org.apache.fop.pdf
Class PDFFunction

java.lang.Object
  org.apache.fop.pdf.PDFObject
      org.apache.fop.pdf.PDFFunction

public class PDFFunction

extends PDFObject

class representing a PDF Function. PDF Functions represent parameterized mathematical formulas and sampled representations with arbitrary resolution. Functions are used in two areas: device-dependent rasterization information for halftoning and transfer functions, and color specification for smooth shading (a PDF 1.3 feature). All PDF Functions have a FunctionType (0,2,3, or 4), a Domain, and a Range.

Field Summary

protected int	bitsPerSample Required for Type 0: Number of Bits used to represent each sample value.
protected java.util.List	bounds Optional for Type 3: An array of (k-1) Doubles that, in combination with Domain, define the intervals to which each function from the Functions array apply.
protected java.util.List	cOne Required For Type 2: An Array of n Doubles defining the function result when x=1.
protected java.util.List	cZero Required For Type 2: An Array of n Doubles defining the function result when x=0.
protected java.util.List	decode Optional for Type 0: A 2 * n array of Doubles which provides a linear mapping of sample values to the range.
protected java.util.List	domain Required: 2 * m Array of Double numbers which are possible inputs to the function
protected java.util.List	encode Optional for Type 0: A 2 * m array of Doubles which provides a linear mapping of input values to the domain.
protected java.util.List	filter Required (possibly) For Type 0: A vector of Strings for the various filters to be used to decode the stream.
protected java.lang.StringBuffer	functionDataStream Required For Type 4: Postscript Calculator function composed of arithmetic, boolean, and stack operators + boolean constants
protected java.util.List	functions Required for Type 3: An vector of PDFFunctions which form an array of k single input functions making up the stitching function.
protected int	functionType Required: The Type of function (0,2,3,4) default is 0.
protected double	interpolationExponentN Required for Type 2: The interpolation exponent.
protected int	order Optional for Type 0: order of interpolation between samples.
protected java.util.List	range Required: 2 * n Array of Double numbers which are possible outputs to the function
protected java.util.List	size Required: Array containing the Integer size of the Domain and Range, respectively.

Fields inherited from class org.apache.fop.pdf.PDFObject

DATE_FORMAT, log

Constructor Summary

PDFFunction(int theFunctionType, java.util.List theDomain, java.util.List theRange, java.util.List theSize, int theBitsPerSample, int theOrder, java.util.List theEncode, java.util.List theDecode, java.lang.StringBuffer theFunctionDataStream, java.util.List theFilter)
create an complete Function object of Type 0, A Sampled function.

PDFFunction(int theFunctionType, java.util.List theDomain, java.util.List theRange, java.util.List theCZero, java.util.List theCOne, double theInterpolationExponentN)
create an complete Function object of Type 2, an Exponential Interpolation function.

PDFFunction(int theFunctionType, java.util.List theDomain, java.util.List theRange, java.util.List theFunctions, java.util.List theBounds, java.util.List theEncode)
create an complete Function object of Type 3, a Stitching function.

PDFFunction(int theFunctionType, java.util.List theDomain, java.util.List theRange, java.lang.StringBuffer theFunctionDataStream)
create an complete Function object of Type 4, a postscript calculator function.

Method Summary

boolean	equals(java.lang.Object obj) Check if this function is equal to another object.
byte[]	toPDF() represent as PDF.

Methods inherited from class org.apache.fop.pdf.PDFObject

encode, encodeString, encodeText, formatDateTime, getDocument, getDocumentSafely, getGeneration, getObjectID, getObjectNumber, hasObjectNumber, output, referencePDF, setDocument, setObjectNumber, toPDFString

Methods inherited from class java.lang.Object

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

Field Detail

functionType

protected int functionType

Required: The Type of function (0,2,3,4) default is 0.

domain

protected java.util.List domain

Required: 2 * m Array of Double numbers which are possible inputs to the function

range

protected java.util.List range

Required: 2 * n Array of Double numbers which are possible outputs to the function

size

protected java.util.List size

Required: Array containing the Integer size of the Domain and Range, respectively. Note: This is really more like two seperate integers, sizeDomain, and sizeRange, but since they're expressed as an array in PDF, my implementation reflects that.

bitsPerSample

protected int bitsPerSample

Required for Type 0: Number of Bits used to represent each sample value. Limited to 1,2,4,8,12,16,24, or 32

order

protected int order

Optional for Type 0: order of interpolation between samples. Limited to linear (1) or cubic (3). Default is 1

encode

protected java.util.List encode

Optional for Type 0: A 2 * m array of Doubles which provides a linear mapping of input values to the domain. Required for Type 3: A 2 * k array of Doubles that, taken in pairs, map each subset of the domain defined by Domain and the Bounds array to the domain of the corresponding function. Should be two values per function, usually (0,1), as in [0 1 0 1] for 2 functions.

decode

protected java.util.List decode

Optional for Type 0: A 2 * n array of Doubles which provides a linear mapping of sample values to the range. Defaults to Range.

functionDataStream

protected java.lang.StringBuffer functionDataStream

Required For Type 4: Postscript Calculator function composed of arithmetic, boolean, and stack operators + boolean constants

filter

protected java.util.List filter

Required (possibly) For Type 0: A vector of Strings for the various filters to be used to decode the stream. These are how the string is compressed. Flate, LZW, etc.

cZero

protected java.util.List cZero

Required For Type 2: An Array of n Doubles defining the function result when x=0. Default is [0].

cOne

protected java.util.List cOne

Required For Type 2: An Array of n Doubles defining the function result when x=1. Default is [1].

interpolationExponentN

protected double interpolationExponentN

Required for Type 2: The interpolation exponent. Each value x will return n results. Must be greater than 0.

functions

protected java.util.List functions

Required for Type 3: An vector of PDFFunctions which form an array of k single input functions making up the stitching function.

bounds

protected java.util.List bounds

Optional for Type 3: An array of (k-1) Doubles that, in combination with Domain, define the intervals to which each function from the Functions array apply. Bounds elements must be in order of increasing magnitude, and each value must be within the value of Domain. k is the number of functions. If you pass null, it will output (1/k) in an array of k-1 elements. This makes each function responsible for an equal amount of the stitching function. It makes the gradient even.

Constructor Detail

PDFFunction

public PDFFunction(int theFunctionType,
                   java.util.List theDomain,
                   java.util.List theRange,
                   java.util.List theSize,
                   int theBitsPerSample,
                   int theOrder,
                   java.util.List theEncode,
                   java.util.List theDecode,
                   java.lang.StringBuffer theFunctionDataStream,
                   java.util.List theFilter)

create an complete Function object of Type 0, A Sampled function. Use null for an optional object parameter if you choose not to use it. For optional int parameters, pass the default.

Parameters:

theDomain - List objects of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.

theRange - List objects of Double objects. This is the Range of the function. See page 264 of the PDF 1.3 Spec.

theSize - A List object of Integer objects. This is the number of samples in each input dimension. I can't imagine there being more or less than two input dimensions, so maybe this should be an array of length 2. See page 265 of the PDF 1.3 Spec.

theBitsPerSample - An int specifying the number of bits used to represent each sample value. Limited to 1,2,4,8,12,16,24 or 32. See page 265 of the 1.3 PDF Spec.

theOrder - The order of interpolation between samples. Default is 1 (one). Limited to 1 (one) or 3, which means linear or cubic-spline interpolation. This attribute is optional. See page 265 in the PDF 1.3 spec.

theEncode - List objects of Double objects. This is the linear mapping of input values intop the domain of the function's sample table. Default is hard to represent in ascii, but basically [0 (Size0 1) 0 (Size1 1)...]. This attribute is optional. See page 265 in the PDF 1.3 spec.

theDecode - List objects of Double objects. This is a linear mapping of sample values into the range. The default is just the range. This attribute is optional. Read about it on page 265 of the PDF 1.3 spec.

theFunctionDataStream - The sample values that specify the function are provided in a stream. This is optional, but is almost always used. Page 265 of the PDF 1.3 spec has more.

theFilter - This is a vector of String objects which are the various filters that have are to be applied to the stream to make sense of it. Order matters, so watch out. This is not documented in the Function section of the PDF 1.3 spec, it was deduced from samples that this is sometimes used, even if we may never use it in FOP. It is added for completeness sake.

theFunctionType - This is the type of function (0,2,3, or 4). It should be 0 as this is the constructor for sampled functions.

PDFFunction

public PDFFunction(int theFunctionType,
                   java.util.List theDomain,
                   java.util.List theRange,
                   java.util.List theCZero,
                   java.util.List theCOne,
                   double theInterpolationExponentN)

create an complete Function object of Type 2, an Exponential Interpolation function. Use null for an optional object parameter if you choose not to use it. For optional int parameters, pass the default.

Parameters:

theDomain - List objects of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.

theRange - List of Doubles that is the Range of the function. See page 264 of the PDF 1.3 Spec.

theCZero - This is a vector of Double objects which defines the function result when x=0. This attribute is optional. It's described on page 268 of the PDF 1.3 spec.

theCOne - This is a vector of Double objects which defines the function result when x=1. This attribute is optional. It's described on page 268 of the PDF 1.3 spec.

theInterpolationExponentN - This is the inerpolation exponent. This attribute is required. PDF Spec page 268

theFunctionType - The type of the function, which should be 2.

PDFFunction

public PDFFunction(int theFunctionType,
                   java.util.List theDomain,
                   java.util.List theRange,
                   java.util.List theFunctions,
                   java.util.List theBounds,
                   java.util.List theEncode)

create an complete Function object of Type 3, a Stitching function. Use null for an optional object parameter if you choose not to use it. For optional int parameters, pass the default.

Parameters:

theDomain - List objects of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.

theRange - List objects of Double objects. This is the Range of the function. See page 264 of the PDF 1.3 Spec.

theFunctions - A List of the PDFFunction objects that the stitching function stitches. This attributed is required. It is described on page 269 of the PDF spec.

theBounds - This is a vector of Doubles representing the numbers that, in conjunction with Domain define the intervals to which each function from the 'functions' object applies. It must be in order of increasing magnitude, and each must be within Domain. It basically sets how much of the gradient each function handles. This attributed is required. It's described on page 269 of the PDF 1.3 spec.

theEncode - List objects of Double objects. This is the linear mapping of input values intop the domain of the function's sample table. Default is hard to represent in ascii, but basically [0 (Size0 1) 0 (Size1 1)...]. This attribute is required. See page 270 in the PDF 1.3 spec.

theFunctionType - This is the function type. It should be 3, for a stitching function.

PDFFunction

public PDFFunction(int theFunctionType,
                   java.util.List theDomain,
                   java.util.List theRange,
                   java.lang.StringBuffer theFunctionDataStream)

create an complete Function object of Type 4, a postscript calculator function. Use null for an optional object parameter if you choose not to use it. For optional int parameters, pass the default.

Parameters:

theDomain - List object of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.

theRange - List object of Double objects. This is the Range of the function. See page 264 of the PDF 1.3 Spec.

theFunctionDataStream - This is a stream of arithmetic, boolean, and stack operators and boolean constants. I end up enclosing it in the '{' and '}' braces for you, so don't do it yourself. This attribute is required. It's described on page 269 of the PDF 1.3 spec.

theFunctionType - The type of function which should be 4, as this is a Postscript calculator function

Method Detail

toPDF

public byte[] toPDF()

represent as PDF. Whatever the FunctionType is, the correct representation spits out. The sets of required and optional attributes are different for each type, but if a required attribute's object was constructed as null, then no error is raised. Instead, the malformed PDF that was requested by the construction is dutifully output. This policy should be reviewed.

Overrides:

toPDF in class PDFObject

Returns:

the PDF string.

equals

public boolean equals(java.lang.Object obj)

Check if this function is equal to another object. This is used to find if a particular function already exists in a document.

Parameters:

obj - the obj to compare

Returns:

true if the functions are equal