NodeJS base64 image de codage/décodage pas assez de travail

Je pense que vous êtes de malentendu sur l'utilisation de l'encodage argument un peu. Si vous allez spécifier le codage binaire', alors vous avez besoin de le faire de manière cohérente. Mais vraiment, vous n'avez pas besoin du tout. Vous semblez confondre l'utilisation de Tampon vs chaînes binaires.

//This tells node to load the file into a Buffer 'original_data' because you
//have not specified an encoding for the returned values. If you provided an
//encoding, then original_data would be a string with that encoding.
fs.readFile(image_origial, function(err, original_data){

    //This tells node to take that buffer, and write it to the new filename.
    //Again no encoding is provided, so it will assume a Buffer or utf8 string.
    fs.writeFile('image_orig.jpg', original_data, function(err) {});

    //This tells node to create a new buffer from the old buffer, which means
    //it will iterate over original_data copying the bytes one at a time. But
    //they will be identical buffers. It will ignore the 'binary' argument
    //since the object you are passing isn't a string.
    //Then it encodes the content of that Buffer to base64, which is fine.
    var base64Image = new Buffer(original_data, 'binary').toString('base64');

    //Here you decode the base64 to a buffer, which is fine, but then you
    //convert the buffer into a string with encoding 'binary'. This means that
    //it is a string object whose code points are bytes of the buffer.
    var decodedImage = new Buffer(base64Image, 'base64').toString('binary');

    //Here you try to write that String object to a file. Since the argument you
    //have given is a string and you have not given an encoding argument for the
    //write command, then it will assume that 'utf8' is the encoding. It will try to
    //decode your binary string into a utf8 encoded buffer, and write that buffer.
    //This will cause it to fail because that encoding conversion is wrong.
    //Really through, 'binary' is just wrong to use. Buffers are already binary.
    fs.writeFile('image_decoded.jpg', decodedImage, function(err) {});
});

L'exemple suivant fonctionne, mais est très inefficace car le changement de codages tout le temps n'est pas nécessaire, mais je veux juste montrer à être clair. Si vraiment vous NE voulez avoir un codage spécifique, vous devez vous assurer que vous êtes cohérent. Chacune de ces fonctions a l'encodage d'un argument.

fs.readFile(image_origial, 'binary', function(err, original_data){
    fs.writeFile('image_orig.jpg', original_data, 'binary', function(err) {});
    var base64Image = new Buffer(original_data, 'binary').toString('base64');
    var decodedImage = new Buffer(base64Image, 'base64').toString('binary');
    fs.writeFile('image_decoded.jpg', decodedImage, 'binary', function(err) {});
});

C'est la bonne façon de le faire. Tout garder comme un Tampon, sauf lorsque vous le faites en base64.

fs.readFile(image_origial, function(err, original_data){
    fs.writeFile('image_orig.jpg', original_data, function(err) {});
    var base64Image = original_data.toString('base64');
    var decodedImage = new Buffer(base64Image, 'base64');
    fs.writeFile('image_decoded.jpg', decodedImage, function(err) {});
});