Android Camera

In this article, we will delve into the world of Android Camera and guide you through the process of implementing the camera in an Android app, including camera hardware, camera API, camera intents, camera permissions, camera settings, and best practices for capturing high-quality photos and videos.

If you own an Android device, you are likely familiar with the built-in camera app that comes with it. This app allows you to take pictures and record videos with ease. However, as an app developer, you may want to add custom camera functionality to your app.

This is where the Android Camera API comes in handy. With the Camera API, you can access the device’s camera hardware and capture photos or videos directly from your app.

Understanding Camera Hardware

Before diving into the Camera API, it’s essential to understand the camera hardware on an Android device.

Android devices typically have two types of cameras:

1. The rear-facing camera (also known as the main camera).
2. The front-facing camera (also known as the selfie camera or the secondary camera).

These cameras may have different specifications, such as resolution, aperture, focal length, and flash support, which can impact the quality of images or videos captured.

Using the Camera API

The Camera API is a set of classes and interfaces provided by Android for interacting with the camera hardware and capturing images or videos. The Camera API allows you to control various aspects of the camera, such as setting camera parameters, previewing camera output, capturing images or videos, and handling camera events.

Here are some of the commonly used Camera API methods in Android:

To use the Camera API in your Android app, you need to first obtain camera permission from the user.

Set Camera Permissions

Camera permission is a sensitive permission and requires explicit user consent.

You can request camera permission using the Android permission system, and handle permission callbacks to ensure proper permission handling in your app.

Once you have obtained camera permission, you can initialize the camera hardware, set camera parameters, and start the camera preview.

The camera preview is a live feed from the camera that shows what the camera is capturing in real-time on the device’s screen.

You can also capture images or record videos using the Camera API, and save them to the device’s storage or process them in your app.

To use the camera in your app, you need to add permissions to the app manifest.

You will need to add the following permissions for camera functionality:

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

We add these permissions to our app manifest to enable camera functionality:

the first line grants access to the device’s camera, and the next two lines confirm that the device has a camera and autofocus functionality.

Create Camera Preview Layout

To display the camera output on the screen, you need to create a layout for the camera preview in your app.

You can create a file called “camera_preview.xml” and include the following code:

<?xml version="1.0" encoding="utf-8"?>
<SurfaceView
android:id="@+id/camera_preview"
android:layout_width="match_parent"
android:layout_height="match_parent" />

Our layout file named camera_preview.xml contains a SurfaceView, which we will use to display the camera preview.

Create Camera Preview Class

To handle the camera preview, you need to create a class named CameraPreview.

Here is an example implementation that you can use:

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;

public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
Log.d("CameraPreview", "Error setting camera preview: " + e.getMessage());
}
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
if (mHolder.getSurface() == null) {
return;
}

try {
mCamera.stopPreview();
} catch (Exception e) {
Log.d("CameraPreview", "Error stopping camera preview: " + e.getMessage());
}

try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e) {
Log.d("CameraPreview", "Error starting camera preview: " + e.getMessage());
}
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
mCamera.stopPreview();
mCamera.release();
}
}

We, as developers, extend the SurfaceView class and implement the SurfaceHolder.Callback interface to create a class named CameraPreview. The CameraPreview class contains a Camera object that enables us to control the camera hardware.

Inside the constructor, we obtain the SurfaceHolder from the SurfaceView and attach a callback to it. We also set the SurfaceHolder’s type to SURFACE_TYPE_PUSH_BUFFERS to make sure that it is compatible with older versions of Android.

The surfaceCreated() method is called when the SurfaceView is created. Within this method, we set the camera preview to display on the SurfaceView.

The surfaceChanged() method is called when the SurfaceView changes size or format. We use this method to stop the camera preview and then restart it with the new parameters.

Now Capture An Image

Once the preview is set up, you can use the camera instance to capture an image.

Here is an example of how to capture an image:

private Camera.PictureCallback mPicture = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
// process the captured image data
}
};

To capture an image, we need to call the takePicture method of the camera instance. We can define a PictureCallback to process the captured image data.

The data parameter contains the raw image data in a byte array, which we can process in the onPictureTaken method.

Here’s an example:

mCamera.takePicture(null, null, mPicture);

We passed null for the first two parameters in the above code since we didn’t need to specify any settings for the captured image. The third parameter was the PictureCallback instance that would be called when the image was captured.

Handling Camera Errors

To handle errors while working with the camera, it’s essential to know about the common errors that you may encounter.

You may come across the following errors:

To handle these errors, you can implement the Camera.ErrorCallback interface.

private Camera.ErrorCallback mErrorCallback = new Camera.ErrorCallback() {
@Override
public void onError(int error, Camera camera) {
Log.e(TAG, "Camera error: " + error);
}
};

To handle errors in our camera implementation, we can define an ErrorCallback interface as shown in the previous code.

This interface logs the error message to the console. However, you can implement your own error handling logic in this callback as per your requirement.

To set the error callback, we need to call the setErrorCallback method of the camera instance as follows:

mCamera.setErrorCallback(mErrorCallback);

Now Close Camera

To release the camera resources, you need to call the release() method of the Camera instance.

This method will free up the camera hardware resources and make it available to other applications.

Here is an example of how to release the camera in your code:

private void releaseCamera() {
if (mCamera != null) {
mCamera.release();
mCamera = null;
}
}

We release the camera resources by calling the release method of the camera instance in the above code.

We also set the camera instance to null to ensure that it is properly released.

Android Camera Advantages

Using the camera in an Android application has several advantages for you as a user:

• By using the camera, developers can create more immersive and engaging user experiences for you. You can take photos, record videos, and use augmented reality features to make your app more fun and interactive.
• With the ubiquity of smartphones, you always have a camera in your pocket. By using the camera in your app, you can take advantage of this convenience and provide you with an easy way to capture images and videos.
• The camera can be used for a variety of applications, from scanning barcodes and documents to recognizing faces and adding virtual objects to the real world. This versatility makes it a valuable tool for many industries and applications.
• The camera API in Android is easy to use and is accessible to developers of all levels. This makes it easy for developers to incorporate camera functionality into their app, regardless of their level of experience.
• The camera API in Android can be integrated with other APIs and services, such as location-based services and cloud storage. This integration allows for even more functionality and flexibility in your app.
• The camera is a constantly evolving technology, with new features and capabilities being added all the time. By incorporating the camera in your app, you can take advantage of these new features and provide you with innovative and cutting-edge functionality.

Best Practices

Capturing high-quality photos and videos is essential to ensure a great user experience in your app.

Here are some best practices to consider when working with the Android Camera:

1. The camera preview is the live feed from the camera that users see on the screen. It’s important to optimize the camera preview for smooth and responsive performance. You can use techniques such as surfaceView, textureView, and camera2 API for efficient camera preview.
2. Android devices can be used in different orientations, so it’s crucial to handle camera orientation correctly in your app. You can use the sensor orientation, display rotation, and camera rotation to ensure that the captured media is displayed correctly regardless of the device orientation.
3. Camera parameters such as focus mode, flash mode, exposure compensation, and white balance can greatly impact the quality of captured media. Experiment with different camera parameters to achieve the desired results based on the lighting conditions and subject of the photo or video.
4. Android Camera API allows you to control the quality of captured images and videos. You can set the image compression level, video bitrate, resolution, and frame rate to optimize the quality of media captured in your app.
5. The camera can generate various events and errors, such as autofocus, shutter callback, and camera errors. It’s important to handle these events and errors properly in your app to provide a smooth and error-free camera experience to the users.
6. Captured images and videos need to be stored properly in the device’s storage to ensure they are accessible and can be used in your app. You can use standard file storage practices, such as creating a dedicated folder for media, using proper file naming conventions, and managing storage space efficiently.
7. Android devices come in various sizes, resolutions, and camera capabilities. It’s crucial to thoroughly test your camera functionality on different devices and orientations to ensure it works well across different devices and screen sizes.

Conclusion

Mastering the Android Camera API is essential for building apps that require camera functionality. By following best practices, such as optimizing camera preview, handling camera permissions and settings, implementing image and video quality control, and handling camera events and errors, you can create apps that capture high-quality photos and videos and provide a seamless camera experience to your users. Remember to thoroughly test your app on different devices and orientations to ensure it works well across various Android devices. Happy capturing!