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Reproducible PDF creation breaks when you add a background-image to your CSS #1666

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DutchGerman opened this issue Jun 29, 2022 · 1 comment
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Reproducible PDF creation breaks when you add a background-image to your CSS #1666

DutchGerman opened this issue Jun 29, 2022 · 1 comment
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bug Existing features not working as expected
Milestone
56.0

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@DutchGerman
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In build v55.0b1 a feature to generate reproducible PDFs was added.

SOURCE_DATE_EPOCH is set to 0

With the following python code

  from weasyprint import HTML, CSS
  import hashlib

  html = """
    <html>
      <head>
        <title>Hello World</title>
        <meta name="dcterms.created" content="2002-01-01">
      </head>
      <body>
        <p>Foobar</p>
      </body>
    </html>
  """
  
  css = """
    body {
      color: #515151;
    }
  """
  
  pdf = HTML(string=html).write_pdf(stylesheets=[CSS(string=css)])
  md5 = hashlib.md5(pdf).hexdigest()
  print(md5)

It runs correctly and outputs the hash 92ae45e4db7a51b1941cd98e8b4c1c8b consistently

But when I add a background-image to the body like so:

  from weasyprint import HTML, CSS
  import hashlib

  html = """
    <html>
      <head>
        <title>Hello World</title>
        <meta name="dcterms.created" content="2002-01-01">
      </head>
      <body>
        <p>Foobar</p>
      </body>
    </html>
  """
  
  css = """
    body {
      color: #515151;
      background-image: url("https://i.imgur.com/o3v4JUp.png");
    }
  """
  
  pdf = HTML(string=html).write_pdf(stylesheets=[CSS(string=css)])
  md5 = hashlib.md5(pdf).hexdigest()
  print(md5)

The output changes with every pass.

1#: bc1c85fdaa77406c185dcab8a94e0602
2#: 88f96791669a895f2a4ff7315613d5d1
3#: c6cc5cf67671110b9c4b64d83f16d263

I also tried to add a base64 background like so:

  css = """
    body {
      color: #515151;
      background-image: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY/j//z8ABf4C/qc1gYQAAAAASUVORK5CYII=')
    }
  """

Which results it the same behavior
@liZe liZe added the bug Existing features not working as expected label Jun 29, 2022
@liZe liZe added this to the 56.0 milestone Jun 29, 2022
@liZe liZe closed this as completed in 00d5b03 Jun 29, 2022
@liZe
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liZe commented Jun 29, 2022

Hi, and thanks a lot for this bug report!

The problem comes from the hash() function that’s not stable. Using md5 instead works well.

Unfortunately, I didn’t find a nice way to test this. If anyone has a good idea, don’t hesitate to open a PR!

netbsd-srcmastr referenced this issue in NetBSD/pkgsrc Jul 9, 2022
@kleink
py-weasyprint: Update to 56.0.
cd63ab5 
Version 56.0
------------

Released on 2022-07-07.

This version also includes the changes from unstable b1 version listed
below.

New features:

* `70f9b62 <https://github.com/Kozea/WeasyPrint/commit/70f9b62>`_:
  Support format 5 for bitmap glyphs

Bug fixes:

* `1666 <https://github.com/Kozea/WeasyPrint/issues/1666>`_
  Fix reproducible PDF generation with embedded images
* `1668 <https://github.com/Kozea/WeasyPrint/issues/1668>`_:
  Fix @page:nth() selector
* `3bd9a8e <https://github.com/Kozea/WeasyPrint/commit/3bd9a8e>`_:
  Don’t limit the opacity groups to the original box size
* `cb9540b <https://github.com/Kozea/WeasyPrint/commit/cb9540b>`_,
  `76d174f <https://github.com/Kozea/WeasyPrint/commit/76d174f>`_,
  `9ce6547 <https://github.com/Kozea/WeasyPrint/commit/9ce6547>`_:
  Minor bugfixes for split table rows
@endelwar endelwar mentioned this issue May 10, 2023
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