Koha/koha-tmpl/intranet-tmpl/prog/js/patron-webcam.js

/* global __ */
/* exported startup */

/* Adapted from Mozilla's article "Taking still photos with WebRTC"
* https://developer.mozilla.org/en-US/docs/Web/API/WebRTC_API/Taking_still_photos
*/

var width = 480; // We will scale the photo width to this
var height = 0; // This will be computed based on the input stream

// |streaming| indicates whether or not we're currently streaming
// video from the camera. Obviously, we start at false.

var streaming = false;

// The various HTML elements we need to configure or control. These
// will be set by the startup() function.

var video = null;
var canvas = null;
var photo = null;
var takebutton = null;
var retakebutton = null;
var downloadbutton = null;
var savebutton = null;
var output = null;
var camera = null;
var uploadfiletext = null;

/**
 * Initiate the camera and add some click handlers
 */

function startup() {
    video = document.getElementById('viewfinder');
    canvas = document.getElementById('canvas');
    photo = document.getElementById('photo');
    takebutton = document.getElementById('takebutton');
    retakebutton = document.getElementById('retakebutton');
    downloadbutton = document.getElementById('downloadbutton');
    savebutton = document.getElementById('savebutton');
    output = document.getElementById("output");
    camera = document.getElementById("camera");
    uploadfiletext = document.getElementById("uploadfiletext");

    if ( ! video ){
        //If there is no video element, don't try to start up camera
        return;
    }

    try {
        navigator.mediaDevices.getUserMedia({
            video: true,
            audio: false
        })
            .then(function (stream) {
                video.srcObject = stream;
                video.play();
            })
            .catch(function (err) {
                $("#capture-patron-image").hide();
                $("#camera-error").css("display", "flex");
                $("#camera-error-message").text( showMediaErrors( err ) );
            });
    } catch(err) {
        $("#capture-patron-image").hide();
        $("#camera-error").css("display", "flex");
        $("#camera-error-message").text( showMediaErrors( err ) );
    }

    video.addEventListener('canplay', function () {
        if (!streaming) {
            height = video.videoHeight / (video.videoWidth / width);

            // Firefox currently has a bug where the height can't be read from
            // the video, so we will make assumptions if this happens.

            if (isNaN(height)) {
                height = width / (4 / 3);
            }

            video.setAttribute('width', width);
            video.setAttribute('height', height);
            canvas.setAttribute('width', width);
            canvas.setAttribute('height', height);
            photo.setAttribute('width', width);
            photo.setAttribute('height', height);
            streaming = true;
        }
    }, false);

    takebutton.addEventListener('click', function (ev) {
        takepicture();
        ev.preventDefault();
    }, false);

    retakebutton.addEventListener('click', function (ev) {
        ev.preventDefault();
        retakephoto();
    }, false);

    clearphoto();
}

function showMediaErrors( err ){
    // Example error: "NotAllowedError: Permission denied"
    var errorcode = err.toString().split(":");
    var output;
    switch ( errorcode[0] ) {
    case "NotFoundError":
    case "DevicesNotFoundError":
        output = __("No camera detected.");
        break;
    case "NotReadableError":
    case "TrackStartError":
        output = __("Could not access camera.");
        break;
    case "NotAllowedError":
    case "PermissionDeniedError":
        output = __("Access to camera denied.");
        break;
    case "TypeError":
        output = __("This feature is available only in secure contexts (HTTPS).");
        break;
    default:
        output = __("An unknown error occurred: ") + err;
        break;
    }
    return output;
}

/**
 * Clear anything passed to the canvas element and the corresponding image.
 */

function clearphoto() {
    var context = canvas.getContext('2d');
    context.fillStyle = "#AAA";
    context.fillRect(0, 0, canvas.width, canvas.height);

    var data = canvas.toDataURL('image/jpeg', 1.0);
    photo.setAttribute('src', data);
}

/**
 * Reset the interface to hide download and save buttons.
 * Redisplay camera "shutter" button.
 */

function retakephoto(){
    downloadbutton.href= "";
    downloadbutton.style.display = "none";
    takebutton.style.display = "inline-block";
    retakebutton.style.display = "none";
    savebutton.style.display = "none";
    output.style.display = "none";
    photo.src = "";
    camera.style.display = "block";
    uploadfiletext.value = "";
}

/**
 * Capture the data from the user's camera and write it to the canvas element.
 * The canvas data is converted to a data-url, and that URL set as the src
 * attribute of an image.
 * Display two controls for the captured photo: Download (to save to the
 * user's computer) and Upload (save to the patron's record in Koha).
 */

function takepicture() {
    var context = canvas.getContext('2d');
    var cardnumber = document.getElementById("cardnumber").value;
    camera.style.display = "none";
    downloadbutton.style.display = '';
    output.style.display = "block";
    takebutton.style.display = "none";
    retakebutton.style.display = "inline-block";
    savebutton.style.display = "inline-block";
    if (width && height) {
        canvas.width = width;
        canvas.height = height;
        context.drawImage(video, 0, 0, width, height);

        var data = canvas.toDataURL('image/jpeg', 1.0);
        photo.setAttribute('src', data);
        if( cardnumber !== '' ){
            // Download a file which the patrons card number as its name
            downloadbutton.download = cardnumber + ".jpg";
        } else {
            downloadbutton.download = "patron-photo.jpg";
        }
        downloadbutton.href = data;
        uploadfiletext.value = data;

    } else {
        clearphoto();
    }
}