请帮我用django websocket循环截图后用cv2压缩图像并发送到前端用canvas显示的例子
时间: 2023-06-02 07:07:02 浏览: 67
很抱歉,由于您的问题涉及技术实现,我可以回答。以下是一个简单的用Django Websocket循环截图并用CV2压缩图像并发送到前端用Canvas显示的代码示例:
后端代码:
```python
# views.py
import cv2
import asyncio
import base64
import websockets
from django.shortcuts import render
from django.http import HttpResponse
from django.views.decorators.csrf import csrf_exempt
async def index(request):
t = request.GET.get("t", 0.5)
return render(request, "index.html", {"t": t})
async def generate_frames(t):
cap = cv2.VideoCapture(0)
while True:
await asyncio.sleep(t) # 循环截图间隔时间
ret, frame = cap.read()
if not ret:
return
# 压缩图像
_, img = cv2.imencode('.jpg', frame, [int(cv2.IMWRITE_JPEG_QUALITY), 50])
img = base64.b64encode(img).decode('utf-8')
yield img
@csrf_exempt
async def video_feed(request):
t = float(request.GET.get("t", 0.5))
return HttpResponse(await video_feed_generator(t), content_type='multipart/x-mixed-replace; boundary=frame')
async def video_feed_generator(t):
async with websockets.connect('ws://localhost:8000/ws') as websocket:
async for img in generate_frames(t):
await websocket.send(img)
yield (b'--frame\r\n'
b'Content-Type: image/jpeg\r\n\r\n' + base64.b64decode(img.encode('utf-8')) + b'\r\n\r\n')
async def websocket_handler(websocket, path):
while True:
img = await websocket.recv()
await websocket.send(img)
@csrf_exempt
def video_stream(request):
return render(request, "video_stream.html")
```
前端代码:
```html
<!-- index.html -->
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Django WebSocket Example</title>
<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script>
$(function() {
var ws_scheme = window.location.protocol == "https:" ? "wss" : "ws";
var ws_url = ws_scheme + '://' + window.location.host + "/ws";
var streaming = false;
var video = $('#video')[0];
var startStreaming = function() {
if (streaming) {
return;
}
streaming = true;
var canvas = document.createElement('canvas');
var context = canvas.getContext('2d');
canvas.width = video.width;
canvas.height = video.height;
video.addEventListener('play', function() {
var $this = this;
(function loop() {
if (!$this.paused && !$this.ended) {
context.drawImage($this, 0, 0);
var imageData = canvas.toDataURL('image/jpeg');
websocket.send(imageData);
}
setTimeout(loop, 1000 / 30);
})();
}, 0);
};
var websocket = new WebSocket(ws_url);
websocket.onmessage = function(e) {
var imageData = e.data;
var image = new Image();
image.src = imageData;
$('#video').attr('src', image.src);
if (!streaming) {
video.addEventListener('canplay', startStreaming, false);
}
};
websocket.onerror = function(e) {
console.error(e);
};
});
</script>
</head>
<body>
<video id="video" width="640" height="480" autoplay></video>
</body>
</html>
```
这个例子使用了Django框架,利用Websocket协议实现了从后端循环截图并进行压缩发送图片,前端通过Canvas显示图片。