[android-developers] Re: Multi-touch for a Piano

I think you should first take a look at:
http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent(android.view.MotionEvent)
and here:
http://android.git.kernel.org/?p=platform/frameworks/base.git;a=blob;f=core/java/android/view/ViewGroup.java

I really think that this can be solved on framework level without
changing whole layout.

--
Bart Janusz

On 26 Wrz, 09:48, ArcDroid <jacobrjohn...@gmail.com> wrote:
> Thanks Robert,
> Sure which I could simply use the multitouch with multiple views.
> Looks like I am going to have one heck of a time mapping all the
> locations of the keys.
> Jake
>
> On Sep 6, 10:01 pm, Robert Green <rbgrn....@gmail.com> wrote:
>
>
>
> > ArcDroid,
>
> > I would do the following:
>
> > Mock up the screen in a graphics creation/editing application.  Slice
> > out the parts that you're going to use for your app.
>
> > Create a custom view.  I use surfaceview if it's going to be primary.
>
> > Load all of your assets and draw them to the screen.  Tweak to get it
> > to work right.
>
> > Now write your touch handling code.  Mostly you'll want to look for
> > touch downs (**note on that for multitouch below) and trigger a sound
> > on a touchdown point intersecting a key.
>
> > For multitouch, when the second touch point comes down you won't get a
> > down event but instead will have a move event with 2 touch points in
> > it instead just one.  There is a flaw in the implementation of the API
> > though that no event is sent when the second touch point is lifted.
> > You'll only find out when the first touch point has moved, as the
> > event will have a pointer count of 1 instead of 2 like it did
> > previously.  That may not have much of an impact on your app but
> > knowing to look for the pointer count going from 1 to 2 is key for
> > you.
>
> > A quick and dirty way to implement MT of any number of touches
> > (Remember - some new phones support up to 5 touchpoints) is to keep an
> > array of the keys and their states (up or down).  If touch down or
> > movement is occuring in any of those keys where the state is up, set
> > the state to down and trigger the sound.  If no touch is intersecting
> > a key's bounds, set the state to up.  This also makes for nice
> > rendering since all you have to do is draw an alternate image for the
> > current down keys.
>
> > Good luck and have fun with your app
>
> > On Sep 6, 10:12 pm,ArcDroid<jacobrjohn...@gmail.com> wrote:
>
> > > Hello,
> > > I would like to add multi-touch to my piano app and would like
> > > feedback on the best way to do it.  I hate the idea that multi-touch
> > > is only for one view and not multiple views (ie buttons).
> > > Thanks,
> > > Jake

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