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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 | =head1 NAME
Imager::Tutorial - an introduction to Imager.
=head1 DESCRIPTION
=head2 Before you start
If you have the necessary knowledge, install the image format
libraries you want Imager image file support for, and Imager itself,
otherwise arrange to have it done.
=for stopwords Photoshop
You will also want some sort of image viewer tool, whether an image
editor like Photoshop or the GIMP, or a web browser.
=head2 Hello Boxes! - A Simple Start
As with any perl program it's useful to start with a #! line, and to
enable strict mode:
#!/usr/bin/perl -w
# you might to 'use warnings;' instead of the -w above
use strict;
These lines will be omitted in further examples.
As with any module, you need to load it:
use Imager;
Now create a image to draw on:
my $image = Imager->new(xsize => 100, ysize => 100);
and draw a couple of filled rectangles on it:
$image->box(xmin => 0, ymin => 0, xmax => 99, ymax => 99,
filled => 1, color => 'blue');
$image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
filled => 1, color => 'green');
Since the first box fills the whole image, it can be simplified to:
$image->box(filled => 1, color => 'blue');
and save it to a file:
$image->write(file=>'tutorial1.ppm')
or die 'Cannot save tutorial1.ppm: ', $image->errstr;
So our completed program is:
use Imager;
my $image = Imager->new(xsize => 100, ysize => 100);
$image->box(filled => 1, color => 'blue');
$image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
filled => 1, color => 'green');
$image->write(file=>'tutorial1.ppm')
or die 'Cannot save tutorial1.ppm: ', $image->errstr;
=head2 Adding some text
The first thing you need to draw text is a font object:
# use a different file, depending on the font support you have in
# your installed Imager.
my $font_filename = 'fontfiles/ImUgly.ttf';
my $font = Imager::Font->new(file=>$font_filename)
or die "Cannot load $font_filename: ", Imager->errstr;
If you're on Windows, you can supply a face name instead:
my $font = Imager::Font->new(face=>'Arial Bold')
or die "Cannot load 'Arial Bold: ", Imager->errstr;
and draw the text:
my $text = "Hello Boxes!";
my $text_size = 12;
$font->align(string => $text,
size => $text_size,
color => 'red',
x => $image->getwidth/2,
y => $image->getheight/2,
halign => 'center',
valign => 'center',
image => $image);
So inserting this into our existing code we have:
use Imager;
my $image = Imager->new(xsize => 100, ysize => 100);
$image->box(xmin => 0, ymin => 0, xmax => 99, ymax => 99,
filled => 1, color => 'blue');
$image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
filled => 1, color => 'green');
# use a different file, depending on the font support you have in
# your installed Imager.
my $font_filename = 'fontfiles/ImUgly.ttf';
my $font = Imager::Font->new(file=>$font_filename)
or die "Cannot load $font_filename: ", Imager->errstr;
my $text = "Hello Boxes!";
my $text_size = 12;
$font->align(string => $text,
size => $text_size,
color => 'red',
x => $image->getwidth/2,
y => $image->getheight/2,
halign => 'center',
valign => 'center',
image => $image);
$image->write(file=>'tutorial2.ppm')
or die 'Cannot save tutorial2.ppm: ', $image->errstr;
=head2 Using an existing image as a base
To load an image from a file, first create an empty image object:
my $read_image = Imager->new;
then call the read method:
my $image_source = shift; # from the command-line
$read_image->read(file=>$image_source)
or die "Cannot load $image_source: ", $image->errstr;
To keep to our working size, we'll scale the image:
# the scale() method always does a proportional scale, we don't want
# that here
my $scaled_image = $read_image->scaleX(pixels=>100)->scaleY(pixels=>100);
draw our inner box on that, and save the result:
$scaled_image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
filled => 1, color => 'green');
$scaled_image->write(file=>'tutorial3.ppm')
or die 'Cannot save tutorial3.ppm: ', $image->errstr;
so the complete program is:
use Imager;
my $read_image = Imager->new;
my $image_source = shift; # from the command-line
$read_image->read(file=>$image_source)
or die "Cannot load $image_source: ", $image->errstr;
# the scale() method always does a proportional scale, we don't want
# that here
my $scaled_image = $read_image->scaleX(pixels=>100)->scaleY(pixels=>100);
$scaled_image->box(xmin => 20, ymin => 20, xmax => 79, ymax => 79,
filled => 1, color => 'green');
$scaled_image->write(file=>'tutorial3.ppm')
or die 'Cannot save tutorial3.ppm: ', $image->errstr;
=head1 AUTHOR
Tony Cook <tonyc@cpan.org>
=head1 REVISION
$Revision$
=cut
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