# PdfFunctionBasedShading Class

In Type 1 (function-based) shadings, the color at every point in the domain is defined by a specified mathematical function. The function need not be smooth or continuous. This type is the most general of the available shading types and is useful for shadings that cannot be adequately described with any of the other types.

`public sealed class PdfFunctionBasedShading : PdfShading`

```
Public NotInheritable Class PdfFunctionBasedShading
Inherits PdfShading
```

- Inheritance:
- PdfFunctionBasedShading

### Constructors

#### PdfFunctionBasedShading(PdfFunction, PdfColorSpace)

Initializes a new instance of the PdfFunctionBasedShading class.

The DomainX and DomainY are set from the `function`

's Domain.

Use the SetTransform(PdfPoint, PdfSize) method afterwards if DomainX and DomainY do not correspond to the shading's target coordinate space.

`public PdfFunctionBasedShading(PdfFunction function, PdfColorSpace colorSpace = null)`

`Public Sub New(function As PdfFunction, colorSpace As PdfColorSpace = Nothing)`

##### Parameters

`function`

- PdfFunction

A 2-in, *n*-out function (where *n* is the number of color components in the shading dictionary's color space).

`colorSpace`

- PdfColorSpace

The color space in which color values shall be expressed. If omitted, the DeviceRGB is used.

##### Exceptions

`function`

is null.

The `function`

's input dimensionality is invalid (the Domain's Count should be 2) or the `function`

's output dimensionality is invalid (should be equal to the ColorSpace.ColorantCount).

#### PdfFunctionBasedShading(IList<PdfFunction>, PdfColorSpace)

Initializes a new instance of the PdfFunctionBasedShading class.

The DomainX and DomainY are set as a subset of the Domain of all PdfFunctions contained in the `function`

list.

Use the SetTransform(PdfPoint, PdfSize) method afterwards if DomainX and DomainY do not correspond to the shading's target coordinate space.

`public PdfFunctionBasedShading(IList<PdfFunction> function, PdfColorSpace colorSpace = null)`

`Public Sub New(function As IList(Of PdfFunction), colorSpace As PdfColorSpace = Nothing)`

##### Parameters

`function`

- IList<PdfFunction>

An array of *n* 2-in, 1-out functions (where *n* is the number of color components in the shading dictionary's color space).

`colorSpace`

- PdfColorSpace

The color space in which color values shall be expressed. If omitted, the DeviceRGB is used.

##### Exceptions

`function`

is null or empty or any of its elements is null.

The `function`

's count is not equal to the ColorSpace.ColorantCount or the function's input dimensionality is invalid (the Domain's Count should be 2) or the function's output dimensionality is invalid (should be 1) for any PdfFunction contained in the `function`

list.

### Properties

#### DomainX

A PdfNumberRange specifying the horizontal component of the rectangular domain of coordinates over which the color function(s) are defined.

Default value: [0, 1].

##### Property Value

A PdfNumberRange specifying the horizontal component of the rectangular domain of coordinates over which the color function(s) are defined.

##### See Also

#### DomainY

A PdfNumberRange specifying the vertical component of the rectangular domain of coordinates over which the color function(s) are defined.

Default value: [0, 1].

##### Property Value

A PdfNumberRange specifying the vertical component of the rectangular domain of coordinates over which the color function(s) are defined.

##### See Also

#### Function

*(Required)* A 2-in, *n*-out function or an array of *n* 2-in, 1-out functions (where *n* is the number of color components in the shading dictionary's color space). Each function's domain shall be a superset of that of the shading dictionary. If the value returned by the function for a given color component is out of range, it shall be adjusted to the nearest valid value.

`public IList<PdfFunction> Function { get; set; }`

`Public Property Function As IList(Of PdfFunction)`

##### Property Value

A 2-in, *n*-out function or an array of *n* 2-in, 1-out functions.

##### Exceptions

Value is null or empty or any of its elements is null.

The number of functions is not 1 and is not equal to the ColorSpace.ColorantCount or the function's input dimensionality is invalid (the Domain's Count should be 2) or the function's output dimensionality is invalid (if the number of functions is 1, then it should be equal to the ColorSpace.ColorantCount; otherwise, it should be 1) for any function contained in the PdfFunction list.

##### See Also

#### ShadingType

Gets the FunctionBased value.

`public override PdfShadingType ShadingType { get; }`

`Public Overrides ReadOnly Property ShadingType As PdfShadingType`

##### Property Value

The FunctionBased value.

##### Overrides

#### Transform

*(Optional)* An array of six numbers specifying a transformation matrix mapping the coordinate space specified by DomainX and DomainY entries into the shading's target coordinate space.

##### note

To map the domain rectangle [{0, 1}, {0, 1}] to a 1-inch square with lower-left corner at coordinates (100, 100) in default user space, the Transform value would be [72 0 0 72 100 100].

Default value: the Identity matrix [1 0 0 1 0 0].

##### Property Value

##### See Also

### Methods

#### SetTransform(PdfPoint, PdfSize)

Sets the Transform to a a PdfMatrix that transforms the rectangle specified by DomainX and DomainY entries to the rectangle specified by `point`

and `size`

parameters. This method is useful if the shading's DomainX and DomainY doesn't correspond to the shading's target coordinate space.

`public PdfFunctionBasedShading SetTransform(PdfPoint point, PdfSize size)`

`Public Function SetTransform(point As PdfPoint, size As PdfSize) As PdfFunctionBasedShading`

##### Parameters

`point`

- PdfPoint

`size`

- PdfSize

##### Returns

A reference to this PdfFunctionBasedShading instance after the setting the Transform has completed.

### Inherited Properties

Background |
## noteIn the opaque imaging model, the effect is as if the painting operation were performed twice: first with the background color and then with the shading. ## noteThe background color is applied only when the shading is used as part of a PdfShadingPattern, not when it is painted directly with the PdfShadingContent operator. (Inherited from PdfShading) |

BoundingBox |
(Inherited from PdfShading) |

ColorSpace |
(Inherited from PdfShading) |

Document | Gets the PdfDocument associated with this PdfContentResource or null if no PdfDocument is associated with this PdfContentResource. (Inherited from PdfContentResource) |

IsAntiAlias |
## noteThe shading operators sample shading functions at a rate determined by the resolution of the output device. Aliasing can occur if the function is not smooth—that is, if it has a high spatial frequency relative to the sampling rate. Anti-aliasing can be computationally expensive and is usually unnecessary, since most shading functions are smooth enough or are sampled at a high enough frequency to avoid aliasing effects. Anti-aliasing may not be implemented on some output devices, in which case this flag is ignored. Default value: false. (Inherited from PdfShading) |

Metadata |
(Inherited from PdfObject) |

### Inherited Methods

CreateFunction(IList<PdfShadingColor>) | Creates an interpolation function from the specified list of PdfShadingColors. Two The function's Domain is set from the Offset of the first and the last PdfShadingColor. (Inherited from PdfShading) |

SetBoundingBox(Double, Double, Double, Double) | Sets the BoundingBox. (Inherited from PdfShading) |