This has been discussed multiple times since last ~15months. The basic assumption a "middle-point" when touching with 2 fingers might be anyway exactly in the middle is incorrect. It depends on pressure of each touchpoint. There have been many different opinions about feasibility of this approach, I for one think it won't work.
cheers jOERG Am Do 19. März 2009 schrieb Yaroslav Halchenko: > Hi All, > > I've been cherishing the idea for a while but got no spare time to even > code a proof of concept. so I decided to share it with you so someone > could do that for the common advantage ;) > > Indeed we can't register both touches -- as a result hardware returns > midpoint. BUT what if > > you touch screen with two fingers (at some inter-finger distance like > half of screen width) not at the same time but within > lets say 100-200ms. Ie you "click" with one finger just slightly before > the other one. > > then driver reports 2 coordinates where there is a significant > immediate jump from first coordinate to the midpoint between the two, > which would be as much as 1/2 of distance between the fingers. > > such behavior would signal that 2 fingers are on the screen! > > then if you move 2nd finger somewhere, midpoint would move and that > movement can be taken as a multitouch gesture, ie if you are expanding > 2nd finger away from first one -- it is like 'zoom-out' or increase of > smth. analogously, by comparing to the first coordinate (of 1st finger) > rotations / horizontal zoomin/ vertical zooming etc could be derived > > multitouch gesture mode would stop when fingers leave the screen or > there is once again a singificant jump from prev coordinate (like you > raise one finger up prior to the other one) > > alternative mode can be that after 'two finger' non-synchroneous touch > which switches to "multitouch mode" you drive your gesture with only > second finger (ie raise the first one off the screen) -- that would > allow for better control over the gesture since no averaging of > coordinates between two points would happen. And again, multitouch mode > is left whenever finger is raised of the screen. > > if someone is to implement/test such approach, qwo might be a nice code > base to start from... alternatively I guess tslib for those with > debian+fbdev xserver. > > -- > .-. > =------------------------------ /v\ ----------------------------= > Keep in touch // \\ (yoh@|www.)onerussian.com > Yaroslav Halchenko /( )\ ICQ#: 60653192 > Linux User ^^-^^ [175555] > > > > _______________________________________________ > Openmoko community mailing list > [email protected] > http://lists.openmoko.org/mailman/listinfo/community >
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