Colin,
Wow!
I am working on using multitouch for a game and remain equally
confused by similar behavior and will be anxious to see how this is
resolved. So far the answer has eluded me too, sigh...
Thanks for positing such a clear explain. Maybe a Google person will
get involved.
On Jan 6, 12:41 am, Mirmathrax <mirmath...@gmail.com> wrote:
> OK, So I have been racking my brain to try to figure out what is going
> wrong here. I wanted to experiment with multi-touch, so I decided to
> add the controls for LunarLander to the touchscreen.
>
> Instead of adding buttons, I defined regions on the screen that when
> touched, would act like the buttons on the keyboard (for example, the
> gas fires as long as you press the screen in the area defined for the
> gas button, and stops firing when you release.)
>
> To do this, I added the onTouchEvent override to the LunarView class
> as follows:
>
> /**
> * Standard override to get Touch Screen Events.
> */
> @Override
> public boolean onTouchEvent(MotionEvent event) {
> return thread.doTouchScreen(event);
> }
>
> Then, I added a function to the LunarThread called doTouchScreen. I
> also added variables to define the boundaries of the touch areas on
> the screen for the "buttons" The boundaries are defined as follows and
> placed in the variable declaration location of the LunarThread:
>
> //* Y boundary of left and right turn button **/
> private float TurnButton_Y;
>
> //* X Boundary of the fire Button (left side of button)
> private float fireButton_X;
>
> //* X boundary of left turn button **/
> private float leftTurnButton_X = 100;
>
> //* X boundary of right turn button **/
> private float rightTurnButton_X = 200;
>
> The doTouchScreen code is the following:
>
> boolean doTouchScreen(MotionEvent event) {
>
> boolean handled = true;
>
> synchronized (mSurfaceHolder) {
>
> int numevents = event.getPointerCount();
> int action = event.getAction();
> int ptrId = event.getPointerId(0);
>
> if(numevents > 1)
> ptrId = (action & MotionEvent.ACTION_POINTER_ID_MASK)
>
>
>
> MotionEvent.ACTION_POINTER_ID_SHIFT;
> action = action & MotionEvent.ACTION_MASK;
>
> int ptrIndex = event.findPointerIndex(ptrId);
>
> float X = event.getX(ptrIndex);
> float Y = event.getY(ptrIndex);
>
> if(action == event.ACTION_DOWN || action ==
> event.ACTION_MOVE)
> {
> if(Y > TurnButton_Y)
> {
> if(X < leftTurnButton_X)
> {
> mRotating = -1;
> turnButtonID = ptrId;
> }
> else if (X < rightTurnButton_X)
> {
> mRotating = 1;
> turnButtonID = ptrId;
> }
> else if (X > fireButton_X)
> {
> setFiring(true);
> gasButtonID = ptrId;
> }
>
> handled = true;
> }
> handled = true;
> }
> else if(action == event.ACTION_UP || action ==
> event.ACTION_CANCEL)
> {
>
> if(gasButtonID == ptrId)
> {
> setFiring(false);
> gasButtonID = -1;
> handled = true;
> }
> if(turnButtonID == ptrId)
> {
> mRotating = 0;
> turnButtonID = -1;
> handled = true;
> }
> handled = true;
> }
>
> }
> return handled;
> }
>
> During testing I found consistent problems when performing the
> following pattern:
>
> 1) Touch finger 1 down on gas button area
> 2) Touch finger 2 down on turn button area
> 3) Lift finger 1 off of gas button
> 4) Touch finger 1 back on to gas button
>
> The problem is that after performing this pattern, the gas button
> fails to work. Lifting the gas button and then placing it down a
> third time causes the button to work again. This is consistent every
> time I try this. Debugging yielded the following strange results:
>
> 1) Finger 1 goes down at location X, Y.
> X = X
> Y = Y
> action = ACTION_DOWN,
> ptrID = 0
> ptrIndex = 0
> numEvents = 1
> 2) Finger 2 goes down at location X2, Y2.
> X = X2
> Y = Y2
> action = ACTION_POINTER_DOWN
> ptrID = 1
> ptrIndex = 1
> numEvents = 2
> 3) Finger 1 goes up
> X = X
> Y = Y
> action = ACTION_POINTER_UP
> ptrID = 0
> ptrIndex = 0
> numEvents = 2
>
> So far, so good...
>
> 4) Finger 1 goes back down at location X, Y
> X = X2
> Y = Y2
> action = ACTION_POINTER_DOWN
> ptrID = 0
> ptrIndex = 0
> numEvents = 2
>
> ****** Here is the first problem: The X and Y coordinates returned
> are incorrect, they are the coordinates for the other finger (finger
> 2). When finger 1 was removed, finger 2's data moved to the 0 index,
> but it still retained ID 1. When finger 1 went back down, it
> correctly was identified as ID 0, but instead of adding a new index
> for finger 1 data, it just returns index 0, which is finger 2's
> data!
>
> 5) Lift Finger 1 back up again from location X, Y
> X = X2
> Y= Y2
> action = ACTION_POINTER_UP
> ptrIndex = 1
> ptrID = 1
> numEvents = 2
>
> *** WHATWHAT?!? I lifted finger 1 up, which should be ID 0, why is
> ID 1 reporting that it goes up. Also, why is it given data index 1,
> which I would assume should be finger 1's data, but the coordinates
> are still those of finger 2. Yes, I have a headache too...
>
> 6) Place Finger 1 back on the screen at location X, Y. Again...
> X = X
> Y = Y
> action = ACTION_POINTER_DOWN
> ptrIndex = 1
> ptrID = 1
> numEvents = 2
>
> OK, now finger 1 has taken ID 1, which originally belonged to finger
> 2. Keep in mind, this whole time, Finger 2 has NEVER moved. It
> should still have ID 1 if I understand correctly, only the data
> indexes should change. This behavior is not consistent with the
> documentation. And wait, it gets better....
>
> 7) Remove Finger 1 from location X, Y for the last time
> X = X
> Y = Y
> action = ACTION_POINTER_UP
> ptrIndex = 1
> ptrID = 1
> numEvents = 2
>
> This looks good. But what about finger 2 which should still have ID
> 1, but apparently does not.
>
> 8) Remove Finger 2 from location X2, Y2
> X = X2
> Y = Y2
> action = ACTION_UP
> ptrIndex = 0
> ptrID = 0
> numEvents = 1
>
> So, even though finger 2 went down second and was originally assigned
> ID 1, it somehow magically has ID 0, and the correct data at index 0.
> I am perfuddled. Or maybe stupifused. Any insight into what I might
> be doing wrong, or if I am indeed NOT crazy would be greatly greatly
> appreciated.
>
> I know this is a long note so I pray that some of you have the
> gumption to read the whole thing and give it a try yourself to see if
> you can duplicate my results. This was all debugged on a live DROID,
> connected to the PC via a USB cable.
>
> Thanks in advance to any who may help, or just console me.
>
> -Colin
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