java.awt.image

Class DirectColorModel

java.lang.Object

java.awt.image.ColorModel

java.awt.image.DirectColorModel

All Implemented Interfaces:

Transparency

public class DirectColorModel
extends ColorModel

The DirectColorModel class is a ColorModel class that works with pixel values that represent RGB color and alpha information as separate samples and that pack all samples for a single pixel into a single int, short, or byte quantity. This class can be used only with ColorSpaces of type ColorSpace.TYPE_RGB. There must be three color samples in the pixel values and there can be a single alpha sample. 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, DataBuffer.TYPE_USHORT, and DataBuffer.TYPE_INT. Color and alpha samples are stored in the single element of the array in bits indicated by bit masks. Each bit mask must be contiguous and masks must not overlap. The same masks apply to the single int pixel representation used by other methods. The correspondence of masks and color/alpha samples is as follows:

• Masks are identified by indices running from 0 through 2 if no alpha is present, or 3 if an alpha is present.
• The first three indices refer to color samples; index 0 corresponds to red, index 1 to green, and index 2 to blue.
• Index 3 corresponds to the alpha sample, if present.

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 which use this representation will not throw an IllegalArgumentException due to an invalid pixel value.

This color model is similar to an X11 TrueColor visual. The default RGB ColorModel specified by the getRGBdefault method is a DirectColorModel with the following parameters:

 Number of bits:        32
 Red mask:              0x00ff0000
 Green mask:            0x0000ff00
 Blue mask:             0x000000ff
 Alpha mask:            0xff000000
 Color space:           sRGB
 isAlphaPremultiplied:  False
 Transparency:          Transparency.TRANSLUCENT
 transferType:          DataBuffer.TYPE_INT
 

Many of the methods in this class are final. This is because 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 behavior of those methods.

Version:

10 Feb 1997

See Also:

ColorModel, ColorSpace, BufferedImage, ColorModel.getRGBdefault()

Field Summary

Fields inherited from class java.awt.image.ColorModel

pixel_bits

Fields inherited from interface java.awt.Transparency

BITMASK, OPAQUE, TRANSLUCENT

Constructor Summary

Constructors

Constructor and Description
DirectColorModel(ColorSpace space, int bits, int rmask, int gmask, int bmask, int amask, boolean isAlphaPremultiplied, int transferType) Constructs a DirectColorModel from the specified parameters.
DirectColorModel(int bits, int rmask, int gmask, int bmask) Constructs a DirectColorModel from the specified masks that indicate which bits in an int pixel representation contain the red, green and blue color samples.
DirectColorModel(int bits, int rmask, int gmask, int bmask, int amask) Constructs a DirectColorModel from the specified masks that indicate which bits in an int pixel representation contain the red, green and blue color samples and the alpha sample, if present.

Method Summary

Methods

Modifier and Type	Method and Description
int	getAlpha(int pixel) Returns the alpha component for the specified pixel, scaled from 0 to 255.
int	getAlphaMask() Returns the mask indicating which bits in an int pixel representation contain the alpha component.
int	getBlue(int pixel) Returns the blue color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB.
int	getBlueMask() Returns the mask indicating which bits in an int pixel representation contain the blue color component.
int	getGreen(int pixel) Returns the green color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB.
int	getGreenMask() Returns the mask indicating which bits in an int pixel representation contain the green color component.
int	getRed(int pixel) Returns the red color component for the specified pixel, scaled from 0 to 255 in the default RGB ColorSpace, sRGB.
int	getRedMask() Returns the mask indicating which bits in an int pixel representation contain the red color component.
int	getRGB(int pixel) Returns the color/alpha components of the pixel in the default RGB color model format.
String	toString() Returns a String that represents this DirectColorModel.

Methods inherited from class java.awt.image.ColorModel

equals, finalize, getColorSpace, getComponentSize, getComponentSize, getNumColorComponents, getNumComponents, getPixelSize, getRGBdefault, getTransferType, getTransparency, hasAlpha, hashCode, isAlphaPremultiplied

Methods inherited from class java.lang.Object

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

Constructor Detail

DirectColorModel

public DirectColorModel(int bits,
                int rmask,
                int gmask,
                int bmask)

Constructs a DirectColorModel from the specified masks that indicate which bits in an int pixel representation contain the red, green and blue color samples. As pixel values do not contain alpha information, all pixels are treated as opaque, which means that alpha = 1.0. All of the bits in each mask must be contiguous and fit in the specified number of least significant bits of an int pixel representation. The ColorSpace is the default sRGB space. The transparency value is Transparency.OPAQUE. The transfer type is the smallest of DataBuffer.TYPE_BYTE, DataBuffer.TYPE_USHORT, or DataBuffer.TYPE_INT that can hold a single pixel.

Parameters:

bits - the number of bits in the pixel values; for example, the sum of the number of bits in the masks.

rmask - specifies a mask indicating which bits in an integer pixel contain the red component

gmask - specifies a mask indicating which bits in an integer pixel contain the green component

bmask - specifies a mask indicating which bits in an integer pixel contain the blue component

DirectColorModel

public DirectColorModel(int bits,
                int rmask,
                int gmask,
                int bmask,
                int amask)

Constructs a DirectColorModel from the specified masks that indicate which bits in an int pixel representation contain the red, green and blue color samples and the alpha sample, if present. If amask is 0, pixel values do not contain alpha information and all pixels are treated as opaque, which means that alpha = 1.0. All of the bits in each mask must be contiguous and fit in the specified number of least significant bits of an int pixel representation. Alpha, if present, is not premultiplied. The ColorSpace is the default sRGB space. The transparency value is Transparency.OPAQUE if no alpha is present, or Transparency.TRANSLUCENT otherwise. The transfer type is the smallest of DataBuffer.TYPE_BYTE, DataBuffer.TYPE_USHORT, or DataBuffer.TYPE_INT that can hold a single pixel.

Parameters:

bits - the number of bits in the pixel values; for example, the sum of the number of bits in the masks.

rmask - specifies a mask indicating which bits in an integer pixel contain the red component

gmask - specifies a mask indicating which bits in an integer pixel contain the green component

bmask - specifies a mask indicating which bits in an integer pixel contain the blue component

amask - specifies a mask indicating which bits in an integer pixel contain the alpha component

DirectColorModel

public DirectColorModel(ColorSpace space,
                int bits,
                int rmask,
                int gmask,
                int bmask,
                int amask,
                boolean isAlphaPremultiplied,
                int transferType)

Constructs a DirectColorModel from the specified parameters. Color components are in the specified ColorSpace, which must be of type ColorSpace.TYPE_RGB and have minimum normalized component values which are all 0.0 and maximum values which are all 1.0. The masks specify which bits in an int pixel representation contain the red, green and blue color samples and the alpha sample, if present. If amask is 0, pixel values do not contain alpha information and all pixels are treated as opaque, which means that alpha = 1.0. All of the bits in each mask must be contiguous and fit in the specified number of least significant bits of an int pixel representation. If there is alpha, the boolean isAlphaPremultiplied specifies how to interpret color and alpha samples in pixel values. If the boolean is true, color samples are assumed to have been multiplied by the alpha sample. The transparency value is Transparency.OPAQUE, if no alpha is present, or Transparency.TRANSLUCENT otherwise. The transfer type is the type of primitive array used to represent pixel values and must be one of DataBuffer.TYPE_BYTE, DataBuffer.TYPE_USHORT, or DataBuffer.TYPE_INT.

Parameters:

space - the specified ColorSpace

bits - the number of bits in the pixel values; for example, the sum of the number of bits in the masks.

rmask - specifies a mask indicating which bits in an integer pixel contain the red component

gmask - specifies a mask indicating which bits in an integer pixel contain the green component

bmask - specifies a mask indicating which bits in an integer pixel contain the blue component

amask - specifies a mask indicating which bits in an integer pixel contain the alpha component

isAlphaPremultiplied - true if color samples are premultiplied by the alpha sample; false otherwise

transferType - the type of array used to represent pixel values

Throws:

IllegalArgumentException - if space is not a TYPE_RGB space or if the min/max normalized component values are not 0.0/1.0.

Method Detail

getRedMask

public final int getRedMask()

Returns the mask indicating which bits in an int pixel representation contain the red color component.

Returns:

the mask, which indicates which bits of the int pixel representation contain the red color sample.

getGreenMask

public final int getGreenMask()

Returns the mask indicating which bits in an int pixel representation contain the green color component.

Returns:

the mask, which indicates which bits of the int pixel representation contain the green color sample.

getBlueMask

public final int getBlueMask()

Returns the mask indicating which bits in an int pixel representation contain the blue color component.

Returns:

the mask, which indicates which bits of the int pixel representation contain the blue color sample.

getAlphaMask

public final int getAlphaMask()

Returns the mask indicating which bits in an int pixel representation contain the alpha component.

Returns:

the mask, which indicates which bits of the int pixel representation contain the alpha sample.

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. A color conversion is done if necessary. The pixel value is specified as an int. The returned value is a non pre-multiplied value. Thus, if the alpha is premultiplied, this method divides it out before returning the value. If the alpha value is 0, for example, the red value is 0.

Specified by:

getRed in class ColorModel

Parameters:

pixel - the specified pixel

Returns:

the red color component for the specified pixel, from 0 to 255 in the sRGB ColorSpace.

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. A color conversion is done if necessary. The pixel value is specified as an int. The returned value is a non pre-multiplied value. Thus, if the alpha is premultiplied, this method divides it out before returning the value. If the alpha value is 0, for example, the green value is 0.

Specified by:

getGreen in class ColorModel

Parameters:

pixel - the specified pixel

Returns:

the green color component for the specified pixel, from 0 to 255 in the sRGB ColorSpace.

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. A color conversion is done if necessary. The pixel value is specified as an int. The returned value is a non pre-multiplied value. Thus, if the alpha is premultiplied, this method divides it out before returning the value. If the alpha value is 0, for example, the blue value is 0.

Specified by:

getBlue in class ColorModel

Parameters:

pixel - the specified pixel

Returns:

the blue color component for the specified pixel, from 0 to 255 in the sRGB ColorSpace.

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.

Specified by:

getAlpha in class ColorModel

Parameters:

pixel - the specified pixel

Returns:

the value of the alpha component of pixel from 0 to 255.

getRGB

public final int getRGB(int pixel)

Returns the color/alpha components of the pixel in the default RGB color model format. A color conversion is done if necessary. The pixel value is specified as an int. The returned value is in a non pre-multiplied format. Thus, if the alpha is premultiplied, this method divides it out of the color components. If the alpha value is 0, for example, the color values are each 0.

Overrides:

getRGB in class ColorModel

Parameters:

pixel - the specified pixel

Returns:

the RGB value of the color/alpha components of the specified pixel.

See Also:

ColorModel.getRGBdefault()

toString

public String toString()

Returns a String that represents this DirectColorModel.

Overrides:

toString in class ColorModel

Returns:

a String representing this DirectColorModel.