org.geotools.coverage.grid

Class GridEnvelope2D

Object

RectangularShape

Rectangle2D

Rectangle

GridEnvelope2D

All Implemented Interfaces:

Shape, Serializable, Cloneable, GridEnvelope

public class GridEnvelope2D
extends Rectangle
implements GridEnvelope, Cloneable

Defines a range of two-dimensional grid coverage coordinates. This implementation extends Rectangle for interoperability with Java2D. Note that at the opposite of GeneralGridEnvelope, this class is mutable.

CAUTION: ISO 19123 defines high coordinates as inclusive. We follow this specification for all getters methods, but keep in mind that this is the opposite of Java2D usage where Rectangle maximal values are exclusive.

Since:

2.5

Author:

Martin Desruisseaux

See Also:

GeneralGridEnvelope, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class Rectangle2D

Rectangle2D.Double, Rectangle2D.Float

Field Summary

Fields inherited from class Rectangle

height, width, x, y

Fields inherited from class Rectangle2D

OUT_BOTTOM, OUT_LEFT, OUT_RIGHT, OUT_TOP

Constructor Summary

Constructors

Constructor and Description
GridEnvelope2D() Creates an initially empty grid envelope.
GridEnvelope2D(Envelope2D envelope, PixelInCell anchor) Casts the specified envelope into a grid envelope.
GridEnvelope2D(Envelope2D envelope, PixelInCell anchor, boolean isHighIncluded) Casts the specified envelope into a grid envelope.
GridEnvelope2D(int x, int y, int width, int height) Creates a grid envelope initialized to the specified rectangle.
GridEnvelope2D(Rectangle rectangle) Creates a grid envelope initialized to the specified rectangle.

Method Summary

Modifier and Type	Method and Description
GridEnvelope2D	clone() Returns a clone of this grid envelope.
int	getDimension() Returns the number of dimensions, which is always 2.
GridCoordinates2D	getHigh() Returns the valid maximum inclusive grid coordinates.
int	getHigh(int dimension) Returns the valid maximum inclusive grid coordinate along the specified dimension.
GridCoordinates2D	getLow() Returns the valid minimum inclusive grid coordinates.
int	getLow(int dimension) Returns the valid minimum inclusive grid coordinate along the specified dimension.
int	getSpan(int dimension) Returns the number of integer grid coordinates along the specified dimension.
String	toString() Returns a string représentation of this grid envelope.

Methods inherited from class Rectangle

add, add, add, contains, contains, contains, contains, createIntersection, createUnion, equals, getBounds, getBounds2D, getHeight, getLocation, getSize, getWidth, getX, getY, grow, inside, intersection, intersects, isEmpty, move, outcode, reshape, resize, setBounds, setBounds, setLocation, setLocation, setRect, setSize, setSize, translate, union

Methods inherited from class Rectangle2D

add, add, add, contains, contains, getPathIterator, getPathIterator, hashCode, intersect, intersects, intersectsLine, intersectsLine, outcode, setFrame, setRect, union

Methods inherited from class RectangularShape

contains, contains, getCenterX, getCenterY, getFrame, getMaxX, getMaxY, getMinX, getMinY, intersects, setFrame, setFrame, setFrameFromCenter, setFrameFromCenter, setFrameFromDiagonal, setFrameFromDiagonal

Methods inherited from class Object

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

Methods inherited from interface Shape

contains, contains, contains, contains, getPathIterator, getPathIterator, intersects, intersects

Constructor Detail

GridEnvelope2D

public GridEnvelope2D()

Creates an initially empty grid envelope.

GridEnvelope2D

public GridEnvelope2D(Rectangle rectangle)

Creates a grid envelope initialized to the specified rectangle.

Parameters:

rectangle - The rectangle to use for initializing this grid envelope.

GridEnvelope2D

public GridEnvelope2D(int x,
                      int y,
                      int width,
                      int height)

Creates a grid envelope initialized to the specified rectangle.

Parameters:

x - The minimal x ordinate.

y - The minimal y ordinate.

width - The number of valid ordinates along the x axis.

height - The number of valid ordinates along the y axis.

GridEnvelope2D

public GridEnvelope2D(Envelope2D envelope,
                      PixelInCell anchor)
               throws IllegalArgumentException

Casts the specified envelope into a grid envelope. This is sometime useful after an envelope has been transformed from "real world" coordinates to grid coordinates using the grid to CRS transform. The floating point values are rounded toward the nearest integers.

Notice that highest values are interpreted as non-inclusive

Anchor
According OpenGIS specification, grid geometry maps pixel's center. But envelopes typically encompass all pixels. This means that grid coordinates (0,0) has an envelope starting at (-0.5, -0.5). In order to revert back such envelope to a grid envelope, it is necessary to add 0.5 to every coordinates (including the maximum value since it is exclusive in a grid envelope). This offset is applied only if anchor is PixelInCell.CELL_CENTER. Users who don't want such offset should specify PixelInCell.CELL_CORNER.

The convention is specified as a PixelInCell code instead than the more detailed PixelOrientation because the latter is restricted to the two-dimensional case while the former can be used for any number of dimensions.

Parameters:

envelope - The envelope to use for initializing this grid envelope.

anchor - Whatever envelope coordinates map to pixel center or pixel corner. Should be PixelInCell.CELL_CENTER for OGC convention (an offset of 0.5 will be added to every envelope coordinate values), or PixelInCell.CELL_CORNER for Java2D/JAI convention (no offset will be added).

Throws:

IllegalArgumentException - If anchor is not valid.

GridEnvelope2D

public GridEnvelope2D(Envelope2D envelope,
                      PixelInCell anchor,
                      boolean isHighIncluded)
               throws IllegalArgumentException

Casts the specified envelope into a grid envelope. This is sometime useful after an envelope has been transformed from "real world" coordinates to grid coordinates using the grid to CRS transform. The floating point values are rounded toward the nearest integers.

Note about rounding mode
It would have been possible to round the minimal value toward floor and the maximal value toward ceil in order to make sure that the grid envelope encompass fully the envelope - like what Java2D does when converting Rectangle2D to Rectangle). But this approach may increase by 1 or 2 units the image width or height. For example the range [-0.25 ... 99.75] (which is exactly 101 units wide) would be casted to [-1 ... 100], which is 102 units wide. This leads to unexpected results when using grid envelope with image operations like "Affine". For avoiding such changes in size, it is necessary to use the same rounding mode for both minimal and maximal values. The selected rounding mode is nearest integer in this implementation.

Anchor
According OpenGIS specification, grid geometry maps pixel's center. But envelopes typically encompass all pixels. This means that grid coordinates (0,0) has an envelope starting at (-0.5, -0.5). In order to revert back such envelope to a grid envelope, it is necessary to add 0.5 to every coordinates (including the maximum value since it is exclusive in a grid envelope). This offset is applied only if anchor is PixelInCell.CELL_CENTER. Users who don't want such offset should specify PixelInCell.CELL_CORNER.

The convention is specified as a PixelInCell code instead than the more detailed PixelOrientation because the latter is restricted to the two-dimensional case while the former can be used for any number of dimensions.

Parameters:

envelope - The envelope to use for initializing this grid envelope.

anchor - Whatever envelope coordinates map to pixel center or pixel corner. Should be PixelInCell.CELL_CENTER for OGC convention (an offset of 0.5 will be added to every envelope coordinate values), or PixelInCell.CELL_CORNER for Java2D/JAI convention (no offset will be added).

isHighIncluded - true if the envelope maximal values are inclusive, or false if they are exclusive. This argument does not apply to minimal values, which are always inclusive.

Throws:

IllegalArgumentException - If anchor is not valid.

Method Detail

getDimension

public final int getDimension()

Returns the number of dimensions, which is always 2.

Specified by:

getDimension in interface GridEnvelope

Returns:

The number of dimensions.

getLow

public GridCoordinates2D getLow()

Returns the valid minimum inclusive grid coordinates. The sequence contains a minimum value for each dimension of the grid coverage.

Specified by:

getLow in interface GridEnvelope

Returns:

The minimal coordinate values for all grid points, inclusive.

getHigh

public GridCoordinates2D getHigh()

Returns the valid maximum inclusive grid coordinates. The sequence contains a maximum value for each dimension of the grid coverage.

Specified by:

getHigh in interface GridEnvelope

Returns:

The maximal coordinate values for all grid points, inclusive.

getLow

public int getLow(int dimension)

Returns the valid minimum inclusive grid coordinate along the specified dimension.

Specified by:

getLow in interface GridEnvelope

Parameters:

dimension - The dimension for which to obtain the coordinate value.

Returns:

The coordinate value at the given dimension, inclusive.

See Also:

getLow()

getHigh

public int getHigh(int dimension)

Returns the valid maximum inclusive grid coordinate along the specified dimension.

Specified by:

getHigh in interface GridEnvelope

Parameters:

dimension - The dimension for which to obtain the coordinate value.

Returns:

The coordinate value at the given dimension, inclusive.

See Also:

getHigh()

getSpan

public int getSpan(int dimension)

Returns the number of integer grid coordinates along the specified dimension. This is equals to getHigh(dimension) - getLow(dimension).

Specified by:

getSpan in interface GridEnvelope

Parameters:

dimension - The dimension for which to obtain the coordinate value.

Returns:

The coordinate value at the given dimension.

See Also:

Rectangle.width, Rectangle.height

toString

public String toString()

Returns a string représentation of this grid envelope. The returned string is implementation dependent. It is usually provided for debugging purposes.

Overrides:

toString in class Rectangle

clone

public GridEnvelope2D clone()

Returns a clone of this grid envelope.

Overrides:

clone in class RectangularShape

Returns:

A clone of this grid envelope.

See Also:

Object.clone()