Re: Goo canvas runaway zoom, and adjustment warning - SOLVED

[zentara <zzmiloschxx gmail com>]

On Sun, 6 May 2012 11:04:10 -0400
zentara <zzmiloschxx gmail com> wrote:

> " help me with runaway zoom" :-)

Eh, it was a bad day for me, as you could tell by
my duplicated posts, but Monday has come, some
good sleep intervened, and I found the solution.

It is slightly different code, but shows how to control
the zoom with an event handler.  I worked this out awhile
ago, but seemed to have forgotten what I did.
:-)

Once again, sorry to have cluttered the list.

0m,
zentara

#!/usr/bin/perl
use strict;
use warnings;
use Gtk2 '-init';
use Goo::Canvas;


my ($lastx,$lasty)=(0,0);
my $center_set = 0;

my $mw = Gtk2::Window->new('toplevel');
$mw->set_default_size( 400, 300 );
$mw->signal_connect (destroy => sub { Gtk2->main_quit });

my $vbox = Gtk2::VBox->new(0,0);
$mw->add ($vbox);

my $swin = Gtk2::ScrolledWindow->new;
$swin->set_shadow_type('in');
my $ha1  = $swin->get_hadjustment;
my $va1  = $swin->get_vadjustment;

my $canvas = Goo::Canvas->new();
my ($cw,$ch) = (600, 450);
$canvas->set_size_request($cw, $ch);
my($xbound,$ybound) = (1000,1000);
$canvas->set_bounds(0, 0, $xbound, $ybound);
my ($cx,$cy) = ($xbound/2,$ybound/2);
my $root = $canvas->get_root_item();

my $white = Gtk2::Gdk::Color->new (0xFFFF,0xFFFF,0xFFFF);
my $green = Gtk2::Gdk::Color->new (0x0000,0xFFFF,0x0000);
my $black = Gtk2::Gdk::Color->new (0x0000,0x0000,0x0000);

$canvas->modify_base('normal',$black);

$vbox->pack_start ($swin, 1,1,1);
$swin->add($canvas);

# Zoom
my $hbox = Gtk2::HBox->new(0, 4);
$vbox->pack_start($hbox, 0, 0, 0);
$hbox->show;

my $z = Gtk2::Label->new("Zoom:");
$hbox->pack_start($z, 0, 0, 0);
$z->show;

my $adj = Gtk2::Adjustment->new(1, 0.05, 100, 0.05, 0.5, 0.0);
my $sb = Gtk2::SpinButton->new($adj, 0.1, 2);

$adj->signal_connect("value-changed", \&zoom_changed, $canvas);

$sb->set_editable(0);
$hbox->pack_start($sb, 1, 1, 10);
$sb->show;

#fixes runaway zoom
$canvas->signal_connect (event => \&event_handler);

$canvas->can_focus(1);
$canvas->grab_focus($root);

&fill_canvas();

$mw->show_all;

Gtk2->main;
exit 0;


sub event_handler{
     my ( $widget, $event ) = @_;
#     print $widget ,' ',$event->type,"\n";

     my $scale = $adj->get_value;
     # print "scale->$scale\n"; 

    if ( $event->type eq "button-press" ) {
    
        my ($x,$y) = ($event->x,$event->y);
        print "$x  $y\n";
        
     }

    if ( $event->type eq "button-release" ) {
    
    }


    if ( $event->type eq "focus-change" ) {
        return 0;
    }
    
    if ( $event->type eq "expose" ) {
        return 0;
    }

Gtk2->main_iteration while Gtk2->events_pending;      
return 1;

}

sub zoom_changed {
    my ($adj, $canvas) = @_;

    $canvas->set_scale($adj->get_value);
#    $canvas->scroll_to (0,0);   

     my $cur_xscr_setting = $ha1->get_value;
     my $cur_yscr_setting = $va1->get_value;
#     print "xvalue-> ",$ha1->get_value,' ',"yvalue-> ",$va1->get_value,"\n";
my $scale = $adj->get_value;
my $dx = $lastx;
my $dy = $lasty;
#works 
$canvas->scroll_to( $dx - $cw/(2*$scale), $dy - $ch/(2*$scale)   );   

return 0;
}


sub fill_canvas{
for (my $x = 0; $x <= $xbound; $x += 50) {  
     my $y = $x;
 
    my $e1 = Goo::Canvas::Ellipse->new(
         $root, $x, $y, 30, 30,
         'stroke-color' => 'blue',
         'line-width' => 2,
         'fill-color-rgba' => 0x3cb3f199,
    );

    my $markup = "<span foreground= 'white' size='15000'>$x</span>";

   my $t1 = Goo::Canvas::Text->new(
             $root, 
             $markup,
             $x ,$y , -1, 
             'w',
             use_markup=>1,
         );
  }
}

sub event_after {
  my ($mw, $event) = @_;

 my $rect = $canvas->allocation;
 $cw = $rect->width;
 $ch = $rect->height;

 return 0;
}
__END__