關于Android手勢縮放圓球

這個主要是根據手勢縮放圖片功能改裝的一個簡易Demo.熟悉一下圖形操作..

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();

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.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
    }

@Override
public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    Log.d("Infor", "觸摸監聽到了...");
    switch(event.getActionMasked()){
    case MotionEvent.ACTION_DOWN://單點觸碰
    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://多點觸碰
        oldDist=this.spacing(event);
        if(oldDist>10f){
             Log.d("Infor", "oldDist"+oldDist);     
        }
    mode=ZOOM;
    break;       
    case MotionEvent.ACTION_MOVE://移動
        if(mode==DRAG){
            Log.d("Infor", "單點移動。。。");
            mx=event.getX();
            my=event.getY();            
        }
        else if(mode==ZOOM){
            float newDist=spacing(event);           
            if(newDist>10){
                mr=newDist/oldDist*100;
                Log.d("Infor", "多點移動。。。");
                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);  

}

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
        Paint paint=new Paint();
        paint.setColor(Color.BLUE);
        canvas.drawCircle(mx, my, mr, paint);

}



}</pre>展示結果如下：