net.sourceforge.jiu.gui.awt

Class RGBA


public class RGBA
extends java.lang.Object

This class converts between the 32 bit RGBA int values (used throughout the AWT) and various standard pixel formats like 24 bits RGB, 8 bits gray, 16 bits gray, 1 bit black and white.

The conversion is done in a number of static methods. This class is not supposed to be instantiated.

The method names of this class can be interpreted as follows. If they contain fromXYZ (where XYZ is a pixel format type like Gray8, RGB24 etc.), a conversion from another pixel format to RGBA is done. If the names contains toXYZ, a conversion from RGBA to that pixel format will be performed.

Not all conversions are lossless or well-defined. If 48 bpp RGB truecolor is used as source, only the top eight bits of each 16 bit sample will be used (thus, the procedure is lossy). If RGBA data is to be converted to bilevel (black and white), the conversion is undefined if there are input RGBA pixels that are neither black nor white.

Author:
Marco Schmidt

Field Summary

static int
DEFAULT_ALPHA
The default value for the alpha part of RGBA.

Constructor Summary

RGBA()

Method Summary

static void
convertFromGray16(short[] src, int srcOffset, int alpha, int[] dest, int destOffset, int num)
Convert a number of 16 bit grayscale pixels to RGBA type int pixels, adding the given alpha value.
static void
convertFromGray8(byte[] src, int srcOffset, int alpha, int[] dest, int destOffset, int num)
Convert a number of 8 bit grayscale pixels, shades of gray between 0 (for black) and 255 (for white), given as bytes, to RGBA type int pixels, adding the given alpha value.
static void
convertFromPackedBilevel(byte[] src, int srcOffset, int alpha, int[] dest, int destOffset, int num)
Converts pixels from bilevel packed bytes to RGBA format.
static void
convertFromPaletted8(byte[] src, int srcOffset, int alpha, int[] red, int[] green, int[] blue, int[] dest, int destOffset, int num)
Converts a byte array of palette index values to an array of RGBA values, using palette color data.
static void
convertFromRGB24(byte[] srcRed, int srcRedOffset, byte[] srcGreen, int srcGreenOffset, byte[] srcBlue, int srcBlueOffset, int alpha, int[] dest, int destOffset, int num)
Converts 24 bit RGB truecolor data to RGBA int values.
static void
convertFromRGB48(short[] srcRed, int srcRedOffset, short[] srcGreen, int srcGreenOffset, short[] srcBlue, int srcBlueOffset, int alpha, int[] dest, int destOffset, int num)
Converts 48 bit RGB truecolor data to RGBA int values, dropping the least significant eight bits of each short sample.

Field Details

DEFAULT_ALPHA

public static final int DEFAULT_ALPHA
The default value for the alpha part of RGBA. The alpha value is eight bits long left-shifted by 24. This default value is no transparency - the underlying image cannot be seen: 0xff000000.
Field Value:
-16777216

Constructor Details

RGBA

private RGBA()

Method Details

convertFromGray16

public static void convertFromGray16(short[] src,
                                     int srcOffset,
                                     int alpha,
                                     int[] dest,
                                     int destOffset,
                                     int num)
Convert a number of 16 bit grayscale pixels to RGBA type int pixels, adding the given alpha value. Note that the lower 8 bits of each grayscale value are dropped.
Parameters:
src - array with grayscale pixels
srcOffset - index of first entry of src to be converted
alpha - transparency value to be used in resulting RGBA array (only top eight bits can be set)
dest - array to store resulting RGBA pixels
destOffset - index of first entry in dest to be used
num - number of pixels to be converted

convertFromGray8

public static void convertFromGray8(byte[] src,
                                    int srcOffset,
                                    int alpha,
                                    int[] dest,
                                    int destOffset,
                                    int num)
Convert a number of 8 bit grayscale pixels, shades of gray between 0 (for black) and 255 (for white), given as bytes, to RGBA type int pixels, adding the given alpha value.
Parameters:
src - array with grayscale pixels
srcOffset - index of first entry of src to be converted
alpha - transparency value to be used in resulting RGBA array (only top eight bits can be set)
dest - array to store resulting RGBA pixels
destOffset - index of first entry in dest to be used
num - number of pixels to be converted

convertFromPackedBilevel

public static void convertFromPackedBilevel(byte[] src,
                                            int srcOffset,
                                            int alpha,
                                            int[] dest,
                                            int destOffset,
                                            int num)
Converts pixels from bilevel packed bytes to RGBA format. A byte is supposed to store eight pixels, the most significant bit being the leftmost pixel.
Parameters:
src - the array with the packed bytes
srcOffset - the index of the first byte to be converted from src
alpha - the alpha value to be used for the destination RGBA values
dest - the array where the destination RGBA pixels will be stored
destOffset - the index of the first destination pixel in the dest array; that array must be at least destOffset + ((num + 7) / 8) large
num - the number of pixels (not bytes) to be converted

convertFromPaletted8

public static void convertFromPaletted8(byte[] src,
                                        int srcOffset,
                                        int alpha,
                                        int[] red,
                                        int[] green,
                                        int[] blue,
                                        int[] dest,
                                        int destOffset,
                                        int num)
Converts a byte array of palette index values to an array of RGBA values, using palette color data.
Parameters:
src - the byte array with the palette index values
srcOffset - index of the first entry of src to be used
alpha - transparency value to be used (only top eight bits should be set)
red - the red palette values
green - the green palette values
blue - the blue palette values
dest - the destination array to store the RGBA values
destOffset - the first entry of dest to be used
num - the number of pixels to be converted

convertFromRGB24

public static void convertFromRGB24(byte[] srcRed,
                                    int srcRedOffset,
                                    byte[] srcGreen,
                                    int srcGreenOffset,
                                    byte[] srcBlue,
                                    int srcBlueOffset,
                                    int alpha,
                                    int[] dest,
                                    int destOffset,
                                    int num)
Converts 24 bit RGB truecolor data to RGBA int values.
Parameters:
srcRed - the red pixel values
srcRedOffset - the first entry of srcRed to be used
srcGreen - the green pixel values
srcGreenOffset - the first entry of srcGreen to be used
srcBlue - the blue pixel values
srcBlueOffset - the first entry of srcBlue to be used
alpha - the transpancy value to be used in the destination RGBA array (only top 8 bits should be set)
dest - array to store RGBA pixel values
destOffset - first entry of dest to be used
num - number of pixels to be converted

convertFromRGB48

public static void convertFromRGB48(short[] srcRed,
                                    int srcRedOffset,
                                    short[] srcGreen,
                                    int srcGreenOffset,
                                    short[] srcBlue,
                                    int srcBlueOffset,
                                    int alpha,
                                    int[] dest,
                                    int destOffset,
                                    int num)
Converts 48 bit RGB truecolor data to RGBA int values, dropping the least significant eight bits of each short sample.
Parameters:
srcRed - the red pixel values
srcRedOffset - the first entry of srcRed to be used
srcGreen - the green pixel values
srcGreenOffset - the first entry of srcGreen to be used
srcBlue - the blue pixel values
srcBlueOffset - the first entry of srcBlue to be used
alpha - the transpancy value to be used in the destination RGBA array (only top 8 bits should be set)
dest - array to store RGBA pixel values
destOffset - first entry of dest to be used
num - number of pixels to be converted
Since:
0.12.0