- java.lang.Object
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- java.awt.geom.Area
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public class Area extends Object implements Shape, Cloneable
AnAreaobject stores and manipulates a resolution-independent description of an enclosed area of 2-dimensional space.Areaobjects can be transformed and can perform various Constructive Area Geometry (CAG) operations when combined with otherAreaobjects. The CAG operations include areaaddition,subtraction,intersection, andexclusive or. See the linked method documentation for examples of the various operations.The
Areaclass implements theShapeinterface and provides full support for all of its hit-testing and path iteration facilities, but anAreais more specific than a generalized path in a number of ways:- Only closed paths and sub-paths are stored.
Areaobjects constructed from unclosed paths are implicitly closed during construction as if those paths had been filled by theGraphics2D.fillmethod. - The interiors of the individual stored sub-paths are all non-empty and non-overlapping. Paths are decomposed during construction into separate component non-overlapping parts, empty pieces of the path are discarded, and then these non-empty and non-overlapping properties are maintained through all subsequent CAG operations. Outlines of different component sub-paths may touch each other, as long as they do not cross so that their enclosed areas overlap.
- The geometry of the path describing the outline of the
Arearesembles the path from which it was constructed only in that it describes the same enclosed 2-dimensional area, but may use entirely different types and ordering of the path segments to do so.
Areainclude:- Creating an
Areafrom an unclosed (open)Shaperesults in a closed outline in theAreaobject. - Creating an
Areafrom aShapewhich encloses no area (even when "closed") produces an emptyArea. A common example of this issue is that producing anAreafrom a line will be empty since the line encloses no area. An emptyAreawill iterate no geometry in itsPathIteratorobjects. - A self-intersecting
Shapemay be split into two (or more) sub-paths each enclosing one of the non-intersecting portions of the original path. - An
Areamay take more path segments to describe the same geometry even when the original outline is simple and obvious. The analysis that theAreaclass must perform on the path may not reflect the same concepts of "simple and obvious" as a human being perceives.
- Since:
- 1.2
- Only closed paths and sub-paths are stored.
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Constructor Summary
Constructors Constructor and Description Area()Default constructor which creates an empty area.Area(Shape s)TheAreaclass creates an area geometry from the specifiedShapeobject.
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Method Summary
Methods Modifier and Type Method and Description voidadd(Area rhs)Adds the shape of the specifiedAreato the shape of thisArea.Objectclone()Returns an exact copy of thisAreaobject.booleancontains(double x, double y)Tests if the specified coordinates are inside the boundary of theShape, as described by the definition of insideness.booleancontains(double x, double y, double w, double h)Tests if the interior of theShapeentirely contains the specified rectangular area.booleancontains(Point2D p)Tests if a specifiedPoint2Dis inside the boundary of theShape, as described by the definition of insideness.booleancontains(Rectangle2D r)Tests if the interior of theShapeentirely contains the specifiedRectangle2D.AreacreateTransformedArea(AffineTransform t)Creates a newAreaobject that contains the same geometry as thisAreatransformed by the specifiedAffineTransform.booleanequals(Area other)Tests whether the geometries of the twoAreaobjects are equal.voidexclusiveOr(Area rhs)Sets the shape of thisAreato be the combined area of its current shape and the shape of the specifiedArea, minus their intersection.RectanglegetBounds()Returns a boundingRectanglethat completely encloses thisArea.Rectangle2DgetBounds2D()Returns a high precision boundingRectangle2Dthat completely encloses thisArea.PathIteratorgetPathIterator(AffineTransform at)Creates aPathIteratorfor the outline of thisAreaobject.PathIteratorgetPathIterator(AffineTransform at, double flatness)Creates aPathIteratorfor the flattened outline of thisAreaobject.voidintersect(Area rhs)Sets the shape of thisAreato the intersection of its current shape and the shape of the specifiedArea.booleanintersects(double x, double y, double w, double h)Tests if the interior of theShapeintersects the interior of a specified rectangular area.booleanintersects(Rectangle2D r)Tests if the interior of theShapeintersects the interior of a specifiedRectangle2D.booleanisEmpty()Tests whether thisAreaobject encloses any area.booleanisPolygonal()Tests whether thisAreaconsists entirely of straight edged polygonal geometry.booleanisRectangular()Tests whether thisAreais rectangular in shape.booleanisSingular()Tests whether thisAreais comprised of a single closed subpath.voidreset()Removes all of the geometry from thisAreaand restores it to an empty area.voidsubtract(Area rhs)Subtracts the shape of the specifiedAreafrom the shape of thisArea.voidtransform(AffineTransform t)Transforms the geometry of thisAreausing the specifiedAffineTransform.
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Constructor Detail
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Area
public Area()
Default constructor which creates an empty area.- Since:
- 1.2
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Area
public Area(Shape s)
TheAreaclass creates an area geometry from the specifiedShapeobject. The geometry is explicitly closed, if theShapeis not already closed. The fill rule (even-odd or winding) specified by the geometry of theShapeis used to determine the resulting enclosed area.- Parameters:
s- theShapefrom which the area is constructed- Throws:
NullPointerException- ifsis null- Since:
- 1.2
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Method Detail
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add
public void add(Area rhs)
Adds the shape of the specifiedAreato the shape of thisArea. The resulting shape of thisAreawill include the union of both shapes, or all areas that were contained in either this or the specifiedArea.// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.add(a2); a1(before) + a2 = a1(after) ################ ################ ################ ############## ############## ################ ############ ############ ################ ########## ########## ################ ######## ######## ################ ###### ###### ###### ###### #### #### #### #### ## ## ## ##- Parameters:
rhs- theAreato be added to the current shape- Throws:
NullPointerException- ifrhsis null- Since:
- 1.2
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subtract
public void subtract(Area rhs)
Subtracts the shape of the specifiedAreafrom the shape of thisArea. The resulting shape of thisAreawill include areas that were contained only in thisAreaand not in the specifiedArea.// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.subtract(a2); a1(before) - a2 = a1(after) ################ ################ ############## ############## ## ############ ############ #### ########## ########## ###### ######## ######## ######## ###### ###### ###### #### #### #### ## ## ##- Parameters:
rhs- theAreato be subtracted from the current shape- Throws:
NullPointerException- ifrhsis null- Since:
- 1.2
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intersect
public void intersect(Area rhs)
Sets the shape of thisAreato the intersection of its current shape and the shape of the specifiedArea. The resulting shape of thisAreawill include only areas that were contained in both thisAreaand also in the specifiedArea.// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.intersect(a2); a1(before) intersect a2 = a1(after) ################ ################ ################ ############## ############## ############ ############ ############ ######## ########## ########## #### ######## ######## ###### ###### #### #### ## ##- Parameters:
rhs- theAreato be intersected with thisArea- Throws:
NullPointerException- ifrhsis null- Since:
- 1.2
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exclusiveOr
public void exclusiveOr(Area rhs)
Sets the shape of thisAreato be the combined area of its current shape and the shape of the specifiedArea, minus their intersection. The resulting shape of thisAreawill include only areas that were contained in either thisAreaor in the specifiedArea, but not in both.// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.exclusiveOr(a2); a1(before) xor a2 = a1(after) ################ ################ ############## ############## ## ## ############ ############ #### #### ########## ########## ###### ###### ######## ######## ################ ###### ###### ###### ###### #### #### #### #### ## ## ## ##- Parameters:
rhs- theAreato be exclusive ORed with thisArea.- Throws:
NullPointerException- ifrhsis null- Since:
- 1.2
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reset
public void reset()
Removes all of the geometry from thisAreaand restores it to an empty area.- Since:
- 1.2
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isEmpty
public boolean isEmpty()
Tests whether thisAreaobject encloses any area.- Returns:
trueif thisAreaobject represents an empty area;falseotherwise.- Since:
- 1.2
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isPolygonal
public boolean isPolygonal()
Tests whether thisAreaconsists entirely of straight edged polygonal geometry.- Returns:
trueif the geometry of thisAreaconsists entirely of line segments;falseotherwise.- Since:
- 1.2
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isRectangular
public boolean isRectangular()
Tests whether thisAreais rectangular in shape.- Returns:
trueif the geometry of thisAreais rectangular in shape;falseotherwise.- Since:
- 1.2
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isSingular
public boolean isSingular()
Tests whether thisAreais comprised of a single closed subpath. This method returnstrueif the path contains 0 or 1 subpaths, orfalseif the path contains more than 1 subpath. The subpaths are counted by the number ofSEG_MOVETOsegments that appear in the path.- Returns:
trueif theAreais comprised of a single basic geometry;falseotherwise.- Since:
- 1.2
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getBounds2D
public Rectangle2D getBounds2D()
Returns a high precision boundingRectangle2Dthat completely encloses thisArea.The Area class will attempt to return the tightest bounding box possible for the Shape. The bounding box will not be padded to include the control points of curves in the outline of the Shape, but should tightly fit the actual geometry of the outline itself.
- Specified by:
getBounds2Din interfaceShape- Returns:
- the bounding
Rectangle2Dfor theArea. - Since:
- 1.2
- See Also:
Shape.getBounds()
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getBounds
public Rectangle getBounds()
Returns a boundingRectanglethat completely encloses thisArea.The Area class will attempt to return the tightest bounding box possible for the Shape. The bounding box will not be padded to include the control points of curves in the outline of the Shape, but should tightly fit the actual geometry of the outline itself. Since the returned object represents the bounding box with integers, the bounding box can only be as tight as the nearest integer coordinates that encompass the geometry of the Shape.
- Specified by:
getBoundsin interfaceShape- Returns:
- the bounding
Rectanglefor theArea. - Since:
- 1.2
- See Also:
Shape.getBounds2D()
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clone
public Object clone()
Returns an exact copy of thisAreaobject.
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equals
public boolean equals(Area other)
Tests whether the geometries of the twoAreaobjects are equal. This method will return false if the argument is null.- Parameters:
other- theAreato be compared to thisArea- Returns:
trueif the two geometries are equal;falseotherwise.- Since:
- 1.2
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transform
public void transform(AffineTransform t)
Transforms the geometry of thisAreausing the specifiedAffineTransform. The geometry is transformed in place, which permanently changes the enclosed area defined by this object.- Parameters:
t- the transformation used to transform the area- Throws:
NullPointerException- iftis null- Since:
- 1.2
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createTransformedArea
public Area createTransformedArea(AffineTransform t)
Creates a newAreaobject that contains the same geometry as thisAreatransformed by the specifiedAffineTransform. ThisAreaobject is unchanged.- Parameters:
t- the specifiedAffineTransformused to transform the newArea- Returns:
- a new
Areaobject representing the transformed geometry. - Throws:
NullPointerException- iftis null- Since:
- 1.2
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contains
public boolean contains(double x, double y)Tests if the specified coordinates are inside the boundary of theShape, as described by the definition of insideness.
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contains
public boolean contains(Point2D p)
Tests if a specifiedPoint2Dis inside the boundary of theShape, as described by the definition of insideness.
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contains
public boolean contains(double x, double y, double w, double h)Tests if the interior of theShapeentirely contains the specified rectangular area. All coordinates that lie inside the rectangular area must lie within theShapefor the entire rectanglar area to be considered contained within theShape.The
Shape.contains()method allows aShapeimplementation to conservatively returnfalsewhen:-
the
intersectmethod returnstrueand -
the calculations to determine whether or not the
Shapeentirely contains the rectangular area are prohibitively expensive.
Shapesthis method might returnfalseeven though theShapecontains the rectangular area. TheAreaclass performs more accurate geometric computations than mostShapeobjects and therefore can be used if a more precise answer is required.- Specified by:
containsin interfaceShape- Parameters:
x- the X coordinate of the upper-left corner of the specified rectangular areay- the Y coordinate of the upper-left corner of the specified rectangular areaw- the width of the specified rectangular areah- the height of the specified rectangular area- Returns:
trueif the interior of theShapeentirely contains the specified rectangular area;falseotherwise or, if theShapecontains the rectangular area and theintersectsmethod returnstrueand the containment calculations would be too expensive to perform.- Since:
- 1.2
- See Also:
Area,Shape.intersects(double, double, double, double)
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the
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contains
public boolean contains(Rectangle2D r)
Tests if the interior of theShapeentirely contains the specifiedRectangle2D. TheShape.contains()method allows aShapeimplementation to conservatively returnfalsewhen:-
the
intersectmethod returnstrueand -
the calculations to determine whether or not the
Shapeentirely contains theRectangle2Dare prohibitively expensive.
Shapesthis method might returnfalseeven though theShapecontains theRectangle2D. TheAreaclass performs more accurate geometric computations than mostShapeobjects and therefore can be used if a more precise answer is required.- Specified by:
containsin interfaceShape- Parameters:
r- The specifiedRectangle2D- Returns:
trueif the interior of theShapeentirely contains theRectangle2D;falseotherwise or, if theShapecontains theRectangle2Dand theintersectsmethod returnstrueand the containment calculations would be too expensive to perform.- Since:
- 1.2
- See Also:
Shape.contains(double, double, double, double)
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the
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intersects
public boolean intersects(double x, double y, double w, double h)Tests if the interior of theShapeintersects the interior of a specified rectangular area. The rectangular area is considered to intersect theShapeif any point is contained in both the interior of theShapeand the specified rectangular area.The
Shape.intersects()method allows aShapeimplementation to conservatively returntruewhen:-
there is a high probability that the rectangular area and the
Shapeintersect, but - the calculations to accurately determine this intersection are prohibitively expensive.
Shapesthis method might returntrueeven though the rectangular area does not intersect theShape. TheAreaclass performs more accurate computations of geometric intersection than mostShapeobjects and therefore can be used if a more precise answer is required.- Specified by:
intersectsin interfaceShape- Parameters:
x- the X coordinate of the upper-left corner of the specified rectangular areay- the Y coordinate of the upper-left corner of the specified rectangular areaw- the width of the specified rectangular areah- the height of the specified rectangular area- Returns:
trueif the interior of theShapeand the interior of the rectangular area intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform;falseotherwise.- Since:
- 1.2
- See Also:
Area
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there is a high probability that the rectangular area and the
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intersects
public boolean intersects(Rectangle2D r)
Tests if the interior of theShapeintersects the interior of a specifiedRectangle2D. TheShape.intersects()method allows aShapeimplementation to conservatively returntruewhen:-
there is a high probability that the
Rectangle2Dand theShapeintersect, but - the calculations to accurately determine this intersection are prohibitively expensive.
Shapesthis method might returntrueeven though theRectangle2Ddoes not intersect theShape. TheAreaclass performs more accurate computations of geometric intersection than mostShapeobjects and therefore can be used if a more precise answer is required.- Specified by:
intersectsin interfaceShape- Parameters:
r- the specifiedRectangle2D- Returns:
trueif the interior of theShapeand the interior of the specifiedRectangle2Dintersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform;falseotherwise.- Since:
- 1.2
- See Also:
Shape.intersects(double, double, double, double)
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there is a high probability that the
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getPathIterator
public PathIterator getPathIterator(AffineTransform at)
- Specified by:
getPathIteratorin interfaceShape- Parameters:
at- an optionalAffineTransformto be applied to the coordinates as they are returned in the iteration, ornullif untransformed coordinates are desired- Returns:
- the
PathIteratorobject that returns the geometry of the outline of thisArea, one segment at a time. - Since:
- 1.2
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getPathIterator
public PathIterator getPathIterator(AffineTransform at, double flatness)
Creates aPathIteratorfor the flattened outline of thisAreaobject. Only uncurved path segments represented by the SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point types are returned by the iterator. ThisAreaobject is unchanged.- Specified by:
getPathIteratorin interfaceShape- Parameters:
at- an optionalAffineTransformto be applied to the coordinates as they are returned in the iteration, ornullif untransformed coordinates are desiredflatness- the maximum amount that the control points for a given curve can vary from colinear before a subdivided curve is replaced by a straight line connecting the end points- Returns:
- the
PathIteratorobject that returns the geometry of the outline of thisArea, one segment at a time. - Since:
- 1.2
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Document created the 11/06/2005, last modified the 04/03/2020
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