find Intersection between points - Android Graphics

Android examples for Graphics:Path Point

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Description

find Intersection between points

Demo Code


import android.graphics.PointF;
import android.graphics.RectF;
import com.android.volley.DefaultRetryPolicy;

public class Main{
    static PointF findIntersection(PointF p1, PointF p2, PointF p3,
            PointF p4) {//from w  ww  .j  a  va2  s.c  o m
        float xD1 = p2.x - p1.x;
        float xD2 = p4.x - p3.x;
        float yD1 = p2.y - p1.y;
        float yD2 = p4.y - p3.y;
        float xD3 = p1.x - p3.x;
        float yD3 = p1.y - p3.y;
        float len1 = (float) Math
                .sqrt((double) ((xD1 * xD1) + (yD1 * yD1)));
        float len2 = (float) Math
                .sqrt((double) ((xD2 * xD2) + (yD2 * yD2)));
        if (Math.abs(((xD1 * xD2) + (yD1 * yD2)) / (len1 * len2)) == DefaultRetryPolicy.DEFAULT_BACKOFF_MULT) {
            return null;
        }
        PointF pt = new PointF(0.0f, 0.0f);
        float div = (yD2 * xD1) - (xD2 * yD1);
        float ua = ((xD2 * yD3) - (yD2 * xD3)) / div;
        float ub = ((xD1 * yD3) - (yD1 * xD3)) / div;
        pt.x = p1.x + (ua * xD1);
        pt.y = p1.y + (ua * yD1);
        xD1 = pt.x - p1.x;
        xD2 = pt.x - p2.x;
        yD1 = pt.y - p1.y;
        yD2 = pt.y - p2.y;
        float segmentLen1 = (float) (Math
                .sqrt((double) ((xD1 * xD1) + (yD1 * yD1))) + Math
                .sqrt((double) ((xD2 * xD2) + (yD2 * yD2))));
        xD1 = pt.x - p3.x;
        xD2 = pt.x - p4.x;
        yD1 = pt.y - p3.y;
        yD2 = pt.y - p4.y;
        float segmentLen2 = (float) (Math
                .sqrt((double) ((xD1 * xD1) + (yD1 * yD1))) + Math
                .sqrt((double) ((xD2 * xD2) + (yD2 * yD2))));
        if (((double) Math.abs(len1 - segmentLen1)) <= 0.01d) {
            if (((double) Math.abs(len2 - segmentLen2)) <= 0.01d) {
                return pt;
            }
        }
        return null;
    }
}

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