<ImageViewandroid:id="@+id/imageview"android:layout_width="wrap_content"android:layout_height="wrap_content"                android:src="@drawable/zixun"android:scaleType="matrix"/>关键点：缩放的内容不能是图片的背景，一定要是图片的内容

public class HelpActivity extends Activity
{private static final int NONE = 0;private static final int DRAG = 1;private static final int ZOOM = 2;private int mode = NONE;private float oldDist;private Matrix matrix = new Matrix();private Matrix savedMatrix = new Matrix();private PointF start = new PointF();private PointF mid = new PointF();protected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.help);ImageView view = (ImageView) findViewById(R.id.imageview);
//        view.setImageResource(R.drawable.icon);view.setOnTouchListener(mOnTouchListener);}OnTouchListener mOnTouchListener = new OnTouchListener(){public boolean onTouch(View v, MotionEvent event){Trace.Log("------------------"+event.toString());ImageView view = (ImageView) v;switch (event.getAction() & MotionEvent.ACTION_MASK){case MotionEvent.ACTION_DOWN:savedMatrix.set(matrix);start.set(event.getX(), event.getY());mode = DRAG;break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_POINTER_UP:mode = NONE;break;// 多点触控case MotionEvent.ACTION_POINTER_DOWN:oldDist = spacing(event);if (oldDist > 10f){savedMatrix.set(matrix);midPoint(mid, event);mode = ZOOM;}break;case MotionEvent.ACTION_MOVE:if (mode == DRAG){matrix.set(savedMatrix);matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);}else if (mode == ZOOM){float newDist = spacing(event);if (newDist > 10f){matrix.set(savedMatrix);float scale = newDist / oldDist;matrix.postScale(scale, scale, mid.x, mid.y);Trace.Log("------------------"+newDist);}}break;}view.setImageMatrix(matrix);
//            view.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);}private void midPoint(PointF point, MotionEvent event){float x = event.getX(0) + event.getX(1);float y = event.getY(0) + event.getY(1);point.set(x / 2, y / 2);}public void onClickBack(View view){backToCardSelect();}
}

ImageVIew 需要在最上面一层，否则可能不会生效