Interacting with geoImage
| This class produces a bidirectional counter that cycles in a given range
upon button presses. |
class Counter extends Statics implements UntilNotifier {
| constructor for a counter object |
public Counter(NumberBvr limit) {
_counterLimit = limit;
| upon a skip event invoke the notifier |
_value = (NumberBvr)untilNotify(_initValue, skip, this);
}
public Behavior notify(Object eventData, Behavior previous, BvrsToRun lst) {
| extract the application data (an integer), into a number behavior |
NumberBvr adjustment = toBvr(((Integer)eventData).intValue());
| use it as an inc/decrement |
NumberBvr value = add((NumberBvr)previous, adjustment);
| cycle between 0 and (limit - 1) |
value = (NumberBvr)cond(eq(value, toBvr(-1)),
sub(_counterLimit, toBvr(1)),
if -1, wrap around
cond(eq(value, _counterLimit), toBvr(0), value));
if limit, wrap around
| repeat with the new value |
return untilNotify(value, skip, this);
}
public NumberBvr getBvr () {
return _value;
}
| Key events with corresponding event data.
For non-ASCII keys use the Java designation for the key. |
private static final DXMEvent skipForward1 = keyDown(Event.RIGHT).attachData(new Integer(1));
private static final DXMEvent skipBack1 = keyDown(Event.LEFT).attachData(new Integer(-1));
| For ASCII keys use the ASCII letter between single quotes. |
private static final DXMEvent skipForward2 = keyDown(' ').attachData(new Integer(1));
| There is also a timeout event for automatically switching between pictures
if no manual key presses are issued. |
private static final DXMEvent auto = timer(toBvr(8)).attachData(new Integer(1));
| Aggregate the four events above into a single event. |
private static final DXMEvent skip = orEvent(skipForward1,
orEvent(skipBack1,
orEvent(skipForward2, auto)));
| These are aspects of the counter. |
private NumberBvr _counterLimit;
private NumberBvr _initValue = toBvr(0);
start counting at 0
private NumberBvr _value; current value of counter
}
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.
