Saving Image in a temporary file in django

Question

I am very new in python and django.I have developed a project using django. Here all the images are watermarked.I have watermarked all the images using the following code...

from PIL import Image
    def image_watermark(request,image_id):
        photo = Photo.objects.get(pk=image_id)
        watermark = Image.open('{0}/{1}'.format(settings.MEDIA_ROOT,'wmark.png'))
        img = Image.open(photo.photo.file)

        img.paste(watermark,(img.size[0]-watermark.size[0],img.size[1]- watermark.size[1]),watermark)

        img.save('{0}/{1}'.format(settings.MEDIA_ROOT,photo.photo.name), quality=80)


        wrapper = FileWrapper(open(photo.photo.url, 'rb'))
        response = StreamingHttpResponse(wrapper, 'image/jpeg')
        response['Content-Length'] = os.path.getsize(photo.photo.url)
        response['Content-Disposition'] = 'attachment; filename=photo.jpg'
        return response

all of my images are watermarked now.But the problem is,as a user ,if i download these images,i found that the downloaded images are also watermarked,but i want to download the actual image,not the watermarked image,how can i solve the problem?

Answer 1

You need to store the watermarked image into a different file. First you need to create another column to store the Watermarked image.

class Photo(models.Model):
    ...
    watermarked_photo = ImageField()

Then when you save the watermarked image into that column.

from PIL import Image
def image_watermark(request,image_id):
    photo = Photo.objects.get(pk=image_id)

    # Only need to watermark when there's no watermark
    if not photo.watermarked_photo.name:
        photo.watermarked_photo.name = 'watermarked_' + photo.photo.name
        watermark = Image.open('{0}/{1}'.format(settings.MEDIA_ROOT,'wmark.png'))
        img = Image.open(photo.photo.file)
        img.paste(watermark,(img.size[0]-watermark.size[0],img.size[1]- watermark.size[1]),watermark)
        img.save('{0}/{1}'.format(settings.MEDIA_ROOT, photo.watermarked_photo.name), quality=80)
        photo.save()

    wrapper = FileWrapper(open(photo.watermarked_photo.url, 'rb'))
    response = StreamingHttpResponse(wrapper, 'image/jpeg')
    response['Content-Disposition'] = 'attachment; filename=photo.jpg'
    return response

My Django skill is a bit rusty, so this code might not work without some modification. But the idea should be solid.

If you only want to use a temp file, then try this

from PIL import Image
import tempfile

def image_watermark(request,image_id):
    photo = Photo.objects.get(pk=image_id)
    watermark = Image.open('{0}/{1}'.format(settings.MEDIA_ROOT,'wmark.png'))
    img = Image.open(photo.photo.file)
    img.paste(watermark,(img.size[0]-watermark.size[0],img.size[1]- watermark.size[1]),watermark)

    tmpfile = tempfile.TemporaryFile()
    img.save(tmpfile, img.format, quality=80)

    tmpfile.seek(0)
    wrapper = FileWrapper(tmpfile)
    response = StreamingHttpResponse(wrapper, 'image/jpeg')
    response['Content-Disposition'] = 'attachment; filename=photo.jpg'
    return response