create custom components. 1. Create a top-level **components** directory, and inside it, create the **ImageViewer.tsx** file. 2. Move the code to display the image in this file along with the `image` styles. {/* prettier-ignore */} ```tsx components/ImageViewer.tsx|collapseHeight=280 type Props = { imgSource: ImageSourcePropType; }; return ; } const styles = StyleSheet.create({ image: { width: 320, height: 440, borderRadius: 18, }, }); ``` > **info** Since **ImageViewer** is a custom component, we are placing it in a separate directory instead of the **app** directory. Every file inside **app** directory is either a layout file or a route file. For more information, see [Non-navigation components live outside of app directory](/router/basics/core-concepts/#5-non-navigation-components-live-outside-of-app-directory). Import `ImageViewer` and use it in the **app/(tabs)/index.tsx**: {/* prettier-ignore */} ```tsx app/(tabs)/index.tsx|collapseHeight=320 /* @tutinfo */import ImageViewer from '@/components/ImageViewer'; /* @end */ const PlaceholderImage = require('@/assets/images/background-image.png'); return ( <View style={styles.container}> <View style={styles.imageContainer}> /* @tutinfo Replace <CODE>Image</CODE> component with <CODE>ImageViewer</CODE>. */ /* @end */ </View> </View> ); } const styles = StyleSheet.create({ container: { flex: 1, backgroundColor: '#25292e', alignItems: 'center', }, imageContainer: { flex: 1, }, }); ``` <Collapsible summary={<>What is the <CODE>@</CODE> in import statement?</>}> The `@` symbol is a custom [path alias](/guides/typescript/#path-aliases-optional) for importing custom components and other modules instead of relative paths. Expo CLI automatically configures it in **tsconfig.json**. </Collapsible> ## Create buttons using Pressable React Native includes a few different components for handling touch events, but [`<Pressable>`](https://reactnative.dev/docs/pressable) is recommended for its flexibility. It can detect single taps, long presses, trigger separate events when the button is pushed in and released, and more. In the design, there are two buttons we need to create. Each has a different style and label. Let's start by creating a reusable component for these buttons. Create a **Button.tsx** file inside the **components** directory with the following code: {/* prettier-ignore */} ```tsx components/Button.tsx|collapseHeight=280 type Props = { label: string; }; return ( <View style={styles.buttonContainer}> <Pressable style={styles.button} onPress={() => alert('You pressed a button.')}> <Text style={styles.buttonLabel}>{label}</Text> </Pressable> </View> ); } const styles = StyleSheet.create({ buttonContainer: { width: 320, height: 68, marginHorizontal: 20, alignItems: 'center', justifyContent: 'center', padding: 3, }, button: { borderRadius: 10, width: '100%', height: '100%', alignItems: 'center', justifyContent: 'center', flexDirection: 'row', }, buttonLabel: { color: '#fff', fontSize: 16, }, }); ``` The app displays an alert when the user taps any of the buttons on the screen. It happens because `<Pressable>` calls `alert()` on its `onPress` prop. Let's import this component into **app/(tabs)/index.tsx** file and add styles for the `<View>` that encapsulates these buttons: {/* prettier-ignore */} ```tsx app/(tabs)/index.tsx /* @tutinfo */import Button from '@/components/Button'; /* @end */ const PlaceholderImage = require("@/assets/images/background-image.png"); return ( <View style={styles.container}> <View style={styles.imageContainer}> </View> /* @tutinfo Use the reusable <CODE>Button</CODE> component to create two buttons and encapsulate them inside a <CODE>View</CODE> component. */ <View style={styles.footerContainer}> </View> /* @end */ </View> ); } const styles = StyleSheet.create({ container: { flex: 1, backgroundColor: '#25292e', alignItems: 'center', }, imageContainer: { flex: 1, paddingTop: 28, }, /* @tutinfo Add the styles the following styles. */ footerContainer: { flex: 1 / 3, alignItems: 'center', }, /* @end */ }); ``` Let's take a look at our app on Android, iOS and the web: The second button with the label "Use this photo" resembles the actual button from the design. However, the first button needs more styling to match the design. ## Enhance the reusable button component The "Choose a photo" button requires different styling than the "Use this photo" button, so we will add a new button theme prop that will allow us to apply a `primary` theme. This button also has an icon before the label. We will use an icon from the `@expo/vector-icons` library. To load and display the icon on the button, let's use `FontAwesome` from the library. Modify **components/Button.tsx** to add the following code snippet: {/* prettier-ignore */} ```tsx components/Button.tsx /* @tutinfo Import FontAwesome. */import FontAwesome from '@expo/vector-icons/FontAwesome';/* @end */ type Props = { label: string; /* @tutinfo Add theme prop. */theme?: 'primary';/* @end */ }; /* @tutinfo Conditionally render the primary themed button. */ if (theme === 'primary') { /* @end */ /* @tutinfo */ return ( <View style={[ styles.buttonContainer, { borderWidth: 4, borderColor: '#ffd33d', borderRadius: 18 }, ]}> <Pressable style={[styles.button, { backgroundColor: '#fff' }]} onPress={() => alert('You pressed a button.')}> <Text style={[styles.buttonLabel, { color: '#25292e' }]}>{label}</Text> </Pressable> </View> ); /* @end */ /* @tutinfo */ } /* @end */ return ( <View style={styles.buttonContainer}> <Pressable style={styles.button} onPress={() => alert('You pressed a button.')}> <Text style={styles.buttonLabel}>{label}</Text> </Pressable> </View> ); } const styles = StyleSheet.create({ buttonContainer: { width: 320, height: 68, marginHorizontal: 20, alignItems: 'center', justifyContent: 'center', padding: 3, }, button: { borderRadius: 10, width: '100%', height: '100%', alignItems: 'center', justifyContent: 'center', flexDirection: 'row', }, /* @tutinfo Conditionally render the primary themed button. */ buttonIcon: { paddingRight: 8, }, /* @end */ buttonLabel: { color: '#fff', fontSize: 16, }, }); ``` Let's learn what the above code does: - The primary theme button uses **inline styles**, which overrides the styles defined in `StyleSheet.create()` with an object directly passed in the `style` prop. - The `<Pressable>` component in the primary theme uses a `backgroundColor` property with a value `#fff` to set the button's background to white. If we add this property to the `styles.button`, the background color value will be set for both the primary theme and the unstyled one. - Inline styles use JavaScript and override the default styles for a specific value. Now, modify the **app/(tabs)/index.tsx** file to use the `theme="primary"` prop on the first button. {/* prettier-ignore */} ```tsx app/(tabs)/index.tsx const PlaceholderImage = require('@/assets/images/background-image.png'); return ( <View style={styles.container}> <View style={styles.imageContainer}> </View> <View style={styles.footerContainer}> /* @tutinfo Add <CODE>"primary"</CODE> theme on the first button. */ /* @end */ </View> </View> ); } const styles = StyleSheet.create({ container: { flex: 1, backgroundColor: '#25292e', alignItems: 'center', }, imageContainer: { flex: 1, }, footerContainer: { flex: 1 / 3, alignItems: 'center', }, }); ``` Let's take a look at our app on Android, iOS and the web: ## Summary