Depend on supported and tested libpng versions

Let me know if there are any blockers to merging my patch.

Hi Joe, thanks for the patch.

As far as I am aware, libpng doesn't provide any backward compatibility guarantee. The code works with 1.2, but, e.g., for 1.5 we need the change you propose in the other bug. There is no guarantee that the code will continue to work with libpng > 1.5 without further changes.

Therefore, depending on libpng >= 1.2 is not reliable enough; we need to explicitly depend on tested libpng versions (1.2 or 1.5 or any other tested version).

> Therefore, depending on libpng >= 1.2 is not reliable enough; we need to
> explicitly depend on tested libpng versions (1.2 or 1.5 or any other tested version).

To be clear, I don't mean depend on a single supported version, but ensure that we are building with any one of the supported and tested versions.

Thanks afrantzis.

This rev of the patch replaces the req_pkgs logic, checking for tested/supported libpng versions, with the assumption that libpng continues providing libpngXY.pc files in subsequent major releases:

http://bazaar.launchpad.net/~jbkonno/+junk/glmark2/revision/269

How about:

for pkg in supp_png_pkgs:
        try:
            ctx.check_cfg(package=pkg, uselib_store='libpng', args = ['--cflags', '--libs'])
        except:
            pass
        else:
            have_png = True
            break

This way we only check for the package once (and get saner config output).

Do we need an atleast_version in there somewhere? That's what I was playing with in my version of the patches.

Thanks afrantzis, jesse-barker. Updated my patch blending both of your suggestions:

http://bazaar.launchpad.net/~jbkonno/+junk/glmark2/revision/269

Feedback appreciated. Cheers.

Feedback? Cheers.

Hi Joe, sorry for the delay. Commit applied as rev 270 in trunk.