Class PackedColorModel

public abstract class PackedColorModel extends ColorModel

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.