Creating image from base64 string in NodeJS

问题

I am trying to upload an image that I extract from a my canvas and post via ajax, and I have trouble creating the image file on my server side.

I have following this answer: https://stackoverflow.com/a/7347358/1358670 but still I seem to miss something here or there.

Here is my javascript (browser) code:

var img = myCanvas.toDataURL("image/jpeg");

// ajax request to send the image

and in server side, I do the following:

var fd =  fs.openSync('./img.jpeg', 'w');
req.body.image = req.body.image.replace(/^data:image\/\w+;base64,/, "");
console.log( req.body.image );

var buff = new Buffer(req.body.image, 'base64');
fs.write(fd, buff, 0, buff.length, 0, function(err,written){
    console.log( ">> "+ err );
    fs.closeSync( fd );
});

As you can see, I've logged the image to see if it was properly sent, and IT IS, but still I can't open the created img.jpeg file

any help or hint is very welcome.

---

EDIT

I've also tried the solution in here: https://stackoverflow.com/a/6933413/1358670 but I still have the same problem

---

EDIT:2

I've tested my front-end side, with a PHP script in the server side, and the image produced was very good, so I would conclude that the problem is in my NodeJS code.

回答1:

The problem was in the treatment on NodeJS, and I didn't doubt the code since it was the same every where with people commenting that its worked for them, nothing were different so I didn't doubt the process, but either something done wrong.

When checking it in my PHP script I've found a step that is not in the NodeJS code, and here is the PHP code:

$img = $_POST[ 'image' ];

$img = str_replace('data:image/jpeg;base64,', '', $img);
$img = str_replace(' ', '+', $img);

$data = base64_decode($img);
$file = "./". uniqid() . '.png';
$success = file_put_contents($file, $data);
print $success ? $file : 'Unable to save the file.';

The difference is here: str_replace(' ', '+', $img);

I don't know how it worked for others, but for me replacing EVERY space in the base64 by + solved my problem.

---

New NodeJS code

req.body.image = req.body.image.replace(/^data:image\/\w+;base64,/, "");
req.body.image = req.body.image.replace(/ /g, '+');
console.log( req.body.image );

var buff = new Buffer(req.body.image, 'base64');
fs.write(fd, buff, 0, buff.length, 0, function(err,written){
    console.log( ">> "+ err );
    fs.closeSync( fd );
});

I hope this will help someone else

---

A better version of the code:

req.body.image = req.body.image.replace(/^data:image\/jpeg+;base64,/, "");
req.body.image = req.body.image.replace(/ /g, '+');

fs.writeFile('./records/'+model+'/out.jpeg', req.body.image, 'base64', function(err) {
    console.log(err);
});

来源：https://stackoverflow.com/questions/22687939/creating-image-from-base64-string-in-nodejs