自定义一个View类(放大镜)，在其onDraw()方法中根据原图片资源，以及想要展现的放大区域(我用的矩形)，根据触摸点的位置，去原图找到相对应的点(我是用的比例算出来的)，然后用矩形区域切割出这一部分，用PopupWindow组件显示就可以了，就这么简单。。。。具体更复杂的功能可以随着需要自己添加，部分代码如下：

java代码： public class Magnifier extends

View

{

private Paint

paint;

private Rect

rect;

public Magnifier(Context

context){

super(context);

paint = new

Paint();

paint.setAntiAlias(true);

paint.setColor(0xff008000);

paint.setStyle(Style.STROKE);

rect = new Rect(0, 0, AppConstants.EDGE*2,

AppConstants.EDGE*2);

}

protected void onDraw(Canvas

canvas)

{

canvas.save();

paint.setAlpha(255);

canvas.drawBitmap(resBitmap, srcRect, rect,

paint);

canvas.restore();

}

}

触摸事件响应(前面的部分是对应点的计算和对于越界的处理。)

java代码：

public boolean onTouchEvent(MotionEvent

event)

{

// TODO Auto-generated method

stub

int action =

event.getAction();

if(MotionEvent.ACTION_DOWN == action ||

MotionEvent.ACTION_MOVE ==

action)

{

float x =

(float)event.getX();

、float y =

(float)event.getY();

System.out.println("X: " + x + ", Y: " +

y);

srcRect.set((int)(x*760/480-AppConstants.EDGE),

(int)(y*1030/840-AppConstants.EDGE),

(int)(x*760/480+AppConstants.EDGE),

(int)(y*1030/840+AppConstants.EDGE));

point.set((int)x,

(int)y);

if(srcRect.left <

0)

{

srcRect.offset(-srcRect.left,

0);

}

else

if(srcRect.right >

resBitmap.getWidth())

{

srcRect.offset(resBitmap.getWidth()-srcRect.right,

0);

}

if(srcRect.top <

0)

{

srcRect.offset(0,

-srcRect.top);

}

else

if(srcRect.bottom >

resBitmap.getHeight())

{

srcRect.offset(0,

resBitmap.getHeight()-srcRect.bottom);

}

if((x<0) ||

(y<0))

{

popup.dismiss();

layout.invalidate();

return

true;

}

layout.removeCallbacks(showPopup);

layout.postDelayed(showPopup,

200);

magnifier.invalidate();

}

else

if(MotionEvent.ACTION_UP ==

action)

{

layout.removeCallbacks(showPopup);

popup.dismiss();

}

layout.invalidate();

return

true;

}