android 图片点击一下就放大到全屏，再点一下就回到原界面

    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);  
             }  
       
          
              
          
          
    }   

    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);  
             }  
       
          
              
          
          
    }