Page size issue PDF creation of barcodes using reportlab

Okay i created a script today that takes an item# or any number for that purpose to generate a barcode. Now i wanted to print 60 same barcodes in 4 columns, that would make it a matrix of (15 X 4) only making it easy to understand. Now i successfully achieved it with a custom sized page (900*850) and fitted in 15 rows and 4 columns of barcodes generated by reportlab code128.

Here is the code:

from reportlab.graphics.barcode import code128
from reportlab.lib.units import mm
from reportlab.pdfgen import canvas

#----------------------------------------------------------------------#
def createBarCodes():
    codeName = "NOT_C17"

    c = canvas.Canvas(codeName+".pdf")
    c.setPageSize((900, 850))

    barcode_value = codeName
    barcode128 = code128.Code128(
                            barcode_value,
                            barHeight=20,
                            barWidth=1.05,
                            fontSize=15,
                            humanReadable = True
                        )

    x = 15 * mm
    for i in range(4):
        y = 275 * mm
        i=0
        while i < 15:
            barcode128.drawOn(c, x, y)
            y = y - 18 * mm
            i+=1
        x=x+(70*mm)
    c.save()

if __name__ == "__main__":
    createBarCodes()

A file generated by this script

The issue is that now I am restricted to using only US Letter size and no other custom size. I tried few variations but none worked.

Tries:

from reportlab.lib.pagesizes import letter
c = canvas.Canvas(codeName+".pdf", pagesize=letter)

barcode_value = codeName
barcode128 = code128.Code128(
                          barcode_value,
                          barHeight=16.7564*mm,
                          barWidth=44.45*mm,
                          fontSize=15,
                          humanReadable = True
                     )

x = 7.526 * mm
for i in range(4):
    y = 265.524 * mm
    i=0
    while i < 15:
        barcode128.drawOn(c, x, y)
        y = y - 18 * mm
        i+=1
        break
    x=x+(70*mm)
    break
c.save()

and here is the required format that it must fit in. Would be nice to have to help.

Solution

You code requires a lot of improvement

Use the letter size from reportlab.lib.pagesizes import letter

Set your margins and other variables as specified in the document :

margin_x        =  7.526
margin_y        =  13.876
padding_x       =  7.526
font_size       =  15
width, height   =  letter

Calculate the total size of the generated codebar

bars_width   = (float(width-margin_x*2)-3*padding_x)/4
bars_height  = float(height-margin_y*2)/15

The width value passed to the function Code128 is the width of a single bar within the codebar and not the whole codebar, you should keep this value below 1.1
```
bar_height   = bars_height - font_size
bar_width    = 1
```

your loops would be better this way :

for i in range(0,4):
    for j in range(0,15):
        x = margin_x + i * (bars_width+padding_x)
        y = margin_y + j * bars_height
        barcode128.drawOn(c, x , y)

this is the final script :

from reportlab.graphics.barcode import code128
from reportlab.lib.units import mm
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import letter

#----------------------------------------------------------------------#
def createBarCodes():
    codeName = "NOT_C17"

    c = canvas.Canvas(codeName+".pdf",pagesize=letter)

    margin_x        =  7.526
    margin_y        =  13.876
    padding_x       =  7.526
    font_size       =  15
    width, height   =  letter
    extra_padding   =  20

    bars_width   = (float(width-margin_x*2)-3*padding_x)/4
    bars_height  = float(height-margin_y*2)/15

    bar_height   = bars_height - font_size
    #For alphanumeric values, the total number of bars is calculated as:
    #total = (11*string_length+35)
    bar_width    = (bars_width-extra_padding)/(len(codeName)*11+35)


    barcode_value = codeName
    barcode128 = code128.Code128(
                            barcode_value,
                            barHeight=bar_height,
                            barWidth=bar_width,
                            humanReadable = True
                        )

    for i in range(0,4):
        for j in range(0,15):
            x = margin_x + i * (bars_width+padding_x)
            y = margin_y + j * bars_height
            barcode128.drawOn(c, x , y)

    c.save()

if __name__ == "__main__":
    createBarCodes()