GitNex/app/src/main/java/org/mian/gitnex/helpers/ColorInverter.java

package org.mian.gitnex.helpers;

import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.drawable.BitmapDrawable;
import android.widget.ImageView;
import androidx.annotation.ColorInt;
import androidx.annotation.NonNull;

/**
 * Author M M Arif
 */

public class ColorInverter {

    @ColorInt
    public int getContrastColor(@ColorInt int color) {

        double a = 1 - (0.299 * Color.red(color) + 0.587 * Color.green(color) + 0.114 * Color.blue(color)) / 255;

        int d = (a < 0.30) ?
	        30 : // almost black
	        255; // white

        return Color.rgb(d, d, d);
    }

    @ColorInt
    public int getBitmapContrastColor(@NonNull Bitmap bitmap) {

	    int colorSum = 0;
	    int divisionValue = 0;

	    for(int height=0; height<bitmap.getHeight(); height += 10) {
		    for(int width=0; width<bitmap.getWidth(); width += 10) {

			    colorSum += bitmap.getPixel(width, height);
			    divisionValue++;
		    }
	    }

	    // Calculate average color
	    return getContrastColor(colorSum / divisionValue);

    }

	@ColorInt
	public int getImageViewContrastColor(@NonNull ImageView imageView) {

    	return getBitmapContrastColor(((BitmapDrawable) imageView.getDrawable()).getBitmap());
	}

}