Android编程实现ImageView图片抛物线动画效果的方法

//分300步进行移动动画 
final int count = 300; 
/** 
* 要start 动画的那张图片的ImageView 
* @param imageView 
*/ 
private void startAnimation(final ImageView imageView) { 
  Keyframe[] keyframes = new Keyframe[count]; 
  final float keyStep = 1f / (float) count; 
  float key = keyStep; 
  for (int i = 0; i < count; ++i) { 
   keyframes[i] = Keyframe.ofFloat(key, i + 1); 
   key += keyStep; 
  } 
  PropertyValuesHolder pvhX = PropertyValuesHolder.ofKeyframe("translationX", keyframes); 
  key = keyStep; 
  for (int i = 0; i < count; ++i) { 
   keyframes[i] = Keyframe.ofFloat(key, -getY(i + 1)); 
   key += keyStep; 
  } 
  PropertyValuesHolder pvhY = PropertyValuesHolder.ofKeyframe("translationY", keyframes); 
  ObjectAnimator yxBouncer = ObjectAnimator.ofPropertyValuesHolder(imageView, pvhY, pvhX).setDuration(1500); 
  yxBouncer.setInterpolator(new BounceInterpolator()); 
  yxBouncer.start(); 
} 
final float a = -1f / 75f; 
/** 
* 这里是根据三个坐标点{（0,0），（300,0），（150,300）}计算出来的抛物线方程 
* 
* @param x 
* @return 
*/ 
private float getY(float x) { 
  return a * x * x + 4 * x; 
}

package com.freesonfish; 
public class ParabolaAlgorithm { 
 public static void main(String[] args) { 
  final float[][] points = { { 6, 15 }, { 15, 70 }, { 40, 60 } }; 
  calculate(points); 
 } 
 /** 
  * a = (y1 * (x2 - x3) + y2 * (x3 - x1) + y3 * (x1 - x2)) / (x1 * x1 * (x2 - 
  * x3) + x2 * x2 * (x3 - x1) + x3 * x3 * (x1 - x2)) 
  * b = (y1 - y2) / (x1 - x2) - a * (x1 + x2); 
  * c = y1 - (x1 * x1) * a - x1 * b; 
  */ 
 private static void calculate(float[][] points) { 
  float x1 = points[0][0]; 
  float y1 = points[0][1]; 
  float x2 = points[1][0]; 
  float y2 = points[1][1]; 
  float x3 = points[2][0]; 
  float y3 = points[2][1]; 
  final float a = (y1 * (x2 - x3) + y2 * (x3 - x1) + y3 * (x1 - x2)) 
    / (x1 * x1 * (x2 - x3) + x2 * x2 * (x3 - x1) + x3 * x3 * (x1 - x2)); 
  final float b = (y1 - y2) / (x1 - x2) - a * (x1 + x2); 
  final float c = y1 - (x1 * x1) * a - x1 * b; 
  System.out.println("-a->" + a + " b->" +b + " c->" +c); 
 } 
}