Module org.apache.sis.referencing

Package org.apache.sis.referencing.operation.transform

Class AbstractMathTransform2D

Object

FormattableObject

AbstractMathTransform

AbstractMathTransform2D

All Implemented Interfaces:

Parameterized, Lenient­Comparable, Math­Transform, Math­Transform2D

Direct Known Subclasses:

Pole­Rotation

public abstract class AbstractMathTransform2D
extends AbstractMathTransform
implements MathTransform2D

Base class for math transforms that are known to be two-dimensional in all cases. Two-dimensional math transforms are not required to extend this class, however doing so may simplify their implementation.

The simplest way to implement this abstract class is to provide an implementation for the following methods only:

• Abstract­Math­Transform.transform(double[], int, double[], int, boolean)

However, more performance may be gained by overriding the other transform methods as well.

Immutability and thread safety

All Apache SIS implementations of Math­Transform2D are immutable and thread-safe. It is highly recommended that third-party implementations be immutable and thread-safe too. This means that unless otherwise noted in the javadoc, Math­Transform2D instances can be shared by many objects and passed between threads without synchronization.

Serialization

Math­Transform2D may or may not be serializable, at implementation choices. Most Apache SIS implementations are serializable, but the serialized objects are not guaranteed to be compatible with future SIS versions. Serialization should be used only for short term storage or RMI between applications running the same SIS version.

Since:

0.5

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	Abstract­Math­Transform2D.Inverse	Base class for implementation of inverse math transforms.

Field Summary

Fields

Modifier and Type	Field	Description
protected static final int	DIMENSION	Number of input and output dimensions of all Abstract­Math­Transform2D, which is 2.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Abstract­Math­Transform2D()	Constructor for subclasses.

Method Summary

Modifier and Type	Method	Description
Shape	create­Transformed­Shape(Shape shape)	Transforms the specified shape.
Matrix	derivative(Point2D point)	Gets the derivative of this transform at a point.
final int	get­Source­Dimensions()	Returns the dimension of input points, which is always 2.
final int	get­Target­Dimensions()	Returns the dimension of output points, which is always 2.
Math­Transform2D	inverse()	Returns the inverse transform of this object.
Point2D	transform(Point2D pt­Src, Point2D pt­Dst)	Transforms the specified pt­Src and stores the result in pt­Dst.

Methods inherited from class AbstractMathTransform

compute­Hash­Code, derivative, equals, equals, format­To, get­Contextual­Parameters, get­Domain, get­Parameter­Descriptors, get­Parameter­Values, hash­Code, is­Identity, transform, transform, transform, transform, transform, transform, try­Concatenate

Methods inherited from class FormattableObject

print, to­String, to­String, to­WKT

Methods inherited from class Object

clone, finalize, get­Class, notify, notify­All, wait, wait, wait

Methods inherited from interface MathTransform

derivative, is­Identity, to­WKT, transform, transform, transform, transform, transform

Field Details

DIMENSION

protected static final int DIMENSION

Number of input and output dimensions of all Abstract­Math­Transform2D, which is 2. We define this constant for clarity only; its value shall not be modified. This is used for making clearer in the code when the literal 2 stands for the number of dimensions. It reduces confusion in contexts where the literal 2 also appear for other meanings than the number of dimensions.

Since:

1.2

See Also:

• get­Source­Dimensions()
• get­Target­Dimensions()
• Constant Field Values

Constructor Details

AbstractMathTransform2D

protected AbstractMathTransform2D()

Constructor for subclasses.

Method Details

getSourceDimensions

public final int getSourceDimensions()

Returns the dimension of input points, which is always 2.

Specified by:

get­Source­Dimensions in interface Math­Transform

Specified by:

get­Source­Dimensions in class Abstract­Math­Transform

Returns:

the number of dimensions of input points.

See Also:

• Default­Operation­Method.get­Source­Dimensions()

getTargetDimensions

public final int getTargetDimensions()

Returns the dimension of output points, which is always 2.

Specified by:

get­Target­Dimensions in interface Math­Transform

Specified by:

get­Target­Dimensions in class Abstract­Math­Transform

Returns:

the number of dimensions of output points.

See Also:

• Default­Operation­Method.get­Target­Dimensions()

transform

public Point2D transform(Point2D ptSrc,
 Point2D ptDst)
                  throws TransformException

Transforms the specified pt­Src and stores the result in pt­Dst. The default implementation invokes Abstract­Math­Transform.transform(double[], int, double[], int, boolean) using a temporary array of doubles.

Specified by:

transform in interface Math­Transform2D

Parameters:

pt­Src - the coordinate tuple to be transformed.

pt­Dst - the coordinate tuple that stores the result of transforming pt­Src, or null if a new point shall be created.

Returns:

the coordinate tuple after transforming pt­Src and storing the result in pt­Dst, or in a new point if pt­Dst was null.

Throws:

Transform­Exception - if the point cannot be transformed.

See Also:

• Math­Transform2D.transform(Point2D, Point2D)

createTransformedShape

public Shape createTransformedShape(Shape shape)
                             throws TransformException

Transforms the specified shape. The default implementation computes quadratic curves using three points for each line segment in the shape. The returned object is often a Path2D, but may also be a Line2D or a Quad­Curve2D if such simplification is possible.

Specified by:

create­Transformed­Shape in interface Math­Transform2D

Parameters:

shape - shape to transform.

Returns:

transformed shape, or shape if this transform is the identity transform.

Throws:

Transform­Exception - if a transform failed.

derivative

public Matrix derivative(Point2D point)
                  throws TransformException

Gets the derivative of this transform at a point. The default implementation performs the following steps:

• Copy the coordinates in a temporary array and pass that array to the Abstract­Math­Transform.transform(double[], int, double[], int, boolean) method, with the derivate boolean argument set to true.
• If the latter method returned a non-null matrix, returns that matrix. Otherwise throws Transform­Exception.

Specified by:

derivative in interface Math­Transform2D

Parameters:

point - the coordinate tuple where to evaluate the derivative.

Returns:

the derivative at the specified point as a 2×2 matrix.

Throws:

Transform­Exception - if the derivative cannot be evaluated at the specified point.

inverse

public MathTransform2D inverse()
                        throws NoninvertibleTransformException

Returns the inverse transform of this object. The default implementation returns this if this transform is an identity transform, or throws an exception otherwise. Subclasses should override this method.

Specified by:

inverse in interface Math­Transform

Specified by:

inverse in interface Math­Transform2D

Overrides:

inverse in class Abstract­Math­Transform

Throws:

Noninvertible­Transform­Exception