get Symmetry Point - Android java.lang

Android examples for java.lang:Math Geometry

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Description

get Symmetry Point

Demo Code


//package com.java2s;

import android.graphics.PointF;

public class Main {

    public static PointF getSymmetryPoint(PointF result, float x1,
            float y1, float a, float b, float c, float lineX) {
        float x2;
        float y2;
        if (a == 0 && b == 0) {
            y2 = y1;/* w  w w  .j  a  v a 2 s. c  o m*/
            x2 = lineX * 2 - x1;
        } else {

            float aa = a * a;
            float bb = b * b;
            float ab2 = 2 * a * b;
            float aa_bb = aa + bb;
            x2 = ((bb - aa) * x1 - ab2 * y1 - 2 * a * c) / aa_bb;
            y2 = ((aa - bb) * y1 - ab2 * x1 - 2 * b * c) / aa_bb;
        }
        result.set(x2, y2);
        return result;
    }
}

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