Package org.eclipse.swt.graphics

Class 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, Sample code and further information

    • Field Summary

      Fields 
      Modifier and Type Field Description
      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

      Constructors 
      Constructor Description
      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.

    • 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 RGB.
        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