Class PngTrnsChunk

java.lang.Object

org.eclipse.swt.internal.image.PngChunk

org.eclipse.swt.internal.image.PngTrnsChunk

public class PngTrnsChunk
extends PngChunk

Field Summary

Fields

Modifier and Type	Field	Description
(package private) static final int	RGB_DATA_LENGTH
(package private) static final int	TRANSPARENCY_TYPE_ALPHAS
(package private) static final int	TRANSPARENCY_TYPE_PIXEL

Fields inherited from class PngChunk

CHUNK_IDAT, CHUNK_IEND, CHUNK_IHDR, CHUNK_PLTE, CHUNK_tRNS, CHUNK_UNKNOWN, CRC_TABLE, DATA_OFFSET, length, LENGTH_FIELD_LENGTH, LENGTH_OFFSET, MIN_LENGTH, reference, TYPE_FIELD_LENGTH, TYPE_IDAT, TYPE_IEND, TYPE_IHDR, TYPE_OFFSET, TYPE_PLTE, TYPE_tRNS

Constructor Summary

Constructors

Constructor	Description
PngTrnsChunk(byte[] reference)
PngTrnsChunk(RGB rgb)

Method Summary

Modifier and Type	Method	Description
(package private) byte[]	getAlphaValues(PngIhdrChunk header, PngPlteChunk paletteChunk)	Answer an array of Alpha values that correspond to the colors in the palette.
(package private) int	getChunkType()
(package private) int	getSwtTransparentPixel(PngIhdrChunk header)	Answer the transparent pixel RGB value.
(package private) int	getTransparencyType(PngIhdrChunk header)
(package private) void	validate(PngFileReadState readState, PngIhdrChunk headerChunk, PngPlteChunk paletteChunk)	Answer whether the chunk is a valid tRNS chunk.
(package private) void	validateLength(PngIhdrChunk header, PngPlteChunk paletteChunk)

Methods inherited from class PngChunk

checkCRC, computeCRC, contributeToString, getCRC, getData, getInt16, getInt32, getLength, getReference, getSize, getTypeBytes, isCritical, readNextFromStream, setCRC, setData, setInt16, setInt32, setLength, setReference, setType, toString, typeMatchesArray, validate

Methods inherited from class Object

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

Field Details

TRANSPARENCY_TYPE_PIXEL

static final int TRANSPARENCY_TYPE_PIXEL

See Also:

• Constant Field Values

TRANSPARENCY_TYPE_ALPHAS

static final int TRANSPARENCY_TYPE_ALPHAS

See Also:

• Constant Field Values

RGB_DATA_LENGTH

static final int RGB_DATA_LENGTH

See Also:

• Constant Field Values

Constructor Details

PngTrnsChunk

PngTrnsChunk(RGB rgb)

PngTrnsChunk

PngTrnsChunk(byte[] reference)

Method Details

getChunkType

int getChunkType()

Overrides:

getChunkType in class PngChunk

validateLength

void validateLength(PngIhdrChunk header,
 PngPlteChunk paletteChunk)

validate

void validate(PngFileReadState readState,
 PngIhdrChunk headerChunk,
 PngPlteChunk paletteChunk)

Answer whether the chunk is a valid tRNS chunk.

getTransparencyType

int getTransparencyType(PngIhdrChunk header)

getSwtTransparentPixel

int getSwtTransparentPixel(PngIhdrChunk header)

Answer the transparent pixel RGB value. This is not valid for palette color types. This is not valid for alpha color types. This will convert a grayscale value into a palette index. It will compress a 6 byte RGB into a 3 byte RGB.

getAlphaValues

byte[] getAlphaValues(PngIhdrChunk header,
 PngPlteChunk paletteChunk)

Answer an array of Alpha values that correspond to the colors in the palette. This is only valid for the COLOR_TYPE_PALETTE color type.