Tips for saving HTML Canvas content to Google Storage

My goal is to save the content of an HTML canvas to Google Storage. Here is my approach:

  1. Generate a signed URL for the image file.
class ThumbnailUploadSignedURL(APIView):
@method_decorator(login_required(login_url='/login/'))
    def post(self, request):
        filename = request.POST.get('filename')
        filetype = request.POST.get('type')
        filesize = request.POST.get('size', 0)
        path =  '{0}-{1}/{2}/'.format(request.user, request.user.id, thumbnail.name)
        blob = default_storage.open(full_path, 'wb')
        signed_url = blob.blob.generate_signed_url(expiration=default_storage.expiration, method='PUT', content_type='image/png')
        return Response({"thumbnail_signed_url":signed_url})
  1. Retrieve the canvas content and upload it to Google Storage.
var image = canvas.toDataURL("image/png");
const xhr = new XMLHttpRequest();
xhr.open("PUT", data.thumbnail_signed_url, true);
xhr.setRequestHeader('Content-Type', 'image/png');
xhr.send(image);

Although the file is successfully created on Google Storage, the content is reported as corrupt, likely due to being in base64 format.

I have attempted various methods to convert the base64 to PNG without success, including referencing this example of PHP-JS-canvas.

Any suggestions on how to accomplish this using JavaScript and Google Storage?

Answer №1

Discover the amazing canvas2image library that demonstrates how to convert canvas drawings into images.

Additionally, explore the Stackoverflow post that discusses drawing base64-encoded images onto a canvas using the drawImage() method if necessary.

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