Check color whether lighter or darker foreground elements - Android Graphics

Android examples for Graphics:Color Darken

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Description

Check color whether lighter or darker foreground elements

Demo Code


//package com.java2s;
import android.graphics.Color;

public class Main {
    private static final float CONTRAST_LIGHT_ITEM_THRESHOLD = 3f;

    /**//from ww w  . j  ava  2s  . c om
     * Check whether lighter or darker foreground elements (i.e. text, drawables etc.)
     * should be used depending on the given background color.
     *
     * @param backgroundColor The background color value which is being queried.
     * @return Whether light colored elements should be used.
     */
    public static boolean shouldUseLightForegroundOnBackground(
            int backgroundColor) {
        return getContrastForColor(backgroundColor) >= CONTRAST_LIGHT_ITEM_THRESHOLD;
    }

    /**
     * Calculates the contrast between the given color and white, using the algorithm provided by
     * the WCAG v2 in http://www.w3.org/TR/WCAG20/#contrast-ratiodef.
     */
    private static float getContrastForColor(int color) {
        float bgR = Color.red(color) / 255f;
        float bgG = Color.green(color) / 255f;
        float bgB = Color.blue(color) / 255f;
        bgR = (bgR < 0.03928f) ? bgR / 12.92f : (float) Math.pow(
                (bgR + 0.055f) / 1.055f, 2.4f);
        bgG = (bgG < 0.03928f) ? bgG / 12.92f : (float) Math.pow(
                (bgG + 0.055f) / 1.055f, 2.4f);
        bgB = (bgB < 0.03928f) ? bgB / 12.92f : (float) Math.pow(
                (bgB + 0.055f) / 1.055f, 2.4f);
        float bgL = 0.2126f * bgR + 0.7152f * bgG + 0.0722f * bgB;
        return Math.abs((1.05f) / (bgL + 0.05f));
    }
}

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