求解 android 圖片點擊壹下就放大到全屏，再點壹下就回到原界面，這個android源碼誰有呢？

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Matrix;

import android.os.Bundle;

import android.view.Display;

import android.view.KeyEvent;

import android.view.MotionEvent;

import android.widget.ImageView;

public class TestanroidpicActivity extends Activity {

/** Called when the activity is first created. */

Bitmap bp=null;

ImageView imageview;

float scaleWidth;

float scaleHeight;

int h;

boolean num=false;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

Display display=getWindowManager().getDefaultDisplay();

imageview=(ImageView)findViewById(R.id.imageview);

bp=BitmapFactory.decodeResource(getResources(),R.drawable.icon);

int width=bp.getWidth();

int height=bp.getHeight();

int w=display.getWidth();

int h=display.getHeight();

scaleWidth=((float)w)/width;

scaleHeight=((float)h)/height;

imageview.setImageBitmap(bp);

}

@Override

public boolean onTouchEvent(MotionEvent event) {

switch(event.getAction()){

case MotionEvent.ACTION_DOWN:

if(num==true) {

Matrix matrix=new Matrix();

matrix.postScale(scaleWidth,scaleHeight);

Bitmap newBitmap=Bitmap.createBitmap(bp, 0, 0, bp.getWidth(), bp.getHeight(), matrix, true);

imageview.setImageBitmap(newBitmap);

num=false;

}

else{

Matrix matrix=new Matrix();

matrix.postScale(1.0f,1.0f);

Bitmap newBitmap=Bitmap.createBitmap(bp, 0, 0, bp.getWidth(), bp.getHeight(), matrix, true);

imageview.setImageBitmap(newBitmap);

num=true;

}

break;

}

return super.onTouchEvent(event);

}

}