[Javascript] Scattare una foto da webcam quando avviene un evento

[francabbestia]

Ciao ragazzi scrivo nel forum perchè vorrei risolvere il mio problema di Javascript.
Ho una pagina web che con html 5 mi attiva la webcam e me la fa visualizzare. Ho usato poi una libreria javascript per fare un rilevamento del volto ed infatti quando il volto mi viene tracciato compare lo stato "found". Attualmente posso fare una foto dell'immagine della webcam con un pulsante "snap". Io vorrei, invece, poter scattare la foto ogni volta che cambia lo stato in found. E' possibile farlo?
Questo è il mio codice:
"
<script src="headtrackr.js"></script>

<canvas id="compare" width="320" height="240" style="display:none"></canvas>
<video id="vid" autoplay loop width="320" height="240"></video>
<canvas id="overlay" width="320" height="240"></canvas>
<canvas id="debug" width="320" height="240"></canvas>


<p id='gUMMessage'></p>
<p>Status : <span id='headtrackerMessage'></span></p>
<p><input type="button" onclick="htracker.stop();htracker.start();" value="reinitiate facedetection"></input>
<br/><br/>
<input type="checkbox" onclick="showProbabilityCanvas()" value="asdfasd"></input>Show probability-map</p>

<button id="snap">Snap Photo</button>

<canvas id="canvas" width="240" height="180"></canvas>


<script>

// Put event listeners into place
window.addEventListener("DOMContentLoaded", function() {
// Grab elements, create settings, etc.
var canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
vid = document.getElementById("vid"),
videoObj = { "vid": true },
image_format= "jpeg",
jpeg_quality= 100,
errBack = function(error) {
console.log("Video capture error: ", error.code);
};

// Put video listeners into place
if(navigator.getUserMedia) { // Standard
navigator.getUserMedia(videoObj, function(stream) {
vid.src = stream;
vid.play();
}, errBack);
} else if(navigator.webkitGetUserMedia) { // WebKit-prefixed
navigator.webkitGetUserMedia(videoObj, function(stream){
vid.src = window.webkitURL.createObjectURL(stream);
vid.play();
}, errBack);
} else if(navigator.mozGetUserMedia) { // WebKit-prefixed
navigator.mozGetUserMedia(videoObj, function(stream){
vid.src = window.URL.createObjectURL(stream);
vid.play();
}, errBack);
}


/*/ Trigger photo take(ipotizzato da me)
document.addEventListener("headtrackrStatus", function(event) {
if (!faceFound) {
headtrackerStatus("found");
faceFound = true;
context.drawImage(vid, 0, 0, 154, 128);
}
});
}, false);

*/

// Trigger photo take
document.getElementById("snap").addEventListener("click", function() {
context.drawImage(vid, 0, 0, 240, 180);
});


</script>

<script>

// set up video and canvas elements needed

var videoInput = document.getElementById('vid');
var canvasInput = document.getElementById('compare');
var canvasOverlay = document.getElementById('overlay')
var debugOverlay = document.getElementById('debug');
var overlayContext = canvasOverlay.getContext('2d');
canvasOverlay.style.position = "absolute";
canvasOverlay.style.top = '0px';
canvasOverlay.style.zIndex = '100001';
canvasOverlay.style.display = 'block';
debugOverlay.style.position = "absolute";
debugOverlay.style.top = '0px';
debugOverlay.style.zIndex = '100002';
debugOverlay.style.display = 'none';

// add some custom messaging

statusMessages = {
"whitebalance" : "checking for stability of camera whitebalance",
"detecting" : "Detecting face",
"hints" : "Hmm. Detecting the face is taking a long time",
"redetecting" : "Lost track of face, redetecting",
"lost" : "Lost track of face",
"found" : "Tracking face"
};

supportMessages = {
"no getUserMedia" : "Unfortunately, <a href='http://dev.w3.org/2011/webrtc/editor/getusermedia.html'>getUserMedia</a> is not supported in your browser. Try <a href='http://www.opera.com/browser/'>downloading Opera 12</a> or <a href='http://caniuse.com/stream'>another browser that supports getUserMedia</a>. Now using fallback video for facedetection.",
"no camera" : "No camera found. Using fallback video for facedetection."
};

document.addEventListener("headtrackrStatus", function(event) {
if (event.status in supportMessages) {
var messagep = document.getElementById('gUMMessage');
messagep.innerHTML = supportMessages[event.status];
} else if (event.status in statusMessages) {
var messagep = document.getElementById('headtrackerMessage');
messagep.innerHTML = statusMessages[event.status];


}
}, true);

// the face tracking setup

var htracker = new headtrackr.Tracker({altVideo : {ogv : "./media/capture5.ogv", mp4 : "./media/capture5.mp4"}, calcAngles : true, ui : false, headPosition : false, debug : debugOverlay});
htracker.init(videoInput, canvasInput);
htracker.start();

// for each facetracking event received draw rectangle around tracked face on canvas

document.addEventListener("facetrackingEvent", function( event ) {
// clear canvas
overlayContext.clearRect(0,0,320,240);
// once we have stable tracking, draw rectangle
if (event.detection == "CS") {
overlayContext.translate(event.x, event.y)
overlayContext.rotate(event.angle-(Math.PI/2));
overlayContext.strokeStyle = "#00CC00";
overlayContext.strokeRect((-(event.width/2)) >> 0, (-(event.height/2)) >> 0, event.width, event.height);
overlayContext.rotate((Math.PI/2)-event.angle);
overlayContext.translate(-event.x, -event.y);
}
});

// turn off or on the canvas showing probability
function showProbabilityCanvas() {
var debugCanvas = document.getElementById('debug');
if (debugCanvas.style.display == 'none') {
debugCanvas.style.display = 'block';
} else {
debugCanvas.style.display = 'none';
}
}
</script>

 

[criric]

Ciao, la mia faccia non la riconosce
nella libreria puoi provare a richiamare una tua funzione che contiene il codice dello scatto

if (!faceFound) {
  headtrackerStatus("found");
  faceFound = true;
tuaFunzione();
  }

e la definisci nella pagina con function tuaFunzione() { etc etc