Module java.desktop
Package 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 (here WEST and x are synonyms, as are and NORTH and y): 

               EAST = WEST + WIDTH
              SOUTH = NORTH + HEIGHT
  HORIZONTAL_CENTER = WEST + WIDTH/2
    VERTICAL_CENTER = NORTH + HEIGHT/2
  ABSOLUTE_BASELINE = NORTH + RELATIVE_BASELINE*

For example, if you have specified the WIDTH and WEST (X) location the EAST is calculated as WEST + WIDTH. If you instead specified the WIDTH and EAST locations the WEST (X) location is then calculated as EAST - WIDTH.

[RELATIVE_BASELINE is a private constraint that is set automatically when the SpringLayout.Constraints(Component) constructor is called or when a constraints object is registered with a SpringLayout object.]

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, a Constraints object can become over-constrained. For example, if the WEST, WIDTH and EAST edges are all set, steps must be taken to ensure that the first of the formulas above holds. To do this, the Constraints object throws away the least recently set constraint so as to make the formulas hold.

Since:
1.4

  • Constructor Summary

    Constructors 
    Constructor Description
    Constraints()
    Creates an empty Constraints object.
    Constraints​(Component c)
    Creates a Constraints object with suitable x, y, width and height springs for component, c.
    Constraints​(Spring x, Spring y)
    Creates a Constraints object with the specified values for its x and y properties.
    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

    Modifier and Type Method Description
    Spring getConstraint​(String edgeName)
    Returns the value of the specified edge, which may be a derived value, or even null.
    Spring getHeight()
    Returns the value of the height property.
    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.
    void setConstraint​(String edgeName, Spring s)
    Sets the spring controlling the specified edge.
    void setHeight​(Spring height)
    Sets the height property, which controls the height of a component.
    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.

    Methods declared in class java.lang.Object

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