多點觸摸demo

     實現功能：圖片的拖動、放大、縮小。獻給大家學習學習

public class Touch extends Activity implements OnTouchListener {private static final String TAG = "Touch";// 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 states/** * 無 */static final int NONE = 0;/** * 拖 */static final int DRAG = 1;/** * 縮放 */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 view = (ImageView) findViewById(R.id.imageView);view.setOnTouchListener(this);}@Overridepublic boolean onTouch(View v, MotionEvent event) {ImageView view = (ImageView) v;// Dump touch event to log// dumpEvent(event);// Handle touch events here...switch (event.getAction() & MotionEvent.ACTION_MASK) {case MotionEvent.ACTION_DOWN:savedMatrix.set(matrix);// 設置初始點位置start.set(event.getX(), event.getY());Log.e(TAG, "mode=DRAG");mode = DRAG;break;case MotionEvent.ACTION_POINTER_DOWN:oldDist = spacing(event);Log.e(TAG, "oldDist=" + oldDist);if (oldDist > 10f) {savedMatrix.set(matrix);midPoint(mid, event);mode = ZOOM;Log.d(TAG, "mode=ZOOM");}break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_POINTER_UP:mode = NONE;Log.e(TAG, "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);Log.e(TAG, "newDist=" + newDist);if (newDist > 10f) {matrix.set(savedMatrix);float scale = newDist / oldDist;matrix.postScale(scale, scale, mid.x, mid.y);}}break;}view.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);}}

圖片大家就隨便弄一張吧