org.foray.fotree.value
Class DtLength

java.lang.Object
  org.foray.fotree.value.Expr
      org.foray.fotree.value.ExprAdditive
          org.foray.fotree.value.ExprMultiplicative
              org.foray.fotree.value.ExprUnary
                  org.foray.fotree.value.ExprPrimary
                      org.foray.fotree.value.Datatype
                          org.foray.fotree.value.DtLength

All Implemented Interfaces:

PropertyValue

public class DtLength
extends Datatype

A "length" property datatype in XSL-FO. Members of this class are immutable.

Field Summary

static String[]	UNIT_ARRAY Array of valid string descriptions for length units.
static byte	UNIT_CENTIMETERS Constant indicating units of "centimeters".
static byte	UNIT_EMS Constant indicating units of "ems".
static byte	UNIT_INCHES Constant indicating units of "inches".
static byte	UNIT_MILLIMETERS Constant indicating units of "millimeters".
static byte	UNIT_PICAS Constant indicating units of "picas".
static byte	UNIT_PIXELS Constant indicating units of "pixels".
static byte	UNIT_POINTS Constant indicating units of "points".
static DtLength	ZERO_LENGTH A property value that evaluates to a length of zero, suitable for use as a default.

Fields inherited from class org.foray.fotree.value.Expr

OPERATION_ADD, OPERATION_DIVIDE, OPERATION_MOD, OPERATION_MULTIPLY, OPERATION_NEGATION, OPERATION_SUBTRACT, UNIT_POWER_AREA, UNIT_POWER_LENGTH, UNIT_POWER_NON_NUMERIC, UNIT_POWER_NUMERIC

Constructor Summary

DtLength(float value, String units)
Constructor.

Method Summary

boolean	canEvalColor() Indicates whether this property value has the ability to express itself as a Color.
boolean	canEvalInteger() Indicates whether this property value has the ability to express itself as an integer Numeric item.
boolean	canEvalKeyword() Indicates whether this property value can evaluate to a keyword.
boolean	canEvalLength() Indicates whether this expression can be evaluated to a unit power = 1 (length) or not.
boolean	canEvalNumeric() Indicates whether this property value has the ability to express itself as a Numeric item.
boolean	canEvalPercentage() Indicates whether this property value can evaluate to a percentage.
static byte	convertUnits(String units) Converts a String unit descriptor to its internal byte equivalent.
Color	evalColor() Return the color value of "this".
int	evalInteger() Return this value as an int.
PvKeyword	evalKeyword() Returns the keyword value of this property value.
int	evalLength(int pointSize) Evaluates the expression to a unit power of 1 (length).
double	evalNumeric() Return the raw numeric value of "this", without regard to unit power.
float	evalPercentage() Returns the percentage value of this property value.
byte	getUnitPower() Each numeric has a "unit power".
int	getValue(int fontSize) Return the value.
boolean	lengthRequiresFontSize() Indicates whether the computation of the length will require an accurate font-size parameter.
static DtLength	makeLengthDT(String input) Factory method for creating a LengthDT instance from a String.
boolean	needsFontSize() Indicates whether this length requires a font-size to compute its value.

Methods inherited from class org.foray.fotree.value.Datatype

convertValueToFoValue

Methods inherited from class org.foray.fotree.value.Expr

evalColorException, evalIntegerException, evalKeywordException, evalLengthException, evalNumericException, evalPercentageException

Methods inherited from class java.lang.Object

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

Field Detail

UNIT_ARRAY

public static final String[] UNIT_ARRAY

Array of valid string descriptions for length units.

UNIT_INCHES

public static final byte UNIT_INCHES

Constant indicating units of "inches".

See Also:

Constant Field Values

UNIT_CENTIMETERS

public static final byte UNIT_CENTIMETERS

Constant indicating units of "centimeters".

See Also:

Constant Field Values

UNIT_MILLIMETERS

public static final byte UNIT_MILLIMETERS

Constant indicating units of "millimeters".

See Also:

Constant Field Values

UNIT_POINTS

public static final byte UNIT_POINTS

Constant indicating units of "points".

See Also:

Constant Field Values

UNIT_PICAS

public static final byte UNIT_PICAS

Constant indicating units of "picas".

See Also:

Constant Field Values

UNIT_PIXELS

public static final byte UNIT_PIXELS

Constant indicating units of "pixels".

See Also:

Constant Field Values

UNIT_EMS

public static final byte UNIT_EMS

Constant indicating units of "ems".

See Also:

Constant Field Values

ZERO_LENGTH

public static final DtLength ZERO_LENGTH

A property value that evaluates to a length of zero, suitable for use as a default.

Constructor Detail

DtLength

public DtLength(float value,
                String units)

Constructor.

Parameters:

value - The signed length value.

units - A byte representation of the unit of measure (points, inches, etc.)

Method Detail

getValue

public int getValue(int fontSize)

Return the value.

Parameters:

fontSize - The font-size, in millipoints. This is used for "em" computations. In environments where computing the font-size is expensive, check needsFontSize() first before computing it. If it returns false, zero or some other constant can safely be passed, as the value will not be used anyway.

Returns:

The value of this length in millipoints.

convertUnits

public static byte convertUnits(String units)

Converts a String unit descriptor to its internal byte equivalent.

Parameters:

units - The String descriptor of the units.

Returns:

The byte equivalent.

canEvalNumeric

public boolean canEvalNumeric()

Description copied from interface: PropertyValue

Indicates whether this property value has the ability to express itself as a Numeric item.

Returns:

True iff this property value is a numeric.

evalNumeric

public double evalNumeric()

Description copied from interface: PropertyValue

Return the raw numeric value of "this", without regard to unit power.

Returns:

A double representation of the value of "this". Type "double" is assumed to be the lowest-common-denominator of all numeric values.

getUnitPower

public byte getUnitPower()

Description copied from interface: PropertyValue

Each numeric has a "unit power". This number refers to the number of spatial dimensions in which the number operates. So, a number that has no relationship to space or refers to a point, has a length power of 0. A number that refers to length has a length power of 1 (1 dimension). Although there are none yet in XSL-FO, a number that referred to area (e.g. square inches) would, we suppose, have a length power of 2, and one referring to volume (e.g. cubic feet) would, we suppose have a length power of 3.

Returns:

The number of spatial dimensions in which this numeric item operates. For XSL-FO items, this should be either Expr.UNIT_POWER_NUMERIC or Expr.UNIT_POWER_LENGTH.

makeLengthDT

public static DtLength makeLengthDT(String input)

Factory method for creating a LengthDT instance from a String.

Parameters:

input - The string from which a LengthDT instance should be created.

Returns:

A LengthDT instance, or null if input is not valid.

canEvalLength

public boolean canEvalLength()

Description copied from interface: PropertyValue

Indicates whether this expression can be evaluated to a unit power = 1 (length) or not.

Returns:

True if the expression can be evaluated to a unit power of 1 (length).

evalLength

public int evalLength(int pointSize)

Description copied from interface: PropertyValue

Evaluates the expression to a unit power of 1 (length).

Parameters:

pointSize - The point size, in millipoints, of the font. This is used in calculations that are relative to the point size. In cases where the computation of the font-size is expensive, check PropertyValue.lengthRequiresFontSize() first. If that method returns false, zero or some other constant can safely be passed, as it will be ignored anyway.

Returns:

The unit power 1 value (length) of this expression if the expression can be so evaluated, or Integer.MIN_VALUE otherwise. The value is expressed in millipoints.

lengthRequiresFontSize

public boolean lengthRequiresFontSize()

Description copied from interface: PropertyValue

Indicates whether the computation of the length will require an accurate font-size parameter.

Returns:

True iff the computation of the length will require an accurate font-size parameter.

needsFontSize

public boolean needsFontSize()

Indicates whether this length requires a font-size to compute its value. In environments where computing the font-size is expensive, checking this method first can avoid that cost.

Returns:

True iff this length requires a font-size to compute its value.

canEvalColor

public boolean canEvalColor()

Description copied from interface: PropertyValue

Indicates whether this property value has the ability to express itself as a Color.

Returns:

True iff this property value is a color.

evalColor

public Color evalColor()

Description copied from interface: PropertyValue

Return the color value of "this".

Returns:

The color representation of the value of "this".

canEvalInteger

public boolean canEvalInteger()

Description copied from interface: PropertyValue

Indicates whether this property value has the ability to express itself as an integer Numeric item.

Returns:

True iff this property value is an integer.

evalInteger

public int evalInteger()

Description copied from interface: PropertyValue

Return this value as an int. This method should only be executed on instances where PropertyValue.canEvalInteger() returns true. Doing so on other instances may result in an IllegalStateException.

Returns:

This value as an int.

canEvalKeyword

public boolean canEvalKeyword()

Description copied from interface: PropertyValue

Indicates whether this property value can evaluate to a keyword.

Returns:

True iff this property value can evaluate to a keyword.

evalKeyword

public PvKeyword evalKeyword()

Description copied from interface: PropertyValue

Returns the keyword value of this property value. This method should only be executed on instances where PropertyValue.canEvalKeyword() returns true. Doing so on other instances may result in an IllegalStateException.

Returns:

The keyword value of this property value.

canEvalPercentage

public boolean canEvalPercentage()

Description copied from interface: PropertyValue

Indicates whether this property value can evaluate to a percentage.

Returns:

True iff this property value can evaluate to a percentage.

evalPercentage

public float evalPercentage()

Description copied from interface: PropertyValue

Returns the percentage value of this property value. This method should only be executed on instances where PropertyValue.canEvalPercentage() returns true. Doing so on other instances may result in an IllegalStateException.

Returns:

The percentage value of this property value.