Question

有关如何提供图像的简单明了的例子吗？从服务器到客户端？通过缓冲或只是直接下载电话？（目标是近乎实时地获取图像文件以排序呈现近乎实时的图像流）并附加到html图像标记或仅在html页面的主体中。

不完整的示例代码:(主要从官方样本中获取，或者只是从stackoverflow中获取代码）

index.js

// basic variables
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);

var fs = require('fs'); // required for file serving

http.listen(3000, function(){
  console.log('listening on *:3000');
});

// location to index.html
app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

// only to test chat sample code from sample
io.on('connection', function(socket){

  console.log('a user connected');
    // broadcast a message
  socket.broadcast.emit('chat message', 'System Broadcast Message: a user has been connected');
  socket.on('chat message', function(msg){
    io.emit('chat message', msg);
  });

// trying to serve the image file from the server
io.on('connection', function(socket){
  fs.readFile(__dirname + '/images/image.jpg', function(err, buf){
    // it's possible to embed binary data
    // within arbitrarily-complex objects
    socket.emit('image', { image: true, buffer: buf });
    console.log('image file is initialized');
  });
});

（客户端html页面）index.html（我们将切换到仅提供图像的部分）我们可以在客户端做什么来获取文件并在html页面上提供图像？

  socket.on("image", function(image, buffer) {
     if(image)
     {
         console.log(" image: from client side");
         // code to handle buffer like drawing with canvas** <--- is canvas drawing/library a requirement?  is there an alternative? another quick and dirty solution?
        console.log(image);
        // what can we do here to serve the image onto an img tag?
     }

 });

感谢您阅读

更新

从下面的代码片段后面它还需要将“buffer”变量更改为image.buffer，以便正确显示图像

基本上改变了

行

img.src = 'data:image/jpeg;base64,' + buffer;

要

img.src = 'data:image/jpeg;base64,' + image.buffer;

Answer 1

一种可能的解决方案是对图像数据进行base64编码，并通过image.src在浏览器中使用它：

在服务器端，尝试更改此内容：

socket.emit('image', { image: true, buffer: buf });

到此：

socket.emit('image', { image: true, buffer: buf.toString('base64') });

然后在客户端：

var ctx = document.getElementById('canvas').getContext('2d');

// ...

socket.on("image", function(info) {
  if (info.image) {
    var img = new Image();
    img.src = 'data:image/jpeg;base64,' + info.buffer;
    ctx.drawImage(img, 0, 0);
  }
});

socket io，node js，从服务器向客户端发送图像/文件的简单示例

更新

1 个答案: