ANDROID APP

134 บทที่ 5 อีเวนต์ต่างๆ ที่เกิดขึ้นในส่วนการติดต่อกับผู้ใช้งาน
public class MultiTouch extends Activity implements OnTouchListener {
// Matrix instances to move and zoom image
Matrix matrix = new Matrix();
Matrix eventMatrix = new Matrix();
// possible touch states
final static int NONE = 0;
final static int DRAG = 1;
final static int ZOOM = 2;
int touchState = NONE;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ImageView view = (ImageView) findViewById(R.id.imageView);
view.setOnTouchListener(this);
}
final static float MIN_DIST = 50;
static float eventDistance = 0;
static float centerX =0, centerY = 0;
@Override
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView) v;
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
//primary touch event starts: remember touch down location
touchState = DRAG;
centerX = event.getX(0);
centerY = event.getY(0);
eventMatrix.set(matrix);
break;
case MotionEvent.ACTION_POINTER_DOWN:
//secondary touch event starts: remember distance and center
eventDistance = calcDistance(event);
calcMidpoint(centerX, centerY, event);
if (eventDistance > MIN_DIST) {
eventMatrix.set(matrix);
touchState = ZOOM;
}
break;