I just did this recently for a project. You can use XHR to send the image inside form data:
let formdata = new FormData();
formdata.append("image", data);
let xhr = new XMLHttpRequest();
xhr.open('POST', 'http://yourserver/image', true);
xhr.onload = function () {
if (this.status === 200)
console.log(this.response);
else
console.error(xhr);
};
xhr.send(formdata);
I had trouble using the toDataURL to convert the canvas, so I used toBlob for an easier conversion:
canvas.toBlob(callBackToMyPostFunctionAbove, 'image/jpeg');
Here is a sample HTML file with embedded JavaScript and my Python server.
HTML & Embedded JavaScript
The JavaScript uses:
- getUserMedia to start a local video stream
- a mouse click on the image to initiate the image capture
- a canvas object to save an image from the getUserMedia stream
- XHR to send the file as form data
The code:
<!DOCTYPE html>
<html>
<head>
<title>Post an Image test</title>
<script src="https://webrtc.github.io/adapter/adapter-latest.js"></script>
</head>
<style>
/* mirror the image */
video, canvas {
transform: scale(-1, 1); /*For Firefox (& IE) */
-webkit-transform: scale(-1, 1); /*for Chrome & Opera (& Safari) */
}
</style>
<body>
<video id="myVideo" autoplay></video>
<script>
let v = document.getElementById("myVideo");
//create a canvas to grab an image for upload
let imageCanvas = document.createElement('canvas');
let imageCtx = imageCanvas.getContext("2d");
//Add file blob to a form and post
function postFile(file) {
let formdata = new FormData();
formdata.append("image", file);
let xhr = new XMLHttpRequest();
xhr.open('POST', 'http://localhost:5000/image', true);
xhr.onload = function () {
if (this.status === 200)
console.log(this.response);
else
console.error(xhr);
};
xhr.send(formdata);
}
//Get the image from the canvas
function sendImagefromCanvas() {
//Make sure the canvas is set to the current video size
imageCanvas.width = v.videoWidth;
imageCanvas.height = v.videoHeight;
imageCtx.drawImage(v, 0, 0, v.videoWidth, v.videoHeight);
//Convert the canvas to blob and post the file
imageCanvas.toBlob(postFile, 'image/jpeg');
}
//Take a picture on click
v.onclick = function() {
console.log('click');
sendImagefromCanvas();
};
window.onload = function () {
//Get camera video
navigator.mediaDevices.getUserMedia({video: {width: 1280, height: 720}, audio: false})
.then(stream => {
v.srcObject = stream;
})
.catch(err => {
console.log('navigator.getUserMedia error: ', err)
});
};
</script>
</body>
</html>
This uses adapter.js to polyfill getUserMedia on different browsers without any error checks.
Python Server
And here is a sample in Python using Flask as a web server:
from flask import Flask, request, Response
import time
PATH_TO_TEST_IMAGES_DIR = './images'
app = Flask(__name__)
@app.route('/')
def index():
return Response(open('./static/getImage.html').read(), mimetype="text/html")
# save the image as a picture
@app.route('/image', methods=['POST'])
def image():
i = request.files['image'] # get the image
f = ('%s.jpeg' % time.strftime("%Y%m%d-%H%M%S"))
i.save('%s/%s' % (PATH_TO_TEST_IMAGES_DIR, f))
return Response("%s saved" % f)
if __name__ == '__main__':
app.run(debug=True, host='0.0.0.0')
