javax.swing
Class SpringLayout.Constraints

java.lang.Object
  javax.swing.SpringLayout.Constraints

Enclosing class:

SpringLayout

public static class SpringLayout.Constraints

extends Object

A Constraints object holds the constraints that govern the way a component's size and position change in a container controlled by a SpringLayout. A Constraints object is like a Rectangle, in that it has x, y, width, and height properties. In the Constraints object, however, these properties have Spring values instead of integers. In addition, a Constraints object can be manipulated as four edges -- north, south, east, and west -- using the constraint property.

The following formulas are always true for a Constraints object:

       west = x
      north = y
       east = x + width
      south = y + height

Note: In this document, operators represent methods in the Spring class. For example, "a + b" is equal to Spring.sum(a, b), and "a - b" is equal to Spring.sum(a, Spring.minus(b)). See the Spring API documentation for further details of spring arithmetic.

Because a Constraints object's properties -- representing its edges, size, and location -- can all be set independently and yet are interrelated, the object can become over-constrained. For example, if both the x and width properties are set and then the east edge is set, the object is over-constrained horizontally. When this happens, one of the values (in this case, the x property) automatically changes so that the formulas still hold.

The following table shows which value changes when a Constraints object is over-constrained horizontally.

Value Being Set (method used)	Result When Over-Constrained Horizontally (x, width, and the east edge are all non-null)
x or the west edge (setX or setConstraint)	width value is automatically set to east - x.
width (setWidth)	east edge's value is automatically set to x + width.
east edge (setConstraint)	x value is automatically set to east - width.

The rules for the vertical properties are similar:

Value Being Set (method used)	Result When Over-Constrained Vertically (y, height, and the south edge are all non-null)
y or the north edge (setY or setConstraint)	height value is automatically set to south - y.
height (setHeight)	south edge's value is automatically set to y + height.
south edge (setConstraint)	y value is automatically set to south - height.

Field Summary

private Spring	east
private Spring	height
private Spring	horizontalDerived
private Spring	south
private Spring	verticalDerived
private Spring	width
private Spring	x
private Spring	y

Constructor Summary

SpringLayout.Constraints()
Creates an empty Constraints object.

SpringLayout.Constraints(Spring x, Spring y)
Creates a Constraints object with the specified values for its x and y properties.

SpringLayout.Constraints(Spring x, Spring y, Spring width, Spring height)
Creates a Constraints object with the specified values for its x, y, width, and height properties.

Method Summary

private Spring	difference(Spring s1, Spring s2)
Spring	getConstraint(String edgeName) Returns the value of the specified edge.
private Spring	getEast()
Spring	getHeight() Returns the value of the height property.
private Spring	getSouth()
Spring	getWidth() Returns the value of the width property.
Spring	getX() Returns the value of the x property.
Spring	getY() Returns the value of the y property.
private boolean	overConstrainedHorizontally()
private boolean	overConstrainedVertically()
(package private) void	reset()
void	setConstraint(String edgeName, Spring s) Sets the spring controlling the specified edge.
private void	setEast(Spring east)
void	setHeight(Spring height) Sets the height property, which controls the height of a component.
private void	setSouth(Spring south)
void	setWidth(Spring width) Sets the width property, which controls the width of a component.
void	setX(Spring x) Sets the x property, which controls the x value of a component's location.
void	setY(Spring y) Sets the y property, which controls the y value of a component's location.
private Spring	sum(Spring s1, Spring s2)

Methods inherited from class java.lang.Object

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

Field Detail

x

private Spring x

y

private Spring y

width

private Spring width

height

private Spring height

east

private Spring east

south

private Spring south

verticalDerived

private Spring verticalDerived

horizontalDerived

private Spring horizontalDerived

Constructor Detail

SpringLayout.Constraints

public SpringLayout.Constraints()

Creates an empty Constraints object.

SpringLayout.Constraints

public SpringLayout.Constraints(Spring x,
                                Spring y)

Creates a Constraints object with the specified values for its x and y properties. The height and width springs have null values.

Parameters:

x - the spring controlling the component's x value

y - the spring controlling the component's y value

SpringLayout.Constraints

public SpringLayout.Constraints(Spring x,
                                Spring y,
                                Spring width,
                                Spring height)

Creates a Constraints object with the specified values for its x, y, width, and height properties. Note: If the SpringLayout class encounters null values in the Constraints object of a given component, it replaces them with suitable defaults.

Parameters:

x - the spring value for the x property

y - the spring value for the y property

width - the spring value for the width property

height - the spring value for the height property

Method Detail

overConstrainedHorizontally

private boolean overConstrainedHorizontally()

overConstrainedVertically

private boolean overConstrainedVertically()

sum

private Spring sum(Spring s1,
                   Spring s2)

difference

private Spring difference(Spring s1,
                          Spring s2)

setX

public void setX(Spring x)

Sets the x property, which controls the x value of a component's location.

Parameters:

x - the spring controlling the x value of a component's location

See Also:

getX(), SpringLayout.Constraints

getX

public Spring getX()

Returns the value of the x property.

Returns:

the spring controlling the x value of a component's location

See Also:

setX(javax.swing.Spring), SpringLayout.Constraints

setY

public void setY(Spring y)

Sets the y property, which controls the y value of a component's location.

Parameters:

y - the spring controlling the y value of a component's location

See Also:

getY(), SpringLayout.Constraints

getY

public Spring getY()

Returns the value of the y property.

Returns:

the spring controlling the y value of a component's location

See Also:

setY(javax.swing.Spring), SpringLayout.Constraints

setWidth

public void setWidth(Spring width)

Sets the width property, which controls the width of a component.

Parameters:

width - the spring controlling the width of this Constraints object

See Also:

getWidth(), SpringLayout.Constraints

getWidth

public Spring getWidth()

Returns the value of the width property.

Returns:

the spring controlling the width of a component

See Also:

setWidth(javax.swing.Spring), SpringLayout.Constraints

setHeight

public void setHeight(Spring height)

Sets the height property, which controls the height of a component.

Parameters:

height - the spring controlling the height of this Constraints object

See Also:

getHeight(), SpringLayout.Constraints

getHeight

public Spring getHeight()

Returns the value of the height property.

Returns:

the spring controlling the height of a component

See Also:

setHeight(javax.swing.Spring), SpringLayout.Constraints

setEast

private void setEast(Spring east)

getEast

private Spring getEast()

setSouth

private void setSouth(Spring south)

getSouth

private Spring getSouth()

setConstraint

public void setConstraint(String edgeName,
                          Spring s)

Sets the spring controlling the specified edge. The edge must have one of the following values: SpringLayout.NORTH, SpringLayout.SOUTH, SpringLayout.EAST, SpringLayout.WEST.

Parameters:

edgeName - the edge to be set

s - the spring controlling the specified edge

See Also:

getConstraint(java.lang.String), SpringLayout.NORTH, SpringLayout.SOUTH, SpringLayout.EAST, SpringLayout.WEST, SpringLayout.Constraints

getConstraint

public Spring getConstraint(String edgeName)

Returns the value of the specified edge. The edge must have one of the following values: SpringLayout.NORTH, SpringLayout.SOUTH, SpringLayout.EAST, SpringLayout.WEST.

Parameters:

edgeName - the edge whose value is to be returned

Returns:

the spring controlling the specified edge

See Also:

setConstraint(java.lang.String, javax.swing.Spring), SpringLayout.NORTH, SpringLayout.SOUTH, SpringLayout.EAST, SpringLayout.WEST, SpringLayout.Constraints

reset

void reset()