The Project | About Us | Contribute | Donations | License
HOME My courses Completed
◄ Previous
◄

Interacting with the Camera

Next ►
►

In this section, we will explore how to interact with the device's camera using Apache Cordova. This includes capturing photos, handling the captured images, and integrating them into your application. By the end of this module, you will be able to create a simple application that uses the device's camera to take pictures and display them.

Key Concepts

  1. Cordova Camera Plugin: The Cordova Camera Plugin provides access to the device's camera and allows you to capture photos and retrieve them.
  2. Camera Options: Configurations that determine how the camera behaves, such as the quality of the image, the source of the image (camera or photo library), and the format of the returned image.
  3. Handling Images: Techniques for displaying and storing the captured images within your application.

Installing the Camera Plugin

To use the camera functionality, you need to install the Cordova Camera Plugin. You can do this using the following command:

cordova plugin add cordova-plugin-camera

Using the Camera API

Basic Example

Here is a basic example of how to use the Camera API to capture a photo and display it in an image element.

<!DOCTYPE html>
<html>
<head>
    <title>Camera Example</title>
    <script type="text/javascript" src="cordova.js"></script>
    <script type="text/javascript">
        document.addEventListener('deviceready', function() {
            document.getElementById('capturePhoto').addEventListener('click', capturePhoto);
        });

        function capturePhoto() {
            navigator.camera.getPicture(onSuccess, onFail, {
                quality: 50,
                destinationType: Camera.DestinationType.DATA_URL
            });
        }

        function onSuccess(imageData) {
            var image = document.getElementById('photo');
            image.src = "data:image/jpeg;base64," + imageData;
        }

        function onFail(message) {
            alert('Failed because: ' + message);
        }
    </script>
</head>
<body>
    <button id="capturePhoto">Capture Photo</button>
    <img id="photo" src="" alt="Your Photo">
</body>
</html>

Explanation

  • HTML Structure: The HTML contains a button to capture the photo and an image element to display the captured photo.
  • JavaScript:
    • Event Listener: Listens for the deviceready event to ensure Cordova is fully loaded.
    • capturePhoto Function: Calls navigator.camera.getPicture to open the camera interface.
    • onSuccess Function: Handles the successful capture of the photo by setting the src attribute of the image element to the captured photo.
    • onFail Function: Handles any errors that occur during the photo capture process.

Camera Options

The getPicture method accepts several options to customize the camera behavior. Here are some commonly used options:

Option Description
quality Quality of the saved image (0-100).
destinationType Format of the returned image (DATA_URL or FILE_URI).
sourceType Source of the image (CAMERA, PHOTOLIBRARY, or SAVEDPHOTOALBUM).
allowEdit Allow simple editing of the image before selection.
encodingType Encoding type of the image (JPEG or PNG).
targetWidth Width in pixels to scale the image.
targetHeight Height in pixels to scale the image.
saveToPhotoAlbum Save the image to the photo album on the device.

Example with Options

Here is an example that includes more options:

function capturePhoto() {
    navigator.camera.getPicture(onSuccess, onFail, {
        quality: 75,
        destinationType: Camera.DestinationType.FILE_URI,
        sourceType: Camera.PictureSourceType.CAMERA,
        allowEdit: true,
        encodingType: Camera.EncodingType.JPEG,
        targetWidth: 800,
        targetHeight: 600,
        saveToPhotoAlbum: true
    });
}

Practical Exercise

Exercise: Capture and Display a Photo

Objective: Create a Cordova application that captures a photo using the device's camera and displays it on the screen.

Steps:

  1. Create a new Cordova project.
  2. Install the Cordova Camera Plugin.
  3. Add a button to capture the photo and an image element to display the photo.
  4. Implement the JavaScript to handle the photo capture and display.

Solution:

<!DOCTYPE html>
<html>
<head>
    <title>Camera Exercise</title>
    <script type="text/javascript" src="cordova.js"></script>
    <script type="text/javascript">
        document.addEventListener('deviceready', function() {
            document.getElementById('capturePhoto').addEventListener('click', capturePhoto);
        });

        function capturePhoto() {
            navigator.camera.getPicture(onSuccess, onFail, {
                quality: 75,
                destinationType: Camera.DestinationType.FILE_URI,
                sourceType: Camera.PictureSourceType.CAMERA,
                allowEdit: true,
                encodingType: Camera.EncodingType.JPEG,
                targetWidth: 800,
                targetHeight: 600,
                saveToPhotoAlbum: true
            });
        }

        function onSuccess(imageURI) {
            var image = document.getElementById('photo');
            image.src = imageURI;
        }

        function onFail(message) {
            alert('Failed because: ' + message);
        }
    </script>
</head>
<body>
    <button id="capturePhoto">Capture Photo</button>
    <img id="photo" src="" alt="Your Photo">
</body>
</html>

Common Mistakes and Tips

  • Permissions: Ensure that your application has the necessary permissions to access the camera.
  • Error Handling: Always implement error handling to manage cases where the user cancels the photo capture or an error occurs.
  • Image Quality: Adjust the quality and targetWidth/targetHeight options to balance between image quality and performance.

Conclusion

In this section, you learned how to interact with the device's camera using Apache Cordova. You installed the Camera Plugin, captured photos, and displayed them in your application. You also explored various camera options to customize the behavior of the camera. With these skills, you can now integrate camera functionality into your Cordova applications, enhancing the user experience with multimedia capabilities.

◄ Previous
◄
Next ►
►
The Project | About Us | Contribute | Donations | License
© Copyright 2024. All rights reserved