Hi, another approach you might consider, instead of calculating the fractal center around the mouse click, is to calculate it's center, by taking the bbox of the fractal, and move the center point with tags.

For instance, tag all your lines with 'fractal', after you build the fractal, get a bbox of the tag fractal, take the midpoint values, and store it. Then on each new fractal build, just repeat, take the new bbox, then compute how much you need to move it, to center it on the mouse event point.

I'm not doing the computations here, but this shows the basics. 

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $c_size = 100;
my $scale = 1;

my $centerx;
my $centery;


my $mw = MainWindow -> new;
my $canvas = $mw -> Canvas(-height=>$c_size, -width=>$c_size) -> pack;

$canvas -> Tk::bind('all', '<ButtonPress-1>' => [\&transit,Ev('x'), Ev
+('y') ]);

&MakeMan();

MainLoop;

sub transit{
  my ($canv, $x, $y) = @_;
  print "(x,y) = ", $canv->canvasx($x), ", ", $canv->canvasy($y), "\n"
+;
 
 my $dx = $x - $centerx;
 my $dy = $y - $centery;

  $canvas->move('fractal',$dx,$dy);
}

sub MakeMan(){
  my ($e, $canv_x, $canv_y)=(0,$c_size/2,$c_size/2);
  if($scale > 1){
    $e = $canvas -> XEvent;
    $canv_x = $e->x;
    $canv_y = $e->y;
  }

  my $icount = 1;
#problem here...
  my $i = -2/$scale + (($canv_y-($c_size/2)) / ($c_size/$scale));# + $
+lasti;
  my $rgb;
  while($icount <= $c_size){
#... and here...
    my $r = -2/$scale + (($canv_x-($c_size/2)) / ($c_size/$scale));# +
+ $lastr;
    my $rcount = 1;
    while($rcount <= $c_size){
      my $tr = $r;
      my $ti = $i;
      $rgb = '#000000';
      for my $n(1..15){
        ($tr, $ti) = (($tr ** 2) - ($ti ** 2) + ($r), (2 * $tr * $ti) 
++ ($i));
        if((($tr * $tr) + ($ti * $ti)) > 4){
          $rgb = '#ffffff';
          last;
        }
      }
      $canvas -> createLine($rcount, $icount, 
                     $rcount+1, $icount, 
             -fill => $rgb, 
             -width => 1,
             -tags => ['fractal']
             );
      $rcount ++;
      $r += (4/$scale)/$c_size;
    }
    $icount ++;
    $i += (4/$scale)/$c_size;
  }
  $scale = $scale * 2;

my ($x1,$y1,$x2,$y2) = $canvas->bbox('fractal');

$centerx = ($x1+$x2)/2;
$centery = ($y1+$y2)/2;

print "center-> $centerx $centery\n";

}

[download]
I'm not really a human, but I play one on earth. Cogito ergo sum a bum

In reply to Re: Tk Zooming Fractal Problems by zentara
in thread Tk Zooming Fractal Problems by Melly

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.