// ** Capture a still image **
// This block of code is contained in a self invoked function. 

(function() {
    // Set a width and height for the video/image

    var width = 320; // 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 startbutton = null;

    // ****************************************************************
    // Start capturing video
    function startup() {
        // Define elements 
        video = document.getElementById('video-still');
        canvas = document.getElementById('canvas');
        photo = document.getElementById('photo');
        startbutton = document.getElementById('startbutton');
        
        // Check for vendor version of getUserMedia
        
        navigator.getMedia = (navigator.getUserMedia ||
            navigator.webkitGetUserMedia ||
            navigator.mozGetUserMedia ||
            navigator.msGetUserMedia);
        
        // Check for getUserMedia
        if (!navigator.getMedia) {
            // No user media exit
            console.log("Has get user media");
            return; 
        }
        
        // invoke getUserMedia to start a video stream. 
        navigator.getMedia({
            video: true,    // Get video
            audio: false    // No audio
        }, getMediaSuccess, getMediaError); // Pass a success, and error function
        
        // Media success function
        function getMediaSuccess(stream) {
            // Check for FireFox. 
            if (navigator.mozGetUserMedia) {
                video.mozSrcObject = stream; // Assign the stream to #video-still
            } else {
                var vendorURL = window.URL || window.webkitURL;
                video.src = vendorURL.createObjectURL(stream); // Assign the stream to #video-still
            }
            video.play(); // Tell #video-still to play
        }

        // This is invoked on a user media error. 
        function getMediaError(error) {
            console.log("An error occured! " + error);
        }

        // Add an event to the #video-still. The canplay event occurs when 
        // the video is ready to play. 
        video.addEventListener('canplay', function (event) {
            // Check the streaming flag. 
            if (!streaming) {
                // Not streaming.
                // Get the height of the video
                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);
                }
                
                // Set some attributes of the #video-still element
                video.setAttribute('width', width);
                video.setAttribute('height', height);
                canvas.setAttribute('width', width);
                canvas.setAttribute('height', height);
                // Set streaming to true
                streaming = true;
            }
        }, false);

        // Add click event to #startbutton
        startbutton.addEventListener('click', function (event) {
            event.preventDefault();
            takepicture(); // Take a picture
        }, false);

        clearphoto();
    }
    // End startup function
    // ****************************************************************

    
    // #canvas is used to hold a still image. Here the convas is cleared 
    // by filling with gray. 
    function clearphoto() {
        // Fill with a gray
        var context = canvas.getContext('2d');
        context.fillStyle = "#AAA";
        context.fillRect(0, 0, canvas.width, canvas.height);
        // Set the data url of #photo to the image on the canvas
        var data = canvas.toDataURL('image/png');
        photo.setAttribute('src', data);
    }

    // Capture a photo by fetching the current contents of the video
    // and drawing it into a canvas, then converting that to a PNG
    // format data URL. By drawing it on an offscreen canvas and then
    // drawing that to the screen, we can change its size and/or apply
    // other changes before drawing it.
    
    // Capture an image. 

    function takepicture() {
        var context = canvas.getContext('2d');
        if (width && height) {
            canvas.width = width;
            canvas.height = height;
            context.drawImage(video, 0, 0, width, height);

            var data = canvas.toDataURL('image/png');
            photo.setAttribute('src', data);
        } else {
            clearphoto();
        }
    }

    // Set up our event listener to run the startup process
    // once loading is complete.
    // This calls startup (above)
    window.addEventListener('load', startup, false);
})();