public void Update(GameTime game_time)
{
mCurrentGameTime = game_time;
// cache touches every update in case it's expensive to get
mTouches = Microsoft.Xna.Framework.Input.Touch.TouchPanel.GetState();
// gather what is needed to update triggers first
eContactChange count_change = UpdateTouchCount();
// update state machine last, possibly in new state
mStateMachine.Update(count_change);
}
private eContactChange State_SingleDrag()
{
// we can go quickly to multidrag but if in single drag deliberately, then no
const double k_thresh_seconds = 0.1;
if (mContactCount == eContactCount.Two)
{
double elapsed = mCurrentGameTime.TotalGameTime.TotalSeconds - mSingleDragStartTimeSec;
eContactChange change = (elapsed > k_thresh_seconds) ?
eContactChange.SingleDragToMultiDragTooSlow :
eContactChange.SingleDragToMultiDrag;
return(change);
}
return(eContactChange.NoChange);
}
// state/transition helper functions
private eContactChange UpdateTouchCount()
{
int num_touches = mTouches.Count();
eContactCount prev_contact_count = mContactCount;
eContactChange count_change = eContactChange.NoChange;
eContactCount new_count = num_touches == 5 ? eContactCount.Five :
num_touches == 4 ? eContactCount.Four :
num_touches > 2 ? eContactCount.Many :
num_touches > 1 ? eContactCount.Two :
num_touches > 0 ? eContactCount.One :
eContactCount.Zero;
if (prev_contact_count == eContactCount.Zero)
{
count_change = new_count == eContactCount.One ? eContactChange.ZeroToOne :
new_count == eContactCount.Two ? eContactChange.ZeroToTwo :
new_count == eContactCount.Many ? eContactChange.ZeroToMany :
new_count == eContactCount.Four ? eContactChange.AnyToFour :
new_count == eContactCount.Five ? eContactChange.AnyToFive :
eContactChange.NoChange;
}
else if (prev_contact_count == eContactCount.One)
{
count_change = new_count == eContactCount.Zero ? eContactChange.OneToZero :
new_count == eContactCount.Two ? eContactChange.OneToTwo :
new_count == eContactCount.Many ? eContactChange.OneToMany :
new_count == eContactCount.Four ? eContactChange.AnyToFour :
new_count == eContactCount.Five ? eContactChange.AnyToFive :
eContactChange.NoChange;
}
else if (prev_contact_count == eContactCount.Two)
{
count_change = new_count == eContactCount.Zero ? eContactChange.TwoToZero :
new_count == eContactCount.One ? eContactChange.TwoToOne :
new_count == eContactCount.Many ? eContactChange.TwoToMany :
new_count == eContactCount.Four ? eContactChange.AnyToFour :
new_count == eContactCount.Five ? eContactChange.AnyToFive :
eContactChange.NoChange;
}
else if (prev_contact_count == eContactCount.Many)
{
count_change = new_count == eContactCount.Zero ? eContactChange.ManyToZero :
new_count == eContactCount.One ? eContactChange.ManyToOne :
new_count == eContactCount.Two ? eContactChange.ManyToTwo :
new_count == eContactCount.Four ? eContactChange.AnyToFour :
new_count == eContactCount.Five ? eContactChange.AnyToFive :
eContactChange.NoChange;
}
else if (prev_contact_count == eContactCount.Four)
{
count_change = new_count == eContactCount.Four ? eContactChange.NoChange :
new_count == eContactCount.Zero ? eContactChange.FourToZero :
eContactChange.FourToAnyPositive;
}
else if (prev_contact_count == eContactCount.Five)
{
count_change = new_count == eContactCount.Five ? eContactChange.NoChange :
new_count == eContactCount.Zero ? eContactChange.FiveToZero :
eContactChange.FiveToAnyPositive;
}
else if (prev_contact_count == eContactCount.Unknown)
{
count_change = (new_count == eContactCount.Zero) ?
eContactChange.NoInitialContacts :
eContactChange.InitialContacts;
}
else
{
XUtils.Assert(false);
}
mContactCount = new_count;
return(count_change);
}
