Given a center point and radius of a circle, return a new point on the circle at the given angle. - Android Graphics

Android examples for Graphics:Path Point

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Description

Given a center point and radius of a circle, return a new point on the circle at the given angle.

Demo Code

/*/*from w  ww  .j a  va 2s.  c  om*/
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 ustwo studio inc (www.ustwo.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
//package com.java2s;
import android.graphics.PointF;

public class Main {
    /**
     * Given a center point and radius of a circle, return a new point on the circle at the given angle.
     * Due north of the center point (x=0) is 0 degrees and increasing the degree value will move
     * the point clockwise around the circle.<br><br>
     *
     * Throws IllegalArgumentException if radius < 0.
     *
     * @param radius        Radius of circle
     * @param angleDegrees  Angle from center (in degrees)
     * @param center        Center point of circle
     * @return              New point on circle
     */
    public static PointF getPointOnCircle(float radius,
            double angleDegrees, PointF center) {
        PointF newPoint = new PointF();
        updatePointOnCircle(newPoint, radius, angleDegrees, center);
        return newPoint;
    }

    /**
     * Given a center point and radius of a circle, update a point on the circle at the given angle.
     * Due north of the center point (x=0) is 0 degrees and increasing the degree value will move
     * the point clockwise around the circle.<br><br>
     *
     * Throws IllegalArgumentException if radius < 0.
     *
     * @param pointToUpdate Point on circle updated with x and y values
     * @param radius        Radius of circle
     * @param angleDegrees  Angle from center (in degrees)
     * @param center        Center point of circle
     */
    public static void updatePointOnCircle(PointF pointToUpdate,
            float radius, double angleDegrees, PointF center) {
        if (radius < 0) {
            throw new IllegalArgumentException("Radius cannot be < 0.");
        }
        double angleRadians = Math.toRadians(angleDegrees);
        float x = (float) (radius * Math.sin(angleRadians) + center.x);
        float y = (float) (radius * -Math.cos(angleRadians) + center.y);
        pointToUpdate.set(x, y);
    }
}

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