Java tutorial
//package com.java2s; import android.graphics.Color; public class Main { public static int darken(final int color, float fraction) { return blendColors(Color.BLACK, color, fraction); } /** * Blend {@code color1} and {@code color2} using the given ratio. * * @param ratio of which to blend. 1.0 will return {@code color1}, 0.5 will give an even blend, * 0.0 will return {@code color2}. */ public static int blendColors(int color1, int color2, float ratio) { final float inverseRatio = 1f - ratio; float r = (Color.red(color1) * ratio) + (Color.red(color2) * inverseRatio); float g = (Color.green(color1) * ratio) + (Color.green(color2) * inverseRatio); float b = (Color.blue(color1) * ratio) + (Color.blue(color2) * inverseRatio); return Color.rgb((int) r, (int) g, (int) b); } }