Re: compression (was Re: [Lynx-dev] Problem with mobil.t-online.de)

[Thomas Dickey]

On Wed, 9 Nov 2005, address@hidden wrote:

> In a recent note, Thomas Dickey said:
>
> > Date: Wed, 9 Nov 2005 08:06:29 -0500 (EST)
> >
> > iirc, libz is supposed to be able to do uncompress (perhaps with some
> > option - I don't recall that).  It would be useful to have that, though
> > the bug that I'm interested in at the moment is whether the external
> > uncompress is working properly.
> gunzip will quietly uncompress (no option required) when it
> recognizes a compressed file.
>
> A couple things I've wished for in this area:
>
> o gunzip (and various others) can work as filters (pipe;
>  no temp file required).  It would be nice to:
>
>  - see a partial display during transmission on a slow link.
>
>  - Not tie up the temp space for an otherwise unneeded temp
>    file.

yes. but if source caching worked properly, we wouldn't need the
external filters for decompressing).

>  However:
>
>  - using a filter would require retransmitting the file when
>    switching between source and rendered display or resizing
>    the screen window.  (Same thing happens when invoking Lynx
>    with a character special file as the command argument,
>    then switching to source display.)

yes - I'd like to change that, too.  I spent some time last year
studying this, found that there's no clean interface for source
caching (it's done as an afterthought, using global variables).

The code "should" allow one to setup a decompressor as another
stage of processing after the existing source cache, but there
are no functions for setting it up (and global variables are
still global variables - can be used for one thing at a time).

I could see in general how to approach it, but thought that if I
worked on a simpler but related problem, I could build up some
proper interfaces to make this doable as well.  (I started looking
at making the options screen handled as a stream, for instance).

> o I notice (mostly) that when I leave and re-enter a compressed
>  page, it gets retransmitted.  It would be better if a cached
>  copy were available.  However this may merely be Lynx's
>  respecting a short (zero?) expiration time supplied by the
>  server.
>
> o Using filters is somewhat related to my wish for streaming
>  to an external viewer when the .mailcap entry omits a "%s"
>  conversion specification, rather than writing to a temp file
>  then redirecting that file to stdin of the viewer.

part of that is "easy" of course - if the viewer weren't using
the same screen (and get in the way of lynx), someone probably
would have done it.

--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net