PdfShading Class

Namespace:
GemBox.Pdf.Content.Patterns
Assembly:
GemBox.Pdf.dll

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.

public abstract class PdfShading : PdfContentResource
Public MustInherit Class PdfShading
    Inherits PdfContentResource
Inheritance:
System.Object
PdfShading
Derived
PdfAxialShading
PdfFunctionBasedShading
PdfMeshShading
PdfRadialShading
Remarks

Various shading types are available, depending on the value of the ShadingType entry:

  • PdfFunctionBasedShading: Function-based shadings (type 1) define the color of every point in the domain using a mathematical function (not necessarily smooth or continuous).
  • PdfAxialShading: Axial shadings (type 2) define a color blend along a line between two points, optionally extended beyond the boundary points by continuing the boundary colors.
  • PdfRadialShading: 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.
  • PdfFreeTriangleMeshShading: Free-form Gouraud-shaded triangle meshes (type 4) define a common construct used by many three-dimensional applications to represent complex colored and shaded shapes. Vertices are specified in free-form geometry.
  • PdfLatticeTriangleMeshShading: 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.
  • PdfCoonsPatchMeshShading: Coons patch meshes (type 6) construct a shading from one or more color patches, each bounded by four cubic Bézier curves.
  • PdfTensorPatchMeshShading: 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.

Properties

Background

(Optional) A color appropriate to the ColorSpace, specifying a single background color. If present, this color shall be used, before any painting operation involving the shading, to fill those portions of the area to be painted that lie outside the bounds of the shading object.

note

In 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.

note

The 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.

public PdfColor? Background { get; set; }
Public Property Background As PdfColor?
Property Value
System.Nullable<PdfColor>

A color appropriate to the color space, specifying a single background color.

Exceptions
System.ArgumentException

Shading background Space is not the same as the shading ColorSpace.

See Also

BoundingBox

(Optional) A rectangle giving the left, bottom, right, and top coordinates, respectively, of the shading's bounding box. The coordinates shall be interpreted in the shading's target coordinate space. If present, this bounding box shall be applied as a temporary clipping boundary when the shading is painted, in addition to the current clipping path and any other clipping boundaries in effect at that time.

public PdfRectangle BoundingBox { get; set; }
Public Property BoundingBox As PdfRectangle
Property Value
PdfRectangle

An rectangle giving the left, bottom, right, and top coordinates, respectively, of the shading's bounding box.

See Also

ColorSpace

(Required) The color space in which color values shall be expressed. This may be any device, CIE-based, or special color space except a Pattern space. See 8.7.4.4, "Color Space: Special Considerations" for further information.

public PdfColorSpace ColorSpace { get; }
Public ReadOnly Property ColorSpace As PdfColorSpace
Property Value
PdfColorSpace

The color space in which color values shall be expressed.

See Also

IsAntiAlias

(Optional) A flag indicating whether to filter the shading function to prevent aliasing artifacts.

note

The 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.

public bool IsAntiAlias { get; set; }
Public Property IsAntiAlias As Boolean
Property Value
System.Boolean
See Also

ShadingType

(Required) The shading type.

public virtual PdfShadingType ShadingType { get; }
Public Overridable ReadOnly Property ShadingType As PdfShadingType
Property Value
PdfShadingType

The shading type.

See Also

Methods

CreateFunction(IList<PdfShadingColor>)

Creates an interpolation function from the specified list of PdfShadingColors.

Two colors create a PdfExponentialInterpolationFunction and more than two create a PdfStitchingFunction (stitching two or more PdfExponentialInterpolationFunctions).

The function's Domain is set from the Offset of the first and the last PdfShadingColor.

public static IList<PdfFunction> CreateFunction(IList<PdfShadingColor> colors)
Public Shared Function CreateFunction(colors As IList(Of PdfShadingColor)) As IList(Of PdfFunction)
Parameters
colors
System.Collections.Generic.IList<PdfShadingColor>

The PdfShadingColors for which to create an interpolation function.

Returns
System.Collections.Generic.IList<PdfFunction>
Exceptions
System.ArgumentNullException

colors is null.

System.ArgumentException

colors count is less than 2 or Color spaces of PdfShadingColors are not equal or Offset of any PdfShadingColor is not greater than the Offset of all previous PdfShadingColors.

SetBoundingBox(Double, Double, Double, Double)

Sets the BoundingBox.

public void SetBoundingBox(double left, double bottom, double right, double top)
Public Sub SetBoundingBox(left As Double, bottom As Double, right As Double, top As Double)
Parameters
left
System.Double

The left X coordinate of the BoundingBox.

bottom
System.Double

The bottom Y coordinate of the BoundingBox.

right
System.Double

The right X coordinate of the BoundingBox.

top
System.Double

The top Y coordinate of the BoundingBox.

Inherited Properties

Document

Gets the PdfDocument associated with this PdfContentResource or null if no PdfDocument is associated with this PdfContentResource.

(Inherited from PdfContentResource)

Metadata

(Optional; PDF 1.4) A metadata stream containing metadata for the component.

(Inherited from PdfObject)

Extension Methods

Examples

See Also