net.sf.jguiraffe.gui.layout

Class CellConstraints

java.lang.Object

net.sf.jguiraffe.gui.layout.CellConstraints

All Implemented Interfaces:

Serializable

public final class CellConstraints
extends Object
implements Serializable

A class for describing column and row constraints for the PercentLayout layout manager.

Objects of this class define properties for the single columns and rows that comprise the layout maintained by PercentLayout. Supported properties are:

• The alignment of the represented cell. This can be one of the constants defined by the CellAlignment enumeration class.
• An initial size. This property defines how the column's or row's size depends on the sizes of the contained components. The possible values are defined by the enumeration class CellSize.
• A minimum size for this cell. This is a numeric value specifying the minimum width for columns and minimum height for rows. To determine the size of a column or row the layout first calculates the initial size. If this is less than the minimum size, the minimum size is used. It is possible to use different units for specifying this property.
• A weight factor. This factor determines how this cell should behave if additional space becomes available when the container's size changes (e.g. if the user resizes the window). If this factor is 0, the cell won't change its size; it will always keep its initial size. For other values than 0 the remaining space is given to the affected cells with regard to their factors. It is recommended to use percentage values for these factors, which sum up to 100 percent (hence the name of the PercentLayout layout manager). Then it is easy to understand that each cell with a weight factor greater than 0 is granted as much percent of the remaining space.

Instances of this class are not created directly, but the inner Builder class is used for this purpose (an application of the builder pattern). A typical invocation sequence could look as follows:

 CellConstraints.Builder ccb = new CellConstraints.Builder();
 CellConstraints cc = ccb.withCellSize(CellSize.Preferred).withMinimumSize(
         new NumberWithUnit(20, Unit.PIXEL)).withWeight(25).withCellAlignment(
         CellAlignment.FULL).create();
 

For instances of this class a string representation is defined. Strings conforming to the format explained below can also be passed to the builder for creating instances:

 CONSTRAINT   ::= [ALIGN"/"]SIZE["/"WEIGHT]
 SIZE         ::= INITSIZE | MINSIZE | BOTHSIZES
 BOTHSIZES    ::= INITSIZE "(" MINSIZE ")"
 INITSIZE     ::= "PREFERRED" | "MINIMUM" | "NONE"
 MINSIZE      ::= <Positive number> [UNIT]
 UNIT         ::= "px" | "cm" | "in" | "dlu"
 ALIGN        ::= "START" | "CENTER" | "END" | "FULL"
 WEIGHT       ::= <Positive number>
 

Here are some examples:

• PREFERRED: only the cell size is set, the other properties are set to default values.
• CENTER/MINIMUM(20px)/33: A CellConstraints object is created with the CellSize MINIMUM and the alignment CENTER. The minimum size is set to 20 pixels, and the weight factor is set to 33.
• (20): Here only the minimum size of the cell is set. The CellSize is automatically set to NONE.

Instances of this class are immutable and thus can be shared between multiple threads. The Builder class makes use of this feature and caches the instances that have been created. So if another constraint with already used properties is requested, a shared instance can be returned.

Version:

$Id: CellConstraints.java 205 2012-01-29 18:29:57Z oheger $

Author:

Oliver Heger

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CellConstraints.Builder A builder class for creating instances of CellConstraints.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj) Compares this object with another one.
CellAlignment	getAlignment() Returns the alignment string.
CellSize	getCellSize() Returns the size of the cell.
NumberWithUnit	getMinSize() Returns the minimum size.
int	getWeight() Returns the weight factor.
int	hashCode() Returns a hash code for this object.
String	toSpecificationString() Returns a string specification for this CellConstraints object.
String	toString() Returns a string representation of this constraints object.

Methods inherited from class java.lang.Object

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

Method Detail

getAlignment

public CellAlignment getAlignment()

Returns the alignment string.

Returns:

the alignment string

getCellSize

public CellSize getCellSize()

Returns the size of the cell.

Returns:

the cell size

getMinSize

public NumberWithUnit getMinSize()

Returns the minimum size.

Returns:

the minimum size

getWeight

public int getWeight()

Returns the weight factor.

Returns:

the weight factor

toSpecificationString

public String toSpecificationString()

Returns a string specification for this CellConstraints object. This string conforms to the definition given in the class comment. It can be passed to a Builder instance to obtain a corresponding CellConstraints instance. The string returned by this method contains the values of all properties of this object, even if some have been set to default values.

Returns:

a specification string for this instance

toString

public String toString()

Returns a string representation of this constraints object. This string contains the specification string produced by toSpecificationString().

Overrides:

toString in class Object

Returns:

a string representation for this object

equals

public boolean equals(Object obj)

Compares this object with another one. Two instances of CellConstraints are equal if all of their properties are equal.

Overrides:

equals in class Object

Parameters:

obj - the object to compare to

Returns:

a flag whether these objects are equal

hashCode

public int hashCode()

Returns a hash code for this object.

Overrides:

hashCode in class Object

Returns:

a hash code for this object