use strict;
use Tcl::Tk;

my $status = '';

my $mw = Tcl::Tk::MainWindow("Simple Drag & Drop Demo...");

# label widget that will show status
my $lab_stat = $mw->Label(-textvariable=>\$status, qw/-relief sunken 
    -bd 1 -width 60 -anchor w/)->pack(qw/-side bottom -fill x/);
# three more widgets that will be used for trying DND
my $lab_source = $mw->Label(-text=>"source", qw/-relief groove -bd 2
    -width 20/) ->pack(-pady=>5);
my $lab_text_plain = $mw->Label(-text=>"drop plain text", 
    qw/-relief raised -bd 1 -width 20/)->pack(-pady=>5);
my $lab_t2 = $mw->Label(-text=>"drop color", qw/-relief raised -bd 1
    -width 20 -bg lightyellow/)->pack(-pady=>5);
# and a frame
$mw->Frame(-height=>10)->pack(qw/-side bottom -fill x/);


# following line will do 'package require tkdnd' in Tcl/Tk
$mw->interp->need_tk('tkdnd');

# in order to make DND syntax shorter let's define following methods
sub Tcl::Tk::Widget::dndBindsource {
    my $w = shift;
    $w->interp->call('dnd','bindsource',$w,@_);
}
sub Tcl::Tk::Widget::dndBindtarget {
    my $w = shift;
    $w->interp->call('dnd','bindtarget',$w,@_);
}
# could be done without above two methods that go to Tcl::Tk package:
# $int->call('dnd','bindsource',$widget->path,.....);
# but now we will be allowed to shorter
# $widget->dndBindsource(....);

#---------------------------------------------------------------------
# Before registering a drop target, we always have to make sure the
# corresponding widget has been created:
$mw->update('idle');

# tells the DND protocol source can deliver textual data
$lab_source->dndBindsource('text/plain', q{return "testing DND"});

# bind the DND operation on left button
$lab_source->bind('<1>', 'dnd drag %W');

# tells the DND protocol target can handle textual data
$lab_text_plain->dndBindtarget('text/plain', '<Drop>', \\'WDTA', sub {
	my (undef,$int,$sub) = (shift,shift,shift);
	my ($W,$D,$T,$A) = (@_); # Ev vars
	my $receiver_widget = $int->widget($W);
	$receiver_widget->configure(-text=>$D);
	$status = "[target1] type='$T', action='$A'";
	$int->after(2000, sub {
		$receiver_widget->configure(-text=>"drop plain text")
	    });
    });

# defines an other type on source
$lab_source->dndBindsource('TK_COLOR', q{return "pink"});

# tells the DND protocol target can handle color data
$lab_t2->dndBindtarget('TK_COLOR', '<Drop>', , \\'WDTA', sub {
	my (undef,$int,$sub) = (shift,shift,shift);
	my ($W,$D,$T,$A) = (@_); # Ev vars
	$lab_t2->configure(-bg=>$D);
	$status = "[target1] type='$T', action='$A'";
	$int->after(2000, sub {$lab_t2->configure(-bg=>'lightyellow')});
    });

Tcl::Tk::MainLoop;