Node.JS convert Variable-length binary data to jpeg or png?

StackOverflow https://stackoverflow.com/questions/14667553

Pergunta

I was wondering how to convert Variable-length binary data(255216255224016747073700110010100255) to a jpeg or png to the web browser?

Example Code:

var Connection = require('tedious').Connection;

    var config = {
        "userName": "user@server.database.windows.net",
        "password": "pswd",
        "server": "server.database.windows.net",
        "options": {
                "database": "db",
                "encrypt": true,
        }
    };

    var connection = new Connection(config);

    connection.on('connect', function(err) {
            console.log("Connected");
        }
    );

var Request = require('tedious').Request;
var result,
    resG;

    function sendResponse() {
        var vals;
            // Convert to string then array
        var resultA = result.toString().split(',');
            // Now I can loop through the data returned
        resultA.forEach(function(val, index, ar) {
            if(vals == null) {
                vals = val;
            } else {
                vals += val;
            }   
        });
        resG.writeHead(200, {'Content-Type': 'text/html', 'Content-Length': vals.length});
        //console.log(vals);
        //resG.end("<img src=\"data:image/jpg;base64," + vals + "\" />");
            // Output data returned from db as string
        resG.end("" + vals);
    }

    function executeStatement() {
         request = new Request("SELECT Photos FROM dbo.tbl WHERE FarmerFirstName='someName' AND FarmerLastName='someLastName'", function(err, rowCount) {
                if (err) {
                    console.log(err);
                } else {
                    console.log(rowCount + ' rows');
                }
            });

            request.on('row', function(columns) {
                columns.forEach(function(column) {
                    result = column.value;
                });
            });

        request.on('doneInProc', function(rowCount, more) {
                    // Got everything needed from db move on to sending a response
            sendResponse();
        });

            connection.execSql(request);
    }

var http = require('http'),
    director = require('director');

var router = new director.http.Router({
    "/": {
        get: executeStatement
    }
});

var server = http.createServer(function (req, res) { 
  // set global res var
  resG = res;
  router.dispatch(req, res, function (err) {
    if (err) {
      res.writeHead(404);
      res.end();
    }
 });
});

server.listen(80);

I'm using tedious for my db connector and director as my router.

Foi útil?

Solução

The result is already an array of bytes for the Image. You do not need to do any fancy transformations on it. This should work.

function sendResponse() {
    resG.writeHead(200, {'Content-Type': 'image/jpeg', 'Content-Length': result.length});

    resG.end(new Buffer(result));
}

or if you want to serve it as part of an HTML page, this:

function sendResponse() {
    resG.writeHead(200, {'Content-Type': 'text/html'});

    var vals = (new Buffer(result)).toString('base64')

    resG.end("<html><body>" +
        "<img src=\"data:image/jpg;base64," + vals + "\" />" +
        "</body></html>");
}
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