[MacPorts] #38730: octave-devel @3.6.3 GraphicsMagick limits images to 8 bits per pixel

[MacPorts]

#38730: octave-devel @3.6.3 GraphicsMagick limits images to 8 bits per pixel
---------------------------+--------------------------------
  Reporter:  cwr@…         |      Owner:  macports-tickets@…
      Type:  defect        |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:  2.1.3
Resolution:                |   Keywords:
      Port:  octave-devel  |
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Comment (by ryandesign@…):

 ImageMagick, from which GraphicsMagick was forked some years ago, also
 supports these pixel quantum sizes, but its default is 16 bits.

 The ImageMagick libraries build differently depending on the pixel quantum
 depth, and therefore so do any programs that link against those libraries.
 This causes problems, as I discussed with the ImageMagick developers
 [http://www.imagemagick.org/discourse-
 server/viewtopic.php?f=2&t=22932&p=95966 here]. Consider that our buildbot
 builds ports with the default variants, so ImageMagick on the buildbot was
 built with q16. And therefore any other ports that link with ImageMagick
 libraries were built on the buildbot linked with q16 ImageMagick
 libraries. Now imagine a user installs ImageMagick q8. Since that's not
 the default variant, there's no binary for it on our server, so it builds
 from source on the user's system. Next, the user installs some program X
 that uses ImageMagick libraries. Ports that use ImageMagick don't have q8,
 q16 and q32 variants; they just assume ImageMagick is ImageMagick. So the
 user could receive a binary of X that was built on the buildbot using q16,
 and that program will now behave incorrectly because it was built for q16
 libraries but is now running with q8 libraries. Therefore, in the next
 [ticket:38134 ImageMagick port update], I will remove the possibility to
 select the pixel quantum depth and always use the default of 16. The
 alternative is to completely redesign the ImageMagick port, including
 splitting it into subports for each pixel quantum depth and revising the
 dependencies of every port using ImageMagick. I thought about doing this,
 but it's so much work. Another possible solution is to add q8, q16 and q32
 variants to every port that uses ImageMagick libraries, but that's a mess
 too.

 I do not yet know if the GraphicsMagick libraries also vary depending on
 pixel quantum depth but I assume they do. If they do, they're affected by
 the same problem, so I should remove the possibility to change the pixel
 quantum size from the GraphicsMagick port as well.

-- 
Ticket URL: <https://trac.macports.org/ticket/38730#comment:4>
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