sketcher2/src/com/jotuntech/sketcher/common/Pixels.java

package com.jotuntech.sketcher.common;


public class Pixels {
	private final static int RANDOM_SIZE = 3079;
	private static int[] randomNumbers;
	private static int randomCounter;

	public static int random() {
		if(randomNumbers == null) {
			randomNumbers = new int[RANDOM_SIZE];
			for(int i = 0; i < RANDOM_SIZE; i++) {
				randomNumbers[i] = (int) Math.round(Math.random() * 255f);
			}
		}

		randomCounter %= RANDOM_SIZE;
		return randomNumbers[randomCounter++];
	}
	
	/*
	public final static int squareRoot(int a_nInput)
	{
	    int op  = a_nInput;
	    int res = 0;
	    int one = 1 << 30; // The second-to-top bit is set: use 1u << 14 for uint16_t type; use 1uL<<30 for int type

	    // "one" starts at the highest power of four <= than the argument.
	    while (one > op) {
	        one >>= 2;
	    }

	    while (one != 0) {
	        if (op >= res + one) {
	            op = op - (res + one);
	            res = res +  2 * one;
	        }
	        res >>= 1;
	        one >>= 2;
	    }

	    // Do arithmetic rounding to nearest integer
	    if (op > res) {
	        res++;
	    }

	    return res;
	}
	*/
	
	public static int lerp(int destination, int source, int alpha) {
		/* mask destination */
		int destinationRB = destination & 0x00FF00FF;
		int destinationAG = destination >>> 8 & 0x00FF00FF;

		/* mask source */
		int sourceRB = source & 0x00FF00FF;
		int sourceAG = source >>> 8 & 0x00FF00FF;

		/* calc difference */
		int deltaRB = sourceRB - destinationRB;
		int deltaAG = sourceAG - destinationAG;

		/* scale difference by alpha */
		deltaRB *= alpha;
		deltaAG *= alpha;
		deltaRB >>>= 8;
		deltaAG >>>= 8;

		/* add delta to destination and mask */
		int RB = (deltaRB + destinationRB) & 0x00FF00FF;
		int AG = (deltaAG + destinationAG) << 8 & 0xFF00FF00;

		return RB | AG;
	}

	public static int getChannel0(int pixel) {
		return pixel >>> 24;
	}

	public static int getChannel1(int pixel) {
		return (pixel >>> 16) & 0xFF;
	}

	public static int getChannel2(int pixel) {
		return (pixel >>> 8) & 0xFF;
	}

	public static int getChannel3(int pixel) {
		return pixel & 0xFF;
	}

	public static int stripChannel0(int pixel) {
		return pixel & 0xFFFFFF;
	}

	public static int pack(int c1, int c2, int c3) {
		return (c1 << 16) | (c2 << 8) | c3;
	}

	public static int pack(int c0, int color) {
		return (c0 << 24) | color;
	}

	public static int pack(int c0, int c1, int c2, int c3) {
		return (c0 << 24) | (c1 << 16) | (c2 << 8) | c3;
	}

	private final static float a = 0.055f;

	public static float gammaDecode(float v) {
		v /= 255f;
		if(v <= 0.04045d) {
			v /= 12.92d;
		} else {
			v = (float) Math.pow((v + a) / (1d + a), 2.4f);
		}
		return v;
	}

	public static int gammaEncode(float v) {
		if(v <= 0.0031308) {
			v *= 12.92d;
		} else {
			v = (1f + a) * (float) Math.pow(v, 1 / 2.4f) - a;
		}
		return Math.round(v * 255f);
	}
}