TypeError: a bytes-like object is required, not 'Drawing'

Question

I am trying to convert an Alpha-Numeric Value to PNG and then in ZPL format. Both of them have different libraries and when used independently they work fine. Look at the code:

from base64 import b64encode
from reportlab.lib import units
from reportlab.graphics import renderPM
from reportlab.graphics.barcode import createBarcodeDrawing
from reportlab.graphics.shapes import Drawing
import os

def get_barcode(value, width, barWidth = 0.05 * units.inch, fontSize = 30, humanReadable = True):

    barcode = createBarcodeDrawing('Code128', value = value, barWidth = barWidth, fontSize = fontSize)

    drawing_width = width
    barcode_scale = drawing_width / barcode.width
    drawing_height = barcode.height * barcode_scale
    drawing = Drawing(drawing_width, drawing_height)
    drawing.scale(barcode_scale, barcode_scale)
    drawing.add(barcode, name='barcode')

    return drawing

sku = []      #rough data
path = r'C:\Users\Rahul\Desktop\Barcodes'
for i in range(0,10):
    sku.append('A10{}'.format(i)) 

for i in sku:
    barcode = get_barcode(value = i, width = 600)
    barcode.save(formats=['PNG'],outDir=path,fnRoot=i)

This generates barcodes in PNG Format and now the conversion to ZPL is like this:

from zplgrf import GRF
with open(r'C:\Users\Rahul\Desktop\Barcodes\A100.png','rb') as image:
    grf = GRF.from_image(image.read(), 'DEMO')
grf.optimise_barcodes()
print(grf.to_zpl())

Output:

~DGR:DEMO.GRF,5400,75,:Z64:eJztlrENxSAMRI8qJSMwCpv9hM0YhRFSUnxxQelSfn0jEXQuaECW3/kMAHdsTBUfwNWQEQhEeDbEtmVHJhZXEVn2b1+ZydI8j36whr6HR3i7VIZV/ZPqXB3QsIPnsKomARznKwEKUIACFOAkWgnwdYCGFl3+JyPAtwMaVqVnQreoZnAqX60HOE6r9QANO6gZ/F2rCxESD8A=:4C36^XA^MMC,Y^PON^MNY^FO0,0^XGR:DEMO.GRF,1,1^FS^PQ1,0,0,N^XZ^XA^IDR:DEMO.GRF^FS^XZ

What I want to do is eliminate the process of saving the file and then reading it again for the conversion so I did this:

for i in sku:
    barcode = get_barcode(value = i, width = 600)
    barcode.save(formats=['PNG'],fnRoot=i)
    print(barcode)
    grf = GRF.from_image(barcode, 'DEMO')
    grf.optimise_barcodes()
    print(grf.to_zpl())

but I get the following error:

TypeError: a bytes-like object is required, not 'Drawing'

How can I convert the following object into "bytes-like" object??

<reportlab.graphics.shapes.Drawing object at 0x000001BF2C59DF28>

Error:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-14-2b88439d6661> in <module>
      3     barcode.save(formats=['PNG'],fnRoot=i)
      4     print(barcode)
----> 5     grf = GRF.from_image(barcode, 'DEMO')
      6     grf.optimise_barcodes()
      7     print(grf.to_zpl())

~\Anaconda3\lib\site-packages\zplgrf\__init__.py in from_image(cls, image, filename)
    354         """
    355 
--> 356         source = Image.open(BytesIO(image))
    357         source = source.convert('1')
    358         width = int(math.ceil(source.size[0] / 8.0))

TypeError: a bytes-like object is required, not 'Drawing'

@dspencer Updated the question with complete error message – Rahul Sharma Mar 16 '20 at 09:58 — Rahul Sharma, Mar 16 '20 at 09:58

dspencer · Accepted Answer · 2020-03-16T10:59:57.953

3

To call GRF.from_image, you need to pass a bytes-like object. Currently, you have saved your Drawing as a png file, then pass that the the function. Instead, you should open the saved png file and pass the read object to from_image like:

with open(barcode_file, "rb") as image:
    grf = GRF.from_image(image.read(), "DEMO")
os.remove(barcode_file)

where barcode_file is the path to which your Drawing was saved. os.remove can be used to remove the temporary file after it has been read.

To avoid creating a temporary file like this, you could use the asString method of the Drawing class and pass the result to from_image:

grf = GRF.from_image(barcode.asString("png"), "DEMO")

edited Mar 16 '20 at 10:59

answered Mar 16 '20 at 10:17

dspencer

4,297
4
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43

I ended up on the same solution like this: `a = barcode.save(formats=['PNG'],fnRoot=i) with open(a,'rb') as image: grf = GRF.from_image(image.read(), str(i)) grf.optimise_barcodes()` – Rahul Sharma Mar 16 '20 at 10:19
1

But as I stated in the question, I don't want to save the image at all, in this case the image is being saved, However can we do something like "save the image, read the image and delete the image" ? – Rahul Sharma Mar 16 '20 at 10:21

TypeError: a bytes-like object is required, not 'Drawing'

1 Answers1