add support for modifying the image

2 files changed, 105 insertions, 9 deletions

diff --git a/lib/Image/PNM.pm b/lib/Image/PNM.pm
index b089851..6239d23 100644
--- a/lib/Image/PNM.pm
+++ b/lib/Image/PNM.pm
@@ -69,25 +69,53 @@ sub as_string {
     return $self->$method;
 }
 
-=method width
+=method width($w)
 
-Returns the width of the image in pixels.
+Returns the width of the image in pixels. If C<$w> is given, sets the width of
+the image to C<$w>.
 
 =cut
 
 sub width {
     my $self = shift;
+    my ($w) = @_;
+    if (defined($w)) {
+        for my $row (@{ $self->{pixels} }) {
+            if ($w > $self->{w}) {
+                push @$row, 0
+                    for 1..($w - $self->{w});
+            }
+            else {
+                pop @$row
+                    for 1..($self->{w} - $w);
+            }
+        }
+        $self->{w} = $w;
+    }
     return $self->{w};
 }
 
-=method height
+=method height($h)
 
-Returns the height of the image in pixels.
+Returns the height of the image in pixels. If C<$h> is given, sets the height
+of the image to C<$h>.
 
 =cut
 
 sub height {
     my $self = shift;
+    my ($h) = @_;
+    if (defined($h)) {
+        if ($h > $self->{h}) {
+            push @{ $self->{pixels} }, [ (0) x $self->{w} ]
+                for 1..($h - $self->{h});
+        }
+        else {
+            pop @{ $self->{pixels} }
+                for 1..($self->{h} - $h);
+        }
+        $self->{h} = $h;
+    }
     return $self->{h};
 }
 
@@ -100,10 +128,17 @@ and they are interpreted as being scaled by this value.
 
 sub max_pixel_value {
     my $self = shift;
+    my ($max) = @_;
+    if (defined($max)) {
+        for my $row (@{ $self->{pixels} }) {
+            @$row = map { $_ * $self->{max} / $max } @$row;
+        }
+        $self->{max} = $max;
+    }
     return $self->{max};
 }
 
-=method pixel($row, $col)
+=method pixel($row, $col, $new_value)
 
 Returns the value of a pixel at the given C<$row> and C<$col>. The value is
 returned as an arrayref of three RGB values, where each value ranges from
@@ -113,13 +148,18 @@ C<0.0> to C<1.0>.
 
 sub pixel {
     my $self = shift;
-    my ($row, $col) = @_;
+    my ($row, $col, $new_value) = @_;
 
-    my $pixel = $self->raw_pixel($row, $col);
+    if (defined($new_value)) {
+        $new_value = ref($new_value)
+            ? [ map { $_ * $self->{max} } @$new_value ]
+            : $new_value * $self->{max};
+    }
+    my $pixel = $self->raw_pixel($row, $col, $new_value);
     return [ map { $_ / $self->{max} } @$pixel ];
 }
 
-=method raw_pixel($row, $col)
+=method raw_pixel($row, $col, $new_value)
 
 Returns the value of a pixel at the given C<$row> and C<$col>. The value is
 returned as an arrayref of three RGB values, where each value is an integer
@@ -129,12 +169,17 @@ ranging from C<0> to C<< $image->max_pixel_value >>.
 
 sub raw_pixel {
     my $self = shift;
-    my ($row, $col) = @_;
+    my ($row, $col, $new_value) = @_;
 
     my $pixel = $self->{pixels}[$row][$col];
     die "invalid pixel location ($row, $col)"
         unless defined $pixel;
 
+    if (defined($new_value)) {
+        $self->{pixels}[$row][$col] = $new_value;
+        $pixel = $new_value;
+    }
+
     if (!ref $pixel) {
         $pixel = [ $pixel, $pixel, $pixel ];
     }
diff --git a/t/write.t b/t/write.t
new file mode 100644
index 0000000..36f716e
--- /dev/null
+++ b/t/write.t
@@ -0,0 +1,51 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use Test::More;
+
+use Image::PNM;
+
+{
+    my $image = Image::PNM->new;
+    $image->width(6);
+    $image->height(8);
+    $image->max_pixel_value(255);
+
+    for my $col (0..5) {
+        for my $row (0..7) {
+            $image->pixel($row, $col, [1, 1, 1]);
+        }
+    }
+    $image->raw_pixel(1, 2, [0, 84, 255]);
+    $image->raw_pixel(1, 3, [0, 84, 255]);
+    $image->raw_pixel(2, 1, [0, 0, 0]);
+    $image->raw_pixel(2, 4, [0, 0, 0]);
+    $image->raw_pixel(3, 0, [0, 0, 0]);
+    $image->raw_pixel(3, 5, [0, 0, 0]);
+    $image->raw_pixel(4, 0, [0, 0, 0]);
+    $image->raw_pixel(4, 1, [255, 0, 0]);
+    $image->raw_pixel(4, 2, [255, 0, 0]);
+    $image->raw_pixel(4, 3, [255, 0, 0]);
+    $image->raw_pixel(4, 4, [255, 0, 0]);
+    $image->raw_pixel(4, 5, [0, 0, 0]);
+    $image->raw_pixel(5, 0, [0, 0, 0]);
+    $image->raw_pixel(5, 5, [0, 0, 0]);
+    $image->raw_pixel(6, 0, [0, 0, 0]);
+    $image->raw_pixel(6, 5, [0, 0, 0]);
+
+    is($image->as_string('P3'), <<IMAGE);
+P3
+6 8
+255
+255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
+255 255 255 255 255 255 0 84 255 0 84 255 255 255 255 255 255 255
+255 255 255 0 0 0 255 255 255 255 255 255 0 0 0 255 255 255
+0 0 0 255 255 255 255 255 255 255 255 255 255 255 255 0 0 0
+0 0 0 255 0 0 255 0 0 255 0 0 255 0 0 0 0 0
+0 0 0 255 255 255 255 255 255 255 255 255 255 255 255 0 0 0
+0 0 0 255 255 255 255 255 255 255 255 255 255 255 255 0 0 0
+255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
+IMAGE
+}
+
+done_testing;