[Scons-dev] Documentation in EPUB-format

[Andrew Featherstone]

On 10/10/2013 12:59 AM, William Deegan wrote:

> All,

>

> On Oct 9, 2013, at 3:38 PM, Andrew Featherstone <andrew.featherstone at cantab.net> wrote:

>

>> On 10/09/2013 09:18 AM, Dirk Bächle wrote:

>>> Andrew,

>>>

>>> thanks for the update on your progress. Sounds good so far...

>>>

>>> On 09.10.2013 00:26, Andrew Featherstone wrote:

>>>> Hi Dirk,

>>>>

>>>> Yes my tool takes care of zipping up and formatting the container correctly. Unfortunately the SCons Zip builder method doesn't support source files with different compression types; perhaps that's a separate feature that could be added. For now I'm using the Python zipfile module directly and achieving what's required.

>>>>

>>> I had a look at the Zip Builder too. From what I understood you should be able to call it repeatedly, such that you append files to an already existing archive. Wouldn't this open the possibility of specifying different compression modes then?

>> Whilst that's true, I can't get the desired results. As a simple example where foo.txt and bar.txt are two files to be compressed using different compression algorithms

>>

>> # SConstruct

>> import zipfile

>> Zip('out', 'foo.txt', ZIPCOMPRESSION=zipfile.ZIP_STORED)

>> Zip('out', 'bar.txt', ZIPCOMPRESSION=zipfile.ZIP_DEFLATED)

>>

>> $ scons

>> scons: Reading SConscript files ...

>>

>> scons: *** Two environments with different actions were specified for the same target: out.zip

>>

>> Creating a intermediate target doesn't help, as the result is simply nested zip archives. E.g.

>>

>> # SConstruct

>> import zipfile

>> Zip('tmp', 'foo.txt', ZIPCOMPRESSION=zipfile.ZIP_STORED)

>> Zip('outer', ['bar.txt', 'tmp.zip'], ZIPCOMPRESSION=zipfile.ZIP_DEFLATED)

>>

>> results in outer.zip containing bar.txt compressed using the deflate algorithm, and an archive containing a single uncompressed foo.txt.

>>>

>>> The EPUB recipes on the Internet that I found used the simple "zip -X9rD OEBPS" to archive the stuff together. So I'm wondering whether it's really required to support special compression settings...

>>>

>> My understanding of the specification is that the mimetype file needs to be uncompressed. See http://www.idpf.org/epub/30/spec/epub30-ocf.html#sec-zip-container-mime . It's permitted for all files to be uncompressed, but that results in needlessly large EPUB files. I imagine that lots of EPUB readers are designed to be tolerant of recipes that compress everything, despite it being against the specification.

> The ZIPCOMPRESSION is stored in the OverrideEnvironment used for the target, and not on the sources (sadly), in this case.

> Definitely worth filing an enhancement report (bug) on tigris.org.

>

> I'm thinking there's likely an entire class of use cases where storing such on the source rather on the Builder would be useful..

> (forced static library,etc)..

>

> -Bill

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Dirk: I've pushed what I've got so far to 
https://bitbucket.org/ajf58/scons_docbook/branch/epub . I've run a basic 
Docbook through it and generated an EPUB file that passes the validation 
test here http://validator.idpf.org/ . In it's current form there's a 
bug in that the files added to the OEBPS directory aren't re-added when 
the source files are changed. Is it possible for the action functions 
passed to a Command builder to modify target and source lists?

Bill: I can raise an issue there if you think that's sensible. A quick 
glance at http://scons.tigris.org/ shows a large number of open tickets. 
Is this because issues are tracked elsewhere? 
https://bitbucket.org/scons/scons itself seems to be active, and indeed 
shows some work using Ghostscript to create EPUB files.

Cheers,
Andrew
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