Package org.loboevolution.pdfview.pattern

Class PDFShader

java.lang.Object

org.loboevolution.pdfview.pattern.PDFShader

Direct Known Subclasses:

DummyShader, ShaderType2, ShaderType3

public abstract class PDFShader
extends Object

A PDFShader fills a given region with a shading, such as a gradient.

Shading Dictionaries (section 4.6)
A shading dictionary specifies details of a particular gradient fill, including the type of shading to be used, the geometry of the area to be shaded, and the geometry of the gradient fill. Various shading types are available, depending on the value of the dictionary’s ShadingType entry:

Function-based shadings (type 1) define the color of every point in the domain using a mathematical function (not necessarily smooth or continuous).

Axial shadings (type 2) define a color blend along a pne between two points, optionally extended beyond the boundary points by continuing the boundary colors.

Radial shadings (type 3) define a blend between two circles, optionally extended beyond the boundary circles by continuing the boundary colors. This type of shading is commonly used to represent three-dimensional spheres and cones.

Free-form Gouraud-shaded triangle meshes (type 4) define a common construct used by many three-dimensional apppcations to represent complex colored and shaded shapes. Vertices are specified in free-form geometry.

Lattice-form Gouraud-shaded triangle meshes (type 5) are based on the same geometrical construct as type 4 but with vertices specified as a pseudorectangular lattice.

Coons patch meshes (type 6) construct a shading from one or more color patches, each bounded by four cubic Bézier curves.

Tensor-product patch meshes (type 7) are similar to type 6 but with additional control points in each patch, affording greater control over color mapping.

Table 4.28 shows the entries that all shading dictionaries share in common; entries specific to particular shading types are described in the relevant sections below.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	AXIAL_SHADING	Constant AXIAL_SHADING=2
static final int	COONS_PATCH_MESH_SHADING	Constant COONS_PATCH_MESH_SHADING=6
static final int	FREE_FORM_SHADING	Constant FREE_FORM_SHADING=4
static final int	FUNCTION_SHADING	Constant FUNCTION_SHADING=1
static final int	LATTICE_SHADING	Constant LATTICE_SHADING=5
static final int	RADIAL_SHADING	Constant RADIAL_SHADING=3
static final int	TENSOR_PRODUCTS_MESH_SHADING	Constant TENSOR_PRODUCTS_MESH_SHADING=7
static final float	TOLERANCE	The tolerance for reevaluating the shading function again

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	PDFShader(int type)	Creates a new instance of PDFShader

Method Summary

Modifier and Type	Method	Description
abstract PDFPaint	getPaint()	Returns paint that represents the selected shader
static PDFShader	getShader(PDFObject shaderObj, Map resources)	Parse a pdf shader into a shader object
abstract void	parse(PDFObject shareObj)	Parse the shader-specific data

Methods inherited from class java.lang.Object

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

Field Details

FUNCTION_SHADING

public static final int FUNCTION_SHADING

Constant FUNCTION_SHADING=1

See Also:

• Constant Field Values

AXIAL_SHADING

public static final int AXIAL_SHADING

Constant AXIAL_SHADING=2

See Also:

• Constant Field Values

RADIAL_SHADING

public static final int RADIAL_SHADING

Constant RADIAL_SHADING=3

See Also:

• Constant Field Values

FREE_FORM_SHADING

public static final int FREE_FORM_SHADING

Constant FREE_FORM_SHADING=4

See Also:

• Constant Field Values

LATTICE_SHADING

public static final int LATTICE_SHADING

Constant LATTICE_SHADING=5

See Also:

• Constant Field Values

COONS_PATCH_MESH_SHADING

public static final int COONS_PATCH_MESH_SHADING

Constant COONS_PATCH_MESH_SHADING=6

See Also:

• Constant Field Values

TENSOR_PRODUCTS_MESH_SHADING

public static final int TENSOR_PRODUCTS_MESH_SHADING

Constant TENSOR_PRODUCTS_MESH_SHADING=7

See Also:

• Constant Field Values

TOLERANCE

public static final float TOLERANCE

The tolerance for reevaluating the shading function again

See Also:

• Constant Field Values

Constructor Details

PDFShader

protected PDFShader(int type)

Creates a new instance of PDFShader

Parameters:

type - a Integer object.

Method Details

getShader

public static PDFShader getShader(PDFObject shaderObj,
 Map resources)
                           throws IOException

Parse a pdf shader into a shader object

Parameters:

shaderObj - a PDFObject object.

resources - a Map object.

Returns:

a PDFShader object.

Throws:

IOException - if any.

parse

public abstract void parse(PDFObject shareObj)
                    throws IOException

Parse the shader-specific data

Parameters:

shareObj - a PDFObject object.

Throws:

IOException - if any.

getPaint

public abstract PDFPaint getPaint()

Returns paint that represents the selected shader

Returns:

a PDFPaint object.