Create label image for container

labelprinter/labels.py

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+"""Utilities for label generation.
+   stolen from: https://github.com/Edinburgh-Genome-Foundry/blabel
+"""
+import base64
+from io import BytesIO
+import datetime
+import textwrap
+from math import floor
+import barcode as python_barcode
+from PIL import Image, ImageDraw, ImageFont
+
+
+def now(fmt="%Y-%m-%d %H:%M"):
+    """Display the current time.
+    Default format is "year-month-day hour:minute" but another format can be
+    provided (see ``datetime`` docs for date formatting).
+    """
+    now = datetime.datetime.now()
+    if fmt is not None:
+        now = now.strftime(fmt)
+    return now
+
+
+def pil_to_html_imgdata(img, fmt='PNG'):
+    """Convert a PIL image into HTML-displayable data.
+
+    The result is a string ``data:image/FMT;base64,xxxxxxxxx`` which you
+    can provide as a "src" parameter to a ``<img/>`` tag.
+    Examples:
+    ---------
+    >>> data = pil_to_html_imgdata(my_pil_img)
+    >>> html_data = '<img src="%s"/>' % data
+    """
+    buffered = BytesIO()
+    img.save(buffered, format=fmt)
+    img_str = base64.b64encode(buffered.getvalue())
+    prefix = 'data:image/%s;charset=utf-8;base64,' % fmt.lower()
+    return prefix + img_str.decode()
+
+
+def wrap(text, col_width):
+    """Breaks the text into lines with at maximum 'col_width' characters."""
+    return "\n".join(textwrap.wrap(text, col_width))
+
+
+def container_label(data, barcode_class='code128', fmt='png', logo_file='./static/images/djlogo256.png',owner_name='Dirk Jahnke', description='', **writer_options):
+    """Return a barcode's image data.
+    Powered by the Python library ``python-barcode``. See this library's
+    documentation for more details.
+    Parameters
+    ----------
+    data
+      Data to be encoded in the datamatrix.
+    barcode_class
+      Class/standard to use to encode the data. Different standards have
+      different constraints.
+    fmt
+        The format to be used when rendering the resulting image
+        png -> png image
+        svg -> embeddable code for html img tag
+    logo_file
+        File path to logo file to be included
+    writer_options
+      Various options for the writer to tune the appearance of the barcode
+      (see python-barcode documentation).
+    Returns
+    -------
+    image_base64_data
+      A string ``data:image/png;base64,xxxxxxxxx`` which you can provide as a
+      "src" parameter to a ``<img/>`` tag.
+    Examples:
+    ---------
+    >>> data = barcode('EGF12134', barcode_class='code128')
+    >>> html_data = '<img src="%s"/>' % data
+    Examples of writer options:
+    >>> { 'background': 'white',
+    >>>   'font_size': 10,
+    >>>   'foreground': 'black',
+    >>>   'module_height': 15.0,
+    >>>   'module_width': 0.2,
+    >>>   'quiet_zone': 6.5,
+    >>>   'text': '',
+    >>>   'text_distance': 5.0,
+    >>>   'write_text': True
+    >>> }
+    """
+
+    with Image.open(logo_file) as logo_img:
+        font_size = 16
+        logo_img = logo_img.resize((128,128))
+        logo_img = logo_img.convert('L')
+        threshold = 20
+        logo_img = logo_img.point(lambda p: 255 if p < threshold else 0)
+        logo_img = logo_img.convert('1')
+        constructor = python_barcode.get_barcode_class(barcode_class)
+        data = str(data).zfill(constructor.digits)
+        writer = {
+            'svg': python_barcode.writer.ImageWriter,
+            'png': python_barcode.writer.ImageWriter
+        }[fmt]
+        barcode_img = constructor(data, writer=writer())
+        img = barcode_img.render(writer_options=writer_options)
+        barcode_xsize, barcode_ysize = img.size
+        logo_xsize, logo_ysize = logo_img.size
+        result_img = Image.new('1', (696, barcode_ysize+20), 1)
+        result_img.paste(logo_img, (0, floor(barcode_ysize/3)-floor(logo_ysize/2)))
+        start_x_for_barcode = logo_xsize + 10
+        max_x_for_barcode = 696 - start_x_for_barcode
+        result_img.paste(img, (start_x_for_barcode + floor((max_x_for_barcode-barcode_xsize)/2), 5))
+        # fnt = ImageFont.truetype("Pillow/Tests/fonts/FreeMono.ttf", 40)
+        fnt = ImageFont.truetype("./static/fonts/DejaVuSerif.ttf", font_size)
+
+        d = ImageDraw.Draw(result_img)
+        d.text((20,logo_ysize+40), owner_name, font=fnt)
+        d.text((30+floor((660-fnt.getlength(description))/2),barcode_ysize), description, font=fnt)
+
+        if fmt == 'png':
+            return pil_to_html_imgdata(result_img, fmt='PNG')
+        else:
+            prefix = "data:image/svg+xml;charset=utf-8;base64,"
+            return prefix + base64.b64encode(result_img).decode()