– Introduction to CGI 4/8/ Introduction to CGI Introduction to CGI – Session 2 · Introduction to CGI:  Generating images with Perl  GD.pm module  Databases: introduction  Database simulation with CSV  Working Bulletin Board example

– Introduction to CGI 4/8/ Introduction to CGI 2 Drawing Images with Perl CPAN provides a multitude of different modules for generating different kinds of graphic output

– Introduction to CGI 4/8/ Introduction to CGI 3 On image formats supported by GD.pm · GIF · Last version of GD.pm which supports GIF format is 1.19, · GIF features: 256 colors, Interlace, Animated GIF (Gif89a) LZW compression (lossless) · PNG · LZW-stripped GIF, · Additional features: · Alternative compression algorithm, · 3modes: 256 color; 16-bit grayscale, 48-bit truecolor · Support for alpha channel, · Better interlacing · JPEG · Ideal for photographs, as it designed for encoding continuous tone images · 24-bit color, · Compression with losses Legal battle between Unisys (creator of LZW compression algorithm) and developers resulted in dropping of GIF support in newer versions of GD.pm

– Introduction to CGI 4/8/ Introduction to CGI 4 GD.pm - module by Lincoln Stein #!/usr/local/bin/perl -wT use CGI qw(:standard); use GD;.. my $im = new GD::Image(400,400); my %color = (black=>$im->colorAllocate(0,0,0), white=>$im->colorAllocate(255,255,255), yellow=>$im->colorAllocate(255,255,0) ); $im->fill(200,200,$color{white}); $im->arc(200,200,150,150,0,360,$color{black}); $im->fill(200,200,$color{yellow}); $im->arc(170,170,10,10,0,360,$color{black}); $im->arc(230,170,10,10,0,360,$color{black}); $im->fill(200,200,$color{yellow}); $im->arc(200,200,110,110,0,180,$color{black}); print header(-type=>"image/gif"); binmode STDOUT; print $im->gif; First Example: simple drawing This code uses $image->gif method, so it runs only with Version 1.19 of GD

– Introduction to CGI 4/8/ Introduction to CGI 5 GD.pm drawing methods · Some drawing methods of GD.pm: · Coordinate system. The start of coordinate axis screen. X lies horizontally and Y - vertically use GD;.. my $im = new GD::Image($width,$height); $im->line($x1,$y1,$x2,$y2,$color); $im->arc($x,$y,$width,$height,$start,$end,$color); $im->ellipse($cx,$cy,$width,$height,$color); $image->filledRectangle($x1,$y1,$x2,$y2,$color); $im->string($font,$x,$y,$string,$color); $im->fill(200,200,$color); $im->fillToBorder($x,$y,$bordercolor,$color); print header(-type=>"image/png"); binmode STDOUT; print $im->png;

– Introduction to CGI 4/8/ Introduction to CGI 6 Calling CGI-generated images · Referencing Images: · In the URL box of a web browser: · In HTML code of your web page: · Object-oriented way (CGI.pm style):.. print img({-src=>”

– Introduction to CGI 4/8/ Introduction to CGI 7 Manipulating static images #!/usr/bin/perl -w use CGI qw(:standard); use GD; use IO::File; use strict; my $fh = new IO::File; $fh->open("Myimage.gif") or die "Couldn't open file\n"; my $im2 = GD::Image->newFromGif($fh); $fh->close; my $im = new GD::Image(500,635); my %color = (black => $im->colorAllocate(0,0,0), white => $im->colorAllocate(255,255,255), green => $im->colorAllocate(0,255,0) ); $im->fill(100,100,$color{green}); $im->arc(390,100,250,150,0,360,$color{black}); $im->fill(390,100,$color{white}); $im->transparent($color{green}); $im->string(gdGiantFont,310,90,“Some stuff",$color{black}); $im2->copy($im,0,0,0,0,500,635); print header(-type=>"image/gif"); binmode STDOUT; print $im2->gif; GD may be also used for rotating, cloning, merging Images etc

– Introduction to CGI 4/8/ Introduction to CGI 8 Debriefing: First, we are bringing in the external image into the script using its file handle as an argument for newFromGif() method When an image is merged with another one, its pixel data overwrites the pixel data of the target image #!/usr/bin/perl -w use CGI qw(:standard); use GD; use IO::File; use strict; my $fh = new IO::File; $fh->open("Myimage.gif") or die "Couldn't open file\n"; my $im2 = GD::Image->newFromGif($fh); $fh->close; $im2->copy($im,0,0,0,0,500,635); print header(-type=>"image/gif"); binmode STDOUT; print $im2->gif; Beware of newer methods in later versions of GD, as the given example might benefit greatly by using some newer stuff and the code would have been much shorter!

– Introduction to CGI 4/8/ Introduction to CGI 9 GD::Graph modules · GD::Graph provides basic diagram modules: · Points, Bars, Pie Charts, Area, 3D graphs etc.

– Introduction to CGI 4/8/ Introduction to CGI 10 Simple example of using GG::Graph::bars · Printing bars in CGI:.. use CGI; use GD::Graph::bars; use constant TITLE => "Number of Chromosomes in mammals"; my $q = new CGI; my $graph = new GD::Graph::bars(400,400); = ( [ qw(Cow Chimp Human Dog Mouse Camel)], [ 60,48,46,78,40,74 ] ); $graph->set(x_label=> 'Species', y_label=> 'chromosomes', title => TITLE, ) or die $graph->error; print $q->header(-type=>"image/gif"); my $image = binmode STDOUT; print $image->gif; As the previous example, this code uses GIF format, so please note that it runs only with version 1.19 of GD set() and plot() methods are common for all GD::Graph modules

– Introduction to CGI 4/8/ Introduction to CGI 11 Common methods for GD::Graph modules · Use array of anonymous arrays to pass the data to GD::Graph modules, X series goes first. Please note, that there are specific procedures are required to make X axis numeric. Sort your data by X value. · Set() and plot() methods · = ( · [ qw(Cow Chimp Human Dog Mouse Camel)], · [ 60,48,46,78,40,74 ] · ); · $graph->set(x_label=> 'Species', · y_label=> 'chromosomes', · title => “some title”, · ) or die $graph->error; · my $image = Look for more bells and whistles in documentation for GD::Graph modules available on CPAN website

– Introduction to CGI 4/8/ Introduction to CGI 12 Examples from scientific websites NCBI Mapviewer. Wormbase website.

– Introduction to CGI 4/8/ Introduction to CGI 13 Using databases in Perl · DBI and DBD interaction: Definitions: DBI - Database interface DBD - Database driver

– Introduction to CGI 4/8/ Introduction to CGI 14 Checking on DBD drivers:.. use CGI; use DBI; use CGI::Carp(fatalsToBrowser); my $q = new CGI; print $q->header(-type=>"text/html"); print $q->start_html(-title=>"Testing DBI drivers"); = DBI->available_drivers; print print "CGI version ".$q->version; print $q->end_html; Interpreter: usr/local/bin/perl (above) usr/bin/perl (below)

– Introduction to CGI 4/8/ Introduction to CGI 15 Connection to mysql databse: example · First, get a handle for that database: · Second, hmm….. There two things could be done: · If you need to get some data from database, create a statement handle: use DBI; my $dbh = DBI->connect(‘DBI:mysql:database:host:3306’,’user’,’password’) or die “No luck\n”;.. $dbh->do(qq(insert into table_name values(‘Frodo’, ‘hobbit’,’ ’))); my $sth = $dbh->prepare(qq(select from table_name name, occupation, phone_number)); $sth->execute;

– Introduction to CGI 4/8/ Introduction to CGI 16 Getting data with statement handle · First thing to do after execution: · Other methods for fetching data from statement handle: · Clean after yourself: = $sth->fetchrow_array){.. do something here } $sth->finish; $dbh->disconnect; $ary_ref = $sth->fetchrow_arrayref; $hash_ref = $sth->fetchrow_hashref; $ary_ref = $sth->fetchall_arrayref; $ary_ref = $sth->fetchall_arrayref( $slice, $max_rows ); Perl can disconnect on exit but it is not a good thing to leave it neglected

– Introduction to CGI 4/8/ Introduction to CGI 17 DBI::CSV - testing ground for database development DBD::CSV provides SQL-database functionality without database engine · CSV stands for Comma Separated Values. There is no database backend in case of CSV (no db engine running). Relies on flock() method (file locking system). · CSV database understands SQL - migration to fully-functional mySQL database requires only couple of lines of code! · Note: CSV driver may not work correctly over NFS, the best way to make it work - run Apache on localhost for testing CSV-powered cgi scripts. Offline scripts work just fine! #!/usr/bin/perl -w use DBI; my $dbh = DBI->connect("DBI:CSV:f_dir=/home/user/www/cgi-bin/db") or die "Couldn't connect\n”;

– Introduction to CGI 4/8/ Introduction to CGI 18 Simple example (table creation and insertion of data) · Simple example · The following script does two things: · creates a table · puts some records into table #!/usr/bin/perl -w use DBI; my $dbh = DBI->connect("DBI:CSV:f_dir=/home/user/www/cgi-bin/db") or die "Couldn't connect to the database\n"; my $sth = $dbh->prepare(qq( create table forum( Name CHAR(15), Message CHAR(100) )) ) or die "CAN NOT PREPARE STMT\n"; $sth->execute; $dbh->do("insert into forum values('Frodo','Umm... Ring')"); $dbh->do("insert into forum values('Gollum','This is my precois')"); $dbh->do("insert into forum values('Gandalf','Relax, buddy - you can not pass')"); $dbh->disconnect;

– Introduction to CGI 4/8/ Introduction to CGI 19 Connecting to database from CGI script · Let’s build a CGI script which reads from CSV table · This script connects to the database from the previous example, reads our records and print them in a HTML table.. use DBI; my $dbh = DBI->connect("DBI:CSV:f_dir=db") or die "Couldn't connect to the database\n"; my $sth = $dbh->prepare("select * from forum") or $dbh->errstr(); $sth->execute or $dbh->errstr(); = $sth->fetchrow_array){ } $sth->finish; $dbh->disconnect; print header(-type=>"text/html"); print start_html(-title=>"Creator of tables"); print end_html;

– Introduction to CGI 4/8/ Introduction to CGI 20 Dynamic update of CSV database from a web page use DBI; my $name = param("Name"); my $message = param("Message"); if($name && $message){ my $dbh = DBI->connect("DBI:CSV:f_dir=db") or die "Couldn't connect to the database\n"; $dbh->do("insert into forum values('$name','$message')"); $dbh->disconnect; print redirect("forum_csv.cgi"); }.. print start_form(-name =>"poster", -action=>"forum_csv.cgi", -method=>"post"), "Name:", textfield(-name =>"Name", -maxlength=>18), br, textarea(-name=>"Message", -cols=>40, -rows=>15), br, submit(-name=>"sender", -value=>"Send"), end_form, end_html;

– Introduction to CGI 4/8/ Introduction to CGI Introduction to CGI – Session 2 · Images: · CGI can make images dynamic · GD.pm is good for schematic drawings · Use CPAN to look for fancy stuff · Database: · DBI is your friend · Use DBI::CSV for apps development