NAME
Geometry::AffineTransform - Affine Transformation to map 2D coordinates to other 2D coordinates
SYNOPSIS
use Geometry::AffineTransform;
my $t = Geometry::AffineTransform->new();
$t->translate($delta_x, $delta_y);
$t->rotate($degrees);
my $t2 = Geometry::AffineTransform->new()->scale(3.1, 2.3);
$t->concatenate($t2);
my ($x1, $y1, $x2, $y2, ...) = $t->transform($x1, $y1, $x2, $y2, ...);DESCRIPTION
Geometry::AffineTransform instances represent 2D affine transformations that map 2D coordinates to other 2D coordinates. The references in "SEE ALSO" provide more information about affine transformations.
You create a new instance with "new", configure it to perform the desired transformation with a combination of "scale", "rotate" and "translate" and then perform the actual transformation on one or more x/y coordinate pairs with "transform".
The state of a newly created instance represents the identity transform, that is, it transforms all input coordinates to the same output coordinates.
Most methods return the instance so that you can chain method calls:
my $t = Geometry::AffineTransform->new();
$t->scale(...)->translate(...)->rotate(...);
($x, $y) = Geometry::AffineTransform->new()->rotate(..)->transform($x, $y);METHODS
new
Constructor, returns a new instance configured with an identity transform.
You can optionally supply any of the six specifiable parts of the transformation matrix. The six values in the first two columns are the specifiable values:
[ m11 m21 0 ]
[ m21 m22 0 ]
[ tx ty 1 ]The constructor lets you initialize them with key/value parameters:
my $t = Geometry::AffineTransform->new(tx => 10, ty => 15);By default, the identity transform represented by this matrix is used:
[ 1 0 0 ]
[ 0 1 0 ]
[ 0 0 1 ]In other words, invoking the constructor without arguments is equivalent to this:
my $t = Geometry::AffineTransform->new(
m11 => 1,
m12 => 0,
m21 => 0,
m22 => 1,
tx => 0,
ty => 0
);clone
Returns a clone of the instance.
invert
Inverts the state of the transformation.
my $inverted_clone = $t->clone()->invert();transform
Transform one or more coordinate pairs according to the current state.
This method expects an even number of positional parameters, each pair representing the x and y coordinates of a point.
Returns the transformed list of coordinates in the same form as the input list.
my @output = $t->transform(2, 4, 10, 20);concatenate
Combine the receiver's state with that of another transformation instance.
This method expects a list of one or more Geometry::AffineTransform instances and combines the transformation of each one with the receiver's in the given order.
Returns $self.
scale
Adds a scaling transformation.
This method expects positional parameters.
- sx
-
The scaling factor for the x dimension.
- sy
-
The scaling factor for the y dimension.
Returns $self.
translate
Adds a translation transformation, i.e. the transformation shifts the input coordinates by a constant amount.
This method expects positional parameters.
- tx
-
The offset for the x dimension.
- ty
-
The offset for the y dimension.
Returns $self.
rotate
Adds a rotation transformation.
This method expects positional parameters.
- angle
-
The rotation angle in degrees. With no other transformation active, positive values rotate counterclockwise.
Returns $self.
matrix
Returns the current value of the 3 x 3 transformation matrix, including the third, fixed column, as a 9-element list:
my ($m11, $m12, undef,
$m21, $m22, undef,
$tx, $ty, undef) = $t->matrix();SEE ALSO
- Apple Quartz 2D Programming Guide - The Math Behind the Matrices
- Sun Java java.awt.geom.AffineTransform
-
http://download.oracle.com/javase/1.4.2/docs/api/java/awt/geom/AffineTransform.html
- Wikipedia - Matrix Multiplication
AUTHOR
Marc Liyanage <liyanage@cpan.org>
COPYRIGHT AND LICENSE
Copyright 2008 Marc Liyanage.
Distributed under the Artistic License 2.