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

[Maurice L. <mj...@ga...>]

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 :).

 > 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; 
    } 

-- 
Maurice LeBrun    mj...@ga...