[OLPC library] questions about PDFs

[Brian Jordan]

On Sun, Oct 5, 2008 at 10:28 AM, Sayamindu Dasgupta <sayamindu at gmail.com> wrote:
> On Sun, Oct 5, 2008 at 3:40 PM, S Page <info at skierpage.com> wrote:
>> Sayamindu Dasgupta wrote:
>>
>>> [lots of nifty plans for Read]
>>
>> That's great and undoubtedly worthwhile for legacy documents, but to quote
>> Shakespeare, "I come to bury page representations like PDF, not request
>> enhancements unto them".  Nobody is contesting my argument that HTML in a
>> browser whups PDF upside the head six ways to Sunday; therefore the aim of
>> OLPC library advocates should be to get content as HTML (and encourage the
>> advanced canvas, CSS, JavaScript and SVG that Browse/Firefox 3 supports),
>> rather than making hundreds of thousands of kids who will never print from
>> their XO look at "page representations".
>>
>
> Agreed. However, there will always be PDF documents, especially in
> languages with complex scripts (mainly because of legacy encoding
> issues, very hackish fonts, no Unicode support for complex scripts in
> authoring applications, etc). So what I'm trying to do is make sure
> that we support PDFs as well as we can here :-).
>
>>> I am wondering if I can use the evince library that we are
>>> shipping to implement a small and effiecient mozilla plugin, so that
>>> the PDF can be directly viewed from within the Browser itself.
>>
>> That would indeed solve a lot of download-journal-launch issues, and maybe
>> the OOM problem when zooming in Read (trac 7090 and 6002).  As you probably
>> know, the evince team's position is that rather than provide a plug-in,
>> users should use mozplugger (http://mozplugger.mozdev.org/) to run the
>> evince app within the browser.  I tried `su -l; yum install mozplugger; yum
>> install evince`, but evince wants to install dozens of other packages.
>> I wonder when someone will write a PDF parser in JavaScript rendering to
>> <canvas> or Cairo.
>>
>
> Right now, I'm cooking up a stripped down PDF viewer which can be
> invoked by mozplugger to view PDFs (and maybe save them to Journal -
> dunno if that is possible right now). I have a basic pdf viewer
> working inside Browse now (with security and everything enabled).
> Expect more progress soon.
>
> With respect to the zoom problem, it seems to affect the Image Viewer
> activity I wrote recently as well (as a result, I had to restrict zoom
> to 400% in there) - if someone can do some profiling to figure out
> what is going on, it would be great.
>

Would it make sense to restrict zoom to a similar level in the read
activity, at least for the time being?

>>> Some backends which are experimental and are not
>>> enabled in our builds include ones for impress files, dvi files, and
>>> whatnot :-).
>>
>> Wiki pages like http://wiki.laptop.org/go/Image_file_formats say that DjVu
>> is the best of these, and Chris Marshal on devel list cared about it.  Every
>> time I look at the samples at http://djvu.org/docs/ , either Browse or Read
>> crashes unless I remember to zoom out (trac 6223). Interesting, but I would
>> defer all such bugs until some deployment cares.
>>
>
> I noticed some patches to Evince modifying the page caching mechanism
> (right now Evince caches around 5 pages in memory, which is not good).
> I'll figure out if those patches are already in our version of Evince
> or not.
>
> Thanks,
> Sayamindu
> --
> Sayamindu Dasgupta
> [http://sayamindu.randomink.org/ramblings]
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