package com.android.imooc.goo;import android.graphics.PointF;/** * 幾何圖形工具 */public class GeometryUtil {  /**   * As meaning of method name. 獲得兩點之間的距離   *   * @param p0   * @param p1   * @return   */  public static float getDistanceBetween2Points(PointF p0, PointF p1) {    float distance = (float) Math.sqrt(Math.pow(p0.y - p1.y, 2) + Math.pow(p0.x - p1.x, 2));    return distance;  }  /**   * Get middle point between p1 and p2. 獲得兩點連線的中點   *   * @param p1   * @param p2   * @return   */  public static PointF getMiddlePoint(PointF p1, PointF p2) {    return new PointF((p1.x + p2.x) / 2.0f, (p1.y + p2.y) / 2.0f);  }  /**   * Get point between p1 and p2 by percent. 根據百分比獲取兩點之間的某個點坐標   *   * @param p1   * @param p2   * @param percent   * @return   */  public static PointF getPointByPercent(PointF p1, PointF p2, float percent) {    return new PointF(evaluateValue(percent, p1.x, p2.x), evaluateValue(percent, p1.y, p2.y));  }  /**   * 根據分度值，計算從start到end中，fraction位置的值。fraction范圍為0 -> 1   *   * @param fraction   * @param start   * @param end   * @return   */  public static float evaluateValue(float fraction, Number start, Number end) {    return start.floatValue() + (end.floatValue() - start.floatValue()) * fraction;  }  /**   * Get the point of intersection between circle and line. 獲取   * 通過指定圓心，斜率為lineK的直線與圓的交點。   *   * @param pMiddle   *      The circle center point.   * @param radius   *      The circle radius.   * @param lineK   *      The slope of line which cross the pMiddle.   * @return   */  public static PointF[] getIntersectionPoints(PointF pMiddle, float radius, Double lineK) {    PointF[] points = new PointF[2];    float radian, xOffset = 0, yOffset = 0;    if (lineK != null) {      radian = (float) Math.atan(lineK);      xOffset = (float) (Math.sin(radian) * radius);      yOffset = (float) (Math.cos(radian) * radius);    } else {      xOffset = radius;      yOffset = 0;    }    points[0] = new PointF(pMiddle.x + xOffset, pMiddle.y - yOffset);    points[1] = new PointF(pMiddle.x - xOffset, pMiddle.y + yOffset);    return points;  }}