/*
* @(#)PackedColorModel.java 1.38 03/12/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.awt.image;
import java.awt.Transparency;
import java.awt.color.ColorSpace;
/**
* 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
* @version 10 Feb 1997
*/
public abstract class PackedColorModel extends ColorModel {
int[] maskArray;
int[] maskOffsets;
float[] scaleFactors;
/**
* 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 <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, <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.
* @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 <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 <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;
}
for (int i=0; i < bitMasks.length; i++) {
if (bitMasks[i] != maskArray[i]) {
return false;
}
}
return true;
}
/**
* 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 <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;
}
}
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