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<button id="detect" onclick="detect()" class="btn btn-lg btn-primary">Detect faces</button>
<div>
<img hidden id="image" crossorigin="anonymous" src="https://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Google_team_group_photo_with_Vanhanen.jpg/640px-Google_team_group_photo_with_Vanhanen.jpg"> <br>
<canvas id="canvas" width=640 height=480>
</div>
<footer></footer>
var image = document.getElementById('image');
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext("2d");
ctx.drawImage(image,
0, 0, image.width, image.height,
0, 0, canvas.width, canvas.height);
const scale = canvas.width / image.width;
function detect() {
if (window.FaceDetector == undefined) {
console.error('Face Detection not supported');
return;
}
console.log('ignition!');
var faceDetector = new FaceDetector();
faceDetector.detect(image)
.then(faces => {
console.log('yes');
// Draw the faces on the <canvas>.
var ctx = document.getElementById('canvas').getContext("2d");
ctx.lineWidth = 2;
for(var i = 0; i < faces.length; i++) {
const face = faces[i].boundingBox;
ctx.beginPath();
ctx.strokeStyle = "red";
ctx.rect(Math.floor(face.x * scale),
Math.floor(face.y * scale),
Math.floor(face.width * scale),
Math.floor(face.height * scale));
ctx.stroke();
for(var j = 0; j < faces[i].landmarks.length; j++) {
const landmark = faces[i].landmarks[j];
drawAxis(ctx, landmark.location.x, landmark.location.y,
canvas.width, canvas.height);
}
}
// Add the faces as strings to the <footer>
var footer = document.getElementsByTagName('footer')[0];
footer.innerHTML =
'<p>Detected ' + faces.length + ' faces</p><ul>';
for(var i = 0; i < faces.length; i++) {
const face = faces[i].boundingBox;
footer.innerHTML +=
'<li>@ (' + face.x + ',' + face.y + '), size ' +
face.width + 'x' + face.height + '</li>';
}
footer.innerHTML += '</ul>';
}).catch((e) => {
console.log('no');
console.error("Boo, Face Detection failed: " + e);
})
}
function drawAxis(ctx, x, y, width, height) {
const sizeX = width / 40;
const sizeY = height / 40;
ctx.beginPath();
ctx.strokeStyle = 'yellow';
ctx.moveTo(x, y);
ctx.lineTo(x + sizeX, y);
ctx.moveTo(x, y);
ctx.lineTo(x - sizeX, y);
ctx.moveTo(x, y);
ctx.lineTo(x, y - sizeY);
ctx.moveTo(x, y);
ctx.lineTo(x, y + sizeY);
ctx.stroke();
}
Also see: Tab Triggers