WebcamJS

WebcamJS is a small (~2.7K minified and gzipped) standalone JavaScript library for capturing still images from your computer's camera, and delivering them to you as JPEG or PNG Data URIs. The images can then be displayed in your web page, rendered into a canvas, or submitted to your server. WebcamJS uses HTML5 getUserMedia, but provides an automatic and invisible Flash fallback.

WebcamJS is based on my old JPEGCam project, but has been redesigned for the modern web. Instead of relying on Flash and only being able to submit images directly to a server, WebcamJS delivers your images as client-side Data URIs, and it uses HTML5 getUserMedia where available. Flash is only used if your browser doesn't support getUserMedia, and the fallback is handled automatically.

Check out a live demo here!

Open Source

WebcamJS is open source, MIT licensed, and available on GitHub:

https://github.com/jhuckaby/webcamjs

QuickStart Guide

Host the webcam.js and webcam.swf files on your web server, and drop in this HTML snippet:

	<script src="webcam.js"></script>

	<div id="my_camera" style="width:320px; height:240px;"></div>
	<div id="my_result"></div>

	<script language="JavaScript">
		Webcam.attach( '#my_camera' );
		
		function take_snapshot() {
			var data_uri = Webcam.snap();
			document.getElementById('my_result').innerHTML = '<img src="'+data_uri+'"/>';
		}
	</script>

	<a href="javascript:void(take_snapshot())">Take Snapshot</a>

This will create a live camera view in the my_camera DIV, and when the Take Snapshot link is clicked it will take a still snapshot, convert it to a JPEG, and deliver a Data URI which is inserted into the my_result DIV as a standard <IMG SRC> tag.

Data URIs may be passed around like any URL, and can be submitted to your server as well (see below for example of this).

Configuration

If you want to override the default settings, just call Webcam.set() and pass in a hash with any of the following keys:

Param Name	Default Value	Notes
width	(Auto)	Width of the live camera viewer in pixels, defaults to the actual size of the DOM element.
height	(Auto)	Height of the live camera viewer in pixels, defaults to the actual size of the DOM element.
dest_width	(Auto)	Width of the captured camera image in pixels, defaults to the live viewer size.
dest_height	(Auto)	Height of the captured camera image in pixels, defaults to the live viewer size.
image_format	jpeg	Desired image format of captured image, may be "jpeg" or "png".
jpeg_quality	90	For JPEG images, this is the desired quality, from 0 (worst) to 100 (best).
force_flash	false	Setting this to true will always run in Adobe Flash fallback mode.

Here is an example of overriding some parameters. Remember to call this before you attach the viewer.

	Webcam.set({
		width: 320,
		height: 240,
		dest_width: 640,
		dest_height: 480,
		image_format: 'jpeg',
		jpeg_quality: 90,
		force_flash: false
	});
	
	// Attach camera here

Initialization

WebcamJS is initialized and activated by "attaching" a live camera viewer to a DOM element. The DOM element must already be created and empty. Pass in an ID or CSS selector to the Webcam.attach() function. Example:

	Webcam.attach( '#my_camera' );

This will activate the user's webcam, ask for the appropriate permission, and begin showing a live camera image in the specified DOM element.

Snapping a Picture

To snap a picture, just call the Webcam.snap() function. The image data will be returned as a Data URI, which you can then display in your web page, or submit to a server. Example:

	var data_uri = Webcam.snap();
	
	document.getElementById('my_result').innerHTML = '<img src="'+data_uri+'"/>';

Customizing Image Size

WebcamJS will automatically size the live camera viewer based on the DOM element it is attached to. However, you can override this by setting the width and/or height parameters:

	Webcam.set({
		width: 320,
		height: 240
	});
	
	// Attach camera here

The size of the captured JPEG / PNG image is set to match the live camera viewer by default. However, you can override this by setting the dest_width and/or dest_height. Note that you can set the destination image size different than the viewer size. So you can have a small live viewer, but capture a large image. Example:

	Webcam.set({
		width: 320,
		height: 240,
		dest_width: 640,
		dest_height: 480,
	});
	
	// Attach camera here

Setting an Alternate SWF Location

By default WebcamJS looks for the SWF file in the same directory as the JS file. If you are hosting the SWF in a different location, please set it using the Webcam.setSWFLocation() function. Example:

	Webcam.setSWFLocation("/path/to/the/webcam.swf");

Reset (Shutdown)

To shut down the live camera preview and reset the system, call Webcam.reset(). This removes any DOM elements we added, including a Flash movie if applicable, and resets everything in the library to the initial state. Example:

	Webcam.reset();

To use the library again after resetting, you must call Webcam.attach() and pass it your DOM element.

Custom Events

WebcamJS fires a number of events you can intercept using a JavaScript hook system. Events are fired when the library is fully loaded, when the camera is live, and when an error occurs. To register an event listener, call the Webcam.on() function, passing an event name and callback function. Here is a table of the available event types:

Event Name	Notes
load	Fires when the library finishes loading.
live	Fires when the user's camera goes live (i.e. showing a live preview).
error	Fires when an error occurs (your callback function is passed an error string).
uploadProgress	Fires repeatedly while an upload is in progress (see below).
uploadComplete	Fires once when the upload completes (see below).

Example:

	Webcam.on( 'load', function() {
		// library is loaded
	} );
	
	Webcam.on( 'live', function() {
		// camera is live, showing preview image
	} );
	
	Webcam.on( 'error', function(err) {
		// an error occurred (see 'err')
	} );

By default the error event shows a JavaScript alert dialog, but if you register your own event handler this action is suppressed, and your function is called instead.

Submitting Images to a Server

The Webcam.snap() function delivers your image by way of a client-side JavaScript Data URI. The binary image data is encoded with Base64 and stuffed into the URI. You can use this image in JavaScript and display it on your page. However, the library also provides a way to decode and submit this image data to a server API endpoint, via binary AJAX. Example:

	var data_uri = Webcam.snap();
	
	Webcam.upload( data_uri, 'myscript.php', function(code, text) {
		// Upload complete!
		// 'code' will be the HTTP response code from the server, e.g. 200
		// 'text' will be the raw response content
	} );

The Webcam.upload() function accepts three arguments: the Data URI containing the Base64 encoded image data as returned from snap(), a URL to your server API endpoint (PHP script, etc.), and a callback function to execute when the upload is complete. You can alternatively specify the callback using Webcam.on('uploadComplete', YOUR_FUNC).

The image data is uploaded as part of a standard multipart form post, and included as a form element named webcam. To gain access to this data, write some server-side code like this (PHP shown):

	// be aware of file / directory permissions on your server
	move_uploaded_file($_FILES['webcam']['tmp_name'], 'webcam.jpg');

Treat the uploaded data as if you were receiving a standard form submission with a <input type="file" name="webcam"> element. The data is sent in the same exact way.

If you need to pass any additional information along with your image to the server, please add a query string to your script URL. For example:

	var username = 'jhuckaby';
	var image_fmt = 'jpeg';
	var url = 'myscript.php?username=' + username + '&format=' + image_fmt;
	Webcam.upload( data_uri, url, function(code, text) {...} );

Those variables will then be available to your server-side code however you would normally access the query string, e.g. $_GET['username'] in PHP.

Tracking Upload Progress

If you want to track progress while your image is uploading, you can register an event listener for the uploadProgress event. This event is called very frequently while an upload is in progress, and passes the function a floating point number between 0.0 and 1.0 representing the upload progress. Here is how to use:

	var data_uri = Webcam.snap();
	
	Webcam.on( 'uploadProgress', function(progress) {
		// Upload in progress
		// 'progress' will be between 0.0 and 1.0
	} );
	
	Webcam.on( 'uploadComplete', function(code, text) {
		// Upload complete!
		// 'code' will be the HTTP response code from the server, e.g. 200
		// 'text' will be the raw response content
	} );
	
	Webcam.upload( data_uri, 'myscript.php' );

Including in an Existing Form

If you are already submitting a form on your page, and simply want to include the image data in your form, you can do this. However, note that the data will be Base64 encoded until it gets to the server, so you will need to decode it on the server-side, and the file size in transit will be about 30% larger than normal.

This alternate upload technique is also shown here because it's probably the only way it'll ever work in IE 7, 8, and 9. Those older IE versions do not support binary AJAX and blobs, so the standard Webcam.upload() function will not work, and you'll have to use a form trick like this:

First, add a hidden text element to your form:

	<form id="myform" method="post" action="myscript.php">
		<input id="mydata" type="hidden" name="mydata" value=""/>
	</form>

Then, when you snap your picture, stuff the Data URI into the form field value (minus the header), and submit the form:

	var data_uri = Webcam.snap();
	var raw_image_data = data_uri.replace(/^data\:image\/\w+\;base64\,/, '');
	
	document.getElementById('mydata').value = raw_image_data;
	document.getElementById('myform').submit();

Finally, in your server-side script, grab the form data as if it were a plain form text field, decode the Base64, and you have your binary image file! Example here in PHP, which assumes JPEG format:

	$encoded_data = $_POST['mydata'];
	$binary_data = base64_decode( $encoded_data );
	
	// save to server (beware of permissions)
	$result = file_put_contents( 'webcam.jpg', $binary_data );
	if (!$result) die("Could not save image!  Check file permissions.");

License

The MIT License (MIT)

Copyright (c) 2012 - 2014 Joseph Huckaby

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.