Re: Printing from WindowXP version of emacs

[Ilya Zakharevich <nospam-abuse@ilyaz.org>]

[A complimentary Cc of this posting was sent to
Eli Zaretskii 
<eliz@gnu.org>], who wrote in article <mailman.19861.1135028638.20277.help-gnu-emacs@gnu.org>:
> > > Set printer-name to "/pipe/printer-input" and invoke lpr-buffer.

> > Will not do anything.  This pipe does not accept arbitrary-ASCII input.

> Are we talking about a pipe that you invented or about a pipe that
> represents the MS-Windows way of talking to a remote printer?  If it's
> a pipe that you invented, then of course you are free to define
> whatever behavior for it that suits your current pleasure in this
> argument.

You are right that I do not know exactly the semantic of the pipe in
question (well, I said this in the preceeding message as well).

> But if it's a Windows-style so called ``printer share
> name'', then writing `a' to it _will_ print `a' (give or take some
> command to force the printer to eject the page after printing a single
> character).

What is "a command" when a pipe is concerned?  Do you mean FormFeed
character, or what?

But I still doubt very much that what you say is actually universally
true.  Here are some questions which force my doubts:

 In what encoding is this 'a' printed?  Are long lines wrapped or
 lost?  What is the page size in lines of input?  Should line be
 terminated by CRLF, CR, or LF?

My understanding of printer pipes was that they are just ways to
communicate with the printer without any "format translation" software
in between; and contemporary printers do not have "DOS compatibility"
mode, when you can dump arbitrary ASCII text to them, and they will
print in Courier.

Maybe Win* stuff is organized differently, but then I would like to
see an exact specification - your claim that 'a' is printed as 'a'
shows that one cannot expect to print any Unicode character (given
that UTF-8 is not the "Win* way").

> I will assume what happens in reality, not some silly rules of game
> that you just invented.  In reality, the printer expects the text sent
> to it to come in some encoding.

Definitely, *IF* it accepts text.

> > I know very little about Win*, but AFAICS, this thread is about the
> > fact that it does not.

> I think you didn't understand at all what we were talking about.  If
> you know how to send text from an Emacs buffer to a printer at all,
> then sending `a' _will_ print `a'.

You again discuss "sending text".  This is hardly correlates with
"printing" as it stands today.

> > BTW, "connection" is the communication channel between the printer and
> > the computer.  There is no reason to assume that one can print using
> > one-sided communication (computer --> printer) only; at some moment
> > the printer may send some information back to computer, and expect it
> > perform some action.
> 
> We are not talking at this level, since normal applications never
> communicate to printers directly, but through some device driver or
> some other piece of software.

On Win* this piece of software is called "the operating system".  You
open GDI context (sp?), and draw to this context.

> That funny pipe you invented is normally a symbolic name whose I/O
> is intercepted by such an interface software and converted into
> signals that run on the wire; then the issue of uni- vs
> bi-directional communications is relevant.

True; but you need a way to configure this interface software.  At
least a way to switch it to Unicode input.

Hope this helps,
Ilya