Mega Code Archive
Utility for working with natively-ordered integer-packed RGBA-format colours
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//package com.ryanm.droid.rugl.util;
import java.nio.ByteOrder;
/**
* Utility for working with natively-ordered integer-packed RGBA-format colours.
* Nice and easy to squirt to OpenGL. Beware that byte order can change from
* machine to machine, so if you're saving the packed values to disk, use
* {@link #toBigEndian(int)} to write and {@link #fromBigEndian(int)} to read
*
* @author ryanm
*/
public class Colour {
private Colour() {
// no instances please
}
private static final int redOffset, greenOffset, blueOffset, alphaOffset;
static {
boolean big = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN;
redOffset = big ? 24 : 0;
greenOffset = big ? 16 : 8;
blueOffset = big ? 8 : 16;
alphaOffset = big ? 0 : 24;
}
/***/
public static final int white = packFloat(1, 1, 1, 1);
/***/
public static final int black = packFloat(0, 0, 0, 1);
/***/
public static final int grey = packFloat(0.5f, 0.5f, 0.5f, 1);
/***/
public static final int darkgrey = packFloat(0.25f, 0.25f, 0.25f, 1);
/***/
public static final int lightgrey = packFloat(0.75f, 0.75f, 0.75f, 1);
/***/
public static final int red = packFloat(1, 0, 0, 1);
/***/
public static final int green = packFloat(0, 1, 0, 1);
/***/
public static final int blue = packFloat(0, 0, 1, 1);
/***/
public static final int yellow = packFloat(1, 1, 0, 1);
/***/
public static final int cyan = packFloat(0, 1, 1, 1);
/***/
public static final int magenta = packFloat(1, 0, 1, 1);
/***/
public static final int orange = packFloat(1, 0.5f, 0, 1);
/***/
public static final int springGreen = packFloat(0.5f, 1, 0, 1);
/***/
public static final int turquoise = packFloat(0, 1, 0.5f, 1);
/***/
public static final int ocean = packFloat(0, 0.5f, 1, 1);
/***/
public static final int violet = packFloat(0.5f, 0, 1, 1);
/***/
public static final int raspberry = packFloat(1, 0, 0.5f, 1);
/**
* Converts from a native-order packed colour int to a big-endian packed
* colour int
*
* @param rgba
* @return The big-endian int
*/
public static int toBigEndian(int rgba) {
return redi(rgba) << 24 | greeni(rgba) << 16 | bluei(rgba) << 8
| alphai(rgba);
}
/**
* Converts from a big-endian packed colouor int to a native-order packed
* colour int
*
* @param rgba
* @return the native-order int
*/
public static int fromBigEndian(int rgba) {
int r = rgba >> 24 & 0xff;
int g = rgba >> 16 & 0xff;
int b = rgba >> 8 & 0xff;
int a = rgba >> 0 & 0xff;
return packInt(r, g, b, a);
}
/**
* @param rgba
* packed colour int
* @param array
* destination array, or <code>null</code> to allocate a new
* array
* @return a float[]{ r, g, b, a } array, in ranges 0-1
*/
public static float[] toArray(int rgba, float[] array) {
if (array == null) {
array = new float[4];
}
array[0] = redf(rgba);
array[1] = bluef(rgba);
array[2] = greenf(rgba);
array[3] = alphaf(rgba);
return array;
}
/**
* Packs colour components into an integer
*
* @param r
* range 0-255
* @param g
* range 0-255
* @param b
* range 0-255
* @param a
* range 0-255
* @return a packed colour integer
*/
public static int packInt(int r, int g, int b, int a) {
r = (r & 0xff) << redOffset;
g = (g & 0xff) << greenOffset;
b = (b & 0xff) << blueOffset;
a = (a & 0xff) << alphaOffset;
return r | g | b | a;
}
/**
* Packs colour components into an integer
*
* @param r
* range 0-1
* @param g
* range 0-1
* @param b
* range 0-1
* @param a
* range 0-1
* @return a packed colour integer
*/
public static int packFloat(float r, float g, float b, float a) {
return packInt((int) (r * 255f), (int) (g * 255f), (int) (b * 255f),
(int) (a * 255f));
}
/**
* Extracts the red component
*
* @param rgba
* packed colour value
* @return The component 0-1
*/
public static float redf(int rgba) {
return redi(rgba) / 255f;
}
/**
* Extracts the green component
*
* @param rgba
* packed colour value
* @return The component 0-1
*/
public static float greenf(int rgba) {
return greeni(rgba) / 255f;
}
/**
* Extracts the blue component
*
* @param rgba
* packed colour value
* @return The component 0-1
*/
public static float bluef(int rgba) {
return bluei(rgba) / 255f;
}
/**
* Extracts the alpha component
*
* @param rgba
* packed colour value
* @return The component 0-1
*/
public static float alphaf(int rgba) {
return alphai(rgba) / 255f;
}
/**
* Extracts the red component
*
* @param rgba
* packed colour value
* @return The component 0-255
*/
public static int redi(int rgba) {
return rgba >> redOffset & 0xff;
}
/**
* Extracts the green component
*
* @param rgba
* packed colour value
* @return The component 0-255
*/
public static int greeni(int rgba) {
return rgba >> greenOffset & 0xff;
}
/**
* Extracts the blue component
*
* @param rgba
* packed colour value
* @return The component 0-255
*/
public static int bluei(int rgba) {
return rgba >> blueOffset & 0xff;
}
/**
* Extracts the alpha component
*
* @param rgba
* packed colour value
* @return The component 0-255
*/
public static int alphai(int rgba) {
return rgba >> alphaOffset & 0xff;
}
/**
* Mask to get only the alpha bits
*/
private static int alphaMask = 0xff << alphaOffset;
/**
* Mask to get only the colour bits
*/
private static int colourmask = ~alphaMask;
/**
* Amends a colour by changing the alpha component
*
* @param colour
* source colour
* @param alpha
* new alpha component (0-255)
* @return new colour
*/
public static int withAlphai(int colour, int alpha) {
colour = colour & colourmask;
alpha = (alpha & 0xff) << alphaOffset;
colour |= alpha;
return colour;
}
/**
* Amends an array of colour ints by changing the alpha component
*
* @param colours
* source colours
* @param alpha
* new alpha component (0-255)
*/
public static void withAlphai(int[] colours, int alpha) {
for (int i = 0; i < colours.length; i++) {
colours[i] = withAlphai(colours[i], alpha);
}
}
/**
* @param rgba
* @return a string in r:g:b:a format
*/
public static String toString(int rgba) {
return redi(rgba) + ":" + greeni(rgba) + ":" + bluei(rgba) + ":"
+ alphai(rgba);
}
}
]]>