Question

I have a folder full of html files created for a Kindle ebook. The images are coded with width and height, as per the Kindle guidelines:

<img width="328" height="234" src="images/224p_fmt.jpeg" alt="224p.tif"/>

What I need to create/find is a script that will process all the image tags, multiply the width an height attributes by a specified amount (coded into the script) and write them back into the html files.

So, for the above example, say I want to multiply by 1.5, and wind up with

<img width="492" height="351" src="images/224p_fmt.jpeg" alt="224p.tif"/>

Scripts like this are not my forte, so help appreciated. I especially am unclear on how to write a script that I can run on file(s) from the command line and just input/output html.

I assume the meat of the code would be something like

s/<img width="([0-9]+)" height="([0-9]+)" src="(.*?)" alt=".*"/>/'<img width="'.$1*1.5.'" height="'.$2*1.5.'" src="'.$3.'" alt=""/>'/eg;

Which I realize is incorrect (the multiplication part) which is why help appreciated.

Answer 1

In Python I’d do it like this.

import sys, re

source = sys.stdin.read()
def multi(by):
  def handler(m):
    updated = int(m.group(2)) * by
    return m.group(1) + str(updated)
  return handler

print re.sub(r'((?:width|height)=["\'])(\d+)', multi(1.5), source)

Then you can handle input and output on the command like using < and >.

$ python resize.py < index.html > new_file.html