/ 
Transform-Canvas-0.15
River stage one • 1 direct dependent • 1 total dependent
/ Transform::Canvas

NAME

Transform::Canvas - Perl extension for performing Coordinate transformation operations from the cartesion to the traditional drawing-model canvas coordinate systems.

VERSION

VERSION 0.14 15 Febuary, 2009

SYNOPSIS

use Transform::Canvas;
# create a mapping transform for data from 
#x=-100,y=-100,x=100,y=100  to x=10,y=10,x=100,y=100
$t = Transform::Canvas->new(canvas=>[10,10,100,100],data=>[-100,-100,100,100]);
# create a arrays of x and y values
$r_x = [-100,-10, 0, 20, 40, 60, 80, 100];
$r_y = [-100,-10, 0, 20, 40, 60, 80, 100];
#map the two arrays into the canvas data space
($pr_x,$pr_y) = $t->map($r_x,$r_y);

DESCRIPTION

Transform::Canvas is a module which automates reference-frame transformations beween two cartesian coordinate systems. it is specifically intended to be used as a facilitator for coordinate-system transformation procedures between the traditional, right-hand-rule coordinate system used in mathematics graphing and the visual-arts coordinate system with a y-axis pointing down.

The module allows for arbitrary 2-D transform mappings.

Methods

new

Module constructor.

#there are two ways to invoke this module
#one-step constructo
$t = Transform::Canvas->new (canvas => [x0 y0 x1 y1], data=>[x0 y0 x1 y1])
# or two-step connstructor
$t-> Transform::Canvas->new ();
$t->prepareMap (canvas => [x0 y0 x1 y1], data=>[x0 y0 x1 y1])

generate the conversion object through which all data points will be passed. NB: svg drawings use the painter's model and use a coordinate system which starts at the top, left corner of the document and has x-axis increasing to the right and y-axis increasing down.

In certain drawings, the y-axis is inverted compared to mathematical representation systems which prefer y to increase in the upwards direction.

canvas (target):
       x0 = paper-space minimum x value
       y0 = paper-space maximum x value
       x1 = paper-space minimum y value
       y1 = paper-space maximum y value
data (source):
       x0 = data-space minimum x value
       y0 = data--space maximum x value
       x1 = data-space minimum y value
       y1 = data-space maximum y value

prepareMap hash %args

Prepare the transformation space for the conversions; Currently only handles linear transformations, but this is a perfect candidate for non-spacial, non-cartesian transforms...

sub cx0 [string $value]

set and/or return the canvas x min value

sub cx1 [string $value]

set and/or return the canvas x max value

sub cy0 [string $value]

set and/or return return the canvas y min value

sub cy1 [string $value]

set and/or return the canvas y max value

sub dx0 [string $value]

set and/or return the data space x min value

sub dx1 [string $value]

set and/or return the data space x max value

sub dy0 [string $value]

set and/or return the data space y min value

sub dy1 [string $value]

set and/or return the data space y max value.

map($x,$y)

Map an array or a value from the (x,y) data axes to the (x,y) canvas axes

mapX

Map an array or a value of the x data axis to the x canvas axis

mapY

Map an array or a value of the y data axis to the y canvas axis

Max

Find th of an array

my $x = $t->Max([1,2,3,4,5]);

This utility needed a home and this seems like a convenient place to stick it

Min

Find th of an array

my $x = $t->Max([1,2,3,4,5]);

SEE ALSO

SVG SVG::Parser SVG::DOM SVG::Element SVG::Graph SVG::Extension

AUTHOR

Ronan Oger, <ronan@cpan.com>

COPYRIGHT AND LICENSE

Copyright (C) 2004-2009 by Ronan Oger

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.3 or, at your option, any later version of Perl 5 you may have available.