Re: ncurses and line feed in multi line fields

[tjareson]

Am 28.05.2013 19:54, schrieb Thomas Dickey:
> On Tue, May 28, 2013 at 02:38:44PM -0700, Tjareson wrote:
> > Hello,
> >
> > not sure if someone can give me a hint how to solve/approach my problem:
> >
> > I'm currently developing a very light database application for using on
> > linux text console based on ncurses.
> > When working with multi line fields in forms, I run into the issue that I
> > don't know how to handle CR / LF at the end of a line properly. The field
> > buffer of a multi line field is simply always filled up with blanks until
> > the line ends and the next line begins.
> > If I save that in mysql as field type "text" I get practically one line with
> > a lot of blanks between each "real" line, as the field buffer cannot handle
> > LF as it looks. As long as I write that back into an ncurses multi line
> > field of exactly the same size it is not really a problem. But when the size
> > is different that of course doesn't work anymore.
> >
> > Any ideas or hints how to handle that with a multi line field in ncurses
> > properly?
> I'd handle it by a wrapper function for the field_buffer functions which
> uses the field length (rows * cols) to set/get a more usable value, e.g.,
> splitting a value up by works to set and return a string with trailing
> blanks reduced to a single blank (or interpret the separator as a newline).
>
> I haven't added a function like that to the forms library for various
> reasons (not wanting to mess up compatibility - and also since most users
> are for the ncurses library).  But I could add an example to test/demo_forms.c
> which could be reused...
Ok, thanks for reply - at least that means that I didn't miss something. :-)

Regarding realization: my issue is that I would like to use the 
multiline field also to write application internal scripting, so the 
text also contains sql queries for example, hence I can't simply remove 
all except one trailing blank per line, as that might create a problem 
with the query syntax.

I wonder if it would make sense to simply insert a special character as 
CR/LF-marker whenever one hits return to indicate that a line ends here 
before requesting a new line from the formdriver. The only issue then 
is, that I can't stop the user from moving behind this CR/LF-character 
with the cursor, as I do not have any visibility where exactly the 
cursor is in the field nor what character there is in the buffer?