RE: pTk Scrolled Text problem

Vadim Konovalov <[email protected]> writes:
>> Here is a script that will show the problem...  When it starts up it
>> will consume 100% cpu due to the scrollbar attempting to redraw...
>> Watch the thumb bounce up and down in the scroll region.
>
>this problem is in perl/Tk and does not appear to be in Tcl/Tk.
>Because if I replace many "use Tk; use Tk::something" with single
>
>  use Tcl::Tk qw(:perlTk);
>
>, the problem does not appear.
>
>As a side note, following lines in that script are inessential but
>incorrect:
>
># subroutine declarations, needed by strict setting
>use subs qw( CreateMainUI );
>
>removing those do not influence breakage

The problen certainly used to occur with Tcl/Tk.
What happens is: a line at the bottom of in the window is too wide to be 
rendered so a horizontal scrollbar is mapped. But now line isn't in the window
(covered by scrollbar) so scrollbar is unmapped.

A proper "fix" is for Text widget to know the "width" of text as a whole
not just that which fits in the window. But that is a lot of computation 
for a large document. Caching longest line seen might suffice. 

What I personally would like to see is scrollbar's mapped-ness be determined 
by whether ANY line of whole text is wider than window, but slider expand to 
full size if current window contents fit.



>
>Vadim
>
>
>> 
>> Thanks again for any help...
>> 
>> On Tue, 2005-12-13 at 17:46 +0000, [email protected] wrote:
>> > Hello,
>> > 
>> > I've been struggling with a problem with the perl/Tk Text widget for
>> > a while now.  We create a scrolled text widget that has the 
>> scrollbars
>> > as optional (osoe).  If the contents of the widget extend 
>> vertically past the
>> > border of the widget, there is no problem.  The scrollbar 
>> appears and
>> > functions correctly.
>> > 
>> > If on the other hand, it extends past the borders 
>> vertically and in some
>> > spots horizontally, then as it scrolls the x-scrollbar 
>> appears and disappears
>> > as it is needed.  No problem here either.
>> > 
>> > The problem seems to be when the first line above or below 
>> the currently
>> > viewed text is wider than the visible region, the hide/show 
>> scrollbar code
>> > seems to cause an oscillation...  i.e.  the horizontal 
>> scrollbar keeps appearing
>> > and disappearing.  This continues until the app is 
>> killed...  This happens
>> > when scrolling or selecting text.
>> > 
>> > A similar problem to what is going on is easy to reproduce. 
>>  Create a text
>> > widget and add some text.  Have one line off screen that 
>> needs the horizontal
>> > scrollbar.  Have just enough lines after it so that it will 
>> be just off the screen
>> > if you scroll all the way down.
>> > 
>> > Now scroll all the way down.  Notice that it keeps jumping 
>> up and down as
>> > you try to view the last lines....  The problem goes away 
>> if you make the window
>> > wide enough to not need the x-scrollbar...
>> > 
>> > (I'll put together a sample if need be...)
>> > 
>> > This has happened on RedHat 9 Linux with the latest Tk code 
>> as well as with
>> > ActiveState perl and the Tk it is shipped with...
>> > 
>> > Any ideas?  
>> > 
>> > Thanks in advance...
>> > 
>> > - Todd
>> > -++**==--++**==--++**==--++**==--++**==--++**==--++**==
>> > This message was posted through the Stanford campus mailing list
>> > server.  If you wish to unsubscribe from this mailing list, send the
>> > message body of "unsubscribe ptk" to [email protected]
>> -- 
>> 
>>                                                         - Todd
>> 
>-++**==--++**==--++**==--++**==--++**==--++**==--++**==
>This message was posted through the Stanford campus mailing list
>server.  If you wish to unsubscribe from this mailing list, send the
>message body of "unsubscribe ptk" to [email protected]


-++**==--++**==--++**==--++**==--++**==--++**==--++**==
This message was posted through the Stanford campus mailing list
server.  If you wish to unsubscribe from this mailing list, send the
message body of "unsubscribe ptk" to [email protected]