Saving DDS "with existing mipmaps" should be possible for non-quadratic images

[GoogleCodeExporter]

What steps will reproduce the problem?

  1. make/load a non-quadratic dds image with mipmaps (for example aspect ratio 1:2)
  2. try to save it
  3. try to select "use existing mipmaps": its grayed out

What is the expected output? What do you see instead?

  It should be possible to use existing mipmaps - to be able to correct distortions of mipmaps produced after a previous step of creating them automatically.

What version of the product are you using? On what operating system?

  GIMP 2.8.10; GIMP-DDS 3.0.1

Please provide any additional information below.

Original issue reported on code.google.com by [email protected] on 19 May 2014 at 3:55

[GoogleCodeExporter]

This has been reported as debian bug #731486
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=731486

The author of the bug report said it is due to "when exporting existing layers 
as mipmaps it validates the layers by looking for a chain with each successive 
layer being half the size of the previous, using a bitshift for a fast divide 
by 2, so when looking for the next layer after 2x1 it would try to find 1x0 and 
fail."

Original comment by [email protected] on 25 May 2014 at 12:54