Re: NPAPI removal means no DjVu documents in Firefox

Hi Leon,

I'm sorry to hear about your experience viewing DjVu documents in 
Firefox given our plans for removing NPAPI plugins.  I'm really 
interested to understand the details of the performance problems in our 
JavaScript engine that currently prevent the djvu-html5 viewer from 
being a fast and usable replacement for viewing these documents.  I'd 
appreciate if you can help me by providing some examples that would 
allow me to analyze them to ensure that we can address the performance 
issues on our side in order to improve this situation in the future.

The project page you linked to below has a link to a live demo which I 
looked at, which was pretty slow in Firefox 
(http://mateusz-matela.github.io/djvu-html5/demo.html).  I spent a few 
minutes looking into the underlying reason and filed 
https://bugzilla.mozilla.org/show_bug.cgi?id=1384970 about it. The good 
news is that this page is slow due to a limitation of our JS engine that 
we are already aware of and are actively working on addressing, so 
hopefully in the next few months there should be some improvements here.

One thing I'm not sure of is whether the specific overhead I saw on that 
page is affecting all other djvu-html5 content or if there are other 
issues at play.  Since I don't have a lot of experience using djvu-html5 
for viewing DjVu documents, I would really appreciate if you can point 
me to a few other common ways that people typically use it, so that I 
can also test those to see if I can discover other performance issues 
that we should be aware of and working on fixing.

Thanks for taking the time to provide invaluable feedback.

All the best,

Ehsan


On 07/25/2017 10:23 PM, [email protected] wrote:
> DjVu documents used to be viewable within firefox using a very reliable NPAPI plugin. With the removal of the NPAPI support, this no longer works.
>
> Although there have been worthy attempts to use HTML5 technologies (e.g. https://github.com/mateusz-matela/djvu-html5) to view DjVu files, the Firefox JavaScript engine is far too slow to decode and render DjVu files in a manner that makes browsing agreeable. In fact, on a modern machine, the JS version is far slower than the NPAPI viewer ever was, even when it ran on a 1999 Pentium 90 machine.
>
> One cannot even say that the DjVu NPAPI plugin was flimsy. The Unix version was rock-solid, running out-of-process from inception, detecting and supporting the GLib loop and Xembed protocols. The Window was more traditional but also simple and rock-solid. While it is true that some aspects of NPAPI were obsolete, one could have modernized the API instead of simply eliminating the capability.
>
> The decision to support Flash (and only Flash) is very shocking to me. You may argue that many more people are viewing Flash content than are browsing DjVu documents. But is that really the spirit of open-source software?  I thought the idea was to enable people instead of leveraging monopoly power to decide for them which technologies they can use or not.
>
> Anyway, I am very disappointed.
>
> - Leon Bottou
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