Back to index...

	/*
	* Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	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
	*/

	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;
	}

	/* 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 {@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;
	}

	}

Back to index...