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Eclipse Platform
Release 3.0

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org.eclipse.swt.graphics
Class PaletteData

java.lang.Object
  org.eclipse.swt.graphics.PaletteData

public final class PaletteData

extends Object

Instances of this class describe the color data used by an image.

Depending on the depth of the image, the PaletteData can take one of two forms, indicated by the isDirect field:

isDirect is false

If isDirect is false, this palette is an indexed palette which maps pixel values to RGBs. The actual RGB values may be retrieved by using the getRGBs() method.

isDirect is true

If isDirect is true, this palette is a direct color palette. Instead of containing RGB values, it contains red, green and blue mask and shift information which indicates how the color components may be extracted from a given pixel. This means that the RGB value is actually encoded in the pixel value.

In this case, the shift data is the number of bits required to shift the RGB value to the left in order to align the high bit of the corresponding mask with the high bit of the first byte. This number may be negative, so care must be taken when shifting. For example, with a red mask of 0xFF0000, the red shift would be -16. With a red mask of 0x1F, the red shift would be 3.

See Also:

Image, RGB

Field Summary

int	blueMask the blue mask for a direct palette
int	blueShift the blue shift for a direct palette
RGB[]	colors the RGB values for an indexed palette, where the indices of the array correspond to pixel values
int	greenMask the green mask for a direct palette
int	greenShift the green shift for a direct palette
boolean	isDirect true if the receiver is a direct palette, and false otherwise
int	redMask the red mask for a direct palette
int	redShift the red shift for a direct palette

Constructor Summary

PaletteData(int redMask, int greenMask, int blueMask)
Constructs a new direct palette given the red, green and blue masks.

PaletteData(RGB[] colors)
Constructs a new indexed palette given an array of RGB values.

Method Summary

int	getPixel(RGB rgb) Returns the pixel value corresponding to the given RBG.
RGB	getRGB(int pixel) Returns an RGB corresponding to the given pixel value.
RGB[]	getRGBs() Returns all the RGB values in the receiver if it is an indexed palette, or null if it is a direct palette.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

isDirect

public boolean isDirect

true if the receiver is a direct palette, and false otherwise

colors

public RGB[] colors

the RGB values for an indexed palette, where the indices of the array correspond to pixel values

redMask

public int redMask

the red mask for a direct palette

greenMask

public int greenMask

the green mask for a direct palette

blueMask

public int blueMask

the blue mask for a direct palette

redShift

public int redShift

the red shift for a direct palette

greenShift

public int greenShift

the green shift for a direct palette

blueShift

public int blueShift

the blue shift for a direct palette

Constructor Detail

PaletteData

public PaletteData(RGB[] colors)

Constructs a new indexed palette given an array of RGB values.

Parameters:

colors - the array of RGBs for the palette

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null

PaletteData

public PaletteData(int redMask,
                   int greenMask,
                   int blueMask)

Constructs a new direct palette given the red, green and blue masks.

Parameters:

redMask - the red mask

greenMask - the green mask

blueMask - the blue mask

Method Detail

getPixel

public int getPixel(RGB rgb)

Returns the pixel value corresponding to the given RBG.

Parameters:

rgb - the RGB to get the pixel value for

Returns:

the pixel value for the given RGB

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the RGB is not found in the palette

getRGB

public RGB getRGB(int pixel)

Returns an RGB corresponding to the given pixel value.

Parameters:

pixel - the pixel to get the RGB value for

Returns:

the RGB value for the given pixel

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the pixel does not exist in the palette

getRGBs

public RGB[] getRGBs()

Returns all the RGB values in the receiver if it is an indexed palette, or null if it is a direct palette.

Returns:

the RGBs for the receiver or null