I finally decided to convert the base64 image to a Blob so it can be sent via an Ajax request with the formData object as follows.
It saves upload bandwidth (base64 takes 33% more bits than its binary equivalent) and I couldn’t find the reason for no transmission of base64 parameter (due to size limitation somewhere for sure).
The base64ToBlob function is based on this answer to another question.
function base64ToBlob(base64, mime)
{
mime = mime || '';
var sliceSize = 1024;
var byteChars = window.atob(base64);
var byteArrays = [];
for (var offset = 0, len = byteChars.length; offset < len; offset += sliceSize) {
var slice = byteChars.slice(offset, offset + sliceSize);
var byteNumbers = new Array(slice.length);
for (var i = 0; i < slice.length; i++) {
byteNumbers[i] = slice.charCodeAt(i);
}
var byteArray = new Uint8Array(byteNumbers);
byteArrays.push(byteArray);
}
return new Blob(byteArrays, {type: mime});
}
My JS code:
var url = "url/action";
var image = $('#image-id').attr('src');
var base64ImageContent = image.replace(/^data:image\/(png|jpg);base64,/, "");
var blob = base64ToBlob(base64ImageContent, 'image/png');
var formData = new FormData();
formData.append('picture', blob);
$.ajax({
url: url,
type: "POST",
cache: false,
contentType: false,
processData: false,
data: formData})
.done(function(e){
alert('done!');
});
In Symfony2 I can retrieve the image thanks to:
$picture = $request->files->get('picture');