org.geotools.referencing.operation.transform

Class AbstractMathTransform

Object

Formattable

AbstractMathTransform

All Implemented Interfaces:

MathTransform

Direct Known Subclasses:

AbstractMathTransform.Inverse, ConcatenatedTransform, ExponentialTransform1D, GeocentricTransform, IdentityTransform, LinearTransform1D, LogarithmicTransform1D, MapProjection, MolodenskiTransform, NADCONTransform, NTv2Transform, PassThroughTransform, ProjectiveTransform, VerticalTransform, WarpTransform2D

public abstract class AbstractMathTransform
extends Formattable
implements MathTransform

Provides a default implementation for most methods required by the MathTransform interface. AbstractMathTransform provides a convenient base class from which other transform classes can be easily derived. In addition, AbstractMathTransform implements methods required by the MathTransform2D interface, but does not implements MathTransform2D. Subclasses must declare implements MathTransform2D themselves if they know to map two-dimensional coordinate systems.

Since:

2.0

Author:

Martin Desruisseaux (IRD)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	AbstractMathTransform.Inverse Default implementation for inverse math transform.

Field Summary

Fields inherited from class Formattable

SINGLE_LINE

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMathTransform() Constructs a math transform.

Method Summary

Modifier and Type	Method and Description
Shape	createTransformedShape(Shape shape) Transform the specified shape.
Matrix	derivative(DirectPosition point) Gets the derivative of this transform at a point.
Matrix	derivative(Point2D point) Gets the derivative of this transform at a point.
protected static void	ensureNonNull(String name, Object object) Makes sure that an argument is non-null.
boolean	equals(Object object) Compares the specified object with this math transform for equality.
protected String	formatWKT(Formatter formatter) Format the inner part of a Well Known Text (WKT) element.
String	getName() Returns a name for this math transform (never null).
ParameterDescriptorGroup	getParameterDescriptors() Returns the parameter descriptors for this math transform, or null if unknow.
ParameterValueGroup	getParameterValues() Returns the parameter values for this math transform, or null if unknow.
abstract int	getSourceDimensions() Gets the dimension of input points.
abstract int	getTargetDimensions() Gets the dimension of output points.
int	hashCode() Returns a hash value for this transform.
MathTransform	inverse() Creates the inverse transform of this object.
boolean	isIdentity() Tests whether this transform does not move any points.
protected static boolean	needCopy(int srcOff, int dimSource, int dstOff, int dimTarget, int numPts) Checks if source coordinates need to be copied before to apply the transformation.
protected static double	normalizeAngle(double x) Ensures that the specified longitude stay within 0 and {code}PI{code}.
protected static double	rollLongitude(double x) Ensures that the specified longitude stay within ±π radians.
DirectPosition	transform(DirectPosition ptSrc, DirectPosition ptDst) Transforms the specified ptSrc and stores the result in ptDst.
void	transform(double[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts) Transforms a list of coordinate point ordinal values.
void	transform(float[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) Transforms a list of coordinate point ordinal values.
void	transform(float[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts) Transforms a list of coordinate point ordinal values.
Point2D	transform(Point2D ptSrc, Point2D ptDst) Transforms the specified ptSrc and stores the result in ptDst.

Methods inherited from class Formattable

cleanupThreadLocals, toString, toWKT, toWKT, toWKT, toWKT

Methods inherited from class Object

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

Methods inherited from interface MathTransform

toWKT, transform

Constructor Detail

AbstractMathTransform

protected AbstractMathTransform()

Constructs a math transform.

Method Detail

getName

public String getName()

Returns a name for this math transform (never null). This convenience methods returns the name of the parameter descriptors if any, or the short class name otherwise.

Returns:

A name for this math transform (never null).

Since:

2.5

getSourceDimensions

public abstract int getSourceDimensions()

Gets the dimension of input points.

Specified by:

getSourceDimensions in interface MathTransform

Returns:

The dimension of input points.

getTargetDimensions

public abstract int getTargetDimensions()

Gets the dimension of output points.

Specified by:

getTargetDimensions in interface MathTransform

Returns:

The dimension of output points.

getParameterDescriptors

public ParameterDescriptorGroup getParameterDescriptors()

Returns the parameter descriptors for this math transform, or null if unknow. This method is similar to OperationMethod.getParameters(), except that MathTransform returns parameters in standard units (usually meters or decimal degrees).

Returns:

The parameter descriptors for this math transform, or null.

See Also:

OperationMethod.getParameters()

getParameterValues

public ParameterValueGroup getParameterValues()

Returns the parameter values for this math transform, or null if unknow. This method is similar to Operation.getParameterValues(), except that MathTransform returns parameters in standard units (usually meters or decimal degrees). Since this method returns a copy of the parameter values, any change to a value will have no effect on this math transform.

Returns:

A copy of the parameter values for this math transform, or null.

See Also:

Operation.getParameterValues()

isIdentity

public boolean isIdentity()

Tests whether this transform does not move any points. The default implementation always returns false.

Specified by:

isIdentity in interface MathTransform

Returns:

true if this MathTransform is an identity transform; false otherwise.

transform

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

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

Parameters:

ptSrc - The specified coordinate point to be transformed.

ptDst - The specified coordinate point that stores the result of transforming ptSrc, or null.

Returns:

The coordinate point after transforming ptSrc and storing the result in ptDst.

Throws:

MismatchedDimensionException - If this transform doesn't map two-dimensional coordinate systems.

TransformException - If the point can't be transformed.

See Also:

MathTransform2D.transform(Point2D,Point2D)

transform

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

Transforms the specified ptSrc and stores the result in ptDst. The default implementation delegates to MathTransform.transform(double[],int,double[],int,int).

Specified by:

transform in interface MathTransform

Parameters:

ptSrc - the specified coordinate point to be transformed.

ptDst - the specified coordinate point that stores the result of transforming ptSrc, or null.

Returns:

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

Throws:

TransformException - if the point can't be transformed.

transform

public void transform(float[] srcPts,
                      int srcOff,
                      float[] dstPts,
                      int dstOff,
                      int numPts)
               throws TransformException

Transforms a list of coordinate point ordinal values. The default implementation invokes MathTransform.transform(double[],int,double[],int,int) using a temporary array of doubles.

Specified by:

transform in interface MathTransform

Parameters:

srcPts - the array containing the source point coordinates.

srcOff - the offset to the first point to be transformed in the source array.

dstPts - the array into which the transformed point coordinates are returned. May be the same than srcPts.

dstOff - the offset to the location of the first transformed point that is stored in the destination array.

numPts - the number of point objects to be transformed.

Throws:

TransformException - if a point can't be transformed. Some implementations will stop at the first failure, wile some other implementations will fill the untransformable points with NaN values, continue and throw the exception only at end. Implementations that fall in the later case should set the last completed transform to this.

transform

public void transform(double[] srcPts,
                      int srcOff,
                      float[] dstPts,
                      int dstOff,
                      int numPts)
               throws TransformException

Transforms a list of coordinate point ordinal values. The default implementation invokes MathTransform.transform(double[],int,double[],int,int) using a temporary array of doubles.

Specified by:

transform in interface MathTransform

Parameters:

srcPts - the array containing the source point coordinates.

srcOff - the offset to the first point to be transformed in the source array.

dstPts - the array into which the transformed point coordinates are returned.

dstOff - the offset to the location of the first transformed point that is stored in the destination array.

numPts - the number of point objects to be transformed.

Throws:

TransformException - if a point can't be transformed. Some implementations will stop at the first failure, wile some other implementations will fill the untransformable points with NaN values, continue and throw the exception only at end. Implementations that fall in the later case should set the last completed transform to this.

Since:

2.5

transform

public void transform(float[] srcPts,
                      int srcOff,
                      double[] dstPts,
                      int dstOff,
                      int numPts)
               throws TransformException

Transforms a list of coordinate point ordinal values. The default implementation delegates to MathTransform.transform(double[],int,double[],int,int).

Specified by:

transform in interface MathTransform

Parameters:

srcPts - the array containing the source point coordinates.

srcOff - the offset to the first point to be transformed in the source array.

dstPts - the array into which the transformed point coordinates are returned.

dstOff - the offset to the location of the first transformed point that is stored in the destination array.

numPts - the number of point objects to be transformed.

Throws:

TransformException - if a point can't be transformed. Some implementations will stop at the first failure, wile some other implementations will fill the untransformable points with NaN values, continue and throw the exception only at end. Implementations that fall in the later case should set the last completed transform to this.

Since:

2.5

createTransformedShape

public Shape createTransformedShape(Shape shape)
                             throws TransformException

Transform the specified shape. The default implementation computes quadratic curves using three points for each shape segments.

Parameters:

shape - Shape to transform.

Returns:

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

Throws:

IllegalStateException - if this transform doesn't map 2D coordinate systems.

TransformException - if a transform failed.

See Also:

MathTransform2D.createTransformedShape(Shape)

derivative

public Matrix derivative(Point2D point)
                  throws TransformException

Gets the derivative of this transform at a point. The default implementation always throw an exception. Subclasses that implement the MathTransform2D interface should override this method. Other subclasses should override derivative(DirectPosition) instead.

Parameters:

point - The coordinate point where to evaluate the derivative.

Returns:

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

Throws:

MismatchedDimensionException - if the input dimension is not 2.

TransformException - if the derivative can't be evaluated at the specified point.

See Also:

MathTransform2D.derivative(Point2D)

derivative

public Matrix derivative(DirectPosition point)
                  throws TransformException

Gets the derivative of this transform at a point. The default implementation ensure that point has a valid dimension. Next, it try to delegate the work to an other method:

• If the input dimension is 2, then this method delegates the work to derivative(Point2D).
• If this object is an instance of MathTransform1D, then this method delegates the work to derivative(double).

Otherwise, a TransformException is thrown.

Specified by:

derivative in interface MathTransform

Parameters:

point - The coordinate point where to evaluate the derivative.

Returns:

The derivative at the specified point (never null).

Throws:

NullPointerException - if the derivative dependents on coordinate and point is null.

MismatchedDimensionException - if point doesn't have the expected dimension.

TransformException - if the derivative can't be evaluated at the specified point.

inverse

public MathTransform inverse()
                      throws NoninvertibleTransformException

Creates the inverse transform of this object. The default implementation returns this if this transform is an identity transform, and throws a NoninvertibleTransformException otherwise. Subclasses should override this method.

Specified by:

inverse in interface MathTransform

Returns:

The inverse transform.

Throws:

NoninvertibleTransformException - if the transform can't be inversed.

hashCode

public int hashCode()

Returns a hash value for this transform.

Overrides:

hashCode in class Object

equals

public boolean equals(Object object)

Compares the specified object with this math transform for equality. The default implementation checks if object is an instance of the same class than this and use the same parameter descriptor. Subclasses should override this method in order to compare internal fields.

Overrides:

equals in class Object

Parameters:

object - The object to compare with this transform.

Returns:

true if the given object is a transform of the same class and if, given identical source position, the transformed position would be the equals.

formatWKT

protected String formatWKT(Formatter formatter)

Format the inner part of a Well Known Text (WKT) element. The default implementation formats all parameter values returned by getParameterValues(). The parameter group name is used as the math transform name.

Overrides:

formatWKT in class Formattable

Parameters:

formatter - The formatter to use.

Returns:

The WKT element name, which is "PARAM_MT" in the default implementation.

See Also:

Formattable.toWKT(), Formattable.toString()

ensureNonNull

protected static void ensureNonNull(String name,
                                    Object object)
                             throws InvalidParameterValueException

Makes sure that an argument is non-null. This is a convenience method for subclass constructors.

Parameters:

name - Argument name.

object - User argument.

Throws:

InvalidParameterValueException - if object is null.

needCopy

protected static boolean needCopy(int srcOff,
                                  int dimSource,
                                  int dstOff,
                                  int dimTarget,
                                  int numPts)

Checks if source coordinates need to be copied before to apply the transformation. This convenience method is provided for transform(...) method implementation. This method make the following assumptions:

• Coordinates will be iterated from lower index to upper index.
• Coordinates are read and writen in shrunk. For example (longitude,latitude,height) values for one coordinate are read together, and the transformed (x,y,z) values are written together only after.

However, this method does not assumes that source and target dimension are the same (in the special case where source and target dimension are always the same, a simplier and more efficient check is possible). The following example prepares a transformation from 2 dimensional points to three dimensional points:

 public void transform(double[] srcPts, int srcOff,
                       double[] dstPts, int dstOff, int numPts)
 {
     if (srcPts==dstPts && needCopy(srcOff, 2, dstOff, 3, numPts) {
         final double[] old = srcPts;
         srcPts = new double[numPts*2];
         System.arraycopy(old, srcOff, srcPts, 0, srcPts.length);
         srcOff = 0;
     }
 }

This method is for internal usage by the referencing module only. Do not use! It will be replaced by a different mechanism in a future GeoTools version.

Parameters:

srcOff - The offset in the source coordinate array.

dimSource - The dimension of input points.

dstOff - The offset in the destination coordinate array.

dimTarget - The dimension of output points.

numPts - The number of points to transform.

Returns:

true if the source coordinates should be copied before to apply the transformation in order to avoid an overlap with the destination array.

rollLongitude

protected static double rollLongitude(double x)

Ensures that the specified longitude stay within ±π radians. This method is typically invoked after geographic coordinates are transformed. This method may add or substract some amount of 2π radians to x.

Parameters:

x - The longitude in radians.

Returns:

The longitude in the range ±π radians.

normalizeAngle

protected static double normalizeAngle(double x)

Ensures that the specified longitude stay within 0 and {code}PI{code}.

Parameters:

x - An angle

Returns:

The normalized angle