Equivalent to ImageMagick's "trim" with Perl's Imager

imager-trim-inlinec.pl

#!/usr/bin/env perl
use Imager;
use File::Path qw(make_path);
use File::Basename;
use Inline with => 'Imager';
use Inline C => <<'EOS' => WITH => 'Imager';
void trim(Imager::ImgRaw img, int fuzz, SV* res_top, SV* res_left, SV* res_right, SV* res_bottom) {
    int top = 0;
    int left = 0;
    int right = img->xsize;
    int bottom = img->ysize;
    int x, y, ch;
    i_color first, c;

    // Get the "matching" color from first pixel
    i_gpix(img, left, top, &first);

    // Find top
    for (y = top; y < img->ysize; ++y) {
        int match = 0;
        for (x = left; x < img->xsize; ++x) {
            i_gpix(img, x, y, &c);
            for (ch = 0; ch < img->channels; ++ch) {
                if (c.channel[ch] < (first.channel[ch] - fuzz) || c.channel[ch] > (first.channel[ch] + fuzz)) {
                    match = 1;
                    break;
                }
            }
        }
        if (match) {
            top = y;
            break;
        }
    }

    // Find bottom
    for (y = bottom; y > top; --y) {
        int match = 0;
        for (x = left; x < img->xsize; ++x) {
            i_gpix(img, x, y-1, &c);
            for (ch = 0; ch < img->channels; ++ch) {
                if (c.channel[ch] < (first.channel[ch] - fuzz) || c.channel[ch] > (first.channel[ch] + fuzz)) {
                    match = 1;
                    break;
                }
            }
        }
        if (match) {
            bottom = y;
            break;
        }
    }

    // Find left
    for (x = left; x < img->xsize; ++x) {
        int match = 0;
        for (y = top; y < bottom; ++y) {
            i_gpix(img, x, y, &c);
            for (ch = 0; ch < img->channels; ++ch) {
                if (c.channel[ch] < (first.channel[ch] - fuzz) || c.channel[ch] > (first.channel[ch] + fuzz)) {
                    match = 1;
                    break;
                }
            }
        }
        if (match) {
            left = x;
            break;
        }
    }

    // Find right
    for (x = right; x > left; --x) {
        int match = 0;
        for (y = top; y < bottom; ++y) {
            i_gpix(img, x-1, y, &c);
            for (ch = 0; ch < img->channels; ++ch) {
                if (c.channel[ch] < (first.channel[ch] - fuzz) || c.channel[ch] > (first.channel[ch] + fuzz)) {
                    match = 1;
                    break;
                }
            }
        }
        if (match) {
            right = x;
            break;
        }
    }

    sv_setiv(res_top, top);
    sv_setiv(res_bottom, bottom);
    sv_setiv(res_left, left);
    sv_setiv(res_right, right);
}
EOS

die "Usage: trim.pl [source_image] [source_image] [fuzziness]\n"
    unless @ARGV and $ARGV[0] and $ARGV[1];

my ($source, $target, $fuzziness) = @ARGV;
$fuzziness = $fuzziness || 0;
my ($target_filename, $target_path) = fileparse($target);
my $target_filetype = (split(/\./, $target_filename))[1] || 'png';
$target_filetype = 'jpeg' if $target_filetype eq 'jpg' or $target_filetype eq 'jpe';

my $imager = Imager->new( file => $source )
    or die "Cannot open $source -file: ", Imager->errstr();

# Trim background
my ($top, $left, $right, $bottom);
trim($imager, $fuzziness, $top, $left, $right, $bottom);

$imager = $imager->crop(
    left => $left,
    right => $right,
    top => $top,
    bottom => $bottom,
);

# Fit the original image to a square box
# First create directory for the file
make_path($target_path) if $target_path and $target_path ne './';

# Then store it
$imager->write( file => $target, type => $target_filetype )
    or die "Cannot write $target -file: ", Imager->errstr();

print "Done.\n";