Android Open Source - GuiLib Math Util

From Project

Back to project page GuiLib.

License

The source code is released under:

Apache License

If you think the Android project GuiLib listed in this page is inappropriate, such as containing malicious code/tools or violating the copyright, please email info at java2s dot com, thanks.

Java Source Code

/*
 * Copyright (C) 2010 Gandulf Kohlweiss//from   ww  w .ja  v  a 2  s.co  m
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.gandulf.guilib.util;

import android.graphics.Point;

/**
 * Utility class to bundle mathematical helper methods
 * 
 */
public class MathUtil {

  public static float getRatio(Integer value, Integer ref) {
    if (value != null && ref != null && ref != 0) {
      return ((float) value) / ref;
    } else {
      return 1.0f;
    }
  }

  public static float coordinatesToAngle(int x, int y) {
    double theta = Math.atan((double) -y / (double) x);
    theta = Math.toDegrees(theta);
    if (x >= 0 && -y >= 0) {
      // theta = theta;
    } else if (x < 0 && -y >= 0) {
      theta = 180 + theta;
    } else if (x < 0 && -y < 0) {
      theta = 180 + theta;
    } else if (x > 0 && -y < 0) {
      theta = 360 + theta;
    }

    return (float) theta;
  }

  public static int coordinatesToRadius(int x, int y) {
    return (int) Math.sqrt(x * x + y * y);
  }

  /**
   * Convert polar coordinates to cartesian.
   * 
   * @param x
   *            is the x-coordinate of the origin.
   * @param y
   *            is the y-coordinate of the origin.
   * @param degrees
   *            is the number of degrees to go through.
   * @param radius
   *            is the length of the radius.
   * @param pt
   *            is the point to put the results in.
   * @return an (x,y) point.
   */
  public static Point polarToCartesian(int x, int y, double degree, double radius, Point pt) {

    double radian = Math.toRadians(degree);
    // // 1. Convert the polar coordinates.
    // // Normally, the y calculation would be addition instead of
    // // subtraction, but we are dealing with screen coordinates,
    // // which has its y-coordinate at the top and not the bottom.
    pt.x = (int) (x + radius * Math.cos(radian));
    pt.y = (int) (y - radius * Math.sin(radian));

    // // 2. Straighten up the data a little.
    if (Math.abs(pt.x - radius) <= 1) {
      pt.x = (int) radius;
    }
    if (Math.abs(pt.y - radius) <= 1) {
      pt.y = (int) radius;
    }

    return (pt);
  } // of method
}

Java Source Code List