Add util functions to generate qr codes for urls

changelog.d/2887.added.md

@@ -0,0 +1 @@
+Add library utilities to produce QR codes to arbitrary URLs, for use in upcoming features

python/nav/web/utils.py

@@ -14,12 +14,18 @@
 # along with NAV. If not, see <http://www.gnu.org/licenses/>.
 #
 """Utils for views"""
+import base64
+import io
+import os
+from typing import Dict, List
 
 from django.http import HttpResponse
-
-
 from django.views.generic.list import ListView
 
+import qrcode
+from PIL import ImageDraw, ImageFont
+import qrcode.image.pil
+
 
 def get_navpath_root():
     """Returns the default navpath root
@@ -51,6 +57,7 @@ def require_param(parameter):
 
     Will check both GET and POST querydict for the parameter.
     """
+
     # pylint: disable=missing-docstring
     def wrap(func):
         def wrapper(request, *args, **kwargs):
@@ -64,3 +71,58 @@ def wrapper(request, *args, **kwargs):
         return wrapper
 
     return wrap
+
+
+def generate_qr_code(url: str, caption: str = "") -> io.BytesIO:
+    """
+    Generate a QR code from a given url, and, if given, adds a caption to it
+
+    Returns the generated image as a bytes buffer
+    """
+    # Creating QR code
+    qr = qrcode.QRCode(box_size=10)
+    qr.add_data(url)
+    img = qr.make_image()
+    draw = ImageDraw.Draw(img)
+
+    # Adding caption
+    if caption:
+        img_width, img_height = img.size
+        font_path = os.path.join(os.path.dirname(__file__), "static/fonts/OS600.woff")
+        if len(caption) < 25:
+            font = ImageFont.truetype(font_path, 25)
+        elif len(caption) < 50:
+            font = ImageFont.truetype(font_path, 15)
+        else:
+            font = ImageFont.truetype(font_path, 10)
+        caption_width = font.getlength(caption)
+        draw.text(
+            ((img_width - caption_width) / 2, img_height - 40),
+            text=caption,
+            font=font,
+            fill="black",
+        )
+
+    file_object = io.BytesIO()
+    img.save(file_object, "PNG")
+    img.close()
+
+    return file_object
+
+
+def convert_bytes_buffer_to_bytes_string(bytes_buffer: io.BytesIO) -> str:
+    return base64.b64encode(bytes_buffer.getvalue()).decode('utf-8')
+
+
+def generate_qr_codes_as_byte_strings(url_dict: Dict[str, str]) -> List[str]:
+    """
+    Takes a dict of the form {name:url} and returns a list of generated QR codes as
+    byte strings
+    """
+    qr_code_byte_strings = []
+    for caption, url in url_dict.items():
+        qr_code_byte_buffer = generate_qr_code(url=url, caption=caption)
+        qr_code_byte_strings.append(
+            convert_bytes_buffer_to_bytes_string(bytes_buffer=qr_code_byte_buffer)
+        )
+    return qr_code_byte_strings

requirements/base.txt

@@ -9,7 +9,9 @@ pyaml
 twisted~=23.8.0  # last version that still supports Python 3.7
 
 networkx==2.6.3
+# Cannot be removed as long as qrcode is included 
 Pillow>3.3.2
+qrcode>7.4
 pyrad==2.1
 sphinx==5.3.0
 sphinxcontrib-programoutput==0.17

tests/unittests/web/qrcode_test.py

@@ -0,0 +1,16 @@
+import io
+
+from nav.web.utils import generate_qr_code, generate_qr_codes_as_byte_strings
+
+
+def test_generate_qr_code_returns_byte_buffer():
+    qr_code = generate_qr_code(url="www.example.com", caption="buick.lab.uninett.no")
+    assert isinstance(qr_code, io.BytesIO)
+
+
+def test_generate_qr_codes_as_byte_strings_returns_list_of_byte_strings():
+    qr_codes = generate_qr_codes_as_byte_strings(
+        {"buick.lab.uninett.no": "www.example.com"}
+    )
+    assert isinstance(qr_codes, list)
+    assert isinstance(qr_codes[0], str)