android 放大镜 Magnifier 简单实现

public class MainActivity extends Activity implements OnTouchListener {
    private int x;//绘画开始的横坐标
    private int y;//绘画开始的纵坐标

    private int width = 180;//绘画的宽度
    private int height = 40;//绘画的高度
    private Bitmap bitmap;//生成的位图
    //    private MyView myView;//绘画选择区域
    private ImageView image1;
    private ImageView image2;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        image1 = (ImageView) findViewById(R.id.image1);
        image2 = (ImageView) findViewById(R.id.image2);
        image1.setOnTouchListener(this);
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        try {


        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                x = (int) event.getX();
                y = (int) event.getY();
                  moveViewWithFinger(image2,x,y);
                image2.setVisibility(View.VISIBLE);
                image2.setImageBitmap(getBitmap(this));
                break;
            }

            case MotionEvent.ACTION_MOVE: {
                x = (int) event.getX();
                y = (int) event.getY();
                image2.setImageBitmap(getBitmap(this));
                moveViewWithFinger(image2,x,y);
                break;
            }
            case MotionEvent.ACTION_UP: {
                image2.setImageBitmap(null);
                image2.setVisibility(View.GONE);
                break;
            }
            default: {
                image2.setImageBitmap(null);

                image2.setVisibility(View.GONE);
                break;
            }
        }
        }catch (Exception e){
            e.getStackTrace();
        }
        return true;
    }

    private void moveViewWithFinger(View view, float rawX, float rawY) {
        RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) view
                .getLayoutParams();
        params.leftMargin = (int) rawX-250;
        params.topMargin = (int) rawY - 250;
        view.setLayoutParams(params);
    }

    private Bitmap getBitmap(Activity activity) {
        View view = activity.getWindow().getDecorView();
        view.setDrawingCacheEnabled(true);
        view.buildDrawingCache();
        bitmap = view.getDrawingCache();
        bitmap = Bitmap.createBitmap(bitmap, x, y, width, height);
        view.setDrawingCacheEnabled(false);
        return bitmap;
    }
}

///  main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <ImageView
        android:id="@+id/image1"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:src="@drawable/test" />

    <ImageView
        android:id="@+id/image2"
        android:layout_width="180dp"
        android:layout_height="45dp"
        android:visibility="gone"
       />

</RelativeLayout>
源码 ： http://download.csdn.net/detail/icesoul1127/9638232