Draw a rectangle on Image

i want a build a app for face detection in IONIC, i’am using Cloud vision API to detect faces, it returns four points for each face (x,y), present the vertex boundingpoly vertices.

now i want to draw a rectangle on each face.

can someone help.

this is my code :

const options: CameraOptions = {
quality: 100,
destinationType: this.camera.DestinationType.DATA_URL,
encodingType: this.camera.EncodingType.PNG,
mediaType: this.camera.MediaType.PICTURE
};

this.camera.getPicture(options).then((imageData) => {
this.base64Image = ‘data:image/png;base64,’ + imageData;
this.vision.getLabels(imageData).subscribe((result) => {
this.response = result.json().responses[0];
console.log('cloud vision response : ’ + JSON.stringify(this.response));

}, error2 => {
	console.log(' Error API : ' + error2);
});

}, (err) => {
// Handle error
console.log(’ Camera Error’);
});

<img [src]=“base64Image”/>