在Node.js和ImageMagick中使用远程图像

Question

How can I use remote image in ImageMagick with Node.JS?

I want to achieve something like:

im.identify('http://www.website.com/image.jpg', function(error, features) {
    console.log(features);
});

Answer 1

A quick code snippet of image resizing

http://nodejs.org/api/http.html
https://github.com/rsms/node-imagemagick

var thumb = '';

...

var request = http.get(options, function(response) {

    var data = '';

    response.setEncoding('binary');

    response.on('data', function(chunk) {
        data += chunk;
    });

    response.on('end', function () {

        im.resize({
            srcData: data,
            width: 100,
            height: 75,
            format: 'jpg'
        }, function(err, stdout, stderr) {
            if (err) throw err;
            thumb = stdout;
        });
    }

});

Answer 2

This is how I use remote images:

var srcUrl = 'http://domain.com/path/to/image.jpg';
var http = srcUrl.charAt(4) == 's' ? require("https") : require("http");
var url = require("url");

http.get(url.parse(srcUrl), function(res) {

    if(res.statusCode !== 200) {
        throw 'statusCode returned: ' + res.statusCode;
    }
    else {
        var data = new Array;
        var dataLen = 0;

        res.on("data", function (chunk) {
            data.push(chunk);
            dataLen += chunk.length;
        });

        res.on("end", function () {
            var buf = new Buffer(dataLen);
            for(var i=0,len=data.length,pos=0; i<len; i++) {
                data[i].copy(buf, pos);
                pos += data[i].length;
            }

            im(buf).imFunctionYouWantToUse();
        });
    }
});

Credit go to https://stuk.github.io/jszip/documentation/howto/read_zip.html

Answer 3

It's hard to say if i understood you correctly (considering the amount of information you posted here).

The only way you can perform operations on a remote image using imagemagick is to download it to the local server first. This can be done using the http.ClientRequest class of node.js, afterwards you should be able to operate on the image as usual using Imagemagick.

Answer 4

This should work:

var request = require('request');
var fs = require('fs');

request({
        'url': 'http://www.website.com/image.jpg',
        'encoding':'binary'
    }, 
    function (error, response, body) {
        if (!error && response.statusCode == 200) {
            fs.writeFileSync('/mylocalpath/image.jpg', body, 'binary');
            im.identify('/mylocalpath/image.jpg',
                function(error, features) {
                    console.log(features);
                 }
            );
        }else{
            console.error(error, response);
        }
    }
)