PackedColorModelpublic abstract class PackedColorModel extends ColorModel The PackedColorModel 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 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
{@link ColorModel#getNumComponents() getNumComponents} - 1.
- The first
{@link ColorModel#getNumColorComponents() 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
{@link SinglePixelPackedSampleModel} to construct a
{@link BufferedImage}. Normally the masks used by the
{@link 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 {@link DirectColorModel},
which is similar to an X11 TrueColor visual. |
| Fields Summary |
|---|
| int[] | maskArray | | int[] | maskOffsets | | float[] | scaleFactors |
| Constructors Summary |
|---|
public PackedColorModel(ColorSpace space, int bits, int[] colorMaskArray, int alphaMask, boolean isAlphaPremultiplied, int trans, int transferType)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.
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;
}
}
| public PackedColorModel(ColorSpace space, int bits, int rmask, int gmask, int bmask, int amask, boolean isAlphaPremultiplied, int trans, int transferType)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.
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;
}
}
|
| Methods Summary |
|---|
| private void | DecomposeMask(int mask, int idx, java.lang.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);
}
| | private static final 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;
| | private static final 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 static final 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;
| | public java.awt.image.SampleModel | createCompatibleSampleModel(int w, int h)Creates a SampleModel with the specified width and
height that has a data layout compatible with this
ColorModel.
return new SinglePixelPackedSampleModel(transferType, w, h,
maskArray);
| | public boolean | equals(java.lang.Object obj)Tests if the specified Object is an instance
of PackedColorModel and equals this
PackedColorModel.
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;
| | public java.awt.image.WritableRaster | getAlphaRaster(java.awt.image.WritableRaster raster)Returns a {@link 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.
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);
| | public final int | getMask(int index)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;
return maskArray[index];
| | public final int[] | getMasks()Returns a mask array indicating which bits in a pixel
contain the color and alpha samples.
return (int[]) maskArray.clone();
| | public boolean | isCompatibleSampleModel(java.awt.image.SampleModel sm)Checks if the specified SampleModel is compatible
with this ColorModel. If sm is
null, this method returns false.
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;
|
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