Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Browse files

add a drop shadow entry to the cookbook and a sample too

  • Loading branch information...
commit e1317dacf0c5bfd0435d873b1277a56a237df240 1 parent 57520a1
@tonycoz authored
View
1  MANIFEST
@@ -272,6 +272,7 @@ rubthru.im
samples/align-string.pl Demonstrate align_string method.
samples/anaglyph.pl
samples/border.pl Demonstrate adding a border
+samples/drop_shadow.pl Draw a drop shadow or glow
samples/flasher.pl Animate an source image fading to a color and back
samples/gifscale.pl Scale an animated GIF, preserving animation info
samples/inline_capture2image.pl convert captured BGR data to an image
View
92 lib/Imager/Cookbook.pod
@@ -16,6 +16,11 @@ This is described in detail in L<Imager::Files>.
$image->read(file=>$filename) or die $image->errstr;
+Or:
+
+ my $image = Imager->new(file => $filename)
+ or die Imager->errstr;
+
See L<Imager::Files>.
=head2 Writing an image to a file
@@ -443,12 +448,95 @@ L<Imager::Filters/difference()> method.
# make a work image the same size as our input
my $work = Imager->new(xsize => $in->getwidth, ysize => $in->getheight,
channels => $in->getchannels);
- # and fill it with the colour we want transparent
+ # and fill it with the color we want transparent
$work->box(filled => 1, color => $color);
- # get an image with that colour replaced with transparent black
+ # get an image with that color replaced with transparent black
my $out = $work->difference(other => $in);
+=head1 SPECIAL EFFECTS
+
+=head2 Drop Shadows
+X<drop shadow>X<effects, drop shadow>
+
+This can be used for a glow effect as well.
+
+First create a new image, either with an alpha channel (if you want
+transparency behind the shadow) or without, if you want a background
+color:
+
+ my $out = Imager->new
+ (
+ xsize => $shadow_size * 2 + $src->getwidth,
+ ysize => $shadow_size * 2 + $src->getheight,
+ channels => 4,
+ );
+ # fill it with your background color, if you want one
+ # $out->box(filled => 1, color => $back_color);
+
+Make a work image to render the shadow on:
+
+ my $shadow_work = Imager->new
+ (
+ xsize => $back->getwidth,
+ ysize => $back->getheight,
+ channels => 1,
+ );
+
+Extract the alpha channel from the source image, first the alpha version:
+
+ my $alpha = $src->convert(preset => "alpha");
+
+and draw that on the work shadow:
+
+ $shadow_work->paste
+ (
+ src => $slpha,
+ left => $shadow_size,
+ top => $shadow_size,
+ );
+
+otherwise just draw a box for the non-alpha source:
+
+ $shadow_work->box
+ (
+ filled => 1,
+ color => [ 255 ],
+ xmin => $shadow_size,
+ ymin => $shadow_size,
+ xmax => $shadow_size + $src->getwidth() - 1,
+ ymax => $shadow_size + $src->getheight() - 1,
+ );
+
+Blur the work shadow:
+
+ $shadow_work->filter(type => "gaussian", stddev => $shadow_size);
+
+Convert it to an RGB image with alpha:
+
+ $shadow_work = $shadow_work->convert
+ (
+ matrix => [ [ 0, $red / 255 ],
+ [ 0, $green / 255 ],
+ [ 0, $blue / 255 ],
+ [ 1 ] ]
+ );
+
+Draw that on the output image:
+
+ $out->rubthrough(src => $shadow_work);
+
+Draw our original image on the output image, perhaps with an offset:
+
+ $out->rubthrough
+ (
+ src => $src,
+ tx => $shadow_size + $x_offset,
+ ty => $shadow_size + $y_offset,
+ );
+
+See F<samples/drop_shadow.pl> for an example of this recipe.
+
=head1 AUTHOR
Tony Cook <tony@develop-help.com>
View
4 samples/README
@@ -122,3 +122,7 @@ wiggle.pl
Produce an animated GIF that blends back and forth between the two
supplied images. If the input images form a stereo pair the GIF can
be used for wiggle stereoscopy.
+
+drop_shadow.pl
+
+ Produce a drop shadow based on the source image alpha channel.
View
132 samples/drop_shadow.pl
@@ -0,0 +1,132 @@
+#!perl
+use strict;
+use Imager;
+use Getopt::Long;
+
+my $bg;
+my $shadow_size = "10%";
+my $offset = "0x0";
+my $shadow_color = "#404040";
+
+GetOptions(
+ "bg=s" => \$bg,
+ "size|s=s" => \$shadow_size,
+ "o|offset=s" => \$offset,
+ "s|shadow=s" => \$shadow_color,
+ );
+
+my $infile = shift;
+my $outfile = shift
+ or die <<EOS;
+Usage: $0 [options] infile outfile
+Options can be any or all of:
+ -bg color - fill the background with a color instead of using
+ transparency, this can be a translucent color.
+ -size size - size of the shadow in pixels, or percent of min dimension
+ -offset <xsize>x<ysize> - offset of the original image within the shadow
+ -shadow color - color of the shadow
+EOS
+
+my $src = Imager->new(file => $infile)
+ or die "Cannot read image file '$infile': ", Imager->errstr, "\n";
+
+# simplify things by always working in RGB rather than grey
+$src = $src->convert(preset => "rgb");
+
+if ($shadow_size =~ /^([0-9]+)%$/) {
+ my $dim = $src->getwidth < $src->getheight ? $src->getwidth : $src->getheight;
+
+ $shadow_size = int($1 * $dim / 100 + 0.5);
+}
+
+my ($x_offset, $y_offset) = $offset =~ /^([+-]?[0-9]+)x([+-]?[0-9]+)$/
+ or die "$0: invalid offset\n";
+
+my $shc = Imager::Color->new($shadow_color)
+ or die "$0: invalid shadow color: ", Imager->errstr, "\n";
+
+my ($red, $green, $blue) = $shc->rgba;
+
+# First create a new image, either with an alpha channel (if you want
+# transparency behind the shadow) or without, if you want a background
+# colour:
+
+my $out = Imager->new
+ (
+ xsize => $shadow_size * 2 + $src->getwidth,
+ ysize => $shadow_size * 2 + $src->getheight,
+ channels => 4,
+ );
+
+if ($bg) {
+ # fill it with your background color, if you want one
+ my $bgc = Imager::Color->new($bg)
+ or die "$0: invalid color '$bg'\n";
+ $out->box(filled => 1, color => $bgc);
+}
+
+# Make a work image to render the shadow on:
+my $shadow_work = Imager->new
+ (
+ xsize => $out->getwidth,
+ ysize => $out->getheight,
+ channels => 1,
+ );
+
+if ($src->getchannels == 4) {
+ # Extract the alpha channel from the source image, if the image has no
+ # alpha, then a solid box then it's simpler, first the alpha version:
+ my $alpha = $src->convert(preset => "alpha");
+
+ # and draw that on the work shadow:
+ $shadow_work->paste
+ (
+ src => $alpha,
+ left => $shadow_size,
+ top => $shadow_size,
+ );
+}
+else {
+ # otherwise just draw a box for the non-alpha source:
+
+ $shadow_work->box
+ (
+ filled => 1,
+ color => [ 255 ],
+ xmin => $shadow_size,
+ ymin => $shadow_size,
+ xmax => $shadow_size + $src->getwidth() - 1,
+ ymax => $shadow_size + $src->getheight() - 1,
+ );
+}
+
+# Blur the work shadow:
+
+$shadow_work->filter(type => "gaussian", stddev => $shadow_size);
+
+# Convert it to an RGB image with alpha:
+
+$shadow_work = $shadow_work->convert
+ (
+ matrix => [ [ 0, $red / 255 ],
+ [ 0, $green / 255 ],
+ [ 0, $blue / 255 ],
+ [ 1 ] ]
+ ) or die $shadow_work->errstr;
+
+# Draw that on the output image:
+
+$out->rubthrough(src => $shadow_work);
+
+# Draw our original image on the output image, perhaps with an offset:
+$out->rubthrough
+ (
+ src => $src,
+ tx => $shadow_size + $x_offset,
+ ty => $shadow_size + $y_offset,
+ );
+
+$out->write(file => $outfile)
+ or die "Cannot write to '$outfile': ", $out->errstr, "\n";
+
+
View
13 t/950-kwalitee/020-samples.t
@@ -14,11 +14,20 @@ while (<SAMPLES>) {
close SAMPLES;
-plan tests => scalar(@sample_files);
-
my $manifest = maniread();
+my @mani_samples = sort grep m(^samples/\w+\.pl$), keys %$manifest;
+
+plan tests => scalar(@sample_files) + scalar(@mani_samples);
+
for my $filename (@sample_files) {
ok(exists($manifest->{"samples/$filename"}),
"sample file $filename in manifest");
}
+
+my %files = map { $_ => 1 } @sample_files;
+for my $filename (@mani_samples) {
+ $filename =~ s(^samples/)();
+ ok(exists $files{$filename},
+ "sample $filename in manifest found in README");
+}
Please sign in to comment.
Something went wrong with that request. Please try again.