GIMP brush format is native to the GIMP image editor for storing a brush or a texture. It can be used in all Paint Tools, for example Pencil and Paintbrush. It works by repeating the brush bitmap as you move the tool. The Spacing parameter sets the distance between the brush marks as a percentage of brush width. Its default value can be set in the brush file.
You can also use GIMP to create new brushes in this format. Custom brushes can be loaded into GIMP for use in the paint tools by copying them into one of the Brush Folders - select Edit > Preferences in the menu bar, expand the Folders section and choose Brushes to see the recognized Brush Folders or to add new ones.
This page hosts a formal specification of GIMP brush file version 2 using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
use strict;
use warnings;
use IO::KaitaiStruct 0.009_000;
use Encode;
########################################################################
package GimpBrush;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
our $COLOR_DEPTH_GRAYSCALE = 1;
our $COLOR_DEPTH_RGBA = 4;
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{len_header} = $self->{_io}->read_u4be();
$self->{_raw_header} = $self->{_io}->read_bytes(($self->len_header() - 4));
my $io__raw_header = IO::KaitaiStruct::Stream->new($self->{_raw_header});
$self->{header} = GimpBrush::Header->new($io__raw_header, $self, $self->{_root});
}
sub len_body {
my ($self) = @_;
return $self->{len_body} if ($self->{len_body});
$self->{len_body} = (($self->header()->width() * $self->header()->height()) * $self->header()->bytes_per_pixel());
return $self->{len_body};
}
sub body {
my ($self) = @_;
return $self->{body} if ($self->{body});
my $_pos = $self->{_io}->pos();
$self->{_io}->seek($self->len_header());
$self->{body} = $self->{_io}->read_bytes($self->len_body());
$self->{_io}->seek($_pos);
return $self->{body};
}
sub len_header {
my ($self) = @_;
return $self->{len_header};
}
sub header {
my ($self) = @_;
return $self->{header};
}
sub _raw_header {
my ($self) = @_;
return $self->{_raw_header};
}
########################################################################
package GimpBrush::Header;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{version} = $self->{_io}->read_u4be();
$self->{width} = $self->{_io}->read_u4be();
$self->{height} = $self->{_io}->read_u4be();
$self->{bytes_per_pixel} = $self->{_io}->read_u4be();
$self->{magic} = $self->{_io}->read_bytes(4);
$self->{spacing} = $self->{_io}->read_u4be();
$self->{brush_name} = Encode::decode("UTF-8", IO::KaitaiStruct::Stream::bytes_terminate($self->{_io}->read_bytes_full(), 0, 0));
}
sub version {
my ($self) = @_;
return $self->{version};
}
sub width {
my ($self) = @_;
return $self->{width};
}
sub height {
my ($self) = @_;
return $self->{height};
}
sub bytes_per_pixel {
my ($self) = @_;
return $self->{bytes_per_pixel};
}
sub magic {
my ($self) = @_;
return $self->{magic};
}
sub spacing {
my ($self) = @_;
return $self->{spacing};
}
sub brush_name {
my ($self) = @_;
return $self->{brush_name};
}
########################################################################
package GimpBrush::Bitmap;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{rows} = ();
my $n_rows = $self->_root()->header()->height();
for (my $i = 0; $i < $n_rows; $i++) {
push @{$self->{rows}}, GimpBrush::Row->new($self->{_io}, $self, $self->{_root});
}
}
sub rows {
my ($self) = @_;
return $self->{rows};
}
########################################################################
package GimpBrush::Row;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{pixels} = ();
my $n_pixels = $self->_root()->header()->width();
for (my $i = 0; $i < $n_pixels; $i++) {
my $_on = $self->_root()->header()->bytes_per_pixel();
if ($_on == $GimpBrush::COLOR_DEPTH_GRAYSCALE) {
push @{$self->{pixels}}, GimpBrush::Row::PixelGray->new($self->{_io}, $self, $self->{_root});
}
elsif ($_on == $GimpBrush::COLOR_DEPTH_RGBA) {
push @{$self->{pixels}}, GimpBrush::Row::PixelRgba->new($self->{_io}, $self, $self->{_root});
}
}
}
sub pixels {
my ($self) = @_;
return $self->{pixels};
}
########################################################################
package GimpBrush::Row::PixelGray;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{gray} = $self->{_io}->read_u1();
}
sub red {
my ($self) = @_;
return $self->{red} if ($self->{red});
$self->{red} = 0;
return $self->{red};
}
sub green {
my ($self) = @_;
return $self->{green} if ($self->{green});
$self->{green} = 0;
return $self->{green};
}
sub blue {
my ($self) = @_;
return $self->{blue} if ($self->{blue});
$self->{blue} = 0;
return $self->{blue};
}
sub alpha {
my ($self) = @_;
return $self->{alpha} if ($self->{alpha});
$self->{alpha} = $self->gray();
return $self->{alpha};
}
sub gray {
my ($self) = @_;
return $self->{gray};
}
########################################################################
package GimpBrush::Row::PixelRgba;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{red} = $self->{_io}->read_u1();
$self->{green} = $self->{_io}->read_u1();
$self->{blue} = $self->{_io}->read_u1();
$self->{alpha} = $self->{_io}->read_u1();
}
sub red {
my ($self) = @_;
return $self->{red};
}
sub green {
my ($self) = @_;
return $self->{green};
}
sub blue {
my ($self) = @_;
return $self->{blue};
}
sub alpha {
my ($self) = @_;
return $self->{alpha};
}
1;