关于Android手势缩放圆球

这个主要是根据手势缩放图片功能改装的一个简易Demo.熟悉一下图形操作..

代码如下：

package hfut.gmm;import android.app.Activity;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.PointF;import android.os.Bundle;import android.util.FloatMath;import android.util.Log;import android.view.MotionEvent;import android.view.View;public class MultiTouch extends Activity {    PointF start = new PointF();         private Matrix matrix=new Matrix();    private Matrix savedMatrix=new Matrix();   @Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);MyView mv=new MyView(this);this.setContentView(mv);}} class MyView extends View{ static final int NONE = 0;      static final int DRAG = 1;      static final int ZOOM = 2;      int mode = NONE;     float oldDist = 1f;     float mr=0;    float mx;    float my;public MyView(Context context) {super(context);// TODO Auto-generated constructor stub}@Overridepublic boolean onTouchEvent(MotionEvent event) {// TODO Auto-generated method stubLog.d("Infor", "触摸监听到了...");switch(event.getActionMasked()){case MotionEvent.ACTION_DOWN://单点触碰mx=event.getX();mr=50;Log.d("Infor", "mx"+mx);my=event.getY();Log.d("Infor", "my"+my);mode=this.DRAG; break; case MotionEvent.ACTION_POINTER_DOWN://多点触碰oldDist=this.spacing(event);if(oldDist>10f){     Log.d("Infor", "oldDist"+oldDist);}mode=ZOOM;break; case MotionEvent.ACTION_MOVE://移动if(mode==DRAG){Log.d("Infor", "单点移动。。。");mx=event.getX();my=event.getY();}else if(mode==ZOOM){float newDist=spacing(event);if(newDist>10){mr=newDist/oldDist*100;Log.d("Infor", "多点移动。。。");Log.d("Infor", "newDist:"+newDist);}}break;case MotionEvent.ACTION_UP:mode=this.NONE;break;case MotionEvent.ACTION_POINTER_UP:mode=this.NONE;break;}invalidate(); return true;}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);  }   @Overrideprotected void onDraw(Canvas canvas) {// TODO Auto-generated method stubsuper.onDraw(canvas);Paint paint=new Paint();paint.setColor(Color.BLUE);canvas.drawCircle(mx, my, mr, paint);          }}

展示结果如下：