Re: Get Tk::Canvas pixels

I have toyed before with code that checks every
location on a Canvas, and finds what the topmost item
is, and put()s the fill color of that item in the
corresponding location in a Photo object. Something
like this:

  use Tk 804;
  use Tk::PNG;

  sub canv2PNG {
    my $c = shift;   # the canvas
    my $outF = 'out.png';
    $mw->Busy;

    my $p = $mw->Photo(-height => $c->height,
		           -width  => $c->width,
		           -format => 'png',
		          );

    for my $x (0 .. $c->width - 1) {
      for my $y (0 .. $c->height - 1) {
        my @i = $c->find(overlapping => $x, $y, $x,
$y);
        defined $i[0] or next;

        my $tag = $i[-1];
        my $col = $c->itemcget($tag, '-fill');
        $p->put([$col], -to => $x, $y);
      }
    }

    $p->write($outF, -format => 'png');
    $mw->Unbusy;
  }

But it has some severe limitations:

- Only handles simple items: Lines, Rectangles,
Polygons and Ovals. No Text.
- Does not output the -outline color.
- Does not handle transparency and stipples.
- Is somewhat slow.

I'm not sure how to address those issues.

If your application can live with them, then that
might be a good solution.

--Ala


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 
-++**==--++**==--++**==--++**==--++**==--++**==--++**==
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]