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.\" ========================================================================
.\"
.IX Title "Base 3pm"
.TH Base 3pm "2022-12-02" "perl v5.36.0" "User Contributed Perl Documentation"
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.nh
.SH "NAME"
Image::Base \- base class for loading, manipulating and saving images.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
This class should not be used directly. Known inheritors are Image::Xbm and
Image::Xpm.
.PP
.Vb 1
\&    use Image::Xpm ;
\&
\&    my $i = Image::Xpm\->new( \-file => \*(Aqtest.xpm\*(Aq ) ;
\&    $i\->line( 1, 1, 3, 7, \*(Aqred\*(Aq ) ;
\&    $i\->ellipse( 3, 3, 6, 7, \*(Aq#ff00cc\*(Aq ) ;
\&    $i\->rectangle( 4, 2, 9, 8, \*(Aqblue\*(Aq ) ;
.Ve
.PP
If you want to create your own algorithms to manipulate images in terms of
(x,y,colour) then you could extend this class (without changing the file),
like this:
.PP
.Vb 2
\&    # Filename: mylibrary.pl
\&    package Image::Base ; # Switch to this class to build on it.
\&    
\&    sub mytransform {
\&        my $self  = shift ;
\&        my $class = ref( $self ) || $self ;
\&
\&        # Perform your transformation here; might be drawing a line or filling
\&        # a rectangle or whatever... getting/setting pixels using $self\->xy().
\&    }
\&
\&    package main ; # Switch back to the default package.
.Ve
.PP
Now if you \f(CW\*(C`require\*(C'\fR mylibrary.pl after you've \f(CW\*(C`use\*(C'\fRd Image::Xpm or any
other Image::Base inheriting classes then all these classes will inherit your
\&\f(CW\*(C`mytransform()\*(C'\fR method.
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
.SS "\fBnew_from_image()\fP"
.IX Subsection "new_from_image()"
.Vb 3
\&    my $bitmap = Image::Xbm\->new( \-file => \*(Aqbitmap.xbm\*(Aq ) ;
\&    my $pixmap = $bitmap\->new_from_image( \*(AqImage::Xpm\*(Aq, \-cpp => 1 ) ;
\&    $pixmap\->save( \*(Aqpixmap.xpm\*(Aq ) ;
.Ve
.PP
Note that the above will only work if you've installed Image::Xbm and
Image::Xpm, but will work correctly for any image object that inherits from
Image::Base and respects its \s-1API.\s0
.PP
You can use this method to transform an image to another image of the same
type but with some different characteristics, e.g.
.PP
.Vb 3
\&    my $p = Image::Xpm\->new( \-file => \*(Aqtest1.xpm\*(Aq ) ;
\&    my $q = $p\->new_from_image( ref $p, \-cpp => 2, \-file => \*(Aqtest2.xpm\*(Aq ) ;
\&    $q\->save ;
.Ve
.SS "\fBline()\fP"
.IX Subsection "line()"
.Vb 1
\&    $i\->line( $x0, $y0, $x1, $y1, $colour ) ;
.Ve
.PP
Draw a line from point ($x0,$y0) to point ($x1,$y1) in colour \f(CW$colour\fR.
.SS "\fBellipse()\fP"
.IX Subsection "ellipse()"
.Vb 1
\&    $i\->ellipse( $x0, $y0, $x1, $y1, $colour ) ;
.Ve
.PP
Draw an oval enclosed by the rectangle whose top left is ($x0,$y0) and bottom
right is ($x1,$y1) using a line colour of \f(CW$colour\fR.
.SS "\fBrectangle()\fP"
.IX Subsection "rectangle()"
.Vb 1
\&    $i\->rectangle( $x0, $y0, $x1, $y1, $colour, $fill ) ;
.Ve
.PP
Draw a rectangle whose top left is ($x0,$y0) and bottom right is ($x1,$y1)
using a line colour of \f(CW$colour\fR. If \f(CW$fill\fR is true then the rectangle will be
filled.
.SS "\fBnew()\fP"
.IX Subsection "new()"
Virtual \- must be overridden.
.PP
Recommend that it at least supports \f(CW\*(C`\-file\*(C'\fR (filename), \f(CW\*(C`\-width\*(C'\fR and
\&\f(CW\*(C`\-height\*(C'\fR.
.SS "\fBnew_from_serialised()\fP"
.IX Subsection "new_from_serialised()"
Not implemented. Recommended for inheritors. Should accept a string serialised
using \fBserialise()\fR and return an object (reference).
.SS "\fBserialise()\fP"
.IX Subsection "serialise()"
Not implemented. Recommended for inheritors. Should return a string
representation (ideally compressed).
.SS "\fBget()\fP"
.IX Subsection "get()"
.Vb 2
\&    my $width = $i\->get( \-width ) ;
\&    my( $hotx, $hoty ) = $i\->get( \-hotx, \-hoty ) ;
.Ve
.PP
Get any of the object's attributes. Multiple attributes may be requested in a
single call.
.PP
See \f(CW\*(C`xy\*(C'\fR get/set colours of the image itself.
.SS "\fBset()\fP"
.IX Subsection "set()"
Virtual \- must be overridden.
.PP
Set any of the object's attributes. Multiple attributes may be set in a single
call; some attributes are read-only.
.PP
See \f(CW\*(C`xy\*(C'\fR get/set colours of the image itself.
.SS "\fBxy()\fP"
.IX Subsection "xy()"
Virtual \- must be overridden. Expected to provide the following functionality:
.PP
.Vb 2
\&    $i\->xy( 4, 11, \*(Aq#123454\*(Aq ) ;    # Set the colour at point 4,11
\&    my $v = $i\->xy( 9, 17 ) ;       # Get the colour at point 9,17
.Ve
.PP
Get/set colours using x, y coordinates; coordinates start at 0.
.PP
When called to set the colour the value returned is class specific; when
called to get the colour the value returned is the colour name, e.g. 'blue' or
\&'#f0f0f0', etc, e.g.
.PP
.Vb 2
\&    $colour = xy( $x, $y ) ;  # e.g. #123456 
\&    xy( $x, $y, $colour ) ;   # Return value is class specific
.Ve
.PP
We don't normally pick up the return value when setting the colour.
.SS "\fBload()\fP"
.IX Subsection "load()"
Virtual \- must be overridden. Expected to provide the following functionality:
.PP
.Vb 2
\&    $i\->load ;
\&    $i\->load( \*(Aqtest.xpm\*(Aq ) ;
.Ve
.PP
Load the image whose name is given, or if none is given load the image whose
name is in the \f(CW\*(C`\-file\*(C'\fR attribute.
.SS "\fBsave()\fP"
.IX Subsection "save()"
Virtual \- must be overridden. Expected to provide the following functionality:
.PP
.Vb 2
\&    $i\->save ;
\&    $i\->save( \*(Aqtest.xpm\*(Aq ) ;
.Ve
.PP
Save the image using the name given, or if none is given save the image using
the name in the \f(CW\*(C`\-file\*(C'\fR attribute. The image is saved in xpm format.
.SH "CHANGES"
.IX Header "CHANGES"
2000/05/05
.PP
Added some basic drawing methods. Minor documentation changes.
.PP
2000/05/04
.PP
Created.
.SH "AUTHOR"
.IX Header "AUTHOR"
Mark Summerfield. I can be contacted as <summer@perlpress.com> \-
please include the word 'imagebase' in the subject line.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright (c) Mark Summerfield 2000. All Rights Reserved.
.PP
This module may be used/distributed/modified under the \s-1LGPL.\s0