Java java.awt.image Class IndexColorModel（JDK8）

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Java™ Platform
Standard Ed. 8

All Classes

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

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 values used to index into the colormap are taken from the least significant n bits of pixel representations where n is based on the pixel size specified in the constructor. For pixel sizes smaller than 8 bits, n is rounded up to a power of two (3 becomes 4 and 5,6,7 become 8). For pixel sizes between 8 and 16 bits, n is equal to the pixel size. Pixel sizes larger than 16 bits are not supported by this class. Higher order bits beyond n are ignored in pixel representations. Index values greater than or equal to the map size, but less than 2ⁿ, are undefined and return 0 for all color and alpha components.

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

Constructors
Constructor and Description
`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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`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 `ColorModel`object.

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
    
    Since:
    
    1.3
- 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 in class ColorModel
    
    Returns:
    
    an array containing the number of bits of each color and alpha component of this IndexColorModel
  - getMapSize
```
public final int getMapSize()
```
    Returns the size of the color/alpha component arrays in this IndexColorModel.
    
    Returns:
    
    the size of the color and alpha component arrays.
  - getTransparentPixel
```
public final 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. If a transparent pixel was explicitly specified in one of the constructors by its index, then that index will be preferred, otherwise, the index of any pixel which happens to be fully transparent may be returned.
    
    Returns:
    
    the index of a transparent pixel in this IndexColorModel object, or -1 if there is no such pixel
  - getReds
```
public final void getReds(byte[] r)
```
    Copies the array of red color components into the specified array. Only the initial entries of the array as specified by getMapSize are written.
    
    Parameters:
    
    r - the specified array into which the elements of the array of red color components are copied
  - getGreens
```
public final void getGreens(byte[] g)
```
    Copies the array of green color components into the specified array. Only the initial entries of the array as specified by getMapSize are written.
    
    Parameters:
    
    g - the specified array into which the elements of the array of green color components are copied
  - getBlues
```
public final void getBlues(byte[] b)
```
    Copies the array of blue color components into the specified array. Only the initial entries of the array as specified by getMapSize are written.
    
    Parameters:
    
    b - the specified array into which the elements of the array of blue color components are copied
  - getAlphas
```
public final void getAlphas(byte[] a)
```
    Copies the array of alpha transparency components into the specified array. Only the initial entries of the array as specified by getMapSize are written.
    
    Parameters:
    
    a - the specified array into which the elements of the array of alpha components are copied
  - getRGBs
```
public final 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. Only the initial entries of the array as specified by getMapSize are written.
    
    Parameters:
    
    rgb - the specified array into which the converted ARGB values from this array of color and alpha components are copied.
  - getRed
```
public final int getRed(int pixel)
```
    Returns the red color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB. The pixel value is specified as an int. Only the lower n bits of the pixel value, as specified in the class description above, are used to calculate the returned value. The returned value is a non pre-multiplied value.
    
    Specified by:
    
    getRed in class ColorModel
    
    Parameters:
    
    pixel - the specified pixel
    
    Returns:
    
    the value of the red color component for the specified pixel
  - getGreen
```
public final int getGreen(int pixel)
```
    Returns the green color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB. The pixel value is specified as an int. Only the lower n bits of the pixel value, as specified in the class description above, are used to calculate the returned value. The returned value is a non pre-multiplied value.
    
    Specified by:
    
    getGreen in class ColorModel
    
    Parameters:
    
    pixel - the specified pixel
    
    Returns:
    
    the value of the green color component for the specified pixel
  - getBlue
```
public final int getBlue(int pixel)
```
    Returns the blue color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB. The pixel value is specified as an int. Only the lower n bits of the pixel value, as specified in the class description above, are used to calculate the returned value. The returned value is a non pre-multiplied value.
    
    Specified by:
    
    getBlue in class ColorModel
    
    Parameters:
    
    pixel - the specified pixel
    
    Returns:
    
    the value of the blue color component for the specified pixel
  - getAlpha
```
public final int getAlpha(int pixel)
```
    Returns the alpha component for the specified pixel, scaled from 0 to 255. The pixel value is specified as an int. Only the lower n bits of the pixel value, as specified in the class description above, are used to calculate the returned value.
    
    Specified by:
    
    getAlpha in class ColorModel
    
    Parameters:
    
    pixel - the specified pixel
    
    Returns:
    
    the value of the alpha component for the specified pixel
  - getRGB
```
public final int getRGB(int pixel)
```
    Returns the color/alpha components of the pixel in the default RGB color model format. The pixel value is specified as an int. Only the lower n bits of the pixel value, as specified in the class description above, are used to calculate the returned value. The returned value is in a non pre-multiplied format.
    
    Overrides:
    
    getRGB in class ColorModel
    
    Parameters:
    
    pixel - the specified pixel
    
    Returns:
    
    the color and alpha components of the specified pixel
    
    See Also:
    
    ColorModel.getRGBdefault()
  - getDataElements
```
public 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. This array can then be passed to the setDataElements method of a WritableRaster object. If the pixel variable is null, a new array is allocated. If pixel is not null, it must be a primitive array of type transferType; otherwise, a ClassCastException is thrown. An ArrayIndexOutOfBoundsException is thrown if pixel is not large enough to hold a pixel value for this ColorModel. The pixel array is returned.
    Since IndexColorModel can be subclassed, subclasses inherit the implementation of this method and if they don't override it then they throw an exception if they use an unsupported transferType.
    
    Overrides:
    
    getDataElements in class ColorModel
    
    Parameters:
    
    rgb - the integer pixel representation in the default RGB color model
    
    pixel - the specified pixel
    
    Returns:
    
    an array representation of the specified pixel in this IndexColorModel.
    
    Throws:
    
    ClassCastException - if pixel is not a primitive array of type transferType
    
    ArrayIndexOutOfBoundsException - if pixel is not large enough to hold a pixel value for this ColorModel
    
    UnsupportedOperationException - if transferType is invalid
    
    See Also:
    
    WritableRaster.setDataElements(int, int, java.lang.Object), SampleModel.setDataElements(int, int, java.lang.Object, java.awt.image.DataBuffer)
  - getComponents
```
public int[] getComponents(int pixel,
                           int[] components,
                           int offset)
```
    Returns an array of unnormalized color/alpha components for a specified pixel in this ColorModel. The pixel value is specified as an int. If the components array is null, a new array is allocated that contains offset + getNumComponents() elements. The components array is returned, with the alpha component included only if hasAlpha returns true. Color/alpha components are stored in the components array starting at offset even if the array is allocated by this method. An ArrayIndexOutOfBoundsException is thrown if the components array is not null and is not large enough to hold all the color and alpha components starting at offset.
    
    Overrides:
    
    getComponents in class ColorModel
    
    Parameters:
    
    pixel - the specified pixel
    
    components - the array to receive the color and alpha components of the specified pixel
    
    offset - the offset into the components array at which to start storing the color and alpha components
    
    Returns:
    
    an array containing the color and alpha components of the specified pixel starting at the specified offset.
    
    See Also:
    
    ColorModel.hasAlpha(), ColorModel.getNumComponents()
  - getComponents
```
public int[] getComponents(Object pixel,
                           int[] components,
                           int offset)
```
    Returns an array of unnormalized color/alpha components for a specified pixel in this ColorModel. The pixel value is specified by an array of data elements of type transferType passed in as an object reference. If pixel is not a primitive array of type transferType, a ClassCastException is thrown. An ArrayIndexOutOfBoundsException is thrown if pixel is not large enough to hold a pixel value for this ColorModel. If the components array is null, a new array is allocated that contains offset + getNumComponents() elements. The components array is returned, with the alpha component included only if hasAlpha returns true. Color/alpha components are stored in the components array starting at offset even if the array is allocated by this method. An ArrayIndexOutOfBoundsException is also thrown if the components array is not null and is not large enough to hold all the color and alpha components starting at offset.
    Since IndexColorModel can be subclassed, subclasses inherit the implementation of this method and if they don't override it then they throw an exception if they use an unsupported transferType.
    
    Overrides:
    
    getComponents in class ColorModel
    
    Parameters:
    
    pixel - the specified pixel
    
    components - an array that receives the color and alpha components of the specified pixel
    
    offset - the index into the components array at which to begin storing the color and alpha components of the specified pixel
    
    Returns:
    
    an array containing the color and alpha components of the specified pixel starting at the specified offset.
    
    Throws:
    
    ArrayIndexOutOfBoundsException - if pixel is not large enough to hold a pixel value for this ColorModel or if the components array is not null and is not large enough to hold all the color and alpha components starting at offset
    
    ClassCastException - if pixel is not a primitive array of type transferType
    
    UnsupportedOperationException - if transferType is not one of the supported transfer types
    
    See Also:
    
    ColorModel.hasAlpha(), ColorModel.getNumComponents()
  - getDataElement
```
public 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. An ArrayIndexOutOfBoundsException is thrown if the components array is not large enough to hold all of the color and alpha components starting at offset. Since ColorModel can be subclassed, subclasses inherit the implementation of this method and if they don't override it then they throw an exception if they use an unsupported transferType.
    
    Overrides:
    
    getDataElement in class ColorModel
    
    Parameters:
    
    components - an array of unnormalized color and alpha components
    
    offset - the index into components at which to begin retrieving the color and alpha components
    
    Returns:
    
    an int pixel value in this ColorModel corresponding to the specified components.
    
    Throws:
    
    ArrayIndexOutOfBoundsException - if the components array is not large enough to hold all of the color and alpha components starting at offset
    
    UnsupportedOperationException - if transferType is invalid
  - getDataElements
```
public 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. This array can then be passed to the setDataElements method of a WritableRaster object. An ArrayIndexOutOfBoundsException is thrown if the components array is not large enough to hold all of the color and alpha components starting at offset. If the pixel variable is null, a new array is allocated. If pixel is not null, it must be a primitive array of type transferType; otherwise, a ClassCastException is thrown. An ArrayIndexOutOfBoundsException is thrown if pixel is not large enough to hold a pixel value for this ColorModel.
    Since IndexColorModel can be subclassed, subclasses inherit the implementation of this method and if they don't override it then they throw an exception if they use an unsupported transferType
    
    Overrides:
    
    getDataElements in class ColorModel
    
    Parameters:
    
    components - an array of unnormalized color and alpha components
    
    offset - the index into components at which to begin retrieving color and alpha components
    
    pixel - the Object representing an array of color and alpha components
    
    Returns:
    
    an Object representing an array of color and alpha components.
    
    Throws:
    
    ClassCastException - if pixel is not a primitive array of type transferType
    
    ArrayIndexOutOfBoundsException - if pixel is not large enough to hold a pixel value for this ColorModel or the components array is not large enough to hold all of the color and alpha components starting at offset
    
    UnsupportedOperationException - if transferType is not one of the supported transfer types
    
    See Also:
    
    WritableRaster.setDataElements(int, int, java.lang.Object), SampleModel.setDataElements(int, int, java.lang.Object, java.awt.image.DataBuffer)
  - createCompatibleWritableRaster
```
public 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. This method only works for color models with 16 or fewer bits per pixel.
    Since IndexColorModel can be subclassed, any subclass that supports greater than 16 bits per pixel must override this method.
    
    Overrides:
    
    createCompatibleWritableRaster in class ColorModel
    
    Parameters:
    
    w - the width to apply to the new WritableRaster
    
    h - the height to apply to the new WritableRaster
    
    Returns:
    
    a WritableRaster object with the specified width and height.
    
    Throws:
    
    UnsupportedOperationException - if the number of bits in a pixel is greater than 16
    
    See Also:
    
    WritableRaster, SampleModel
  - isCompatibleRaster
```
public boolean isCompatibleRaster(Raster raster)
```
    Returns true if raster is compatible with this ColorModel or false if it is not compatible with this ColorModel.
    
    Overrides:
    
    isCompatibleRaster in class ColorModel
    
    Parameters:
    
    raster - the Raster object to test for compatibility
    
    Returns:
    
    true if raster is compatible with this ColorModel; false otherwise.
  - createCompatibleSampleModel
```
public SampleModel createCompatibleSampleModel(int w,
                                               int h)
```
    Creates a SampleModel with the specified width and height that has a data layout compatible with this ColorModel.
    
    Overrides:
    
    createCompatibleSampleModel in class ColorModel
    
    Parameters:
    
    w - the width to apply to the new SampleModel
    
    h - the height to apply to the new SampleModel
    
    Returns:
    
    a SampleModel object with the specified width and height.
    
    Throws:
    
    IllegalArgumentException - if w or h is not greater than 0
    
    See Also:
    
    SampleModel
  - isCompatibleSampleModel
```
public boolean isCompatibleSampleModel(SampleModel sm)
```
    Checks if the specified SampleModel is compatible with this ColorModel. If sm is null, this method returns false.
    
    Overrides:
    
    isCompatibleSampleModel in class ColorModel
    
    Parameters:
    
    sm - the specified SampleModel, or null
    
    Returns:
    
    true if the specified SampleModel is compatible with this ColorModel; false otherwise.
    
    See Also:
    
    SampleModel
  - convertToIntDiscrete
```
public 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. Only the lower n bits of each index value in the source Raster, as specified in the class description above, are used to compute the color/alpha values in the returned image. If forceARGB is true, a TYPE_INT_ARGB image is returned regardless of whether or not this ColorModel has an alpha component array or a transparent pixel.
    
    Parameters:
    
    raster - the specified Raster
    
    forceARGB - if true, the returned BufferedImage is TYPE_INT_ARGB; otherwise it is TYPE_INT_RGB
    
    Returns:
    
    a BufferedImage created with the specified Raster
    
    Throws:
    
    IllegalArgumentException - if the raster argument is not compatible with this IndexColorModel
  - isValid
```
public boolean isValid(int pixel)
```
    Returns whether or not the pixel is valid.
    
    Parameters:
    
    pixel - the specified pixel value
    
    Returns:
    
    true if pixel is valid; false otherwise.
    
    Since:
    
    1.3
  - isValid
```
public boolean isValid()
```
    Returns whether or not all of the pixels are valid.
    
    Returns:
    
    true if all pixels are valid; false otherwise.
    
    Since:
    
    1.3
  - getValidPixels
```
public BigInteger getValidPixels()
```
    Returns a BigInteger that indicates the valid/invalid pixels in the colormap. A bit is valid if the BigInteger value at that index is set, and is invalid if the BigInteger value at that index is not set. The only valid ranges to query in the BigInteger are between 0 and the map size.
    
    Returns:
    
    a BigInteger indicating the valid/invalid pixels.
    
    Since:
    
    1.3
  - finalize
```
public void finalize()
```
    Disposes of system resources associated with this ColorModel once this ColorModel is no longer referenced.
    
    Overrides:
    
    finalize in class ColorModel
    
    See Also:
    
    WeakReference, PhantomReference
  - toString
```
public String toString()
```
    Returns the String representation of the contents of this ColorModelobject.
    
    Overrides:
    
    toString in class ColorModel
    
    Returns:
    
    a String representing the contents of this ColorModel object.

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Java java.awt.image Class IndexColorModel（JDK8）

Class IndexColorModel

Field Summary

Fields inherited from class java.awt.image.ColorModel

Fields inherited from interface java.awt.Transparency

Constructor Summary

Method Summary

Methods inherited from class java.awt.image.ColorModel

Methods inherited from class java.lang.Object

Constructor Detail

IndexColorModel

IndexColorModel

IndexColorModel

IndexColorModel

IndexColorModel

IndexColorModel

IndexColorModel

Method Detail

getTransparency

getComponentSize

getMapSize

getTransparentPixel

getReds

getGreens

getBlues

getAlphas

getRGBs

getRed

getGreen

getBlue

getAlpha

getRGB

getDataElements

getComponents

getComponents

getDataElement

getDataElements

createCompatibleWritableRaster

isCompatibleRaster

createCompatibleSampleModel

isCompatibleSampleModel

convertToIntDiscrete

isValid

isValid

getValidPixels

finalize

toString