Re: move_panel and getbegxy

[Thomas Dickey]

On Fri, 25 May 2007, Bryan Christ wrote:

> I'm not really a fan of the keeping the bug for compatibility, but I 
> understand it.  Your solution below considers only ncurses.  The problem is 
> that if the bug exists in pcurses and curses, then you have portability 
> problems.  In other words, its best if curses, pcurses, and ncurses all 
> behave the same (even in the ways they are broke).

right - there are several implementations of curses (the SVr4-derived,
PDCurses, NetBSD curses and ncurses), all of which could use forms
and menus.  While there are occasional errors, ncurses "should" behave
the same as the SVr4 forms/menus libraries to make it simple for people to 
move code to/from each.

Extensions can be a nice thing, but (the exceptions in ncurses aren't my 
work, iirc), extensions should be for things that can't be done except by 
modifying the library - and should be optional features that can be easily 
omitted.

For instance, I'd be most interested in adding move_menu() as an extension 
if I investigated SVR4 curses and found that there was no way to move a 
menu with it - not even with code as in my test-driver.  Then there's no 
existing functionality to be incompatible with.  If I found that mvwin() 
somehow (by magic?) did the right thing for moving a menu, then there'd be 
a bug to address in ncurses.  Otherwise, if the same move_menu() worked 
for SVr4 curses, it would be nice for an add-on library, but not useful 
for anyone who's porting code...

> Clive Nicolson wrote:
> > On Thu, 24 May 2007, Bryan Christ wrote:
> >
> > > This is a bug which Thomas and I discussed sometime ago.  You'll basically 
> > > have to move the subwin yourself.  A sample is below.
> > >
> > > Thomas may have the other half of this email, I can't seem to find the 
> > > follow up, but at least this will clear things up for you a bit. 
> > > Basically, even though its a bug, other implementations of curses have 
> > > this problem and so to fix it would break compatibility.
> >
> > Your code snippet below fixed both my problems.
> >
> > I do not support the compatibility idea, once getbegxy returns the wrong 
> > value the caller can not fix the values. Without private curses data it is 
> > not possible, even then a general fix by the caller is very difficult.
> >
> > If there is some case I've missed ncurses could offer the user a runtime
> > switch to fix the problem.
> >
> > eg
> >
> > #ifdef NCURSES_VERSION_PATCH
> > #if NCURSES_VERSION_PATCH >= 20070525
> >   ncurses_hacks_on(XX_FIX_MOVE);
> > #endif
> > #endif
> >
> > I'm prepared to try knocking up a patch to ncurses for this bug.
> >
> > Thanks
> > Clive
> >
> > > On Wed, 31 May 2006, Christ, Bryan wrote:
> > >
> > > Thomas,
> > >
> > > menu_driver() reads window->_begx and window->_begy when determining the
> > > appropriate region/coordinates to update.  The problem with this is that
> > > _begx and _begy don't get updated if the window is a subwin/derwin and
> > > the parent is moved.  the outdated coords cause the mouse hit-test
> > > processed by menu_driver() to fail.  why can't this bug be fixed so that
> > > menu_driver calculates the offset?  currently i am hacking changes to my
> > > subwins (and subwins of subwins of subwins...) to reflect the new data.
> > > code snippet below:
> > >
> > > x=0;
> > > y=0;
> > >
> > > subwin=child_of_window_that_was_moved;
> > > while(subwin->_parent!=NULL)
> > > {
> > >  x+=subwin->_parx;
> > >  y+=subwin->_pary;
> > >  subwin=subwin->_parent;
> > > }
> > > x+=subwin->_begx;
> > > y+=subwin->_begy;
> > >
> > > subwin=child_of_window_that_was_moved;
> > > subwin->_begy=y;
> > > subwin->_begx=x;
> > >
> > > Clive Nicolson wrote:
> > > > I am using ncurses-5.6 .
> > > >
> > > > I have a panel who's window is associated with a menu (for which I 
> > > > provided
> > > > a subwindow via derwin).
> > > >
> > > > I move the panel with move_panel and then do a getbegxy on both the 
> > > > window
> > > > and the menu's subwindow, the coordinate pairs returned indicate that the 
> > > > subwindow has not moved, but that the window has!
> > > >
> > > > Is this expected?
> > > >
> > > > I also note that the menu_driver can no longer select items (with the 
> > > > mouse)
> > > > on the moved menu!
> > > >
> > > > Clive
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > Bug-ncurses mailing list
> > > > address@hidden
> > > > http://lists.gnu.org/mailman/listinfo/bug-ncurses
>
>
> _______________________________________________
> Bug-ncurses mailing list
> address@hidden
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--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net