1 package com.example.mymeshtest;
  2
  3 import android.app.Activity;
  4 import android.content.Context;
  5 import android.graphics.Bitmap;
  6 import android.graphics.BitmapFactory;
  7 import android.graphics.Canvas;
  8 import android.graphics.Color;
  9 import android.os.Bundle;
 10 import android.view.MotionEvent;
 11 import android.view.View;
 12
 13 public class MyMeshTest extends Activity
 14 {
 15
 16     private Bitmap bitmap;
 17
 18
 19     @Override
 20     protected void onCreate(Bundle savedInstanceState)
 21     {
 22         super.onCreate(savedInstanceState);
 23         setContentView(new MyView(this,R.drawable.test));
 24     }
 25
 26     private class MyView extends View
 27     {
 28
 29         //定义两个常量，这两个常量指定该图片横向、纵向上被划分为40格
 30         private final int WIDTH = 40;
 31         private final int HEIGHT = 40;
 32
 33         //记录该图片上包含41*41个顶点
 34         private final int COUNT = (WIDTH +1) * (HEIGHT + 1);
 35
 36         //定义一个数组，保存Bitmap上的41*41个点得坐标
 37         private final float[] orig = new float[COUNT*2];
 38
 39         //定义一个数组，记录Bitmap上的41*41个点经过扭曲后的坐标
 40         //对 图片进行扭曲的关键就是修改该数组里的元素的值
 41         private final float[] verts = new float[COUNT*2];
 42
 43         public MyView(Context context,int drawable_id)
 44         {
 45             super(context);
 46             // TODO Auto-generated constructor stub
 47             setFocusable(true);
 48
 49             //根据指定资源加载图片
 50             bitmap = BitmapFactory.decodeResource(getResources(), drawable_id);
 51
 52             //获取图片的宽和高
 53             float bitmapWidth = bitmap.getWidth();
 54             float bitmapHeight = bitmap.getHeight();
 55             int index = 0;
 56             for (int y = 0; y<= HEIGHT; y++)
 57             {
 58                 float fy = bitmapHeight*y/HEIGHT;
 59                 for (int x = 0; x<= WIDTH; x++)
 60                 {
 61                     float fx = bitmapWidth*x/WIDTH;
 62                     /*初始化orig、verts数组。
 63                     初始化后，orig、verts两个数组均匀地保存了
 64                     41*41个点得x、y坐标*/
 65                     orig[index*2+0] = verts[index*2+0] = fx;
 66                     orig[index*2+1] = verts[index*2+1] = fy;
 67                     index += 1;
 68                 }
 69             }
 70
 71             //设置背景颜色
 72             setBackgroundColor(Color.WHITE);
 73         }
 74
 75         @Override
 76         protected void onDraw(Canvas canvas)
 77         {
 78             /*对bitmap按verts数组进行扭曲
 79             从第一个点(由第5个参数0开始)开始扭曲*/
 80             canvas.drawBitmapMesh(bitmap, WIDTH, HEIGHT, verts, 0, null, 0, null);
 81         }
 82
 83         //工具方法，用于根据触摸事件的位置计算verts数组里各元素的值
 84         private void warp(float cx, float cy)
 85         {
 86             for (int i = 0; i< COUNT * 2; i += 2)
 87             {
 88                 float dx = cx - orig[i +0];
 89                 float dy = cy - orig[i +1];
 90                 float dd = dx*dx + dy*dy;
 91                 //计算每个坐标点与当前点（cx、cy）之间的距离
 92                 float d = (float)Math.sqrt(dd);
 93
 94                 //计算扭曲度，距离当前点（cx，cy）越远，扭曲度越小
 95                 float pull = 80000 / ((float) (dd *d));
 96
 97                 //对verts数组（保存bitmap上41*41个点经过扭曲后的坐标）重新辅助
 98                 if(pull >= 1)
 99                 {
100                     verts[i + 0] = cx;
101                     verts[i + 1] = cy;
102                 }
103                 else
104                 {
105                     //控制各定点向触摸事件发生点偏移
106                     verts[i +0] = orig [i +0] +dx*pull;
107                     verts[i +1] = orig [i +1] +dy*pull;
108                 }
109             }
110             //通知View组建重绘
111             invalidate();
112         }
113         @Override
114         public boolean onTouchEvent(MotionEvent event)
115         {
116             //调用warp方法根据触摸屏事件的坐标点来扭曲verts数组
117             warp(event.getX(),event.getY());
118             return true;
119         }
120
121     }
122
123 }