183 lines
5.0 KiB
Plaintext
183 lines
5.0 KiB
Plaintext
=head1 NAME
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Imager::Tutorial - an introduction to Imager.
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=head1 DESCRIPTION
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=head2 Before you start
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If you have the necessary knowledge, install the image format
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libraries you want Imager image file support for, and Imager itself,
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otherwise arrange to have it done.
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=for stopwords Photoshop
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You will also want some sort of image viewer tool, whether an image
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editor like Photoshop or the GIMP, or a web browser.
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=head2 Hello Boxes! - A Simple Start
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As with any perl program it's useful to start with a #! line, and to
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enable strict mode:
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#!/usr/bin/perl -w
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# you might to 'use warnings;' instead of the -w above
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use strict;
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These lines will be omitted in further examples.
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As with any module, you need to load it:
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use Imager;
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Now create a image to draw on:
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my $image = Imager->new(xsize => 100, ysize => 100);
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and draw a couple of filled rectangles on it:
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$image->box(xmin => 0, ymin => 0, xmax => 99, ymax => 99,
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filled => 1, color => 'blue');
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$image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
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filled => 1, color => 'green');
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Since the first box fills the whole image, it can be simplified to:
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$image->box(filled => 1, color => 'blue');
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and save it to a file:
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$image->write(file=>'tutorial1.ppm')
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or die 'Cannot save tutorial1.ppm: ', $image->errstr;
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So our completed program is:
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use Imager;
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my $image = Imager->new(xsize => 100, ysize => 100);
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$image->box(filled => 1, color => 'blue');
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$image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
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filled => 1, color => 'green');
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$image->write(file=>'tutorial1.ppm')
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or die 'Cannot save tutorial1.ppm: ', $image->errstr;
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=head2 Adding some text
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The first thing you need to draw text is a font object:
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# use a different file, depending on the font support you have in
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# your installed Imager.
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my $font_filename = 'fontfiles/ImUgly.ttf';
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my $font = Imager::Font->new(file=>$font_filename)
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or die "Cannot load $font_filename: ", Imager->errstr;
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If you're on Windows, you can supply a face name instead:
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my $font = Imager::Font->new(face=>'Arial Bold')
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or die "Cannot load 'Arial Bold: ", Imager->errstr;
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and draw the text:
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my $text = "Hello Boxes!";
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my $text_size = 12;
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$font->align(string => $text,
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size => $text_size,
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color => 'red',
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x => $image->getwidth/2,
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y => $image->getheight/2,
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halign => 'center',
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valign => 'center',
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image => $image);
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So inserting this into our existing code we have:
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use Imager;
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my $image = Imager->new(xsize => 100, ysize => 100);
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$image->box(xmin => 0, ymin => 0, xmax => 99, ymax => 99,
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filled => 1, color => 'blue');
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$image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
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filled => 1, color => 'green');
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# use a different file, depending on the font support you have in
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# your installed Imager.
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my $font_filename = 'fontfiles/ImUgly.ttf';
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my $font = Imager::Font->new(file=>$font_filename)
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or die "Cannot load $font_filename: ", Imager->errstr;
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my $text = "Hello Boxes!";
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my $text_size = 12;
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$font->align(string => $text,
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size => $text_size,
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color => 'red',
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x => $image->getwidth/2,
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y => $image->getheight/2,
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halign => 'center',
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valign => 'center',
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image => $image);
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$image->write(file=>'tutorial2.ppm')
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or die 'Cannot save tutorial2.ppm: ', $image->errstr;
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=head2 Using an existing image as a base
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To load an image from a file, first create an empty image object:
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my $read_image = Imager->new;
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then call the read method:
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my $image_source = shift; # from the command-line
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$read_image->read(file=>$image_source)
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or die "Cannot load $image_source: ", $image->errstr;
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To keep to our working size, we'll scale the image:
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# the scale() method always does a proportional scale, we don't want
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# that here
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my $scaled_image = $read_image->scaleX(pixels=>100)->scaleY(pixels=>100);
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draw our inner box on that, and save the result:
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$scaled_image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
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filled => 1, color => 'green');
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$scaled_image->write(file=>'tutorial3.ppm')
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or die 'Cannot save tutorial3.ppm: ', $image->errstr;
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so the complete program is:
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use Imager;
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my $read_image = Imager->new;
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my $image_source = shift; # from the command-line
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$read_image->read(file=>$image_source)
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or die "Cannot load $image_source: ", $image->errstr;
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# the scale() method always does a proportional scale, we don't want
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# that here
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my $scaled_image = $read_image->scaleX(pixels=>100)->scaleY(pixels=>100);
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$scaled_image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
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filled => 1, color => 'green');
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$scaled_image->write(file=>'tutorial3.ppm')
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or die 'Cannot save tutorial3.ppm: ', $image->errstr;
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=head1 AUTHOR
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Tony Cook <tonyc@cpan.org>
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=head1 REVISION
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$Revision$
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=cut
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