Package net.algart.math.rectangles

Class IRectanglesUnion

java.lang.Object

net.algart.math.rectangles.IRectanglesUnion

public class IRectanglesUnion
extends Object

Set-theoretic union of several 2-dimensional rectangles with integer coordinates of vertices and sides, parallel to coordinate axes. This class allows to solve the following main tasks:

1. find connected components in this union;
2. find its boundary as a polygon: a sequence of links, where each link is a horizontal or vertical segment (1st link is horizontal, 2nd is vertical, 3rd is horizontal, etc.);
3. find the largest rectangle (with sides, parallel to the coordinate axes), which is a subset of this union.

This class is immutable and thread-safe: there are no ways to modify settings of the created instance. However, all important information is returned "lazily", i.e. while the 1st attempt to read it. So, the instance creation method newInstance(Collection) works quickly and does not lead to complex calculations and allocating additional memory.

Author:

Daniel Alievsky

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	IRectanglesUnion.BoundaryLink
static class	IRectanglesUnion.Frame
static class	IRectanglesUnion.FrameSide
static class	IRectanglesUnion.HorizontalBoundaryLink
static class	IRectanglesUnion.HorizontalSide
static class	IRectanglesUnion.Side
static class	IRectanglesUnion.VerticalBoundaryLink
static class	IRectanglesUnion.VerticalSide

Method Summary

Modifier and Type	Method	Description
List<List<IRectanglesUnion.BoundaryLink>>	allBoundaries()
List<IRectanglesUnion.HorizontalBoundaryLink>	allHorizontalBoundaryLinks()
List<IRectanglesUnion.VerticalBoundaryLink>	allVerticalBoundaryLinks()
static double	areaInBoundary(List<IRectanglesUnion.BoundaryLink> boundary)
static List<IPoint>	boundaryVerticesAtRectangles(List<IRectanglesUnion.BoundaryLink> boundary)
static List<IPoint>	boundaryVerticesPlusHalf(List<IRectanglesUnion.BoundaryLink> boundary)
IRectangularArea	circumscribedRectangle()
IRectanglesUnion	connectedComponent(int index)
int	connectedComponentCount()
void	findBoundaries()	Forces this object to find the boundary of this union of rectangles.
void	findConnectedComponents()	Forces this object to find all connected components.
void	findLargestRectangleInUnion()	Forces this object to find the largest rectangle (with sides, parallel to the coordinate axes), which is a subset of this union of rectangles.
List<IRectanglesUnion.Frame>	frames()
List<IRectanglesUnion.HorizontalSide>	horizontalSides()
IRectangularArea	largestRectangleInUnion()
static IRectanglesUnion	newInstance(Collection<IRectangularArea> rectangles)
IRectanglesUnion	subtractLargestRectangle()
IRectanglesUnion	subtractRectangle(IRectangularArea whatToSubtract)	Subtracts the given rectangle (via IRectangularArea.subtractCollection(Queue, Collection) method) from the set of rectangles, containing in this object, and return the union of the resulting rectangles.
String	toString()
double	unionArea()
List<IRectanglesUnion.VerticalSide>	verticalSides()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Details

newInstance

public static IRectanglesUnion newInstance(Collection<IRectangularArea> rectangles)

subtractRectangle

public IRectanglesUnion subtractRectangle(IRectangularArea whatToSubtract)

Subtracts the given rectangle (via IRectangularArea.subtractCollection(Queue, Collection) method) from the set of rectangles, containing in this object, and return the union of the resulting rectangles.

Parameters:

whatToSubtract - the subtracted rectangle.

Returns:

the union of the rest of rectangles after subtraction.

Throws:

NullPointerException - if the argument is null.

IllegalArgumentException - if whatToSubtract.coordCount() != 2.

subtractLargestRectangle

public IRectanglesUnion subtractLargestRectangle()

frames

public List<IRectanglesUnion.Frame> frames()

circumscribedRectangle

public IRectangularArea circumscribedRectangle()

horizontalSides

public List<IRectanglesUnion.HorizontalSide> horizontalSides()

verticalSides

public List<IRectanglesUnion.VerticalSide> verticalSides()

connectedComponentCount

public int connectedComponentCount()

connectedComponent

public IRectanglesUnion connectedComponent(int index)

allHorizontalBoundaryLinks

public List<IRectanglesUnion.HorizontalBoundaryLink> allHorizontalBoundaryLinks()

allVerticalBoundaryLinks

public List<IRectanglesUnion.VerticalBoundaryLink> allVerticalBoundaryLinks()

allBoundaries

public List<List<IRectanglesUnion.BoundaryLink>> allBoundaries()

unionArea

public double unionArea()

largestRectangleInUnion

public IRectangularArea largestRectangleInUnion()

findConnectedComponents

public void findConnectedComponents()

Forces this object to find all connected components. It does not affect to results of any other methods, but after this call the following methods will work quickly:

• connectedComponentCount()
• connectedComponent(int)
• horizontalSides()
• verticalSides()

findBoundaries

public void findBoundaries()

Forces this object to find the boundary of this union of rectangles. It does not affect to results of any other methods, but after this call the following methods will work quickly:

• allHorizontalBoundaryLinks()
• allVerticalBoundaryLinks()
• allBoundaries()
• horizontalSides()
• verticalSides()

findLargestRectangleInUnion

public void findLargestRectangleInUnion()

Forces this object to find the largest rectangle (with sides, parallel to the coordinate axes), which is a subset of this union of rectangles. It does not affect to results of any other methods, but after this call the following methods will work quickly:

• largestRectangleInUnion()
• allHorizontalBoundaryLinks()
• allVerticalBoundaryLinks()
• allBoundaries()
• horizontalSides()
• verticalSides()

toString

public String toString()

Overrides:

toString in class Object

areaInBoundary

public static double areaInBoundary(List<IRectanglesUnion.BoundaryLink> boundary)

boundaryVerticesPlusHalf

public static List<IPoint> boundaryVerticesPlusHalf(List<IRectanglesUnion.BoundaryLink> boundary)

boundaryVerticesAtRectangles

public static List<IPoint> boundaryVerticesAtRectangles(List<IRectanglesUnion.BoundaryLink> boundary)