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package java.awt.image;
import java.awt.Transparency;
import java.awt.color.ColorSpace;
The PackedColorModel
class is an abstract ColorModel
class that works with pixel values which represent color and alpha information as separate samples and which pack all samples for a single pixel into a single int, short, or byte quantity. This class can be used with an arbitrary ColorSpace
. The number of color samples in the pixel values must be the same as the number of color components in the ColorSpace
. There can be a single alpha
sample. The array length is always 1 for those methods that use a
primitive array pixel representation of type transferType
.
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
getNumComponents
- 1. - The first
getNumColorComponents
indices refer to color samples. - If an alpha sample is present, it corresponds the last index.
- The order of the color indices is specified
by the
ColorSpace
. Typically, this reflects the name of
the color space type (for example, TYPE_RGB), index 0
corresponds to red, index 1 to green, and index 2 to blue.
The translation from pixel values to color/alpha components for
display or processing purposes is a one-to-one correspondence of
samples to components.
A PackedColorModel
is typically used with image data
that uses masks to define packed samples. For example, a
PackedColorModel
can be used in conjunction with a SinglePixelPackedSampleModel
to construct a BufferedImage
. Normally the masks used by the SampleModel
and the ColorModel
would be the same.
However, if they are different, the color interpretation of pixel data is
done according to the masks of the ColorModel
.
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.
A subclass of PackedColorModel
is DirectColorModel
, which is similar to an X11 TrueColor visual.
See Also:
/**
* The <code>PackedColorModel</code> class is an abstract
* {@link ColorModel} class that works with pixel values which represent
* color and alpha information as separate samples and which pack all
* samples for a single pixel into a single int, short, or byte quantity.
* This class can be used with an arbitrary {@link ColorSpace}. The number of
* color samples in the pixel values must be the same as the number of color
* components in the <code>ColorSpace</code>. There can be a single alpha
* sample. The array length is always 1 for those methods that use a
* primitive array pixel representation of type <code>transferType</code>.
* 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:
* <ul>
* <li> Masks are identified by indices running from 0 through
* {@link ColorModel#getNumComponents() getNumComponents} - 1.
* <li> The first
* {@link ColorModel#getNumColorComponents() getNumColorComponents}
* indices refer to color samples.
* <li> If an alpha sample is present, it corresponds the last index.
* <li> The order of the color indices is specified
* by the <code>ColorSpace</code>. Typically, this reflects the name of
* the color space type (for example, TYPE_RGB), index 0
* corresponds to red, index 1 to green, and index 2 to blue.
* </ul>
* <p>
* The translation from pixel values to color/alpha components for
* display or processing purposes is a one-to-one correspondence of
* samples to components.
* A <code>PackedColorModel</code> is typically used with image data
* that uses masks to define packed samples. For example, a
* <code>PackedColorModel</code> can be used in conjunction with a
* {@link SinglePixelPackedSampleModel} to construct a
* {@link BufferedImage}. Normally the masks used by the
* {@link SampleModel} and the <code>ColorModel</code> would be the same.
* However, if they are different, the color interpretation of pixel data is
* done according to the masks of the <code>ColorModel</code>.
* <p>
* A single <code>int</code> 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 <code>int</code>. Therefore, methods
* that use this representation do not throw an
* <code>IllegalArgumentException</code> due to an invalid pixel value.
* <p>
* A subclass of <code>PackedColorModel</code> is {@link DirectColorModel},
* which is similar to an X11 TrueColor visual.
*
* @see DirectColorModel
* @see SinglePixelPackedSampleModel
* @see BufferedImage
*/
public abstract class PackedColorModel extends ColorModel {
int[] maskArray;
int[] maskOffsets;
float[] scaleFactors;
Constructs a PackedColorModel
from a color mask array,
which specifies which bits in an int
pixel representation
contain each of the color samples, and an alpha mask. Color
components are in the specified ColorSpace
. The length of
colorMaskArray
should be the number of components in
the ColorSpace
. 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 the
alphaMask
is 0, there is no alpha. 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,
trans
, specifies what alpha values can be represented
by this color model. The transfer type is the type of primitive
array used to represent pixel values.
Params: - space – the specified
ColorSpace
- bits – the number of bits in the pixel values
- colorMaskArray – array that specifies the masks representing
the bits of the pixel values that represent the color
components
- alphaMask – specifies the mask representing
the bits of the pixel values that represent the alpha
component
- isAlphaPremultiplied –
true
if color samples are
premultiplied by the alpha sample; false
otherwise - trans – specifies the alpha value that can be represented by
this color model
- transferType – the type of array used to represent pixel values
Throws: - IllegalArgumentException – if
bits
is less than
1 or greater than 32
/**
* Constructs a <code>PackedColorModel</code> from a color mask array,
* which specifies which bits in an <code>int</code> pixel representation
* contain each of the color samples, and an alpha mask. Color
* components are in the specified <code>ColorSpace</code>. The length of
* <code>colorMaskArray</code> should be the number of components in
* the <code>ColorSpace</code>. All of the bits in each mask
* must be contiguous and fit in the specified number of least significant
* bits of an <code>int</code> pixel representation. If the
* <code>alphaMask</code> is 0, there is no alpha. If there is alpha,
* the <code>boolean</code> <code>isAlphaPremultiplied</code> specifies
* how to interpret color and alpha samples in pixel values. If the
* <code>boolean</code> is <code>true</code>, color samples are assumed
* to have been multiplied by the alpha sample. The transparency,
* <code>trans</code>, specifies what alpha values can be represented
* by this color model. The transfer type is the type of primitive
* array used to represent pixel values.
* @param space the specified <code>ColorSpace</code>
* @param bits the number of bits in the pixel values
* @param colorMaskArray array that specifies the masks representing
* the bits of the pixel values that represent the color
* components
* @param alphaMask specifies the mask representing
* the bits of the pixel values that represent the alpha
* component
* @param isAlphaPremultiplied <code>true</code> if color samples are
* premultiplied by the alpha sample; <code>false</code> otherwise
* @param trans specifies the alpha value that can be represented by
* this color model
* @param transferType the type of array used to represent pixel values
* @throws IllegalArgumentException if <code>bits</code> is less than
* 1 or greater than 32
*/
public PackedColorModel (ColorSpace space, int bits,
int[] colorMaskArray, int alphaMask,
boolean isAlphaPremultiplied,
int trans, int transferType) {
super(bits, PackedColorModel.createBitsArray(colorMaskArray,
alphaMask),
space, (alphaMask == 0 ? false : true),
isAlphaPremultiplied, trans, transferType);
if (bits < 1 || bits > 32) {
throw new IllegalArgumentException("Number of bits must be between"
+" 1 and 32.");
}
maskArray = new int[numComponents];
maskOffsets = new int[numComponents];
scaleFactors = new float[numComponents];
for (int i=0; i < numColorComponents; i++) {
// Get the mask offset and #bits
DecomposeMask(colorMaskArray[i], i, space.getName(i));
}
if (alphaMask != 0) {
DecomposeMask(alphaMask, numColorComponents, "alpha");
if (nBits[numComponents-1] == 1) {
transparency = Transparency.BITMASK;
}
}
}
Constructs a PackedColorModel
from the specified
masks which indicate which bits in an int
pixel
representation contain the alpha, red, green and blue color samples.
Color components are in the specified ColorSpace
, which
must be of type ColorSpace.TYPE_RGB. 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
amask
is 0, there is no alpha. 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, trans
, specifies what alpha values
can be represented by this color model.
The transfer type is the type of primitive array used to represent
pixel values.
Params: - space – the specified
ColorSpace
- bits – the number of bits in the pixel values
- rmask – specifies the mask representing
the bits of the pixel values that represent the red
color component
- gmask – specifies the mask representing
the bits of the pixel values that represent the green
color component
- bmask – specifies the mask representing
the bits of the pixel values that represent
the blue color component
- amask – specifies the mask representing
the bits of the pixel values that represent
the alpha component
- isAlphaPremultiplied –
true
if color samples are
premultiplied by the alpha sample; false
otherwise - trans – specifies the alpha value that can be represented by
this color model
- transferType – the type of array used to represent pixel values
Throws: - IllegalArgumentException – if
space
is not a
TYPE_RGB space
See Also:
/**
* Constructs a <code>PackedColorModel</code> from the specified
* masks which indicate which bits in an <code>int</code> pixel
* representation contain the alpha, red, green and blue color samples.
* Color components are in the specified <code>ColorSpace</code>, which
* must be of type ColorSpace.TYPE_RGB. All of the bits in each
* mask must be contiguous and fit in the specified number of
* least significant bits of an <code>int</code> pixel representation. If
* <code>amask</code> is 0, there is no alpha. If there is alpha,
* the <code>boolean</code> <code>isAlphaPremultiplied</code>
* specifies how to interpret color and alpha samples
* in pixel values. If the <code>boolean</code> is <code>true</code>,
* color samples are assumed to have been multiplied by the alpha sample.
* The transparency, <code>trans</code>, specifies what alpha values
* can be represented by this color model.
* The transfer type is the type of primitive array used to represent
* pixel values.
* @param space the specified <code>ColorSpace</code>
* @param bits the number of bits in the pixel values
* @param rmask specifies the mask representing
* the bits of the pixel values that represent the red
* color component
* @param gmask specifies the mask representing
* the bits of the pixel values that represent the green
* color component
* @param bmask specifies the mask representing
* the bits of the pixel values that represent
* the blue color component
* @param amask specifies the mask representing
* the bits of the pixel values that represent
* the alpha component
* @param isAlphaPremultiplied <code>true</code> if color samples are
* premultiplied by the alpha sample; <code>false</code> otherwise
* @param trans specifies the alpha value that can be represented by
* this color model
* @param transferType the type of array used to represent pixel values
* @throws IllegalArgumentException if <code>space</code> is not a
* TYPE_RGB space
* @see ColorSpace
*/
public PackedColorModel(ColorSpace space, int bits, int rmask, int gmask,
int bmask, int amask,
boolean isAlphaPremultiplied,
int trans, int transferType) {
super (bits, PackedColorModel.createBitsArray(rmask, gmask, bmask,
amask),
space, (amask == 0 ? false : true),
isAlphaPremultiplied, trans, transferType);
if (space.getType() != ColorSpace.TYPE_RGB) {
throw new IllegalArgumentException("ColorSpace must be TYPE_RGB.");
}
maskArray = new int[numComponents];
maskOffsets = new int[numComponents];
scaleFactors = new float[numComponents];
DecomposeMask(rmask, 0, "red");
DecomposeMask(gmask, 1, "green");
DecomposeMask(bmask, 2, "blue");
if (amask != 0) {
DecomposeMask(amask, 3, "alpha");
if (nBits[3] == 1) {
transparency = Transparency.BITMASK;
}
}
}
Returns the mask indicating which bits in a pixel
contain the specified color/alpha sample. For color
samples, index
corresponds to the placement of color
sample names in the color space. Thus, an index
equal to 0 for a CMYK ColorSpace would correspond to
Cyan and an index
equal to 1 would correspond to
Magenta. If there is alpha, the alpha index
would be:
alphaIndex = numComponents() - 1;
Params: - index – the specified color or alpha sample
Throws: - ArrayIndexOutOfBoundsException – if
index
is
greater than the number of components minus 1 in this
PackedColorModel
or if index
is
less than zero
Returns: the mask, which indicates which bits of the int
pixel representation contain the color or alpha sample specified
by index
.
/**
* Returns the mask indicating which bits in a pixel
* contain the specified color/alpha sample. For color
* samples, <code>index</code> corresponds to the placement of color
* sample names in the color space. Thus, an <code>index</code>
* equal to 0 for a CMYK ColorSpace would correspond to
* Cyan and an <code>index</code> equal to 1 would correspond to
* Magenta. If there is alpha, the alpha <code>index</code> would be:
* <pre>
* alphaIndex = numComponents() - 1;
* </pre>
* @param index the specified color or alpha sample
* @return the mask, which indicates which bits of the <code>int</code>
* pixel representation contain the color or alpha sample specified
* by <code>index</code>.
* @throws ArrayIndexOutOfBoundsException if <code>index</code> is
* greater than the number of components minus 1 in this
* <code>PackedColorModel</code> or if <code>index</code> is
* less than zero
*/
final public int getMask(int index) {
return maskArray[index];
}
Returns a mask array indicating which bits in a pixel
contain the color and alpha samples.
Returns: the mask array , which indicates which bits of the
int
pixel
representation contain the color or alpha samples.
/**
* Returns a mask array indicating which bits in a pixel
* contain the color and alpha samples.
* @return the mask array , which indicates which bits of the
* <code>int</code> pixel
* representation contain the color or alpha samples.
*/
final public int[] getMasks() {
return (int[]) maskArray.clone();
}
/*
* A utility function to compute the mask offset and scalefactor,
* store these and the mask in instance arrays, and verify that
* the mask fits in the specified pixel size.
*/
private void DecomposeMask(int mask, int idx, String componentName) {
int off = 0;
int count = nBits[idx];
// Store the mask
maskArray[idx] = mask;
// Now find the shift
if (mask != 0) {
while ((mask & 1) == 0) {
mask >>>= 1;
off++;
}
}
if (off + count > pixel_bits) {
throw new IllegalArgumentException(componentName + " mask "+
Integer.toHexString(maskArray[idx])+
" overflows pixel (expecting "+
pixel_bits+" bits");
}
maskOffsets[idx] = off;
if (count == 0) {
// High enough to scale any 0-ff value down to 0.0, but not
// high enough to get Infinity when scaling back to pixel bits
scaleFactors[idx] = 256.0f;
} else {
scaleFactors[idx] = 255.0f / ((1 << count) - 1);
}
}
Creates a SampleModel
with the specified width and
height that has a data layout compatible with this
ColorModel
.
Params: - w – the width (in pixels) of the region of the image data
described
- h – the height (in pixels) of the region of the image data
described
Throws: - IllegalArgumentException – if
w
or
h
is not greater than 0
See Also: Returns: the newly created SampleModel
.
/**
* Creates a <code>SampleModel</code> with the specified width and
* height that has a data layout compatible with this
* <code>ColorModel</code>.
* @param w the width (in pixels) of the region of the image data
* described
* @param h the height (in pixels) of the region of the image data
* described
* @return the newly created <code>SampleModel</code>.
* @throws IllegalArgumentException if <code>w</code> or
* <code>h</code> is not greater than 0
* @see SampleModel
*/
public SampleModel createCompatibleSampleModel(int w, int h) {
return new SinglePixelPackedSampleModel(transferType, w, h,
maskArray);
}
Checks if the specified SampleModel
is compatible
with this ColorModel
. If sm
is
null
, this method returns false
.
Params: - sm – the specified
SampleModel
,
or null
See Also: Returns: true
if the specified SampleModel
is compatible with this ColorModel
;
false
otherwise.
/**
* Checks if the specified <code>SampleModel</code> is compatible
* with this <code>ColorModel</code>. If <code>sm</code> is
* <code>null</code>, this method returns <code>false</code>.
* @param sm the specified <code>SampleModel</code>,
* or <code>null</code>
* @return <code>true</code> if the specified <code>SampleModel</code>
* is compatible with this <code>ColorModel</code>;
* <code>false</code> otherwise.
* @see SampleModel
*/
public boolean isCompatibleSampleModel(SampleModel sm) {
if (! (sm instanceof SinglePixelPackedSampleModel)) {
return false;
}
// Must have the same number of components
if (numComponents != sm.getNumBands()) {
return false;
}
// Transfer type must be the same
if (sm.getTransferType() != transferType) {
return false;
}
SinglePixelPackedSampleModel sppsm = (SinglePixelPackedSampleModel) sm;
// Now compare the specific masks
int[] bitMasks = sppsm.getBitMasks();
if (bitMasks.length != maskArray.length) {
return false;
}
/* compare 'effective' masks only, i.e. only part of the mask
* which fits the capacity of the transfer type.
*/
int maxMask = (int)((1L << DataBuffer.getDataTypeSize(transferType)) - 1);
for (int i=0; i < bitMasks.length; i++) {
if ((maxMask & bitMasks[i]) != (maxMask & maskArray[i])) {
return false;
}
}
return true;
}
Returns a WritableRaster
representing the alpha channel of an image, extracted from the input WritableRaster
.
This method assumes that WritableRaster
objects
associated with this ColorModel
store the alpha band,
if present, as the last band of image data. Returns null
if there is no separate spatial alpha channel associated with this
ColorModel
. This method creates a new
WritableRaster
, but shares the data array.
Params: - raster – a
WritableRaster
containing an image
Returns: a WritableRaster
that represents the alpha
channel of the image contained in raster
.
/**
* Returns a {@link WritableRaster} representing the alpha channel of
* an image, extracted from the input <code>WritableRaster</code>.
* This method assumes that <code>WritableRaster</code> objects
* associated with this <code>ColorModel</code> store the alpha band,
* if present, as the last band of image data. Returns <code>null</code>
* if there is no separate spatial alpha channel associated with this
* <code>ColorModel</code>. This method creates a new
* <code>WritableRaster</code>, but shares the data array.
* @param raster a <code>WritableRaster</code> containing an image
* @return a <code>WritableRaster</code> that represents the alpha
* channel of the image contained in <code>raster</code>.
*/
public WritableRaster getAlphaRaster(WritableRaster raster) {
if (hasAlpha() == false) {
return null;
}
int x = raster.getMinX();
int y = raster.getMinY();
int[] band = new int[1];
band[0] = raster.getNumBands() - 1;
return raster.createWritableChild(x, y, raster.getWidth(),
raster.getHeight(), x, y,
band);
}
Tests if the specified Object
is an instance
of PackedColorModel
and equals this
PackedColorModel
.
Params: - obj – the
Object
to test for equality
Returns: true
if the specified Object
is an instance of PackedColorModel
and equals this
PackedColorModel
; false
otherwise.
/**
* Tests if the specified <code>Object</code> is an instance
* of <code>PackedColorModel</code> and equals this
* <code>PackedColorModel</code>.
* @param obj the <code>Object</code> to test for equality
* @return <code>true</code> if the specified <code>Object</code>
* is an instance of <code>PackedColorModel</code> and equals this
* <code>PackedColorModel</code>; <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (!(obj instanceof PackedColorModel)) {
return false;
}
if (!super.equals(obj)) {
return false;
}
PackedColorModel cm = (PackedColorModel) obj;
int numC = cm.getNumComponents();
if (numC != numComponents) {
return false;
}
for(int i=0; i < numC; i++) {
if (maskArray[i] != cm.getMask(i)) {
return false;
}
}
return true;
}
private final static int[] createBitsArray(int[]colorMaskArray,
int alphaMask) {
int numColors = colorMaskArray.length;
int numAlpha = (alphaMask == 0 ? 0 : 1);
int[] arr = new int[numColors+numAlpha];
for (int i=0; i < numColors; i++) {
arr[i] = countBits(colorMaskArray[i]);
if (arr[i] < 0) {
throw new IllegalArgumentException("Noncontiguous color mask ("
+ Integer.toHexString(colorMaskArray[i])+
"at index "+i);
}
}
if (alphaMask != 0) {
arr[numColors] = countBits(alphaMask);
if (arr[numColors] < 0) {
throw new IllegalArgumentException("Noncontiguous alpha mask ("
+ Integer.toHexString(alphaMask));
}
}
return arr;
}
private final static int[] createBitsArray(int rmask, int gmask, int bmask,
int amask) {
int[] arr = new int[3 + (amask == 0 ? 0 : 1)];
arr[0] = countBits(rmask);
arr[1] = countBits(gmask);
arr[2] = countBits(bmask);
if (arr[0] < 0) {
throw new IllegalArgumentException("Noncontiguous red mask ("
+ Integer.toHexString(rmask));
}
else if (arr[1] < 0) {
throw new IllegalArgumentException("Noncontiguous green mask ("
+ Integer.toHexString(gmask));
}
else if (arr[2] < 0) {
throw new IllegalArgumentException("Noncontiguous blue mask ("
+ Integer.toHexString(bmask));
}
if (amask != 0) {
arr[3] = countBits(amask);
if (arr[3] < 0) {
throw new IllegalArgumentException("Noncontiguous alpha mask ("
+ Integer.toHexString(amask));
}
}
return arr;
}
private final static int countBits(int mask) {
int count = 0;
if (mask != 0) {
while ((mask & 1) == 0) {
mask >>>= 1;
}
while ((mask & 1) == 1) {
mask >>>= 1;
count++;
}
}
if (mask != 0) {
return -1;
}
return count;
}
}