通过注册OnTouchListener，来实现多点触控
public class Main extends Activity implements OnTouchListener {// These matrices will be used to move and zoom imageMatrix matrix = new Matrix();Matrix savedMatrix = new Matrix();// We can be in one of these 3 statesstatic final int NONE = 0;static final int DRAG = 1;static final int ZOOM = 2;int mode = NONE;// Remember some things for zoomingPointF start = new PointF();PointF mid = new PointF();float oldDist = 1f;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);ImageView imageView = (ImageView) findViewById(R.id.imageView);imageView.setOnTouchListener(this);}@Overridepublic boolean onTouch(View v, MotionEvent event) {ImageView imageView = (ImageView) v;switch (event.getAction() & MotionEvent.ACTION_MASK) {case MotionEvent.ACTION_DOWN:savedMatrix.set(matrix);start.set(event.getX(), event.getY()); // 設置初始點位置mode = DRAG;break;case MotionEvent.ACTION_POINTER_DOWN:oldDist = spacing(event);if (oldDist > 10f) {savedMatrix.set(matrix);midPoint(mid, event);mode = ZOOM;}break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_POINTER_UP:mode = NONE;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);}}break;}imageView.setImageMatrix(matrix);return true; // indicate event was handled}/** Determine the space between the first two fingers */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);}/** Calculate the mid point of the first two fingers */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);}}?