def serve_qr_code_image(request):
"""Serve an image that represents the requested QR code."""
qr_code_options = get_qr_code_option_from_request(request)
# Handle image access protection (we do not allow external requests for anyone).
check_image_access_permission(request, qr_code_options)
text = base64.urlsafe_b64decode(request.GET.get('text', ''))
img = make_qr_code_image(
text,
image_factory=SvgPathImage if qr_code_options.image_format
== SVG_FORMAT_NAME else PilImageOrFallback,
qr_code_options=qr_code_options)
# Warning: The largest QR codes, in version 40, with a border of 4 modules, and rendered in SVG format, are ~800
# KB large. This can be handled in memory but could cause troubles if the server needs to generate thousands of
# those QR codes within a short interval! Note that this would also be a problem for the CPU. Such QR codes needs
# 0.7 second to be generated on a powerful machine (2017), and probably more than one second on a cheap hosting.
stream = BytesIO()
if qr_code_options.image_format == SVG_FORMAT_NAME:
img.save(stream, kind=SVG_FORMAT_NAME.upper())
mime_type = 'image/svg+xml'
else:
img.save(stream, format=PNG_FORMAT_NAME.upper())
mime_type = 'image/png'
# Go to the beginning of the stream.
stream.seek(0)
# Build the response.
response = HttpResponse(content=stream, content_type=mime_type)
return response
def make_embedded_qr_code(text, qr_code_options=QRCodeOptions()):
"""
Generates a <svg> or <img> tag representing the QR code for the given text. This tag can be embedded into an
HTML document.
"""
image_format = qr_code_options.image_format
img = make_qr_code_image(text, SvgEmbeddedInHtmlImage if image_format == SVG_FORMAT_NAME else PilImageOrFallback, qr_code_options=qr_code_options)
stream = BytesIO()
if image_format == SVG_FORMAT_NAME:
img.save(stream, kind=SVG_FORMAT_NAME.upper())
html_fragment = (str(stream.getvalue(), 'utf-8'))
else:
img.save(stream, format=PNG_FORMAT_NAME.upper())
html_fragment = '<img src="data:image/png;base64, %s" alt="%s">' % (str(base64.b64encode(stream.getvalue()), encoding='ascii'), escape(text))
return mark_safe(html_fragment)