Android--Velocitytracker

Velocitytracker

Primarily for touch event, Velocitytracker calculates the current speed in real time by tracking a sequence of events.

Method

//get a Velocitytracker object and remember to recycle it when you're done with it//After recycling means that you do not need to use, the system will assign this object to other requestersStatic  PublicVelocitytracker obtain ();  Public voidrecycle (); //calculates the current speed, where units is expressed in units, 1 for px/milliseconds, and 1000 for px/seconds. //maxvelocity The maximum value you want for this calculation speed Public voidComputecurrentvelocity (intUnitsfloatmaxvelocity); //after a computecurrentvelocity, you can use a few methods to get the value of this calculation.//The ID is the ID of the touch event point of contact, which is used to identify the multitouch , which can be ignored when calculating//other contact interference, of course, there must be interference. Public floatgetxvelocity ();  Public floatgetyvelocity ();  Public floatGetxvelocity (intID);  Public floatGetyvelocity (intID);

Code

 Public classVelocitytrackertestextendsActivity {PrivateTextView MInfo; PrivateVelocitytracker Mvelocitytracker; Private intmmaxvelocity; Private intMpointerid; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate); MInfo=NewTextView ( This); Minfo.setlines (4); Minfo.setlayoutparams (Newlayoutparams (layoutparams.fill_parent, layoutparams.fill_parent));            Minfo.settextcolor (Color.White);            Setcontentview (MInfo); Mmaxvelocity= Viewconfiguration.get ( This). Getmaximumflingvelocity (); } @Override Public Booleanontouchevent (Motionevent event) {if(NULL==Mvelocitytracker) {Mvelocitytracker=Velocitytracker.obtain ();          } mvelocitytracker.addmovement (event); FinalVelocitytracker Vertracker =Mvelocitytracker; Switch(Event.getaction ()) { CaseMotionevent.action_down://the ID of the first contact, there may be multiple contacts at this point, but at least oneMpointerid = Event.getpointerid (0);  Break;  CaseMotionevent.action_move://seeking pseudo-instantaneous velocityVertracker.computecurrentvelocity (1000, mmaxvelocity); floatVelocityx =vertracker.getxvelocity (Mpointerid); floatVelocityy =vertracker.getyvelocity (Mpointerid);                  Recodeinfo (Velocityx, velocityy);  Break;  Casemotionevent.action_up: CaseMotionevent.action_cancel:if(NULL!=Mvelocitytracker)                {mvelocitytracker.clear ();                Mvelocitytracker.recycle (); Mvelocitytracker=NULL; }                    Break; default:                   Break; }          return Super. Ontouchevent (event); }          Private Static FinalString sformatstr = "Velocityx=%f\nvelocityy=%f"; /*** Record Current speed * *@paramVelocityx X-Axis speed *@paramvelocityy y-axis speed*/      Private voidRecodeinfo (Final floatVelocityx,Final floatvelocityy) {          FinalString info =String.Format (Sformatstr, Velocityx, velocityy);      Minfo.settext (info); }  }

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Reference: http://blog.csdn.net/bingxianwu/article/details/7446799

Android--Velocitytracker