Package com.sixlegs.png

Class PngConstants

java.lang.Object

com.sixlegs.png.PngConstants

public abstract class PngConstants
extends Object

This interface defines all registered chunk types and provides methods helper methods to examine them. It also defines all of the keys used in the property map of a decoded PngImage, and applicable enumerated values.

See Also:

• PngImage.getProperty(java.lang.String)
• PngImage.getProperties()

Field Summary

Fields

Modifier and Type	Field	Description
static final String	BACKGROUND	bKGD: Background samples
static final String	BIT_DEPTH	IHDR: Bit depth
static final int	bKGD	Background color
static final int	cHRM	Primary chromaticities
static final String	CHROMATICITY	cHRM: Chromaticity
static final String	COLOR_TYPE	IHDR: Color type
static final int	COLOR_TYPE_GRAY	IHDR: Grayscale color type
static final int	COLOR_TYPE_GRAY_ALPHA	IHDR: Grayscale+alpha color type
static final int	COLOR_TYPE_PALETTE	IHDR: Palette color type
static final int	COLOR_TYPE_RGB	IHDR: RGB color type
static final int	COLOR_TYPE_RGB_ALPHA	IHDR: RGBA color type
static final String	COMPRESSION	IHDR: Compression method
static final int	COMPRESSION_BASE	IHDR: Deflate/inflate compression
static final String	FILTER	IHDR: Filter method
static final int	FILTER_BASE	IHDR: Adaptive filtering
static final int	gAMA	Image gamma
static final String	GAMMA	gAMA: Gamma
static final String	GIF_DELAY_TIME	gIFg: GIF delay time (hundredths of a second)
static final String	GIF_DISPOSAL_METHOD	gIFg: GIF disposal method
static final String	GIF_USER_INPUT_FLAG	gIFg: GIF user input flag
static final int	gIFg	GIF Graphic Control Extension
static final int	gIFx	GIF Application Extension
static final String	HEIGHT	IHDR: Height
static final int	hIST	Palette histogram
static final String	HISTOGRAM	hIST: Palette histogram
static final String	ICC_PROFILE	iCCP: ICC profile
static final String	ICC_PROFILE_NAME	iCCP: ICC profile name
static final int	iCCP	Embedded ICC profile
static final int	IDAT	Image data
static final int	IEND	Image trailer
static final int	IHDR	Image header
static final String	INTERLACE	IHDR: Interlace method
static final int	INTERLACE_ADAM7	IHDR: Adam7 interlace
static final int	INTERLACE_NONE	IHDR: No interlace
static final int	iTXt	International textual data
static final int	oFFs	Image offset
static final String	PALETTE	PLTE: Palette entries
static final String	PALETTE_ALPHA	PLTE: Palette alpha
static final int	pCAL	Calibration of pixel values
static final int	pHYs	Physical pixel dimensions
static final String	PIXEL_HEIGHT	sCAL: Physical height of pixel
static final String	PIXEL_WIDTH	sCAL: Physical width of pixel
static final String	PIXELS_PER_UNIT_X	pHYs: Pixels per unit, X axis
static final String	PIXELS_PER_UNIT_Y	pHYs: Pixels per unit, Y axis
static final int	PLTE	Palette
static final String	POSITION_UNIT	oFFs: Unit for image offset
static final int	POSITION_UNIT_MICROMETER	oFFs: Unit is the micrometer (10^-6 meter)
static final int	POSITION_UNIT_PIXEL	oFFs: Unit is the pixel (true dimensions unspecified)
static final String	POSITION_X	oFFs: Image X position
static final String	POSITION_Y	oFFs: Image Y position
static final String	RENDERING_INTENT	sRGB: Rendering intent
static final int	sBIT	Significant bits
static final int	sCAL	Physical scale of image subject
static final String	SCALE_UNIT	sCAL: Unit for physical scale of image subject
static final int	SCALE_UNIT_METER	sCAL: Unit is the meter
static final int	SCALE_UNIT_RADIAN	sCAL: Unit is the radian
static final long	SIGNATURE	Eight byte magic number that begins all PNG images
static final String	SIGNIFICANT_BITS	sBIT: Significant bits
static final int	sPLT	Suggested palette
static final int	sRGB	Standard RGB color space
static final int	SRGB_ABSOLUTE_COLORIMETRIC	sRGB: Absolute colormetric rendering intent
static final int	SRGB_PERCEPTUAL	sRGB: Perceptual rendering intent
static final int	SRGB_RELATIVE_COLORIMETRIC	sRGB: Relative colorimetric rendering intent
static final int	SRGB_SATURATION_PRESERVING	sRGB: Saturation rendering intent
static final int	sTER	Indicator of Stereo Image
static final String	STEREO_MODE	sTER: Indicator of stereo image
static final int	STEREO_MODE_CROSS	sTER: Cross-fuse layout
static final int	STEREO_MODE_DIVERGING	sTER: Diverging-fuse layout
static final String	SUGGESTED_PALETTES	sPLT: List of suggested palettes
static final int	tEXt	Textual data
static final String	TEXT_CHUNKS	tEXt/zTXt/iTXt: List of text chunks
static final int	tIME	Image last-modification time
static final String	TIME	tIME: Image last-modification time
static final String	TRANSPARENCY	tRNS: Transparency samples
static final int	tRNS	Transparency
static final String	UNIT	pHYs: Unit specifier
static final int	UNIT_METER	pHYs: Unit is the meter
static final int	UNIT_UNKNOWN	pHYs: Unit is unknown
static final String	WIDTH	IHDR: Width
static final int	zTXt	Compressed textual data

Constructor Summary

Constructors

Constructor	Description
PngConstants()

Method Summary

Modifier and Type	Method	Description
static String	getChunkName(int chunkType)	Returns the four-character ASCII name corresponding to the given chunk type.
static int	getChunkType(String chunkName)	Returns the chunk type corresponding to the given four-character ASCII chunk name.
static boolean	isAncillary(int chunkType)	Returns true if the given chunk type has the ancillary bit set (the first letter is lowercase).
static boolean	isPrivate(int chunkType)	Returns true if the given chunk type has the private bit set (the second letter is lowercase).
static boolean	isReserved(int chunkType)	Returns true if the given chunk type has the reserved bit set (the third letter is lowercase).
static boolean	isSafeToCopy(int chunkType)	Returns true if the given chunk type has the safe-to-copy bit set (the fourth letter is lowercase).

Methods inherited from class java.lang.Object

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

Field Details

SIGNATURE

public static final long SIGNATURE

Eight byte magic number that begins all PNG images

See Also:

• Constant Field Values

IHDR

public static final int IHDR

Image header

See Also:

• Constant Field Values

PLTE

public static final int PLTE

Palette

See Also:

• Constant Field Values

IDAT

public static final int IDAT

Image data

See Also:

• Constant Field Values

IEND

public static final int IEND

Image trailer

See Also:

• Constant Field Values

bKGD

public static final int bKGD

Background color

See Also:

• Constant Field Values

cHRM

public static final int cHRM

Primary chromaticities

See Also:

• Constant Field Values

gAMA

public static final int gAMA

Image gamma

See Also:

• Constant Field Values

hIST

public static final int hIST

Palette histogram

See Also:

• Constant Field Values

iCCP

public static final int iCCP

Embedded ICC profile

See Also:

• Constant Field Values

iTXt

public static final int iTXt

International textual data

See Also:

• Constant Field Values

pHYs

public static final int pHYs

Physical pixel dimensions

See Also:

• Constant Field Values

sBIT

public static final int sBIT

Significant bits

See Also:

• Constant Field Values

sPLT

public static final int sPLT

Suggested palette

See Also:

• Constant Field Values

sRGB

public static final int sRGB

Standard RGB color space

See Also:

• Constant Field Values

tEXt

public static final int tEXt

Textual data

See Also:

• Constant Field Values

tIME

public static final int tIME

Image last-modification time

See Also:

• Constant Field Values

tRNS

public static final int tRNS

Transparency

See Also:

• Constant Field Values

zTXt

public static final int zTXt

Compressed textual data

See Also:

• Constant Field Values

oFFs

public static final int oFFs

Image offset

See Also:

• Constant Field Values

pCAL

public static final int pCAL

Calibration of pixel values

See Also:

• Constant Field Values

sCAL

public static final int sCAL

Physical scale of image subject

See Also:

• Constant Field Values

gIFg

public static final int gIFg

GIF Graphic Control Extension

See Also:

• Constant Field Values

gIFx

public static final int gIFx

GIF Application Extension

See Also:

• Constant Field Values

sTER

public static final int sTER

Indicator of Stereo Image

See Also:

• Constant Field Values

BIT_DEPTH

public static final String BIT_DEPTH

IHDR: Bit depth

See Also:

• Constant Field Values

COLOR_TYPE

public static final String COLOR_TYPE

IHDR: Color type

See Also:

• Constant Field Values

COMPRESSION

public static final String COMPRESSION

IHDR: Compression method

See Also:

• Constant Field Values

FILTER

public static final String FILTER

IHDR: Filter method

See Also:

• Constant Field Values

GAMMA

public static final String GAMMA

gAMA: Gamma

See Also:

• Constant Field Values

WIDTH

public static final String WIDTH

IHDR: Width

See Also:

• Constant Field Values

HEIGHT

public static final String HEIGHT

IHDR: Height

See Also:

• Constant Field Values

INTERLACE

public static final String INTERLACE

IHDR: Interlace method

See Also:

• Constant Field Values

PALETTE

public static final String PALETTE

PLTE: Palette entries

See Also:

• Constant Field Values

PALETTE_ALPHA

public static final String PALETTE_ALPHA

PLTE: Palette alpha

See Also:

• Constant Field Values

TRANSPARENCY

public static final String TRANSPARENCY

tRNS: Transparency samples

See Also:

• Constant Field Values

BACKGROUND

public static final String BACKGROUND

bKGD: Background samples

See Also:

• Constant Field Values

PIXELS_PER_UNIT_X

public static final String PIXELS_PER_UNIT_X

pHYs: Pixels per unit, X axis

See Also:

• Constant Field Values

PIXELS_PER_UNIT_Y

public static final String PIXELS_PER_UNIT_Y

pHYs: Pixels per unit, Y axis

See Also:

• Constant Field Values

RENDERING_INTENT

public static final String RENDERING_INTENT

sRGB: Rendering intent

See Also:

• Constant Field Values

SIGNIFICANT_BITS

public static final String SIGNIFICANT_BITS

sBIT: Significant bits

See Also:

• Constant Field Values

TEXT_CHUNKS

public static final String TEXT_CHUNKS

tEXt/zTXt/iTXt: List of text chunks

See Also:

• Constant Field Values

TIME

public static final String TIME

tIME: Image last-modification time

See Also:

• Constant Field Values

UNIT

public static final String UNIT

pHYs: Unit specifier

See Also:

• Constant Field Values

CHROMATICITY

public static final String CHROMATICITY

cHRM: Chromaticity

See Also:

• Constant Field Values

ICC_PROFILE

public static final String ICC_PROFILE

iCCP: ICC profile

See Also:

• Constant Field Values

ICC_PROFILE_NAME

public static final String ICC_PROFILE_NAME

iCCP: ICC profile name

See Also:

• Constant Field Values

HISTOGRAM

public static final String HISTOGRAM

hIST: Palette histogram

See Also:

• Constant Field Values

SUGGESTED_PALETTES

public static final String SUGGESTED_PALETTES

sPLT: List of suggested palettes

See Also:

• Constant Field Values

GIF_DISPOSAL_METHOD

public static final String GIF_DISPOSAL_METHOD

gIFg: GIF disposal method

See Also:

• Constant Field Values

GIF_USER_INPUT_FLAG

public static final String GIF_USER_INPUT_FLAG

gIFg: GIF user input flag

See Also:

• Constant Field Values

GIF_DELAY_TIME

public static final String GIF_DELAY_TIME

gIFg: GIF delay time (hundredths of a second)

See Also:

• Constant Field Values

SCALE_UNIT

public static final String SCALE_UNIT

sCAL: Unit for physical scale of image subject

See Also:

• Constant Field Values

PIXEL_WIDTH

public static final String PIXEL_WIDTH

sCAL: Physical width of pixel

See Also:

• Constant Field Values

PIXEL_HEIGHT

public static final String PIXEL_HEIGHT

sCAL: Physical height of pixel

See Also:

• Constant Field Values

POSITION_UNIT

public static final String POSITION_UNIT

oFFs: Unit for image offset

See Also:

• Constant Field Values

STEREO_MODE

public static final String STEREO_MODE

sTER: Indicator of stereo image

See Also:

• Constant Field Values

COLOR_TYPE_GRAY

public static final int COLOR_TYPE_GRAY

IHDR: Grayscale color type

See Also:

• Constant Field Values

COLOR_TYPE_GRAY_ALPHA

public static final int COLOR_TYPE_GRAY_ALPHA

IHDR: Grayscale+alpha color type

See Also:

• Constant Field Values

COLOR_TYPE_PALETTE

public static final int COLOR_TYPE_PALETTE

IHDR: Palette color type

See Also:

• Constant Field Values

COLOR_TYPE_RGB

public static final int COLOR_TYPE_RGB

IHDR: RGB color type

See Also:

• Constant Field Values

COLOR_TYPE_RGB_ALPHA

public static final int COLOR_TYPE_RGB_ALPHA

IHDR: RGBA color type

See Also:

• Constant Field Values

INTERLACE_NONE

public static final int INTERLACE_NONE

IHDR: No interlace

See Also:

• Constant Field Values

INTERLACE_ADAM7

public static final int INTERLACE_ADAM7

IHDR: Adam7 interlace

See Also:

• Constant Field Values

FILTER_BASE

public static final int FILTER_BASE

IHDR: Adaptive filtering

See Also:

• Constant Field Values

COMPRESSION_BASE

public static final int COMPRESSION_BASE

IHDR: Deflate/inflate compression

See Also:

• Constant Field Values

UNIT_UNKNOWN

public static final int UNIT_UNKNOWN

pHYs: Unit is unknown

See Also:

• Constant Field Values

UNIT_METER

public static final int UNIT_METER

pHYs: Unit is the meter

See Also:

• Constant Field Values

SRGB_PERCEPTUAL

public static final int SRGB_PERCEPTUAL

sRGB: Perceptual rendering intent

See Also:

• Constant Field Values

SRGB_RELATIVE_COLORIMETRIC

public static final int SRGB_RELATIVE_COLORIMETRIC

sRGB: Relative colorimetric rendering intent

See Also:

• Constant Field Values

SRGB_SATURATION_PRESERVING

public static final int SRGB_SATURATION_PRESERVING

sRGB: Saturation rendering intent

See Also:

• Constant Field Values

SRGB_ABSOLUTE_COLORIMETRIC

public static final int SRGB_ABSOLUTE_COLORIMETRIC

sRGB: Absolute colormetric rendering intent

See Also:

• Constant Field Values

POSITION_X

public static final String POSITION_X

oFFs: Image X position

See Also:

• Constant Field Values

POSITION_Y

public static final String POSITION_Y

oFFs: Image Y position

See Also:

• Constant Field Values

POSITION_UNIT_PIXEL

public static final int POSITION_UNIT_PIXEL

oFFs: Unit is the pixel (true dimensions unspecified)

See Also:

• Constant Field Values

POSITION_UNIT_MICROMETER

public static final int POSITION_UNIT_MICROMETER

oFFs: Unit is the micrometer (10^-6 meter)

See Also:

• Constant Field Values

SCALE_UNIT_METER

public static final int SCALE_UNIT_METER

sCAL: Unit is the meter

See Also:

• Constant Field Values

SCALE_UNIT_RADIAN

public static final int SCALE_UNIT_RADIAN

sCAL: Unit is the radian

See Also:

• Constant Field Values

STEREO_MODE_CROSS

public static final int STEREO_MODE_CROSS

sTER: Cross-fuse layout

See Also:

• Constant Field Values

STEREO_MODE_DIVERGING

public static final int STEREO_MODE_DIVERGING

sTER: Diverging-fuse layout

See Also:

• Constant Field Values

Constructor Details

PngConstants

public PngConstants()

Method Details

isAncillary

public static boolean isAncillary(int chunkType)

Returns true if the given chunk type has the ancillary bit set (the first letter is lowercase). An ancillary chunk is once which is not strictly necessary in order to meaningfully display the contents of the file.

Parameters:

chunkType - the chunk type

Returns:

whether the chunk type ancillary bit is set

isPrivate

public static boolean isPrivate(int chunkType)

Returns true if the given chunk type has the private bit set (the second letter is lowercase). All unregistered chunk types should have this bit set.

Parameters:

chunkType - the chunk type

Returns:

whether the chunk type private bit is set

isReserved

public static boolean isReserved(int chunkType)

Returns true if the given chunk type has the reserved bit set (the third letter is lowercase). The meaning of this bit is currently undefined, but reserved for future use. Images conforming to the current version of the PNG specification must not have this bit set.

Parameters:

chunkType - the chunk type

Returns:

whether the chunk type reserved bit is set

isSafeToCopy

public static boolean isSafeToCopy(int chunkType)

Returns true if the given chunk type has the safe-to-copy bit set (the fourth letter is lowercase). Chunks marked as safe-to-copy may be copied to a modified PNG file whether or not the software recognizes the chunk type.

Parameters:

chunkType - the chunk type

Returns:

whether the chunk safe-to-copy bit is set

getChunkName

public static String getChunkName(int chunkType)

Returns the four-character ASCII name corresponding to the given chunk type. For example, PngConstants.getChunkName(PngConstants.IHDR) will return "IHDR".

Parameters:

chunkType - the chunk type

Returns:

the four-character ASCII chunk name

getChunkType

public static int getChunkType(String chunkName)

Returns the chunk type corresponding to the given four-character ASCII chunk name.

Parameters:

chunkName - the four-character ASCII chunk name

Returns:

the chunk type

Throws:

NullPointerException - if name is null

IndexOutOfBoundsException - if name has less than four characters