Re: pTk Scrolled Text problem

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.

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
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-- 

                                                        - Todd

#!/usr/bin/perl

# set up modules to be used
use strict;

# UI modules
use Tk;
use Tk::Button;
use Tk::Dialog;
use Tk::HList;
use Tk::ItemStyle;

use Tk::LabFrame;
use Tk::Menu;
use Tk::Optionmenu;
use Tk::Text;

use Tk::LabEntry;

# subroutine declarations, needed by strict setting
use subs qw( CreateMainUI );


# global variables
use vars qw( %widgets );

# Create the main window object... all others are created from this...
$widgets{'MW'} = MainWindow->new( );
$widgets{'MW'}->title( "Scrolled Text Problem" );

my $top  = int( ($widgets{'MW'}->screenheight - 600 ) / 2 );
my $left = int( ($widgets{'MW'}->screenwidth - 800 ) / 2 );


# set the initial size and position of the window...
$widgets{'MW'}->geometry( "800x600+$left+$top" );

# setup the UI
&CreateMainUI( );

# main event loop for the application
MainLoop;





###############################################################################
#
# Create the main UI (the bulk of the work is done here...
#
###############################################################################
sub CreateMainUI
{
    
    $widgets{'commandText'} = $widgets{'MW'}->Scrolled( 'Text',
        -scrollbars => 'osoe',
        -height     => 10,
        -width      => 40,
        -wrap       => 'none',
        )->pack( -side => 'top', -anchor => 'nw',  );

    #
    # insert some lines of text...
    #
    for ( my $i = 0; $i < 10; $i ++)
    {
        $widgets{'commandText'}->insert( 'end',  "1234567890123456789012345678901234567890\n" );
    }


    $widgets{'commandText'}->insert( 'end',  "12345678901234567890123456789012345678901234567890123456789012345678901234567890\n" );

    for ( my $i = 0; $i < 10; $i ++)
    {
        $widgets{'commandText'}->insert( 'end',  "1234567890123456789012345678901234567890\n" );
    }
}