Re: navigation, zooming in/out, how to solve it?

On Sun, 06 Aug 2006 00:46:12 +0100, ksamp@xxxxxxxxxxxxxxx wrote:

On Sat, 05 Aug 2006 12:21:40 GMT, zentara <zentara@xxxxxxxxxxxxxx>
wrote:
Zinc is the way to go. It supports transparency (plain Tk::Canvas
dosn't). Animated zooming would be fairly easy to accomplish.

Look at the "magic lens" in the 'zinc-demos' program.


thank you for the link. it is really cool and partially what i'm
looking to achieve. i didn't explain it well but zooming in and out
aside from enlarging/shrinking the bounding box also add/remove some
text (and this is the main idea). i'm not focusing on enlarging a font
(maybe a little to enrich the user experience) but enlarging the
description. i want to show the user a simple description at the
beginning (e.g. about a particular concept) and further zooming in
would enlarge the bounding area for it and add new more detailed
information, links, etc. i'm mainly considering the ways to create and
manipulate such bounding areas for text. transparency, enlarging the
font etc. are just nice additional features. is there a way in
tkzinc/canvas to create a scalable boudings for a text? i know
how much text i want to display at a time - i have to create a space
for it and add additional features like transparency etc. maybe you
have further thoughts which could be helpful? thanks for all in
advance.

best regards,
ks

Well, it is hard to say exactly what you should do, since you give
just a broad outline of your design.

But in general, zooming is done by scaling groups or tags, which depends
on how you set up your first page.

As to your main question, on how to create bounding areas for text, you
seem to have a few choices, use groups, tags, or a combo of both.

My first idea:
Create a group for each text group, and maybe make a bounding rectangle
for it. Then add text to the group, and have each text addition tagged
with a zoom level. Then setup click bindings on each group, so the first
click will zoom all group members with a level1-zoom tag, a second click
will zoom all level2-zoom tags, etc.
Of course this will take some planning, maybe it would be better to just
assign a number, like 3 as a tag, and that will zoom everything less
than 4. And you will also have the problem, of not zooming
level-1-zooms twice, when you second click.

Here is a very rudimentary proof of concept. Some caveats:
Sometimes Zinc will demand actual objects to work on, instead of tags.
Don't get frustrated, just find a way. This can be seen where I have to
bind to the rectangle and the text, instead of just the common tag.

Text will not scale well, you will need to adjust fonts.

Also, due to inherent inaccuracies, you cannot get back to your original
position with calculated moves. So you must store your positions and
tset them back.

In this example, multiple left clicks will scale and move a box, and a
right click will restore them. If you want animation, use a sub to do it
in small automatic steps.

All the above, just requires alot of detailed hacking, so I will leave
it up to you.

The docs for Zinc are pretty good, so refer to them in case you hit a
snag.

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

my %zgroup;
my $dx = 50; #
my $dy = 50; #the boxlet size

my ($up,$left)=(0,0);

my @colors = qw(DarkGrey orange pink hotpink red
peru goldenrod tan gold wheat
lightyellow yellow khaki lightgreen green
lightsteelblue turquoise cyan violet plum
skyblue powderblue bisque beige snow );

my $mw = MainWindow->new;

$mw->geometry('+30+30');

my $width = $mw->screenwidth() - 100;
my $height = $mw->screenheight() - 100;

my $zinc = $mw->Scrolled('Zinc', -width => $width, -height => $height -
100,
-backcolor => 'black',
-borderwidth => 3,
-relief => 'sunken',
-scrollregion => [-10, -10, 10000, 10000],
)->pack(-fill=>'both',-expand=> 1 );

for(0..scalar @colors){
setup_groups($_ + 1);
}

&fill_groups();

MainLoop;

#####################################################################
sub setup_groups{
my $z = shift;
print "$z\t";

#set color
push (@colors,shift(@colors)); #rotate colors
$zgroup{$z}{'color'} = $colors[0];

$zgroup{$z}{'group'} = $zinc->add('group', 1 ,
-visible => 1,
-tags => [$z],
);

$zinc->translate($zgroup{$z}{'group'}, 30*$z,30*$z);

#save initial matrix settings for resetting position, compatible with
tset
$zgroup{$z}{'init'} = $zinc->tget( $zgroup{$z}{'group'} );

}

#######################################
sub fill_groups{

foreach my $z (sort keys %zgroup){

$zgroup{$z}{'rect'} = $zinc->add('rectangle',
$zgroup{$z}{'group'},
[ 0 , 0 , $dx , $dy],
-linewidth => 2,
-visible => 1,
-filled => 1,
-fillcolor => $zgroup{$z}{'color'},
-tags =>[$z],
);

$zgroup{$z}{'text'} = $zinc->add('text', $zgroup{$z}{'group'},
-position => [$dx/2, $dy/2],
-anchor => 'center',
-text => $z,
-tags =>[$z],
);

$zinc->bind( $zgroup{$z}{'rect'},'<Button-1>',
sub {
print "group-> $z\n";
&scale_group($z);
}
);

$zinc->bind( $zgroup{$z}{'text'} ,'<Button-1>',
sub {
print "group-> $z\n";
&scale_group($z);
}
);


$zinc->bind( $zgroup{$z}{'rect'},'<Button-3>',
sub {
print "group-> $z\n";
&descale_group($z);
}
);

$zinc->bind( $zgroup{$z}{'text'} ,'<Button-3>',
sub {
print "group-> $z\n";
&descale_group($z);
}
);

}

}

sub scale_group{

my $z =shift;
my @pos = $zinc->coords( $zgroup{$z}{'group'} );
print "@pos\n";
# Now, we apply scale transformation to the Group item, using the
'scale'
# Zinc method. Note that we reset group coords before scaling it, in
order
# that the origin of the transformation corresponds to the center of
the
# wheel. When scale is done, we restore previous coords of group.
$zinc->translate($zgroup{$z}{'group'}, 20, -20);
$zinc->scale($zgroup{$z}{'group'}, 1.2, 1.2, $pos[0],$pos[1]);

# text will not scale, you need to configure large and small fonts
# $zinc->scale($zgroup{$z}{'text'}, 1.2, 1.2, $pos[0],$pos[1]);
}

sub descale_group{
my $z =shift;

# descaling dosn't work, you need to do a reset to original position
# my @pos = $zinc->coords( $zgroup{$z}{'group'} );
# $zinc->translate($zgroup{$z}{'group'}, -20, 20);
# $zinc->scale($zgroup{$z}{'group'}, .8, .8, $pos[0],$pos[1]);
$zinc->tset($zgroup{$z}{'group'}, @{ $zgroup{$z}{'init'} } );

}
__END__














--
I'm not really a human, but I play one on earth.
http://zentara.net/japh.html
.

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