pages/tutorial/image-picker.mdx

---
title: Use an image picker
---

import { SnackInline, Terminal } from '~/ui/components/Snippet';
import Video from '~/components/plugins/Video';
import { A } from '~/ui/components/Text';
import { Step } from '~/ui/components/Step';

React Native provides built-in components that are standard building blocks used by every application, such as `<View>`, `<Text>`, and `<Pressable>`.
We want to build a feature that isn't possible with these core components and API: selecting an image from the device's media library. For that, we will need a library.

To achieve this, we'll use an Expo SDK library called <A href="/versions/latest/sdk/imagepicker" openInNewTab>`expo-image-picker`</A>.

> `expo-image-picker` provides access to the system's UI to select images and videos from the phone's library or take a photo with the camera.

<Step label="1">

## Install expo-image-picker

To install the library, run the following command:

<Terminal cmd={['$ npx expo install expo-image-picker']} />

> **Tip:** Any time we install a new library in our project, we must stop the development server by pressing <kbd>Ctrl</kbd> + <kbd>c</kbd> in the terminal and then running the installation command.
> After the installation, we can start the development server again by running `npx expo start` from the same terminal window.

</Step>

<Step label="2">

## Pick an image from the device's media library

`expo-image-picker` provides the `launchImageLibraryAsync()` method that displays the system UI for choosing an image or a video from the device's media library.

We can use the button with the primary theme we created in the previous chapter to pick an image from the device's media library.
We'll create a function to launch the device's image library to implement this functionality.

In **App.js**, import the `expo-image-picker` library and create a `pickImageAsync()` function inside the `App` component:

{/* prettier-ignore */}
```jsx App.js
// ...rest of the import statements remain unchanged
/* @info Import the ImagePicker. */ import * as ImagePicker from 'expo-image-picker'; /* @end */

export default function App() {
  const pickImageAsync = async () => {
    /* @info Pass image picker options to launchImageLibraryAsync() */
    let result = await ImagePicker.launchImageLibraryAsync({
      allowsEditing: true,
      quality: 1,
    });
    /* @end */

    if (!result.canceled) {
      /* @info If the image is picked, print its information in terminal window. */
      console.log(result);
      /* @end */
    } else {
      /* @info If the user does not picks an image, show an alert. */
      alert('You did not select any image.');
      /* @end */
    }
  };

  // ...rest of the code remains same
}
```

Let's learn what the above code does.

- The `launchImageLibraryAsync()` receives an object in which different options are specified.
  This object is an <A href="/versions/latest/sdk/imagepicker/#imagepickeroptions" openInNewTab>`ImagePickerOptions` object</A>.
  We can pass the object to specify different options when invoking the method.
- When `allowsEditing` is set to `true`, the user can crop the image during the selection process on Android and iOS but not on the web.

</Step>

<Step label="3">

## Update the button component

When the primary button gets pressed, we need to call the `pickImageAsync()` function.
To call it, update the `onPress` property of the `<Button>` component in **components/Button.js**:

{/* prettier-ignore */}
```jsx Button.js
export default function Button({ label,  theme, /* @info Pass this prop to trigger the handler method from the parent component. */ onPress/* @end */}) {
  // ...rest of the code remains same
  if (theme === "primary") {
    return (
      <View>
        /* ...rest of the code remains same */
        <Pressable
          style={[styles.button, { backgroundColor: '#fff' }]}
          /* @info */ onPress={onPress} /* @end */
        >
      </View>
    );
  }
}
```

In **App.js**, add the `pickImageAsync()` function to the `onPress` prop on the first `<Button>`.

{/* prettier-ignore */}
```jsx App.js
export default function App() {
  // ...rest of the code remains same

  return (
    <View style={styles.container}>
      /* ...rest of the code remains same */
      <Button theme="primary" label="Choose a photo" /* @info */ onPress={pickImageAsync} /* @end */ />
    </View>
  );
}
```

The `pickImageAsync()` function is responsible for invoking `ImagePicker.launchImageLibraryAsync()` and then handling the result.
The `launchImageLibraryAsync()` method returns an object containing information about the selected image.

To demonstrate what properties the `result` object contains, here is an example result object:

```json
{
  "assets": [
    {
      "assetId": null,
      "base64": null,
      "duration": null,
      "exif": null,
      "height": 4800,
      "rotation": null,
      "type": "image",
      "uri": "file:///data/user/0/host.exp.exponent/cache/ExperienceData/%username%252Fsticker-smash-47-beta/ImagePicker/77c4e56f-4ccc-4c83-8634-fc376597b6fb.jpeg",
      "width": 3200
    }
  ],
  "canceled": false,
  "cancelled": false
}
```

</Step>

<Step label="4">

## Use the selected image

The `result` object provides the `assets` array, which contains the `uri` of the selected image.
Let's take this value from the image picker and use it to show the selected image in the app.

Modify the **App.js** file in the following steps:

- Declare a state variable called `selectedImage` using the <A href="https://reactjs.org/docs/hooks-state.html" openInNewTab>`useState`</A> hook from React.
  We'll use this state variable to hold the URI of the selected image.
- Update the `pickImageAsync()` function to save the image URI in the `selectedImage` state variable.
- Then, pass the `selectedImage` as a prop to the `ImageViewer` component.

{/* prettier-ignore */}
```jsx App.js
/* @info Import useState hook from React. */ import { useState } from 'react'; /* @end */
// ...rest of the import statements remain unchanged

export default function App() {
  /* @info Create a state variable that will hold the value of selected image. */
  const [selectedImage, setSelectedImage] = useState(null);
  /* @end */

  const pickImageAsync = async () => {
    let result = await ImagePicker.launchImageLibraryAsync({
      allowsEditing: true,
      quality: 1,
    });

    if (!result.canceled) {
      /* @info Pick the first uri from the assets array. Also, there is only one image selected at a time so you don't have to change this. */
      setSelectedImage(result.assets[0].uri);
      /* @end */
    } else {
      alert('You did not select any image.');
    }
  };

  return (
    <View style={styles.container}>
      <View style={styles.imageContainer}>
        /* @info Pass the selected image URI to the ImageViewer component. */<ImageViewer
          placeholderImageSource={PlaceholderImage}
          selectedImage={selectedImage}
        />
        /* @end */
      </View>
      /* ...rest of the code remains same */
    </View>
  );
}
```

Now, modify the **components/ImageViewer.js** file to conditionally display the selected image in place of the placeholder image.
We'll need to pass the `selectedImage` prop to the component.

The source of the image is getting long, so let's also move it to a separate variable called `imageSource`.
Then, pass it as the value of the `source` prop on the `<Image>` component.

<SnackInline
label="Image picker"
templateId="tutorial/02-image-picker/App"
dependencies={['expo-image-picker', 'expo-status-bar', '@expo/vector-icons', '@expo/vector-icons/FontAwesome']}
files={{
'assets/images/background-image.png': 'https://snack-code-uploads.s3.us-west-1.amazonaws.com/~asset/503001f14bb7b8fe48a4e318ad07e910',
'components/ImageViewer.js': 'tutorial/02-image-picker/ImageViewer.js',
'components/Button.js': 'tutorial/02-image-picker/Button.js'
}}>

{/* prettier-ignore */}
```jsx
export default function ImageViewer({ placeholderImageSource, /* @info Pass the selectedImage prop.*/selectedImage/* @end */ }) {
  /* @info If the selected image is not null, show the image from the device, otherwise, show the placeholder image. */
  const imageSource = selectedImage !== null
    ? { uri: selectedImage }
    : placeholderImageSource;
  /* @end */

  return <Image /* @info */source={imageSource}/* @end */ style={styles.image} />;
}
```

</SnackInline>

In the above snippet, the `<Image>` component uses a conditional operator to load the source of the image.
This is because the image picked from the image picker is a <A href="https://reactnative.dev/docs/images#network-images" openInNewTab>`uri` string</A>,
not a local asset like the placeholder image.

Let's take a look at our app now:

<Video file="tutorial/03-image-picker-demo.mp4" />

> The images used for the demo in this tutorial were picked from [Unsplash](https://unsplash.com).

</Step>

## Next steps

We added the functionality to pick an image from the device's media library.

In the next chapter, we'll learn how to [create an emoji picker modal component](/tutorial/create-a-modal).