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find_scale(): better document why we use powers of 10

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Johannes Schauer Marin Rodrigues 2022-03-24 12:43:49 +01:00
parent 244f034a2e
commit 7c48bfb868
Signed by: josch
GPG key ID: F2CBA5C78FBD83E1
1 changed files with 5 additions and 1 deletions
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src/img2pdf.py
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@ -2147,7 +2147,11 @@ def get_fixed_dpi_layout_fun(fixed_dpi):
def find_scale(pagewidth, pageheight): def find_scale(pagewidth, pageheight):
"""Find the power of 10 (10, 100, 1000...) that will reduce the scale """Find the power of 10 (10, 100, 1000...) that will reduce the scale
below the PDF specification limit of 14400 PDF units (=200 inches)""" below the PDF specification limit of 14400 PDF units (=200 inches).
In principle we could also choose a scale that is not a power of 10.
We use powers of 10 because numbers in the PDF format are represented
in base-10 and using powers of 10 will thus just shift the comma and
keep the numbers easily readable by humans as well."""
from math import log10, ceil from math import log10, ceil
major = max(pagewidth, pageheight) major = max(pagewidth, pageheight)