Re: transparent layer over image

[dmitriy kuvshinov <dmitriyk genphys phys msu ru>]

Hi!

> (something tells me that this dateline is, erm, wrong)

yes, i use overclocking athlon xp2100+ (and i have some errors in BIOS, 
like bad data, bad HDD, etc.)...

> i'm not sure what you're asking, actually.

> are you wanting to draw annotations on the image without altering the 
> pixbuf's data?
> you can either use Gdk drawing primitives to draw directly on the 
> screen after drawing the image (which can be a pain to keep up), or 
> use Gnome2::Canvas for structured graphics.
> otherwise, you can just alter the image data, keeping a pristine copy 
> separate from the annotated one.
>
> --
> "it's hard to be eventful when you have this much style."
>    - me, rationalizing yet another night of sitting at home.


I want to make the gauge of overcast (then to lay out the gauge under 
GPL the license). I have already made all calculations and have 
collected as *.xs the module. But to supervise as it works, I need to 
display somehow intensity of points as the schedule atop of a picture, 
it is very convenient, rather than than to examine figures. Speed of 
work for a picture c with the sanction 768x576 about 3 staff in a second 
on athlon-xp 2100 +. I can draw a vertical line in each picture thus:

#!/usr/bin/perl

use strict;
use warnings;
use Glib qw(FALSE TRUE);
use Gtk2 -init;

my(@a,@res,$pix,$button,@m,$img,$pixbuf,$pixels,$w,$h,$c);

my $window  = Gtk2::Window->new ( "toplevel" );
my $hbox    = Gtk2::HBox->new (1,1);
my $vbox    = Gtk2::VBox->new (0,1);
my $image   = Gtk2::Image->new;

# read directory with images

&images();

sub render_image{
#  die "Usage: $0 imagefile\n" unless @ARGV;
 $img=$ARGV[0] if $ARGV[0];
 $img=$_[0] if $_[0];
 $pixbuf = Gtk2::Gdk::Pixbuf->new_from_file ($img);
 $pixels = $pixbuf->get_pixels();
 $h = $pixbuf->get_height; $w = $pixbuf->get_width;
 $pix=$pixels;
 $pix=~s!.(.).!$1!gs;

# begin split image data from packed variable $pix.

 @a = @{[unpack "C*",$pix]};
 push @res, [splice(@a, 0, $w)] while @a;

# @res is a massive, with pixel data for one canal (R,G, or B or C,M,Y or K)

 map {
   my @txt;
#    print $c,"\n";
   my $txt=join(' ', @{$_});
   my $t1;
# first version of program akf for clouds conditions
# this return massive of points with coordinates,
# needed for control my algoritm.

   $t1=qx[./akf $txt] if $c++%40==0;
#    print $t1 if $t1;
 } @res;

 $#a=-1;

# begin draw vertical line

 my $t=pack "C*","255";
 $t.=pack "C*","255";$t.=pack "C*","255";
 $c=1; $pixels=~s/(...)/$c++%$w*3-90==0?$t:$1/gex;

# end draw vertical line

 $pixbuf = Gtk2::Gdk::Pixbuf->new_from_data
              ($pixels,  # packed image data in a scalar
               'rgb',  # only 24- or 32-bit RGB are supported
               0, # no alpha, data is 24-bit
               8,     # only 8 bits per sample are supported
               $w,  # in pixels
               $h,  # in pixels
               $w*3);  # number of *bytes* in each row
 $image->set_from_pixbuf ($pixbuf);
 $window->set_title("imaging $img");
 #sleep 1;
 $img=''; $#res=-1;
}

$window->add($hbox);
$hbox->add($vbox);
$vbox->add($image);
$button = Gtk2::Button->new("Begin repaint...");
$button->signal_connect("clicked", \&signal);
$vbox->pack_start($button, 1, 1, 5);
$window->signal_connect( "destroy" , sub { Gtk2->main_quit ; } ) ;
$window->signal_connect (delete_event => sub {Gtk2->main_quit;});
$window->show_all();

eval {
     # this will block for 1000 milliseconds, until the timeout
     # callback dies.
     Gtk2->main;
#      print "nor should this be reached\n";
 };

#Gtk2->main;
# Shouldn't ever get here

exit(0);

sub signal {
 if ($m[$#m]){&render_image($m[$#m])}else {exit 0};
 pop @m;
 Glib::Timeout->add (100, sub {
           # this next statement calls g_signal_emit under the hood
           $button->clicked;
           # print "this line should not be reached\n";
           0});
}

sub images{
# read image directory
 while (</home/vilfred/files/*.*>){
   $m[$c++]=$_;
 }
 reverse @m;
}

this program read and show pics from directory /home/vilfred/files/ and 
show in one by one while -f $m[$i].

But it is difficult for me to draw an any line atop of a picture, it is 
many calculations for a variable $pixels. It seems to me, that the 
program will draw faster atop of a picture not touching a variable $pixels

Dmitriy.

p.s.  i'm very sorry for my bad english.