java.awt.image
Class IndexColorModel

java.lang.Object   
  java.awt.image.ColorModel   
      java.awt.image.IndexColorModel

All Implemented Interfaces:

Transparency

public class IndexColorModel
extends ColorModel   

The IndexColorModel class is a ColorModel class that works with pixel values consisting of a single sample that is an index into a fixed colormap in the default sRGB color space. The colormap specifies red, green, blue, and optional alpha components corresponding to each index. All components are represented in the colormap as 8-bit unsigned integral values. Some constructors allow the caller to specify "holes" in the colormap by indicating which colormap entries are valid and which represent unusable colors via the bits set in a BigInteger object. This color model is similar to an X11 PseudoColor visual.

Some constructors provide a means to specify an alpha component for each pixel in the colormap, while others either provide no such means or, in some cases, a flag to indicate whether the colormap data contains alpha values. If no alpha is supplied to the constructor, an opaque alpha component (alpha = 1.0) is assumed for each entry. An optional transparent pixel value can be supplied that indicates a pixel to be made completely transparent, regardless of any alpha component supplied or assumed for that pixel value. Note that the color components in the colormap of an IndexColorModel objects are never pre-multiplied with the alpha components.

The transparency of an IndexColorModel object is determined by examining the alpha components of the colors in the colormap and choosing the most specific value after considering the optional alpha values and any transparent index specified. The transparency value is Transparency.OPAQUE only if all valid colors in the colormap are opaque and there is no valid transparent pixel. If all valid colors in the colormap are either completely opaque (alpha = 1.0) or completely transparent (alpha = 0.0), which typically occurs when a valid transparent pixel is specified, the value is Transparency.BITMASK. Otherwise, the value is Transparency.TRANSLUCENT, indicating that some valid color has an alpha component that is neither completely transparent nor completely opaque (0.0 < alpha < 1.0).

If an IndexColorModel object has a transparency value of Transparency.OPAQUE, then the hasAlpha and getNumComponents methods (both inherited from ColorModel) return false and 3, respectively. For any other transparency value, hasAlpha returns true and getNumComponents returns 4.

The index represented by a pixel value is stored in the least significant n bits of the pixel representations passed to the methods of this class, where n is the pixel size specified to the constructor for a particular IndexColorModel object; n must be between 1 and 16, inclusive. Higher order bits in pixel representations are assumed to be zero. For those methods that use a primitive array pixel representation of type transferType, the array length is always one. The transfer types supported are DataBuffer.TYPE_BYTE and DataBuffer.TYPE_USHORT. A single int pixel representation is valid for all objects of this class, since it is always possible to represent pixel values used with this class in a single int. Therefore, methods that use this representation do not throw an IllegalArgumentException due to an invalid pixel value.

Many of the methods in this class are final. The reason for this is that the underlying native graphics code makes assumptions about the layout and operation of this class and those assumptions are reflected in the implementations of the methods here that are marked final. You can subclass this class for other reasons, but you cannot override or modify the behaviour of those methods.

See Also:

ColorModel , ColorSpace , DataBuffer

Field Summary

Fields inherited from class java.awt.image.ColorModel

pixel_bits, transferType

Fields inherited from interface java.awt.Transparency

BITMASK , OPAQUE , TRANSLUCENT

Constructor Summary

IndexColorModel (int bits, int size, byte[] r, byte[] g, byte[] b)
Constructs an IndexColorModel from the specified arrays of red, green, and blue components.

IndexColorModel (int bits, int size, byte[] r, byte[] g, byte[] b, byte[] a)
Constructs an IndexColorModel from the given arrays of red, green, blue and alpha components.

IndexColorModel (int bits, int size, byte[] r, byte[] g, byte[] b, int trans)
Constructs an IndexColorModel from the given arrays of red, green, and blue components.

IndexColorModel (int bits, int size, byte[] cmap, int start, boolean hasalpha)
Constructs an IndexColorModel from a single array of interleaved red, green, blue and optional alpha components.

IndexColorModel (int bits, int size, byte[] cmap, int start, boolean hasalpha, int trans)
Constructs an IndexColorModel from a single array of interleaved red, green, blue and optional alpha components.

IndexColorModel (int bits, int size, int[] cmap, int start, boolean hasalpha, int trans, int transferType)
Constructs an IndexColorModel from an array of ints where each int is comprised of red, green, blue, and optional alpha components in the default RGB color model format.

IndexColorModel (int bits, int size, int[] cmap, int start, int transferType, BigInteger validBits)
Constructs an IndexColorModel from an int array where each int is comprised of red, green, blue, and alpha components in the default RGB color model format.

Method Summary

BufferedImage	convertToIntDiscrete (Raster raster, boolean forceARGB) Returns a new BufferedImage of TYPE_INT_ARGB or TYPE_INT_RGB that has a Raster with pixel data computed by expanding the indices in the source Raster using the color/alpha component arrays of this ColorModel.
SampleModel	createCompatibleSampleModel (int w, int h) Creates a SampleModel with the specified width and height that has a data layout compatible with this ColorModel.
WritableRaster	createCompatibleWritableRaster (int w, int h) Creates a WritableRaster with the specified width and height that has a data layout (SampleModel) compatible with this ColorModel.
void	finalize () Disposes of system resources associated with this ColorModel once this ColorModel is no longer referenced.
int	getAlpha (int pixel) Returns the alpha component for the specified pixel, scaled from 0 to 255.
void	getAlphas (byte[] a) Copies the array of alpha transparency components into the specified array.
int	getBlue (int pixel) Returns the blue color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB.
void	getBlues (byte[] b) Copies the array of blue color components into the specified array.
int[]	getComponents (int pixel, int[] components, int offset) Returns an array of unnormalized color/alpha components for a specified pixel in this ColorModel.
int[]	getComponents (Object pixel, int[] components, int offset) Returns an array of unnormalized color/alpha components for a specified pixel in this ColorModel.
int[]	getComponentSize () Returns an array of the number of bits for each color/alpha component.
int	getDataElement (int[] components, int offset) Returns a pixel value represented as an int in this ColorModel given an array of unnormalized color/alpha components.
Object	getDataElements (int[] components, int offset, Object pixel) Returns a data element array representation of a pixel in this ColorModel given an array of unnormalized color/alpha components.
Object	getDataElements (int rgb, Object pixel) Returns a data element array representation of a pixel in this ColorModel, given an integer pixel representation in the default RGB color model.
int	getGreen (int pixel) Returns the green color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB.
void	getGreens (byte[] g) Copies the array of green color components into the specified array.
int	getMapSize () Returns the size of the color/alpha component arrays in this IndexColorModel.
int	getRed (int pixel) Returns the red color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB.
void	getReds (byte[] r) Copies the array of red color components into the specified array.
int	getRGB (int pixel) Returns the color/alpha components of the pixel in the default RGB color model format.
void	getRGBs (int[] rgb) Converts data for each index from the color and alpha component arrays to an int in the default RGB ColorModel format and copies the resulting 32-bit ARGB values into the specified array.
int	getTransparency () Returns the transparency.
int	getTransparentPixel () Returns the index of a transparent pixel in this IndexColorModel or -1 if there is no pixel with an alpha value of 0.
BigInteger	getValidPixels () Returns a BigInteger that indicates the valid/invalid pixels in the colormap.
boolean	isCompatibleRaster (Raster raster) Returns true if raster is compatible with this ColorModel or false if it is not compatible with this ColorModel.
boolean	isCompatibleSampleModel (SampleModel sm) Checks if the specified SampleModel is compatible with this ColorModel.
boolean	isValid () Returns whether or not all of the pixels are valid.
boolean	isValid (int pixel) Returns whether or not the pixel is valid.
String	toString () Returns the String representation of the contents of this ColorModelobject.

Methods inherited from class java.awt.image.ColorModel

coerceData , equals , getAlpha , getAlphaRaster , getBlue , getColorSpace , getComponentSize , getDataElement , getDataElements , getGreen , getNormalizedComponents , getNormalizedComponents , getNumColorComponents , getNumComponents , getPixelSize , getRed , getRGB , getRGBdefault , getTransferType , getUnnormalizedComponents , hasAlpha , hashCode , isAlphaPremultiplied

Methods inherited from class java.lang.Object

clone , getClass , notify , notifyAll , wait , wait , wait

Constructor Detail

IndexColorModel

public IndexColorModel(int bits,
                       int size,
                       byte[] r,
                       byte[] g,
                       byte[] b)

Constructs an IndexColorModel from the specified arrays of red, green, and blue components. Pixels described by this color model all have alpha components of 255 unnormalized (1.0 normalized), which means they are fully opaque. All of the arrays specifying the color components must have at least the specified number of entries. The ColorSpace is the default sRGB space. Since there is no alpha information in any of the arguments to this constructor, the transparency value is always Transparency.OPAQUE. The transfer type is the smallest of DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT that can hold a single pixel.

Parameters:

bits - the number of bits each pixel occupies

size - the size of the color component arrays

r - the array of red color components

g - the array of green color components

b - the array of blue color components

Throws:

IllegalArgumentException - if bits is less than 1 or greater than 16

IllegalArgumentException - if size is less than 1

IndexColorModel

public IndexColorModel(int bits,
                       int size,
                       byte[] r,
                       byte[] g,
                       byte[] b,
                       int trans)

Constructs an IndexColorModel from the given arrays of red, green, and blue components. Pixels described by this color model all have alpha components of 255 unnormalized (1.0 normalized), which means they are fully opaque, except for the indicated pixel to be made transparent. All of the arrays specifying the color components must have at least the specified number of entries. The ColorSpace is the default sRGB space. The transparency value may be Transparency.OPAQUE or Transparency.BITMASK depending on the arguments, as specified in the class description above. The transfer type is the smallest of DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT that can hold a single pixel.

Parameters:

bits - the number of bits each pixel occupies

size - the size of the color component arrays

r - the array of red color components

g - the array of green color components

b - the array of blue color components

trans - the index of the transparent pixel

Throws:

IllegalArgumentException - if bits is less than 1 or greater than 16

IllegalArgumentException - if size is less than 1

IndexColorModel

public IndexColorModel(int bits,
                       int size,
                       byte[] r,
                       byte[] g,
                       byte[] b,
                       byte[] a)

Constructs an IndexColorModel from the given arrays of red, green, blue and alpha components. All of the arrays specifying the components must have at least the specified number of entries. The ColorSpace is the default sRGB space. The transparency value may be any of Transparency.OPAQUE, Transparency.BITMASK, or Transparency.TRANSLUCENT depending on the arguments, as specified in the class description above. The transfer type is the smallest of DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT that can hold a single pixel.

Parameters:

bits - the number of bits each pixel occupies

size - the size of the color component arrays

r - the array of red color components

g - the array of green color components

b - the array of blue color components

a - the array of alpha value components

Throws:

IllegalArgumentException - if bits is less than 1 or greater than 16

IllegalArgumentException - if size is less than 1

IndexColorModel

public IndexColorModel(int bits,
                       int size,
                       byte[] cmap,
                       int start,
                       boolean hasalpha)

Constructs an IndexColorModel from a single array of interleaved red, green, blue and optional alpha components. The array must have enough values in it to fill all of the needed component arrays of the specified size. The ColorSpace is the default sRGB space. The transparency value may be any of Transparency.OPAQUE, Transparency.BITMASK, or Transparency.TRANSLUCENT depending on the arguments, as specified in the class description above. The transfer type is the smallest of DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT that can hold a single pixel.

Parameters:

bits - the number of bits each pixel occupies

size - the size of the color component arrays

cmap - the array of color components

start - the starting offset of the first color component

hasalpha - indicates whether alpha values are contained in the cmap array

Throws:

IllegalArgumentException - if bits is less than 1 or greater than 16

IllegalArgumentException - if size is less than 1

IndexColorModel

public IndexColorModel(int bits,
                       int size,
                       byte[] cmap,
                       int start,
                       boolean hasalpha,
                       int trans)

Constructs an IndexColorModel from a single array of interleaved red, green, blue and optional alpha components. The specified transparent index represents a pixel that is made entirely transparent regardless of any alpha value specified for it. The array must have enough values in it to fill all of the needed component arrays of the specified size. The ColorSpace is the default sRGB space. The transparency value may be any of Transparency.OPAQUE, Transparency.BITMASK, or Transparency.TRANSLUCENT depending on the arguments, as specified in the class description above. The transfer type is the smallest of DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT that can hold a single pixel.

Parameters:

bits - the number of bits each pixel occupies

size - the size of the color component arrays

cmap - the array of color components

start - the starting offset of the first color component

hasalpha - indicates whether alpha values are contained in the cmap array

trans - the index of the fully transparent pixel

Throws:

IllegalArgumentException - if bits is less than 1 or greater than 16

IllegalArgumentException - if size is less than 1

IndexColorModel

public IndexColorModel(int bits,
                       int size,
                       int[] cmap,
                       int start,
                       boolean hasalpha,
                       int trans,
                       int transferType)

Constructs an IndexColorModel from an array of ints where each int is comprised of red, green, blue, and optional alpha components in the default RGB color model format. The specified transparent index represents a pixel that is made entirely transparent regardless of any alpha value specified for it. The array must have enough values in it to fill all of the needed component arrays of the specified size. The ColorSpace is the default sRGB space. The transparency value may be any of Transparency.OPAQUE, Transparency.BITMASK, or Transparency.TRANSLUCENT depending on the arguments, as specified in the class description above.

Parameters:

bits - the number of bits each pixel occupies

size - the size of the color component arrays

cmap - the array of color components

start - the starting offset of the first color component

hasalpha - indicates whether alpha values are contained in the cmap array

trans - the index of the fully transparent pixel

transferType - the data type of the array used to represent pixel values. The data type must be either DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT.

Throws:

IllegalArgumentException - if bits is less than 1 or greater than 16

IllegalArgumentException - if size is less than 1

IllegalArgumentException - if transferType is not one of DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT

IndexColorModel

public IndexColorModel(int bits,
                       int size,
                       int[] cmap,
                       int start,
                       int transferType,
                       BigInteger    validBits)

Constructs an IndexColorModel from an int array where each int is comprised of red, green, blue, and alpha components in the default RGB color model format. The array must have enough values in it to fill all of the needed component arrays of the specified size. The ColorSpace is the default sRGB space. The transparency value may be any of Transparency.OPAQUE, Transparency.BITMASK, or Transparency.TRANSLUCENT depending on the arguments, as specified in the class description above. The transfer type must be one of DataBuffer.TYPE_BYTE DataBuffer.TYPE_USHORT. The BigInteger object specifies the valid/invalid pixels in the cmap array. A pixel is valid if the BigInteger value at that index is set, and is invalid if the BigInteger bit at that index is not set.

Parameters:

bits - the number of bits each pixel occupies

size - the size of the color component array

cmap - the array of color components

start - the starting offset of the first color component

transferType - the specified data type

validBits - a BigInteger object. If a bit is set in the BigInteger, the pixel at that index is valid. If a bit is not set, the pixel at that index is considered invalid. If null, all pixels are valid. Only bits from 0 to the map size are considered.

Throws:

IllegalArgumentException - if bits is less than 1 or greater than 16

IllegalArgumentException - if size is less than 1

IllegalArgumentException - if transferType is not one of DataBuffer.TYPE_BYTE or DataBuffer.TYPE_USHORT

Method Detail

getTransparency

public int getTransparency()

Returns the transparency. Returns either OPAQUE, BITMASK, or TRANSLUCENT

Specified by:

getTransparency in interface Transparency

Overrides:

getTransparency in class ColorModel

Returns:

the transparency of this IndexColorModel

See Also:

Transparency.OPAQUE , Transparency.BITMASK , Transparency.TRANSLUCENT

getComponentSize

public int[] getComponentSize()

Returns an array of the number of bits for each color/alpha component. The array contains the color components in the order red, green, blue, followed by the alpha component, if present.

Overrides:

getComponentSize