Re: [Plplot-devel] Other problems with -locate option on x01c

[Alan W. I. <ir...@be...>]

On Sun, 3 Mar 2002, Maurice LeBrun wrote:

> Alan W. Irwin writes:
>  > Thanks for answering my questions/comments.
>  >
>  > I suggest you could improve the design by printing a warning message when
>  > outside a viewport but continue to stay in locate mode for that situation so
>  > that subsequent clicks inside viewports still work (without having to
>  > reinvoke L).  Otherwise, for an example like x01c with lots of area outside
>  > viewports, the first impression is that locate mode is severely broken.
>  > (At least that was my impression....;-)) Of course to finish locate mode you
>  > don't have to click on an area with no viewport.  Instead, simply type <ESC>
>  > as now.
>
> I only just now got around to looking into this.  As it stands, "it's a
> feature, not a bug".
>
> When I was putting this in, Geoff and I discussed the issue and decided the
> best course on invalid input -- i.e. clicking outside a viewport/window -- was
> to simply turn off locate mode.  The program's stdout (or stderr) isn't always
> handy so it's handy to have a graphical cue that you're giving bogus input,
> and aborting locate mode at that point seems reasonable.  I'm still happy with
> this decision, but I'll admit documentation is a problem (has been, for a
> while, but better recently :).

I am now only mildly unhappy with this since I can always use L to get into
locate mode again.  However, it might be worth changing it to put in some
warning message (e.g., "Locate mode is terminated because you are outside a
viewport.  To restart use L") so that if, e.g., plwarn works, then the user
will get this message.

>
>  > By the way, before you (and recently somebody else also) mentioned the L
>  > command and now <ESC> I had never heard of them and had no idea you could
>  > use locate mode for any of the examples other than x01c.
>  >
>  > Part of the reason it is taking me so long to get up to speed on this
>  > interactive stuff is I cannot find any documentation.  Are there any other
>  > "locate" commands besides L and <ESC>?  Do all interactive drivers have this
>  > capability? Is there some documentation that I have missed?  If you point me
>  > to some documentation or provide me with some, I will put it in the docbook
>  > documentation form so everybody can easily find it.  Probably the best place
>  > would be
>  > http://plplot.sourceforge.net/resources/docbook-manual/plplotdoc-html-0.4.3/interactive-devices.html.
>
> The internally recognized keys in normal (plotting) mode in the xwin driver
> are featured in xwin.c:ProcessKey().  These are:
>
> /* Handle internal events */
>
>     switch (gin->keysym) {
>
>     case PLK_Return:
>     case PLK_Linefeed:
>     case PLK_Next:
>     /* Advance to next page (i.e. terminate event loop) on a <eol> */
>     /* Check for both <CR> and <LF> for portability, also a <Page Down> */
>         dev->exit_eventloop = TRUE;
>         break;
>
>     case 'Q':
>     /* Terminate on a 'Q' (not 'q', since it's too easy to hit by mistake) */
>         pls->nopause = TRUE;
>         plexit("");
>         break;
>
>     case 'L':
>     /* Begin locate mode */
>         dev->locate_mode = LOCATE_INVOKED_VIA_DRIVER;
>         CreateXhairs(pls);
>         break;
>     }

Thanks for this.  I have noticed experimentally, that right-clicking the
mouse when outside locate mode advances to the next page like CR, but I
don't see that right-click implemented above.  Also, from the above I don't
see how <ESC> is used to leave locate mode.  So the above code must only be
part of the interactive story.

Alan