Android imageview 多点触碰(MultiTouch)实现图片拖拽移

import android.content.Context;   import android.util.FloatMath;   import android.view.MotionEvent;   import android.view.animation.TranslateAnimation;   import android.widget.ImageView;   /**   * 继承ImageView 实现了多点触碰的拖动和缩放   * @author Administrator   *   */   public class TouchView extends ImageView   {       static final int NONE = 0;       static final int DRAG = 1;     //拖动中        static final int ZOOM = 2;     //缩放中        static final int BIGGER = 3;   //放大ing        static final int SMALLER = 4;  //缩小ing        private int mode = NONE;       //当前的事件            private float beforeLenght;   //两触点距离        private float afterLenght;    //两触点距离        private float scale = 0.04f;  //缩放的比例 X Y方向都是这个值 越大缩放的越快              private int screenW;       private int screenH;              /*处理拖动 变量 */       private int start_x;       private int start_y;       private int stop_x ;       private int stop_y ;              private TranslateAnimation trans; //处理超出边界的动画               public TouchView(Context context,int w,int h)       {           super(context);           this.setPadding(0, 0, 0, 0);           screenW = w;           screenH = h;       }              /**       * 就算两点间的距离       */       private float spacing(MotionEvent event) {           float x = event.getX(0) - event.getX(1);           float y = event.getY(0) - event.getY(1);           return FloatMath.sqrt(x * x + y * y);       }              /**       * 处理触碰..       */       @Override       public boolean onTouchEvent(MotionEvent event)       {              switch (event.getAction() & MotionEvent.ACTION_MASK) {           case MotionEvent.ACTION_DOWN:                   mode = DRAG;                   stop_x = (int) event.getRawX();                   stop_y = (int) event.getRawY();                   start_x = (int) event.getX();                   start_y = stop_y - this.getTop();                   if(event.getPointerCount()==2)                       beforeLenght = spacing(event);                   break;           case MotionEvent.ACTION_POINTER_DOWN:                   if (spacing(event) > 10f) {                           mode = ZOOM;                           beforeLenght = spacing(event);                   }                   break;           case MotionEvent.ACTION_UP:               /*判断是否超出范围     并处理*/                   int disX = 0;                   int disY = 0;                   if(getHeight()<=screenH || this.getTop()<0)                   {                       if(this.getTop()<0 )                       {                           int dis = getTop();                           this.layout(this.getLeft(), 0, this.getRight(), 0 + this.getHeight());                           disY = dis - getTop();                       }                       else if(this.getBottom()>screenH)                       {                           disY = getHeight()- screenH+getTop();                           this.layout(this.getLeft(), screenH-getHeight(), this.getRight(), screenH);                       }                   }                   if(getWidth()<=screenW)                   {                       if(this.getLeft()<0)                       {                           disX = getLeft();                           this.layout(0, this.getTop(), 0+getWidth(), this.getBottom());                       }                       else if(this.getRight()>screenW)                       {                           disX = getWidth()-screenW+getLeft();                           this.layout(screenW-getWidth(), this.getTop(), screenW, this.getBottom());                       }                   }                   if(disX!=0 || disY!=0)                   {                       trans = new TranslateAnimation(disX, 0, disY, 0);                       trans.setDuration(500);                       this.startAnimation(trans);                   }                   mode = NONE;                   break;           case MotionEvent.ACTION_POINTER_UP:                   mode = NONE;                   break;           case MotionEvent.ACTION_MOVE:                   /*处理拖动*/                   if (mode == DRAG) {                       if(Math.abs(stop_x-start_x-getLeft())<88 && Math.abs(stop_y - start_y-getTop())<85)                       {                           this.setPosition(stop_x - start_x, stop_y - start_y, stop_x + this.getWidth() - start_x, stop_y - start_y + this.getHeight());                                         stop_x = (int) event.getRawX();                           stop_y = (int) event.getRawY();                       }                   }                    /*处理缩放*/                   else if (mode == ZOOM) {                       if(spacing(event)>10f)                       {                           afterLenght = spacing(event);                           float gapLenght = afterLenght - beforeLenght;                                                if(gapLenght == 0) {                                break;                           }                           else if(Math.abs(gapLenght)>5f)                           {                               if(gapLenght>0) {                                    this.setScale(scale,BIGGER);                                  }else {                                     this.setScale(scale,SMALLER);                                  }                                                            beforeLenght = afterLenght;                            }                       }                   }                   break;           }           return true;           }              /**       * 实现处理缩放       */       private void setScale(float temp,int flag) {                         if(flag==BIGGER) {                  this.setFrame(this.getLeft()-(int)(temp*this.getWidth()),                                 this.getTop()-(int)(temp*this.getHeight()),                                 this.getRight()+(int)(temp*this.getWidth()),                                 this.getBottom()+(int)(temp*this.getHeight()));                 }else if(flag==SMALLER){                  this.setFrame(this.getLeft()+(int)(temp*this.getWidth()),                                 this.getTop()+(int)(temp*this.getHeight()),                                 this.getRight()-(int)(temp*this.getWidth()),                                 this.getBottom()-(int)(temp*this.getHeight()));              }          }              /**       * 实现处理拖动       */       private void setPosition(int left,int top,int right,int bottom) {             this.layout(left,top,right,bottom);                    }      }