org.apache.fop.pdf
Class PDFFunction

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.


Constructor Summary
PDFFunction(int theNumber, int theFunctionType, Vector theDomain, Vector theRange, Vector theSize, int theBitsPerSample, int theOrder, Vector theEncode, Vector theDecode, StringBuffer theFunctionDataStream, Vector theFilter)
          create an complete Function object of Type 0, A Sampled function.
PDFFunction(int theNumber, int theFunctionType, Vector theDomain, Vector theRange, Vector theCZero, Vector theCOne, double theInterpolationExponentN)
          create an complete Function object of Type 2, an Exponential Interpolation function.
PDFFunction(int theNumber, int theFunctionType, Vector theDomain, Vector theRange, Vector theFunctions, Vector theBounds, Vector theEncode)
          create an complete Function object of Type 3, a Stitching function.
PDFFunction(int theNumber, int theFunctionType, Vector theDomain, Vector theRange, StringBuffer theFunctionDataStream)
          create an complete Function object of Type 4, a postscript calculator function.

Method Summary
 byte[]toPDF()
          represent as PDF.

Methods inherited from class org.apache.fop.pdf.PDFObject
getNumber, referencePDF

Constructor Detail

PDFFunction

public PDFFunction(int theNumber, int theFunctionType, Vector theDomain, Vector theRange, Vector theSize, int theBitsPerSample, int theOrder, Vector theEncode, Vector theDecode, StringBuffer theFunctionDataStream, Vector 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 - Vector objects of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.
theRange - Vector objects of Double objects. This is the Range of the function. See page 264 of the PDF 1.3 Spec.
theSize - A Vector 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 user 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 - Vector 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 - Vector 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.
theNumber - The object number of this PDF object.
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 theNumber, int theFunctionType, Vector theDomain, Vector theRange, Vector theCZero, Vector 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:
theNumber - the object's number
theDomain - Vector objects of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.
theRange - Vector 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 theNumber, int theFunctionType, Vector theDomain, Vector theRange, Vector theFunctions, Vector theBounds, Vector 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:
theNumber - the object's number
theDomain - Vector objects of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.
theRange - Vector objects of Double objects. This is the Range of the function. See page 264 of the PDF 1.3 Spec.
theFunctions - A Vector 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 - Vector 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 theNumber, int theFunctionType, Vector theDomain, Vector theRange, 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 - Vector object of Double objects. This is the domain of the function. See page 264 of the PDF 1.3 Spec.
theRange - Vector 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.
theNumber - The object number of this PDF object.
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.
Returns: the PDF string.

Association Links

to Class java.util.Vector

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

to Class java.util.Vector

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

to Class java.util.Vector

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.

to Class java.util.Vector

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.

to Class java.util.Vector

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

to Class java.lang.StringBuffer

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

to Class java.util.Vector

Required (?) 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.

to Class java.util.Vector

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

to Class java.util.Vector

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

to Class java.util.Vector

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

to Class java.util.Vector

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.

to Class org.apache.fop.pdf.PDFNumber