=head1 NAME

Image::Xbm - Load, create, manipulate and save xbm image files.

=head1 SYNOPSIS

    use Image::Xbm ;

    my $j = Image::Xbm->new( -file, 'balArrow.xbm' ) ;

    my $i = Image::Xbm->new( -width => 10, -height => 16 ) ;

    my $h = $i->new ; # Copy of $i

    my $p = Image::Xbm->new_from_string( "###\n#-#\n###" ) ;

    my $q = $p->new_from_string( "H##", "#-#", "###" ) ;

    my $s = $q->serialse ; # Compresses a little too.
    my $t = Image::Xbm->new_from_serialsed( $s ) ;

    $i->xybit( 5, 8, 1 ) ;           # Set a bit
    print '1' if $i->xybit( 9, 3 ) ; # Get a bit
    print $i->xy( 4, 5 ) ;           # Will print black or white

    $i->vec( 24, 0 ) ;            # Set a bit using a vector offset
    print '1' if $i->vec( 24 ) ;  # Get a bit using a vector offset

    print $i->get( -width ) ;     # Get and set object and class attributes
    $i->set( -height, 15 ) ;

    $i->load( 'test.xbm' ) ;
    $i->save ;

    print "equal\n" if $i->is_equal( $j ) ; 

    print $j->as_string ;

    #####-
    ###---
    ###---
    #--#--
    #---#-
    -----#

    print $j->as_binstring ;

    1111101110001110001001001000100000010000

View an xbm file from the command line:

    % perl -MImage::Xbm -e'print Image::Xbm->new(-file,shift)->as_string' file

Create an xbm file from the command line:

    % perl -MImage::Xbm -e'Image::Xbm->new_from_string("###\n#-#\n-#-")->save("test.xbm")'

=head1 DESCRIPTION

This class module provides basic load, manipulate and save functionality for
the xbm file format. It inherits from C<Image::Base> which provides additional
manipulation functionality, e.g. C<new_from_image()>. See the C<Image::Base>
pod for information on adding your own functionality to all the C<Image::Base>
derived classes.

=head2 new()

    my $i = Image::Xbm->new( -file => 'test.xbm' ) ;
    my $j = Image::Xbm->new( -width => 12, -height => 18 ) ;
    my $k = $i->new ;

We can create a new xbm image by reading in a file, or by creating an image
from scratch (all the bits are unset by default), or by copying an image
object that we created earlier.

If we set C<-file> then all the other arguments are ignored (since they're
taken from the file). If we don't specify a file, C<-width> and C<-height> are
mandatory.

=over

=item C<-file>

The name of the file to read when creating the image. May contain a full path.
This is also the default name used for C<load>ing and C<save>ing, though it
can be overridden when you load or save.

=item C<-width>

The width of the image; taken from the file or set when the object is created;
read-only.

=item C<-height>

The height of the image; taken from the file or set when the object is created;
read-only.

=item C<-hotx>

The x-coord of the image's hotspot; taken from the file or set when the object
is created. Set to -1 if there is no hotspot.

=item C<-hoty>

The y-coord of the image's hotspot; taken from the file or set when the object
is created. Set to -1 if there is no hotspot.

=item C<-bits>

The bit vector that stores the image; read-only.

=back

=head2 new_from_string()

    my $p = Image::Xbm->new_from_string( "###\n#-#\n###" ) ;
    my $q = $p->new_from_string( "H##", "#-#", "###" ) ;
    my $r = $p->new_from_string( $p->as_string ) ;

Create a new bitmap from a string or from an array or list of strings. If you
want to use different characters you can:

    Image::Xbm->set( -setch => 'X', -unsetch => ' ' ) ;
    my $s = $p->new_from_string( "XXX", "X X", "XhX" ) ;

You can also specify a hotspot by making one of the characters a 'H' (set bit
hotspot) or 'h' (unset bit hotspot) -- you can use different characters by
setting C<-sethotch> and C<-unsethotch> respectively.

=head2 new_from_serialised()

    my $i = Image::Xbm->new_from_serialised( $s ) ;

Creates an image from a string created with the C<serialse()> method. Since
such strings are a little more compressed than xbm files or Image::Xbm objects
they might be useful if storing a lot of bitmaps, or for transferring bitmaps
over comms links.

=head2 serialise()

    my $s = $i->serialise ;

Creates a string version of the image which can be completed recreated using
the C<new_from_serialised> method.

=head2 get()
    
    my $width = $i->get( -width ) ;
    my( $hotx, $hoty ) = $i->get( -hotx, -hoty ) ;

Get any of the object's attributes. Multiple attributes may be requested in a
single call.

See C<xy> and C<vec> to get/set bits of the image itself.

=head2 set()

    $i->set( -hotx => 120, -hoty => 32 ) ;

Set any of the object's attributes. Multiple attributes may be set in a single
call. Except for C<-setch> and C<-unsetch> all attributes are object
attributes; some attributes are read-only.

See C<xy> and C<vec> to get/set bits of the image itself.

=head2 class attributes

    Image::Xbm->set( -setch => 'X' ) ;
    $i->set( -setch => '@', -unsetch => '*' ) ;

=over

=item C<-setch>

The character to print set bits as when using C<as_string>, default is '#'.
This is a class attribute accessible from the class or an object via C<get>
and C<set>.

=item C<-unsetch>

The character to print set bits as when using C<as_string>, default is '-'.
This is a class attribute accessible from the class or an object via C<get>
and C<set>.

=item C<-sethotch>

The character to print set bits as when using C<as_string>, default is 'H'.
This is a class attribute accessible from the class or an object via C<get>
and C<set>.

=item C<-unsethotch>

The character to print set bits as when using C<as_string>, default is 'h'.
This is a class attribute accessible from the class or an object via C<get>
and C<set>.

=back

=head2 xybit()

    $i->xy( 4, 11, 1 ) ;      # Set the bit at point 4,11
    my $v = $i->xy( 9, 17 ) ; # Get the bit at point 9,17

Get/set bits using x, y coordinates; coordinates start at 0.

=head2 xy()

    $i->xy( 4, 11, 'black' ) ;  # Set the bit from a colour at point 4,11
    my $v = $i->xy( 9, 17 ) ;   # Get the bit as a colour at point 9,17

Get/set bits using colours using x, y coordinates; coordinates start at 0.

If set with a colour of 'black' or a numeric value > 0 or a string not
matching /^#0+$/ then the bit will be set, otherwise it will be cleared.

If you get a colour you will always get 'black' or 'white'.

=head2 vec()

    $i->vec( 43, 0 ) ;      # Unset the bit at offset 43
    my $v = $i->vec( 87 ) ; # Get the bit at offset 87

Get/set bits using vector offsets; offsets start at 0.

=head2 load()

    $i->load ;
    $i->load( 'test.xbm' ) ;

Load the image whose name is given, or if none is given load the image whose
name is in the C<-file> attribute.

=head2 save()

    $i->save ;
    $i->save( 'test.xbm' ) ;

Save the image using the name given, or if none is given save the image using
the name in the C<-file> attribute. The image is saved in xbm format, e.g.

    #define test_width 6
    #define test_height 6
    static unsigned char test_bits[] = {
     0x1f, 0x07, 0x07, 0x09, 0x11, 0x20 } ;

=head2 is_equal()

    print "equal\n" if $i->is_equal( $j ) ;

Returns true (1) if the images are equal, false (0) otherwise. Note that
hotspots and filenames are ignored, so we compare width, height and the actual
bits only.

=head2 as_string()

    print $i->as_string ;

Returns the image as a string, e.g.

    #####-
    ###---
    ###---
    #--#--
    #---#-
    -----#

The characters used may be changed by C<set>ting the C<-setch> and C<-unsetch>
characters. If you give C<as_string> a parameter it will print out the hotspot
if present using C<-sethotch> or C<-unsethotch> as appropriate, e.g.

    print $n->as_string( 1 ) ;

    H##
    #-#
    ###

=head2 as_binstring()

    print $i->as_binstring ;

Returns the image as a string of 0's and 1's, e.g.

    1111101110001110001001001000100000010000

=head1 CHANGES

2016/02/23 (Slaven Rezic)

Make sure macro/variable names are always sane.

More strict parsing of bits.


2000/11/09

Added Jerrad Pierce's patch to allow load() to accept filehandles or strings;
will document in next release.


2000/05/05

Added new_from_serialised() and serialise() methods.


2000/05/04

Made xy() compatible with Image::Base, use xybit() for the earlier
functionality.


2000/05/01

Improved speed of vec(), xy() and as_string().

Tried use integer to improve speed but according to Benchmark it made the code
slower so I dropped it; interestingly perl 5.6.0 was around 25% slower than
perl 5.004 with and without use integer.


2000/04/30 

Created. 


=head1 AUTHOR

Mark Summerfield. I can be contacted as <summer@perlpress.com> -
please include the word 'xbm' in the subject line.

=head1 COPYRIGHT

Copyright (c) Mark Summerfield 2000. All Rights Reserved.

This module may be used/distributed/modified under the LGPL. 

=cut