org.icepdf.core.pobjects.graphics
Class SoftMask

java.lang.Object
  org.icepdf.core.pobjects.Dictionary
      org.icepdf.core.pobjects.graphics.SoftMask

public class SoftMask
extends Dictionary

Soft-mask Dictionary specifies the current soft mask in the graphics state. The mask values shall be derived from those of the transparency group, using one of the two methods in "11.5.2 Deriving a Soft Mask from Group Alpha", and "11.5.3 Deriving a Soft Mask from Group Luminosity".

The S subtype entry shall specify which of the two derivation methods to use:

• If the subtype is Alpha, the transparency group XObject G shall be evaluated to compute a group alpha only. The colours of the constituent objects shall be ignored and the colour compositing computations shall not be performed. The transfer function TR shall then be applied to the computed group alpha to produce the mask values. Outside the bounding box of the transparency group, the mask value shall be the result of applying the transfer function to the input value 0.0.
• If the subtype is Luminosity, the transparency group XObject G shall be composited with a fully opaque backdrop whose colour is everywhere defined by the soft-mask dictionary's BC entry. The computed result colour shall then be converted to a single-component luminosity value, and the transfer function TR shall be applied to this luminosity to produce the mask values. Outside the transparency group's bounding box, the mask value shall be derived by transforming the BC colour to luminosity and applying the transfer function to the result.

Field Summary

static Name	BC_KEY
static Name	G_KEY
static Name	S_KEY
static java.lang.String	SOFT_MASK_TYPE_ALPHA
static java.lang.String	SOFT_MASK_TYPE_LUMINOSITY

Fields inherited from class org.icepdf.core.pobjects.Dictionary

entries, FORM_TYPE_KEY, inited, isDeleted, isNew, LENGTH_KEY, library, SUBTYPE_KEY, TYPE_KEY

Constructor Summary

SoftMask(Library library, java.util.HashMap dictionary)

Method Summary

java.util.List<java.lang.Number>	getBC() An array of component values specifying the colour to be used as the backdrop against which to composite the transparency group XObject G.
Form	getG() A transparency group XObject (see "Transparency Group XObjects") to be used as the source of alpha or colour values for deriving the mask.
Name	getS() A subtype specifying the method to be used in deriving the mask values from the transparency group specified by the G entry: Alpha - The group's computed alpha shall be used, disregarding its colour (see "Deriving a Soft Mask from Group Alpha"). LuminosityThe group's computed colour shall be converted to a single-component luminosity value (see "Deriving a Soft Mask from Group Luminosity").

Methods inherited from class org.icepdf.core.pobjects.Dictionary

getEntries, getFloat, getInt, getLibrary, getNumber, getObject, getPObjectReference, init, isDeleted, isNew, setDeleted, setNew, setPObjectReference, toString

Methods inherited from class java.lang.Object

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

Field Detail

S_KEY

public static final Name S_KEY

G_KEY

public static final Name G_KEY

BC_KEY

public static final Name BC_KEY

SOFT_MASK_TYPE_ALPHA

public static final java.lang.String SOFT_MASK_TYPE_ALPHA

See Also:

Constant Field Values

SOFT_MASK_TYPE_LUMINOSITY

public static final java.lang.String SOFT_MASK_TYPE_LUMINOSITY

See Also:

Constant Field Values

Constructor Detail

SoftMask

public SoftMask(Library library,
                java.util.HashMap dictionary)

Method Detail

getS

public Name getS()

A subtype specifying the method to be used in deriving the mask values from the transparency group specified by the G entry:

• Alpha - The group's computed alpha shall be used, disregarding its colour (see "Deriving a Soft Mask from Group Alpha").
• LuminosityThe group's computed colour shall be converted to a single-component luminosity value (see "Deriving a Soft Mask from Group Luminosity").

Returns:

subtype of the soft-mask dictionary.

getG

public Form getG()

A transparency group XObject (see "Transparency Group XObjects") to be used as the source of alpha or colour values for deriving the mask. If the subtype S is Luminosity, the group attributes dictionary shall contain a CS entry defining the colour space in which the compositing computation is to be performed.

Returns:

Xobject associated with G, null otherwise.

getBC

public java.util.List<java.lang.Number> getBC()

An array of component values specifying the colour to be used as the backdrop against which to composite the transparency group XObject G. This entry shall be consulted only if the subtype S is Luminosity. The array shall consist of n numbers, where n is the number of components in the colour space specified by the CS entry in the group attributes dictionary (see "Transparency Group XObjects"). Default value: the colour space's initial value, representing black.

Returns: