package PDF::Reuse::Tutorial;

use strict;

our $VERSION = '0.11';

1;

__END__

=head1 NAME

PDF::Reuse::Tutorial - How to produce PDF-files with PDF::Reuse

=head1 DESCRIPTION

In this tutorial I will show some aspects of PDF::Reuse, so you should be able
to use it in your own programs. Most important is how to produce and B<reuse> PDF-code,
and then if you are interested, you can look at Graphics and JavaScript, so you can
to do special things.

=head2 Reusing code:

You can take advantage of what has been done before, it is not necessary to start
from scratch every time you create a PDF-file. You use old PDF-files as a source for
forms, images, fonts and texts. The components are taken as they are, or rearranged, 
and you add your own texts and you produce new output. 

If you don't care too much about the size of your templates, you should make them 
with a commercial, visual tool, that's most practical; and then you should use 
PDF::Reuse to mass produce your files. In this tutorial I show in many places
how create single files with PDF::Reuse. That is possible, but more of an exception.
I do it here to show the technique. You will anyway need it to add texts and graphics
to your templates.   

=head2 Graphics:

With this module you get a good possibility to program directly with the
basic graphic operators of PDF. This is perhaps an advanced level, and you can
avoid it if you want. On the other hand, it is not very difficult, and if you take
advantage of it, your possibilities to manage text and graphics increase very much.
You should look at the "PDF-reference manual" which probably is possible to download from
http://partners.adobe.com/asn/developer/acrosdk/docs.html.
Look especially at chapter 4 and 5, Graphics and Text, and the Operator summary.

Whenever the function prAdd() is used in this tutorial, you can probably get more
explanations in the "PDF-reference manual". The code, you add to the content
stream with prAdd(), has to follow the PDF syntax completely.

=head2 JavaScript:

You can add JavaScript to your PDF-file programmatically. This works with Acrobat
Reader 5.0.5 or Acrobat 5.0 and higher versions.

You should have the "Acrobat JavaScript Object Specification" by hand. If you
haven't got Acrobat, you can probably download it from http://partners.adobe.com/asn/developer/technotes/acrobatpdf.html.
It is technical note # 5186. 
JavaScript for HTML and PDF differs so much that you need the manual, even if
you know JavaScript very well.

B<WARNING ABOUT JAVASCRIPT: 
There is a complication with Acrobat but not with the Reader. Acrobat has a plug in, 
"webpdf.api", which converts documents fetched over the net, also PDF-documents !!!
When it does its' conversions, there is a great risk that JavaScripts will be lost.>

=head2 Extracting the programs from this document

Here is a snippet of code to extract the programs from this documentation.

   use strict;
   my ($dir, $pod);

   print "From which file(pod?) shall I extract files? ";
   chomp($pod = <STDIN>);
   print "To what directory shall I write the files?   ";
   chomp($dir = <STDIN>);

   if (! $dir)
   {  $dir = './'; }
   elsif ($dir !~ m'\/$'o)
   {  $dir .= '/'; }

   open (IN, "$pod") || die "Couldn't open $pod, $! aborts\n";
   while (my $line = <IN>)
   {  if ($line =~ m'^\=for\s+([\w\d\.\\\/]+)\s+begin'o)
      {  my $srcFile = $dir . $1;
         open (OUT, ">$srcFile") || die "Couldn't open $srcFile, $! aborts\n";
         $line = '';   
      }
      elsif ($line =~ m'^\=for.+end'o)
      {  close OUT; 
      }   
      print OUT $line if OUT;
   }  

Copy and paste. If you need '#!/usr/bin/perl -w' or something like that, modify
the line "$line = '';". Save and run.

Under the examples directory, there are some files, which you could use when you
run the programs, so it might be a good idea to extract the programs to that
directory. Also unzip the files from unzipThis.zip to the same directory. 

The program only works when you have prepared the pod with '=for name begin' and
'=for end', and that has been done with this module, and B<PDF::Reuse::SimpleChart>.

=head1 Ordinary tasks


I have developed PDF::Reuse in a Windows environment, so I don't use the line

    #!/usr/bin/perl -w

It only produces an warning that it's too late for this switch. If you work under
Unix you probably have to add that to all the examples

If you want to run a program under a web server, you can probably replace the
line with prFile(..) in most examples with the lines:

     prInitVars();
     $| = 1;
     print STDOUT "Content-Type: application/pdf \r\n\r\n";
     prFile();

B<N.B. There are no model programs in this document, just examples.>

=head2 A very basic program

=for basic.pl begin

   use PDF::Reuse;                       # Mandatory  
   prFile('ex1.pdf');                    # Mandatory, with or without a file name
   prText(250, 650, 'Hello World !');       
   prEnd();                              # Mandatory

=for end

The line with prText is a directive to put a text 250 pixels to the right and 650
pixels up. If you haven't stated anything else the font will be Helvetica and 12
pixels, the page format will be 595 pixels wide and 842 pixels high.
Later on you will see how to change that. There are many other default values.

If you skip the line with prText, you get an empty page. In fact that can be very
useful if you want to work with JavaScript.

The last line is also necessary to write page structure and other things to the disc
and to close the current file.

=head2 Page breaks

=for pageBreaks.pl begin

    use PDF::Reuse;
    use strict;                            

    prDocDir('doc');                           # Document directory
    prFile('long.pdf');
    prFont('Courier-Bold');                    # Sets font  
    prFontSize(20);                            # And font size  
    for (my $i = 1; $i < 10001; $i++)                 
    {   prText(250, 650, "This is page $i");       
        prPage();                              # Page break
    }
    prEnd();

=for end                               

This little program gives you a hint why I wrote the module as functional. It is slow to start,
because the module is big, but then it should be fast. On my old computer it defines at least
a thousand pages per second, and the capacity should be sufficient. You can easily
increase the number of pages to 100 000.

=head2 Small files

This program is not as fast as the previous one. It is internally more complicated.
On my PC with Windows, it also seems like the operating system needs much
time to catalogue each file.

=for smallFiles.pl begin

    use PDF::Reuse;
    use strict;                            

    prDocDir('doc');                         

    for (my $i = 1; $i < 1001; $i++)                 
    {   prFile("short$i.pdf");
        prFontSize(16);                      
        prFont('Times-Bold');                          
        prText(180, 650, 'This is the first and only page');                                                    
    }
    prEnd();

=for end

Here we produce 1000 documents. When you define a new file the old one is automatically written. You have to set font and font size for each
file if you are not satisfied with Helvetica 12.      


=head2 Starting to reuse 

Now we come to a real reason why PDF::Reuse is needed. It gives you a possibility to reuse pages from
a PDF-file as a form or background. It can be used as a template. 

In this example we are going to send a letter (a physical letter to be printed) to
some of our customers. We imagine that the vice president will give some views about what happened
last year. First he writes a letter in Word. It is converted to PDF. That is done
by a plug in, PDFMaker, which you get when you buy Adobe Acrobat. (Look at next example
if you want to do everything with PDF::Reuse directly. Then you get a better result. But a vice president wouldn't 
work like that. He would like to use a tool like Word. He knows it and it's convenient, and that's
also ok.) Anyway, when PDFMaker has generated the file, you have to do a little trick.
(If it is an important file, take a copy of it first.)
You open the file in Acrobat. Choose the TouchUp tool for text, and remove 1 letter
e.g. 1 space, then insert the same letter and save the file. By doing so, you will
fool Acrobat to concatenate all streams of the page. It can then be transformed
to an "XObject", which is a very practical format. PDF::Reuse can now use it as a background
or template.

When you downloaded the module I hope you also got 'lastYear.pdf' which is the PDF-file
that is the template for the letter. A little text file holds names and addresses.
In reality these things should be taken from a database, and you could produce a file
for many thousand customers.

=for startToReuse.pl begin  
    
    use PDF::Reuse;
    use strict;
    my $line;
    my $step = 14;

    prDocDir('doc');
    prFile('Letter.pdf');
    prFont('Times-Roman');
    prCompress(1);     

    my $infile = 'persons.txt';
    open (INFILE, "<$infile") || die "Couldn't open $infile, $!\n aborts!\n";
    while ($line = <INFILE>)
    {    my ($fName, $lName, $co, $street, $zipCode, $city, $country) = split(/,/, $line);
         my $y = 760;
         my $x = 105;
         prForm('lastYear.pdf');                # Here the template is used
         prText($x, $y, "$fName $lName");
         $y -= $step;
         if ($co)
         {   prText($x, $y, $co);
             $y -= $step;
         }
         prText($x, $y, $street);
         $y -= $step;
         prText($x, $y, $zipCode);
         prText(($x + 50), $y, $city);
         $y -= $step;
         prText($x, $y, $country);

         prText(107, 660, "Dear $fName $lName");
         prPage();
    }
    prEnd();
    close INFILE;

=for end         

Look at the template. It is 50 kB and the file we just produced has 5 pages, using
the template on every page. Yet our new file is only 43 kB. It looks a little bit
confusing. PDF::Reuse only used something like 41 kB of the template. It was defined
once and then the "PDF-code" referred to it, each time it was used. You can get
very compact lists in this way. Try with a template of your own and several
thousand customers, and you will see that this an excellent way of producing
long lists in a very compact format.

If you would had needed some bars for an enveloping machine, you could had added
a snippet of code just before prPage(). Here we use the graphic operators of PDF.
We put the code in a string, and add it to the "content stream" of the current page.
Study the PDF Reference Manual and do some experiments if you want to use it. ( I
don't remember exactly the distances between the bars, but it could be something
like this.) 

         my $string = "q\n";         # save graphic state
         $string   .= "4 w\n";       # make line width 4 pixels
         $string   .= "10 600 m\n";  # move to x=10 y=600, starts a new subpath
         $string   .= "40 600 l\n";  # a line to x=40 y=600 ( a horizontal line)
         $string   .= "10 580 m\n";   
         $string   .= "40 580 l\n";   
         $string   .= "10 510 m\n";   
         $string   .= "40 510 l\n";
         $string   .= "s\n";         # close the path and stroke
         $string   .= "Q\n";         # restore graphic state
         prAdd($string);             # the string is added to the content stream

If you think it is too complicated to program the bars, you could have painted 
them in some program and added them to the word-document.(That would also have
been better, because you would have had the bars defined only once in the document,
and not on every page.)   

=head2 A variation of previous example

Ok, if you want to avoid commercial tools like Word and Acrobat, you have to work
a little bit harder, but it is possible to get a better result.

This time we produce the template also. In the distribution you received a little text file
'Lastyear.txt' and a little jpeg-image with the signature of the vice president.
You also need Image::Info. (smallLetter.pl)

=for smallLetter.pl begin 
    
    use PDF::Reuse;
    use Image::Info qw(image_info dim);        # To get the dimensions of jpeg-images
    use strict;

    my $textFile = 'Lastyear.txt';
    my $file     = 'patric.jpg';     # image with a signature
    my $x        = 107;              # left margin
    my $y        = 646;              # Start 646 points up 
    my $step     = 15;               # Distance between lines (fontsize = 12)

    prDocDir('doc');

    prFile('LetterB.pdf');
    prCompress(1);                   #  Compress the stream
    prFont('Times-Roman');       

    open (INFILE, "<$textFile") || die "The text $textFile couldn't be opened, $!\n";

    while (my $line = <INFILE>)
    {   chomp $line;
        if ($line eq 'Yours sincerely')          # It's time to insert the image 
        {  my $info  = image_info($file);
           my ($width, $height) = dim($info);    # Get the dimensions
           my $intName = prJpeg("$file",         # Define the image and get
                                 $width,         # an internal name
                                 $height);
           #############################################################################
           #  The signature image happened to become a little too big when I made it   #
           #  So I have to scale it down for the sentence where it is shown            #
           #############################################################################

           $width  = $width  * 0.6;                     # Scale it down
           $height = $height * 0.6;                     # Scale it down
           my $yImage = $y - 25;                        # Put the image lower down
           $x += 50;                                    # Indent from now on
       
           #############################################################################
           #  Now we have to add something to the content stream to make the newly     #
           #  defined image visible. This is one possibility                           #
           #############################################################################
     
           my $string = "q\n";                                # save graphic state
           $string   .= "$width 0 0 $height $x $yImage cm\n"; # add numbers to the
                                                              # transformation matrix
           $string   .= "/$intName Do\n";                     # paint the image
           $string   .= "Q\n";                                # restore graphic state 

           prAdd($string);                     # Here we add the graphic directives  
                                              # to the content stream                        
        }

        prText($x, $y, $line);                # A simple way to handle text                       
        if ($y < 40)
        {  prPage();
           $y = 830;
        }
        else
        {  $y -= $step;
        }
    }    
 
    close INFILE;
    prEnd;

=for end  

This template will be smaller than 5 kB. The produced letters could also be sent by
e-mail.

=head2 Usual business documents.

PDF::Reuse has enough speed to produce ordinary business documents like order forms,
receipt, contracts etc. They can be displayed on practically every computer, and if
you pay a little attention to it, they should be small enough, so you can send them
over the net. As an extra plus, you can get a log, which can be used for
archiving or verification of the documents. Usually the log should be much smaller 
than the formatted document. If you have big templates or images the log can be a 
few percent or fractions of a percent of the document. (If that is too much for you,
it is possible to compress it physically or "logically" even more.)

First we design a template for the receipt. We do it in Word and the PDFMaker converts
it to PDF. As usual we have to remove 1 space and put it back to concatenate the streams
You should have 'receipt.pdf' in the distribution. It is 46 kB big. It can be used
as it is, but to me it is a little bit too big.

=head2 Making a small template

You can skip this example, if you think 46 kB is a good size for the template for
receipts.

I reuse 1 font from the previous example, and rewrite the template to get it smaller.
You can use PDF::API2::Util to get a color. If you haven't got that module, you could
use '0 0 0.9333' as blue2.
In the distribution there is a program 'reuseComponent_pl'. Run it to see the
names of included fonts: 

   perl reuseComponent_pl receipt.pdf

and you get 'myFile.pdf'. (The program needs the module PDF, which is totally
independent of PDF::Reuse. PDF sometimes croaks about 'bad object reference >'
when the info-part of the PDF-file is missing. That doesn't hinder 'myFile.pdf'
from being created.) 

=for receiptTemplate.pl begin 

    use PDF::Reuse;
    use PDF::API2::Util;          
    use strict;

    prDocDir("doc");

    my @c = namecolor('blue2');
  
    prFile("ReceiptSmall.pdf");
    prCompress(1); 
   
    prForm( { file   => 'Receipt.pdf',              # Just to get the definitions
              page   => 1,                          # from the page, and not to
              effect => 'load' } );                 # add anything to the page

    my $intName = prFont('FJIILK+Serpentine-Bold'); # "Extract" the font and get a
                                                    # name to use in the stream 
 
    my $string = "q\n";                             # save graphic state
    $string   .= "BT\n";                            # Begin Text
    $string   .= "/$intName 1 Tf\n";                # set font and "size" 
    $string   .= "40 0 0 40 85 784 Tm\n";           # set a text matrix
    $string   .= "-0.05 Tc\n";                      # set character spacing
    # $string   .= "0 Tw\n";                        # set word spacing
    $string   .= "$c[0] $c[1] $c[2] rg\n";          # set color for filling
    $string   .= "(Gigantic Electric Inc.) Tj\n";   # show text
    $string   .= "ET\n";                            # End Text
    $string   .= "Q\n";                             # restore graphic state

    prAdd($string);                                  
    
    prFont('TR');
    prFontSize(18);
    prText(153, 758, 'Everything electrical for home and office');
    prText(167, 702, 'Receipt');
    prFontSize(14);
    prText(120, 665, 'Customer');
    prText(120, 649, 'Address');
    prText(120, 633, 'City');
    prText(120, 617, 'Phone');
    prText(335, 665, 'Seller');
    prText(335, 649, 'Cashier');
    prText( 78, 568, 'Item');
    prText(445, 568, 'Sum');
    prText(508, 568, 'Delivery');
    prAdd("q 0 95 m 700 95 l S Q");                  # draw a horizontal line
    prFontSize(9);
    prText(72, 79, 'Main Office');
    prText(72, 69, 'Box 99999');
    prText(72, 59, 'Stora Allén 99');
    prText(72, 49, 'SE-19999 Stockholm');
    prText(72, 39, 'Phone +46-8-99999999');
    prText(264, 79, 'Shop (This Subsidiary)');
    prText(264, 59, 'Breda Allén 99');
    prText(264, 49, 'SE-15999 Skärholmen');
    prText(264, 39, 'Phone +46-8-19999999');
    prText(432, 79, 'VAT SE-559999-9999');

    prEnd();

=for end

Now your template will be 4,84 kB. If that still is too big for you, you can replace

    prForm( { file   => 'Receipt.pdf', 
              page   => 1,
              effect => 'load' } );

    my $intName = prFont('FJIILK+Serpentine-Bold');

with this sentence

    my $intName = prFont('HB');

Then the template will be 1,22 kB. But then you might get the wrong font for
the company name, and you should adjust the text matrix so you get the text a little
better centered and so on. Perhaps this text matrix would make it better:

    $string   .= "50 0 0 38 75 784 Tm\n";

=head2 Using the template

In this example we use the template and print a receipt similar to one that I received
some time ago. That one was printed with a little printer with at least 3 carbon copies and
without barcodes. At the same time I received a special guarantee for one of the items.
(I haven't done the guarantee certificate here). Anyway all of this could be done as
PDF-files, which are easy to send over the net, and with the additions of a log 
and barcodes they should be easy to store, restore and handle.

In a real situation all data should be taken from an interactive program or a database. Here
I have assigned everything directly in the program.

=for receipt.pl begin

    use PDF::Reuse;
    use Digest::MD5;
    use GD::Barcode::Code39;
    use strict;

    my $itemLines  = 550;             # start to write item lines 550 pixels up
    my $pageBottom = 100;

    my $str;
    ###############################
    # Columns for the item lines
    ###############################
    my $x0         = 41;
    my $x1         = 43;
    my $x2         = 337;
    my $x3         = 400;
    my $x4         = 470;
    my $x5         = 477;
    my $x6         = 506;               
    my $y          = $itemLines;                      
    my $step       = 12;               # Distance between lines (fontsize = 10)
    my $pageNo;
    my $form       = 'ReceiptSmall.pdf';

    prDocDir('doc');
    prLogDir('run');           # To get a log

    prFile('ex7.pdf');
    prTouchUp(0);                      # So you can't change it by mistake
    prCompress(1);
    prForm($form);

    my $now = localtime();
    my @tvec = localtime();
    my $today = sprintf("%02d", $tvec[5] % 100)  . '-'
              . sprintf("%02d", ++$tvec[4])      . '-'
              . sprintf("%02d", $tvec[3]);
 
    my $customer  = 'Anders Svensson';
    my $address   = 'Klämgränd 9';
    my $city      = 'Stockholm';
    my $phone     = '9999999';
    my $seller    = 'Alex Buhre';
    my $cashier   = 'Ritva Axelsson';
    my $refNo     = '123456789';
    my $paid      = '3599.00';
    my $payMethod = 'MC/EC 544819999999999999999';
    my $sum;

    my @items = ( [1, '22292 Microsoft Xbox Sega/Jsrf', 1, 2541, $today, 
                  '      Guarantee, ref No 345678,  is attached'],
                  [2, '20503 Microsoft Project Gotham', 1, 55, ' ',
                  '      To be fetched later by the customer'],
                  [3, '20508 TV-Spel Hårdv DVD-Adapt/Fjärr', 1, 346, $today],
                  [4, '21964 EA Game       SIMS Unleashed', 1, 319, $today],
                  [5, '22249 Nordisk CD/MC/Spelfil Spiderm', 1, 239, $today],
                  [6, '21660 Sony    Videoband 3E-24oV-ORG-EUR', 1, 99, $today]
                );
  
    pageTop();

    prFont('C');
    prFontSize(10);

    for my $item (@items)
    {  my @detail = @$item;
       prText($x0, $y, "$detail[0].", 'right' );
       prText($x1, $y, $detail[1] );
       prText($x2, $y, $detail[2], 'right'); 
       prText($x3, $y, sprintf("%.2f", $detail[3]), 'right');
       my $itemSum = ($detail[2] * $detail[3]);
       $sum += $itemSum;
       prText($x4, $y, sprintf("%.2f", $itemSum ), 'right');
       prText($x5, $y, 'SEK');
       prText($x6, $y, $detail[4]);
   
       if (defined $detail[5])
       {   $y -= $step;
           prText($x1, $y, $detail[5]);
       }
       $y -= $step;
       if ($y < $pageBottom)
       {   pageEnd();
           prPage();
           prForm($form);
           $y = $itemLines;
       }
    }

    my $vat = $sum * 0.25;
    prText($x2 - 12, $y, '(Included VAT');
    prText($x4, $y, sprintf("%.2f", $vat), 'right');
    prText($x5, $y, 'SEK)');
    $y -= $step;
    prText($x2, $y, 'Sum to pay');
    $sum = sprintf("%.2f", $sum);
    prText($x4, $y, $sum, 'right');
    prText($x5, $y, 'SEK');
    $y -= $step;
    prText($x1, $y, "Paid      $payMethod");
    prText($x4, $y, $paid, 'right');
    prText($x5, $y, 'SEK');
    pageEnd();

    prEnd(); 

    ##########################################################################
    #  To print before the end of the page
    ##########################################################################
    sub pageEnd
    {  $y -= $step * 4;
       prText($x1, $y, "Ref No $refNo");
       my $oGdB = GD::Barcode::Code39->new($refNo);
       my $str = $oGdB->barcode();
       prFontSize(17);
       prBar(200, $y, $str);
       prFontSize(10);
       prFont('C');
       prText(($x3 + 30), $y, 'Check No Method: S1');
       $y -= $step;
       my $str2 = prGetLogBuffer() . '436';
       prLog('<S1>');
       $str = Digest::MD5::md5_hex($str2);
       prText($x1, $y, "Check No $str");
    }
   
    sub pageTop
    {  $pageNo++;
       prFont('Times-Roman');
       prFontSize(18);
   
       prText(230, 702, "$now  Page: $pageNo");
   
       prFontSize(14);
       prText(180, 665, $customer);
       prText(180, 649, $address);
       prText(180, 633, $city);
       prText(180, 617, $phone);
       prText(386, 665, $seller);
       prText(386, 649, $cashier);
    }

=for end

When I run this program with the template of 4,84 kB the final file was 6,95 kB.  
In this special case the log was 2,07 kB and compressed 1,00 kB. It would have had
practically the same size if you had used the template of 46 kB.

Note the sentence

     prTouchUp(0);

It more or less "disables" the TouchUp tool in Acrobat. It makes it difficult to change
the document by mistake. Still you can save the document as postscript, distill it
and change whatever you want. But now you have had to put some effort in to it, and 
hopefully you have not had access to my log and you should not know how the check 
numbers are calculated, so it would anyway be difficult to falsify. (Also
the barcodes change from a font to pure graphics if you redistill the page.)

This is the way the check number is calculated

       my $str2 = prGetLogBuffer() . '436';
       prLog('<S1>');
       $str = Digest::MD5::md5_hex($str2);
       prText($x1, $y, "Check No $str");

prGetLogBuffer() returns what has been logged for the current page. This could be
an alternative to accumulating all variables.(The log buffer is 
written to the disc and undefined after every page break. Also you need to have a 
log. It is only activated when you have given a log directory with the function
prLogDir.)  The program concatenates the string from the buffer with a fixed
string, '436', which someone has decided should be used in this check number method.
After that, prLog puts a tag, <S1>, in the log. Now a hexadecimal digest is produced
and printed.  With this check number method you need the log to verify that a document
is consistent. If that is good or not depends on your needs.

=head2 Importing an image

The best way to import an image, is to take it from  another PDF-file:

=for importImage.pl begin

   use PDF::Reuse;
   use strict;

   prFile('doc/ex12.pdf');
   
   prImage(  { file    => 'doc/letterB.pdf',
               page    => 1,
               imageNo => 1,
               x       => 75,
               y       => 645,
               size    => 0.6 }  );
    
   prEnd();

=for end

Use reuseComponent_pl to see which images you can take from a PDF-file.

(If you would have used 'lastYear.pdf' instead of 'letterB.pdf' in ex12_pl you
would have had the image reversed when you extract it. PDFMaker defines it like
that, I don't know why. Perhaps life is not supposed to be too easy. It would have
been necessary to reverse the image with the transformation matrix.)

=head2 Adding a document

You can add a document with many pages to the current document with the function
prDoc() like this:

=for addDocument.pl begin

    use PDF::Reuse;
    use strict;

    prFile('doc/ex13.pdf');
    prForm('ex1.pdf');
    prText(100, 500, 'This is put on the first page');
    prPage();
    prDoc('doc/piped.pdf');
    prForm('ex1.pdf');
    prText(100, 500, 'This is put on the last page');

    prEnd();

=for end

The document from previous example is used for the first and last pages. In between
a document, with all of its pages, is put. Graphic, and for the first prDoc or prDocForm also interactive, 
functions are included. As usual you loose outlines, info and metadata which I haven't
implemented.

prDoc() is not sensitive to the structure of the pages. Each page can consist of
many streams. But you cannot influence the layout of the included pages
in any other way than through JavaScript, and you cannot write anything to the pages.
Also the routine is a little bit slow, but it has a positive
side-effect: If you use it with old PDF-files which have been updated many
times, it only takes the current parts of the files, so the result can be trimmed down. 

=head2 A business card

A PDF-page can often be used as a unit. You can resize it and display it many times
on a new page. For this example I designed a little page with Mayura Draw. (When this text was 
written, you could download the program from http://www.mayura.com and evaluate it for 30 days.) It produces
files in a variant of postscript which can be transformed to PDF by the distiller.
If you want, you can also get PDF-files directly from Mayura Draw, but the files might
become a little big, because it doesn't compress images. 

In the code below you produce 10 cards per page of paper. You print the cards on a 
special paper where each card should be 89 * 51 mm. (I suppose that is close to
253.2584 * 145.126 pixels) The cards start 43 pixels from the left and 59.76 from
the bottom.

Make a PDF-file with your name, photo and so on and replace 'myFile.pdf' with the 
name of your file. You get the best results if the proportions of your file is
something like 89/51 (width/height), but that is not so important. If you haven't
got a photo, you can remove the if..else sentence. Then you can let the x and y-axes
be scaled independently.

=for bizCard.pl begin

    use PDF::Reuse;
    use strict;

    my $y    = 59.76;                  # Margin at the bottom
    my $col1 = 43;                     # First column    
    my $col2 = 296;                    # Second column
    my $step = 145.126;                # Height of the card
    
    prDocDir("doc");
    prFile('bizCard.pdf');

    my @vec = prForm ( {file   => 'myFile.pdf', # Add the form definitions
                        effect => 'add' }       # and get data about the form
                     );
    ###########################################################################
    # The list from prForm contains $internalName, $lowerLeftX, $lowerLeftY,
    # $upperRightX, $upperRightY, $numberOfImages
    ###########################################################################

    my $form = $vec[0];                       
    my $xScale = 253.2584 / ($vec[3] - $vec[1]);
    my $yScale = 145.126 / ($vec[4] - $vec[2]);
    if ($xScale < $yScale)
    {  $yScale = $xScale;
    }
    else
    {  $xScale = $yScale;
    }
    while ($y < 720)
    {   prForm ( {file   => 'myFile.pdf',
                  x      => $col1,
                  y      => $y,
                  xsize  => $xScale,
                  ysize  => $yScale });

        prForm ( {file   => 'myFile.pdf',
                  x      => $col2,
                  y      => $y,
                  xsize  => $xScale,
                  ysize  => $yScale });
   
        $y += $step;
    }  
    prEnd();

=for end

=head2 Merging paper, bookmarks and the web   

Bookmarks can help you to navigate better within a document, this is what they are
mainly used for, but they are not limited to that. They can also e.g. give more
information about your data and connect to links outside your document.  

In this example we imagine that a company sends out printed annual statements to
their customers. Now the company will also make the statements available via the
web and via mail. The paper will look exactly the same, regardless of how
you get it, but if it arrives electronically, the customer will have the chance 
of getting more information from it.

While the program assembles the PDF-document it also creates bookmarks
with references and links.

=for bookmarks.pl begin

      use PDF::Reuse;
      use strict;

      my ($assetsThisYear, $assetsLastYear, %shares, %transactions);

      prFile('report.pdf');

      ##################################################################
      # Define two small JavaScripts functions. The first one fetches  
      # a document over the net. The second one shows an alert box 
      # with information
      ##################################################################

      my $str = 'function get(url) { this.getURL(url, false);}'
              . ' function inf(string) { app.alert(string, 3);}';
      prJs($str);

      # Reading a database	to get shares, links to companies and
      # transactions during the year
      # (In a real case it would be easier to create @sharesArray and @transArray
      # without any intermediate steps)
      #
      # If you want to test-run, remove the '#'-signs below and replace 
      # template.pdf with a file that can be used as a form
      #      
      # $assetsThisYear   = 300000;
      # $assetsLastYear   = 250000;
      # %shares   = ( 'ABB B'     => 'http://www.abb.com',
      #               'Ixzcon B'  => 'http://www.ixzcon.com',
      #               'Nokia B'   => 'http://www.nokia.com');
      #                     
      # %transactions  = ('2003-05-05-SE12345' => 'Sold 200 Alfa Laval B at 150 SEK',
      #                   '2003-05-20-BU23456' => 'Bought 300 Ixzcon B at 99 SEK',
      #                   '2003-05-21-SE34567' => 'Sold 45 Int.Minining at 4000 SEK',
      #                   '2003-06-10-BU7896'  => 'Bought 18000 ABB at 14 SEK',
      #                   '2003-07-15-BU4567'  => 'Bought 2000 Nokia at 200 SEK');
      # 
      # prForm('template.pdf');          

      if (scalar %shares)
      {   my @sharesArray;
          for (keys %shares)
          {   ###############################################################
              # Create an array of bookmark hashes. One hash for each share.
              # The text will be in blue and italic. You can fetch more 
              # information over the net
              ###############################################################
              push @sharesArray, { text  => "External: $_",
                                   style => 1,
                                   color => '0.2 0.2 0.7',
                                   act   => "get('$shares{$_}');" };
          }

          ###################################################################
          # Create a bookmark with the text 'Assets', connect it to a point
          # in the document, and put the bookmarks for shares under it
          ###################################################################
          prBookmark( { text => 'Assets',
                        act  => '0, 350, 380',
                        kids => \@sharesArray } );
      }

      #################################################################
      # Create an array of (closed) bookmarks for each transaction
      # They are here only for information. (The customer should have
      # received more detailed information earlier.)
      #################################################################

      if (scalar %transactions)
      {   my @array;
          for (sort (keys %transactions))
          {   push @array, { text => $_,
                             color => '0.5 0.1 0.1',
                             close => 1,
                             act  => "inf('$transactions{$_}');" };
          }
          prBookmark( { text => "Transactions (Unlinked)",
                        kids => \@array } );
      }

      # ...

      prText(350, 400, $assetsLastYear);
      prText(350, 380, $assetsThisYear);

      prEnd();

=for end

=head2 Hyperlinks

You want to embed links in your document. Then you can use the subroutine hyperLink
from PDF::Reuse::Util, or you can use prLink for more detail control.

=for hyperlinks.pl begin

     use PDF::Reuse;
     use PDF::Reuse::Util;
     use strict;
    
     prFile('doc/hyperLink.pdf');
   
     # ...

     my ($x, $position) = prText(25, 700, "This is written before the link  ");
     hyperLink( $position, 700, 'Press this link',
                    'http://www.purelyInvented.com/info.html' ); 
     
     # ...

     ($x, $position) = prText(25, 650, "This is written before the second link  ");
     my ($from, $to) = prText($position, 650, "Text for the second link");
     
     prLink( {page   => 1,
              x      => $position,
              y      => 650,
              width  => ($to - $from),
              height => 15,
              URI    => 'http://www.purelyInvented.com/info.html' } );

     prEnd();

=for end


=head2 Simple charts

Here is a table with ordered data about prices of Nissan Maxima taken from
a magazine in December 2003. First is model+year, then a column per 20000 km 
with the resulting medium price in Swedish crowns. The table is put in a file, 
'maxima.txt'.

=for maxima.txt begin

    Maxima-02 220 210 205 undef undef undef undef
    Maxima-01 200 195 190 185 undef undef undef
    Maxima-00 undef 180 175 169 162 undef undef
    Maxima-99 undef 110 100 95 90 85 80
    Maxima-98 undef undef 90 85 80 75 70
    Maxima-97 undef undef 85 80 75 70 65
    Maxima-96 undef undef undef 70 65 60 55

=for end

To transform the table to a simple graf, the next program can be used. If the line
used for columns had concisted of alphabetic characters and whole words only,
without spaces, it could also have been a line in the txt-file.

=for simpleChart.pl begin

   use PDF::Reuse::SimpleChart;
   use PDF::Reuse;
   use strict;
     
   prFile('myFile.pdf');
   prCompress(1);
   my $s = PDF::Reuse::SimpleChart->new();

   $s->columns('1000 km Usage',  '20', '40', '60', '80', '100', '120', '140');
   
   open (INFILE, 'maxima.txt') || die "Couldn't open maxima.txt, $!\n";
   while (<INFILE>)
   {  my @list = m'(\S+)'og;
      $s->add(@list) if (scalar @list) ;
   }
   close INFILE; 
  
   $s->draw(x     => 20,
            y     => 460,
            width => 400,
            height => 300,
            yUnit => '1000 SEK',
            type  => 'bars');
   prEnd()

=for end

Look at the pod of PDF::Reuse::SimpleChart for a few more examples. The programs
of that module can also be extracted the same snippet of code as you find in the 
beginning of this pod.

=head2 Barcodes

PDF::Reuse can print barcodes, but most often you want more than that. You want
e.g. the numbers in a form humans can read, you want a white box around, 
perhaps you want to rotate the pattern, change the size etc. Then you can use
PDF::Reuse::Barcode, which is a separate module you can download. Look at its
documentation for a complete list of functions (= type of barcodes), and parameters.

=for barcodes.pl begin 

   use PDF::Reuse;
   use PDF::Reuse::Barcode;
   use strict;

   prFile('doc/ex23.pdf');

   #################################################################
   # First a rectangle is drawn in the upper part of the page
   # just to show the normal white box around the barcodes
   #################################################################

   my $str = "q\n";                    # save the graphic state
   $str   .= "0.9 0.5 0.5 rg\n";       # a fill color
   $str   .= "10 400 440 410 re\n";    # a rectangle
   $str   .= "b\n";                    # fill (and a little more)
   $str   .= "Q\n";                    # restore the graphic state

   prAdd($str);

   #################################################
   # Normal usage, but the size has been increased
   #################################################
 
   PDF::Reuse::Barcode::EAN13(x          => 70,
                              y          => 700,
                              value      => '1234567890123',
                              size       => 1.5);


   #########################################################
   # A barcode "image" rotated 90 degrees counter clockwise
   #########################################################

   PDF::Reuse::Barcode::NW7(x          => 100,
                            y          => 430,
                            value      => '1234567890123',
                            rotate     => 90);

   ##################
   #  Prolonged bars
   ##################

   PDF::Reuse::Barcode::IATA2of5(x          => 70,
                                 y          => 200,
                                 value      => '1234567890123',
                                 prolong    => 4);

   prEnd();

=for end

=head1 Special cases

=head2 Restoring a document from the log

If you have big templates or images in your documents, it might be more practical
to store the logs instead of the formatted documents. The difference in size
can be very big. In the previous example the difference was very small, but I will
anyway show how to restore the document.
To run this program, you have to give the name of the log from previous example 
as an argument. 
The new files are put in new directories to avoid confusion.

=for logRestore.pl begin

   use PDF::Reuse;
   use Digest::MD5;
   use strict vars;

   my $line;
   my $inFile = shift || 'run/ex7.pdf.dat';            # The name of the log

   prDocDir('doc2');
   prLogDir('run2');

   open (INFILE, "<$inFile") || die "Couldn't open file $inFile, $! \n";

   while (chomp($line = <INFILE>))
   {   my @elem = split /~/, $line;
       my $routine = 'PDF::Reuse::pr' .  (shift @elem);
       for (@elem)
       {  s'<tilde>'~'og;
       }
       if ($line eq 'Log~<S1>')
       {  my $str2 = prGetLogBuffer() . '436';
          my $str  = Digest::MD5::md5_hex($str2);
          print "$str\n";
       } 
       &$routine (@elem); 
   }

   close INFILE;
   prEnd();

=for end

If you are not interested in the check number, you can remove these lines:

       if ($line eq 'Log~<S1>')
       {  my $str2 = prGetLogBuffer() . '436';
          my $str  = Digest::MD5::md5_hex($str2);
          print "$str\n";
       } 

If you want to use the possibility to restore documents, always
test a little first, to see that it works for your cases also. I have tried to
avoid errors, but you never know ...
(If there is a need, it would be easy to make a program that checks the restored
documents and the originals, to see that there are not any differences.)

In the log there is often a line like this : 'Cid~1042639354'. It is the time stamp
of the following PDF-file or JavaScript. If you try to restore a document and the
source files have changed, you will have an interruption of the run, the program
will die. If you know that the changes in the source file doesn't affect
the final document, just remove the line 'Cid~1042639354' and try
again.

=head2 Other languages than Perl

As the previous example showed, you can have batch routines to create PDF-files.
You let your Cobol program, or what ever it is, create an ASCII file with 
instructions similar to those of the log file (skip all unusual directives
like Cid, Vers, Id and Idtyp) and let some Perl program similar to ex8_pl
interpret the instructions.  

Also if you have an application in some other language than Perl, and that application
can write ASCII characters to STDOUT, and your operating system supports pipes,
I think you could let the receiving program, the end of the pipe look like this
('pipeEnd.pl'):

=for pipeEnd.pl begin
   
   use PDF::Reuse;
   use strict vars;

   my ($line, $routine, @elem);

   chomp($line = <STDIN>); 
  
   while ($line)
   {   @elem = split /~/, $line;
       $routine = 'PDF::Reuse::' . (shift @elem);
       for (@elem)
       {  s'<tilde>'~'og;
       }
       &$routine (@elem);
       chomp($line = <STDIN>) 
   }

=for end

And here is a Perl program that writes to STDOUT, but it could be any language.
'pipeBegin.pl':

=for pipeBegin.pl begin

   use strict;

   # Getting customer data in some way ...

   my @custData = ( { firstName => 'Anders',
                      lastName  => 'Wallberg' },
                    { firstName => 'Nils',
                      lastName  => 'Versen' },
                    { firstName => 'Niclas',
                      lastName  => 'Lindberg' },
             
                    # and 10000 more records

                    { firstName => 'Sten',
                      lastName  => 'Wernlund' } );

   print "prDocDir~doc\n";
   print "prFile~piped.pdf\n";
   print "prFont~TR\n";

   for my $customer (@custData)
   {    print "prForm~lastYear.pdf\n";
        print "prText~105~685~Dear $customer->{'firstName'}\n";
        # ...
        print "prPage\n";
   }
   print "prEnd\n";

=for end

When I put them in a pipe like this:

   C:\temp>perl pipeBegin.pl | perl pipeEnd.pl

I get a PDF-file with the name 'piped.pdf' in the directory doc.

You can do very many things with a simple pipe like this, but you cannot let
the programs interact, then you need better interprocess communication. 
If you need e.g. an internal name for a "name object", then it is most 
easy to use only Perl and one single program.

An advantage with pipes or daemons is that you can get very good response times.

=head2 "Mixing" output from Progress with Perl code

Here is an end of a pipe that evaluates every sentence it receives, if it doesn't
begin with the word 'file', in that case it evaluates the complete file
('pipeEnd2.pl'):

=for pipeEnd2.pl begin
   
   use strict vars;
   my $logFile = shift;
   my ($line, $routine, @elem, $result);
   if ($logFile)
   {  open (LOG, ">$logFile") || die "Couldn't open $logFile, $! \n";
   }
   chomp($line = <STDIN>);
   while ($line)
   {   if ($line =~ m'^file\s+(.+)'o)
       {   my $fileName = $1;
           open (INFIL, "<$fileName") || die "Couldn't open $fileName, $!\n";
           my $code;
           while (<INFIL>)
           { $code .= $_;
           }
           $result = eval ($code);
           if (! $result)
           {  $result = $@;
           }
           close INFIL;
       }
       else
       {   $result = eval ($line);
           if (! $result)
           {  $result = $@;
           }
       }
       if ($logFile)
       {  
          print LOG "$result $line\n";
       } 
       chomp($line = <STDIN>); 
   } 
   if ($logFile)
   {   close LOG;
   }

=for end

If you run it from a Progress program you can "mix" Progress and Perl statements
like this ('pipe.p'):

=for pipe.p begin

    /************************************************************************/
    /* This is a Progress program that runs together with the Sports2000    */
    /* database, which is a demonstration database that comes with Progress */
    /************************************************************************/

    DEF VAR str         AS CHAR                   NO-UNDO.
    DEF VAR theFirst    AS LOGI  INIT "true"      NO-UNDO.
    OUTPUT THROUGH perl.exe C:\temp\pdf\examples\pipeEnd2.pl.
    
    PUT UNFORMATTED "use PDF::Reuse;" SKIP.
    PUT UNFORMATTED "prFile('C:/temp/pdf/examples/Sports2000.pdf');" SKIP.

    FOR EACH customer:
        
       IF theFirst THEN
           theFirst = false.
       ELSE
           PUT UNFORMATTED "prPage();" SKIP.

       PUT UNFORMATTED "prForm('C:/temp/pdf/examples/lastYear.pdf');" SKIP.        
       str = "prText(107, 700, '" + customer.name + "');".
       PUT UNFORMATTED str SKIP.
       str = "prText(107, 685, '" + customer.address + "');".
       PUT UNFORMATTED str SKIP.
       str = "prText(107, 670, '" + customer.city + "');".
       PUT UNFORMATTED str SKIP.

    END.
    PUT UNFORMATTED "prEnd();"

=for end 

=head2 Using PDF::Reuse from JScript/VBScript

This little section is specific for Windows and is about how to make a very
simple COM/ActiveX wrapper around PDF::Reuse.

You need to have PerlScript installed on your computer. Read the User Guide that 
comes with ActivePerl to see how that is done. 
You also need the Windows Scripting Host (WSH), Windows Script Components,
Windows Script Component Wizard, Windows Script Runtime, VBScript, JScript,
Microsoft Windows Script Control and probably also documentation. Get all of 
it from the download section at http://msdn.microsoft.com/scripting.

To create a Windows Script Component, follow the instructions in ActivePerl
User Guide - Windows Scripting - Windows Script Components - Ten Easy Steps or
do like this:

     Run the Wizard (when I downloaded it, I received the Scriptlet Wizard)
     Enter a name
     Enter a location
     Click on Next
     Choose run on Server
     (If it is possible, choose PerlScript)
     Click on Next
     Click on Next (If you don't want to define a property)
     Enter "act" under method name
     Enter "string" as parameter name
     Click on Next
     Click on Finish
     
Now you could have something that looks a little like this (The ClassID 
should differ):

    <scriptlet>

    <Registration
        Description="PDFReuse"
        ProgID="PDFReuse.Scriptlet"
        Version="1.00"
        ClassID="{6ede1a17-839b-4220-83e3-ac2ad44a45f5}"
    >
    </Registration>

    <implements id=Automation type=Automation>
        <method name=act>
            <PARAMETER name=string/>
        </method>
    </implements>

    <script language=VBScript>

    function act(string)
        act = "Temporary Value"
    end function

    </script>
    </scriptlet>


Now replace "VBScript" with "PerlScript" and replace the function with 
Perl code so it looks something like this:

    <scriptlet>

    <Registration
        Description="PDFReuse"
        ProgID="PDFReuse.Scriptlet"
        Version="1.00"
        ClassID="{6ede1a17-839b-4220-83e3-ac2ad44a45f5}"
    >
    </Registration>

    <implements id=Automation type=Automation>
        <method name=act>
            <PARAMETER name=string/>
        </method>
    </implements>

    <script language=PerlScript>

         use PDF::Reuse;
         use strict vars;

         sub act
         {  my $line = shift;
            my ($routine, @elem);
            @elem = split /~/, $line;
            $routine = 'PDF::Reuse::' . (shift @elem);
            for (@elem)
            {  s'<tilde>'~'og;
            }
            my @vector = &$routine (@elem);
            if (defined @vector)
            {  my $outString = join('~', (@vector));
               return $outString;
            } 
            else
            {  return '';
            } 
          }

    </script>
    </scriptlet>

Save the file and right-click on the file name from the explorer, and choose
"Register"
Now you should be able to run "PDF::Reuse" from VBScript, JScript and perhaps also
other languages which can handle COM/ActiveX objects. You send the parameters
in a ~-separated string and receive the return value in a similar way. (If you
want to run programs like ex23_pl, you have to write specialized COM-objects.)

This is an example in VBScript:

=for Test.vbs begin

    ' Test.vbs
    ' Use PDF::Reuse from VBScript
    '
    Dim pgm
    Dim ans
    Set pgm = CreateObject("PDFReuse.Scriptlet")
        ans = pgm.act("prFile~fromVB.pdf")
        ans = pgm.act("prForm~lastYear.pdf")
        ans = pgm.act("prText~107~685~Mr Vladimir Bosak")
        ans = pgm.act("prEnd")

=for end

Run it from the command line with >cscript Test.vbs or double-click on it from 
the explorer. Here is the same example in JScript

=for Test.js begin

    // Test.js
    // Use PDF::Reuse from JScript
    //

    var pgm = new ActiveXObject("PDFReuse.Scriptlet")
    var ans = pgm.act("prFile~fromJS.pdf")
        ans = pgm.act("prForm~lastYear.pdf")
        ans = pgm.act("prText~107~685~Mr Java Script")
        ans = pgm.act("prEnd")

=for end

Here is an example of how to use it from the Internet Explorer. Probably
it is not a very practical example ('Test.html):

=for Test.html begin

    <HEAD><TITLE>A Simple First Page</TITLE>
    <SCRIPT LANGUAGE="JScript">
    <!--
    function Button1_OnClick()
    {  var pgm = PDFREUSE;
       var ans = pgm.act("prFile~C:/Temp/temp/fromHTML.pdf");
           ans = pgm.act("prForm~C:/Temp/temp/lastYear.pdf~1~1");
           ans = pgm.act("prText~107~685~Mr JavaScript HTML");
           ans = pgm.act("prEnd");
    }
    -->
    </SCRIPT>
    </HEAD>
    <BODY>
    <OBJECT ID=PDFREUSE WIDTH=1 HEIGHT=1 
    CLASSID='CLSID:6ede1a17-839b-4220-83e3-ac2ad44a45f5'>
    </OBJECT>
    <H3>A Simple First Page</H3><HR>
    <FORM><INPUT NAME="Button1" TYPE="BUTTON" VALUE="Click Here" 
       onClick=Button1_OnClick()>
    </FORM>
    </BODY>
    </HTML>

=for end

Change the directories (and CLASSID) so it can be run on your machine
If something goes wrong and it is within the control of PDF::Reuse, you 
get an error log on the desktop.

The first time you run via an ActiveX object, it is fairly slow, but if you
do it repeatedly, the performance is quit acceptable.

=head2 Generate OO-code

You can generate graphic objects and subroutines from B<simple> PDF-files.

(If you want to modify the generated code you need to know a little about the graphic operators
of PDF. Look at "The PDF-reference Manual".)
In the distribution you should have a little program 'graphObj_pl', which I wrote
just for this tutorial. It is far from foolproof, and it could be much more advanced. Anyway
It could anyway be a starting point, and it has produced the graphic objects you will see
here. 

We will write a program that produces weather symbols on a map, and we will use graphic objects,
generated from PDF-files.
The best thing, is probably to run the completed program first. You should have it
in the distribution with the name weatherObj_pl You also need the objects: cloud.pm,
sun.pm, lightn.pm, wind.pm, thermometer.pm, drop.pm, snow.pm. Also there should be
a map of eastern US: EUSA.pdf, and some weather data: weather.dat.

So run the program and look at the result. All the symbols can vary in size, color,
line width, rotation and skew. Of course they can inherit attributes from each other.
All the shapes are vector-based, so you can make them as big as you want and they will
keep there forms. Also you should notice the PDF-file will be fairly small. If you run
the program with weather.dat it will be smaller than 9 kB.

This is the way to make the symbols:
You start by drawing and painting with a program that produces postscript ( or EPS or 
EPSF) or uncompressed PDF-files. I started with the free Pagedraw from http://www.mayura.com
and that's possible. You distill your files with the distiller from Adobe or use the "free"
GhostScript and Gsviewer. A disadvantage with these programs is that you get many
"external references", "name objects", and you have handle them in some way. (You can
do that by having the original PDF-files available. There your modules can find the
appropriate color spaces, fonts, graphic state dictionaries and so on.) But it is
simpler if you start with PDF-files that contain a minimum of "name objects", and
that's why I made most of the symbols here with Mayura Draw. It can export simple PDF-files
straight away. 

When you have distilled or produced your PDF-file, you run the program graphObj_pl
like this:

    perl graphObj_pl myGraphicObject.pdf

and you will (hopefully) get a module 'myGraphicObject.pm'. All the symbols are produced like that.
At the same time as you get the module, you also get a parameter file 'myGraphicObject.dat'.

If you look at the program 'graphObj_pl', you will see that it is not very sophisticated
It only takes the first stream it encounters, and tries to process it. If that is
not what you wanted, it will definitely fail. Then it splits the stream into words
and tries to make standardized lines with the operator at the end. (It 
does not handle long sentences within parenthesis correctly.) It reads the
coordinates of every point to find the minimum values. It tries to analyze the stream
and make it into a module. You get an entry in the objects hash for every unique color, line width and so on.
"External objects" get function calls in the subroutine 'resources'. 

When you use your modules in programs it is B<usually best to avoid external objects.>
If the module needs a font, you can e.g. explicitly give a standard one like 'H' or 'TR'
when you draw the object. That will make your code faster to execute and the PDF-file
smaller. Often you can avoid new graphic state dictionaries by letting the module
use a default one. If you generated a module with 'graphObj_pl',you could write
like this:

   use PDF::Reuse;
   use myGraphicObject;
   use strict;

   prFile('myFile.pdf');

   my $gO = myGraphicObject->new();

   $gO->draw(x => 45,
             y => 100,
             font => 'H',
             defaultGraphState => 1);

   prEnd();

Anyway, if you look in the code of the modules you see that it is a little bit
obscure. Perhaps I should have commented, structured and added better subroutines,
but I haven't had time. It is a starting point.

One interesting case is when the "structure" of a graphic object changes. E.g.
when the mercury of the thermometer goes up and down, depending on the temperature.
To find out what parameters to set you could do like this:

First you draw your object -> transform it to PDF -> generate the module.
Then you make the desired changes to your object -> transform it to PDF with a new
name -> generate a new module and a parameter file.

In the distribution, among the examples, I have put a little experimental program,
which picks out the differences between two parameter files and produces a new one,
with the necessary changes to transform one object to another. E.g.: you make a PDF-file
a thermometer at its lowest point low.pdf, and then one with the highest temperature,
high.pdf, you should be able do the following

    perl graphObj_pl low.pdf                   Produces low.pm and low.dat
    perl graphObj_pl high.pdf                  Produces high.pm and high.dat

    perl paramDiff_pl low.dat high.dat         Produces diff.dat 

If you now run a little program like this:

   use PDF::Reuse;
   use low;
   use strict;

   prFile('myFile.pdf');

   my $l = low->new();

   $l->draw(x => 45,
            y => 700,
                              #  Insert diff.dat here
            font => 'H',
            defaultGraphState => 1);

   prEnd();


If you inserted diff.dat, you would have had "high" drawn. (But more important is
perhaps that you would have seen exactly which parameters to change to vary the
drawing) 


If you modify 'graphObj_pl' a little, you could generate subroutines 
instead of packages. Then you can cut and paste to include the code in
your programs. It is a little more work, but your programs will be faster 
if it is correctly done.

=head2 Efficient storage of text

Just as an example of how to handle text, I saved "Judges" from King James Bible as 
a text file. I found it at http://www.kingjamesversionofthebible.com/7-judges.html
It received the name 'Judges.txt', and was 110 kB. To transform it to PDF, this
little program can be used ('storage1.pl'):

=for storage1.pl begin

   use PDF::Reuse;
   use strict;

   my $textFile   = 'Judges.txt';     # The name of the text file
   my $pageTop    = 800;
   my $pageBottom = 40;
   my $x          = 35;               # Left margin
   my $y          = $pageTop;                     
   my $step       = 15;               # Distance between lines (fontsize = 12)

   prDocDir('doc');

   prFile('Judges.pdf');              
   prCompress(1);                     #  Compress streams
   prFont('Times-Roman'); 

   
   open (INFILE, "<$textFile") || 
            die "The text $textFile couldn't be opened, $!\n";

   while (my $line = <INFILE>)
   {   chomp $line;
       prText($x, $y, $line);         # A simple way to handle text                       
       if ($y < $pageBottom)
       {  prPage();
          $y = $pageTop;
       }
       else
       {  $y -= $step;
       }
   }    
   close INFILE;
   prEnd;

=for end

When you run this program, the result, 'Judges.pdf' will be 59 kB. It is 33 pages 
of text.

The function prText can be convenient, but if you want more control and perhaps
also more compressed files, you can work directly with the text operators of PDF
('storage2.pl'):

=for storage2.pl begin

   use PDF::Reuse;
   use strict;

   my $textFile = 'Judges.txt';    
   my $lineNo   = 0;
   my $str;

   prDocDir('doc');

   prFile('JudgesB.pdf');              
   prCompress(1);                   
   my $font = prFont('Times-Roman');       

   open (INFILE, "<$textFile") || 
            die "The text $textFile couldn't be opened, $!\n";

   while (my $line = <INFILE>)
   {   if ($lineNo == 0)
       {  pageTop();
       }

       chomp $line;
       $line =~ s/\(/\\(/;     # To put a backslash before ( 
       $line =~ s/\)/\\)/;     # and ) in the text
       $str .= "($line)'\n";   # Here goes the text with ' as operator
       $lineNo++;

       if ($lineNo > 51)
       {  pageBottom();
       }

   }
   if ($lineNo > 0)
   {   pageBottom();
   }
                       
   close INFILE;
   prEnd;

   sub pageTop
   {   $str .= "BT\n";
       $str .= "/$font 1 Tf\n";
       $str .= "12 0 0 12 35 815 Tm\n"; 
       $str .= "1.25 TL\n";
   } 

   sub pageBottom
   {   $str .= "ET\n";
       prAdd($str);
       prPage();
       undef $str;
       $lineNo = 0;
   }

=for end

Remove the line prCompress(1); if you want to see how the streams are formed. 
Notice the lines in the subroutine pageTop.

   $str .= "/$font 1 Tf\n";

Here you can use the internal name for Times-Roman. Later when the page
is going to be written, PDF::Reuse will examine the stream and try to
connect any "name objects",(which always begin with a '/') to a resource.
'1' is the font size.

Next sentence sets the text matrix (and text line matrix)

   $str .= "12 0 0 12 35 815 Tm\n";

The first '12' will multiply along the x-axis, the second '12' multiplies 
along the y-axis. '35' will "move" text objects that many pixels to the right,
and '815' in a similar way upwards.

   $str .= "1.25 TL\n";

'TL' sets the (vertical) distance between lines. In this case it will be
1.25 * 12 = 15 pixels

Every text line which is written to the stream will have this form:

   (string)'

The ' is an operator that moves to the next line and shows the text string.   

When you run this program the PDF-file will be 53 kB.


=head1 AUTHOR

Lars Lundberg : larslund@cpan.org

=head1 COPYRIGHT

Copyright (C) 2003 - 2005 Lars Lundberg, Solidez HB. All rights reserved.
This documentation is free; you can redistribute it and/or
modify it under the same terms as Perl itself.

=head1 DISCLAIMER

You get this tutorial free as it is, but nothing is guaranteed to work, whatever 
implicitly or explicitly stated in this document, and everything you do, 
you do at your own risk - I will not take responsibility 
for any damage, loss of money and/or health that may arise from the use of this document!