MathUtils.java

package tv.emby.embyatv.util;

import android.graphics.RectF;

/**
 * Created by Eric on 10/26/2015.
 */
public final class MathUtils {

    /**
     * Truncates a float number {@code f} to {@code decimalPlaces}.
     * @param f the number to be truncated.
     * @param decimalPlaces the amount of decimals that {@code f}
     * will be truncated to.
     * @return a truncated representation of {@code f}.
     */
    public static float truncate(float f, int decimalPlaces) {
        float decimalShift = (float) Math.pow(10, decimalPlaces);
        return Math.round(f * decimalShift) / decimalShift;
    }


    /**
     * Checks whether two {@link RectF} have the same aspect ratio.
     * @param r1 the first rect.
     * @param r2  the second rect.
     * @return {@code true} if both rectangles have the same aspect ratio,
     * {@code false} otherwise.
     */
    public static boolean haveSameAspectRatio(RectF r1, RectF r2) {
        // Reduces precision to avoid problems when comparing aspect ratios.
        float srcRectRatio = MathUtils.truncate(MathUtils.getRectRatio(r1), 2);
        float dstRectRatio = MathUtils.truncate(MathUtils.getRectRatio(r2), 2);

        // Compares aspect ratios that allows for a tolerance range of [0, 0.01]
        return (Math.abs(srcRectRatio-dstRectRatio) <= 0.01f);
    }


    /**
     * Computes the aspect ratio of a given rect.
     * @param rect the rect to have its aspect ratio computed.
     * @return the rect aspect ratio.
     */
    public static float getRectRatio(RectF rect) {
        return rect.width() / rect.height();
    }
}