Java tutorial
//package com.java2s; import android.graphics.Color; public class Main { public static final int darken(int color, float rate) { float[] hsv = new float[3]; Color.colorToHSV(color, hsv); hsv[2] = hsv[2] * rate; return Color.HSVToColor(hsv); } public static final int darken(int color) { return darken(color, 0.8f); } }