I learned a little bit about it today. Velocitytracker, which is used to monitor gesture speed, can have a buffered movement during the view movement. I think the initial use is very simple.
The first move depends on the Scroller class, Scroller has a fling method, the motionevent up after the detection of the gesture speed provided to scroller, you can complete their own scrolling. 1. Initialize some of the variables:Private voidinit (Context context) { Mscroller = new Scroller (GetContext ()); Final viewconfiguration configuration = viewconfiguration. Get (context); mminimumvelocity = configuration.getscaledminimumflingvelocity (); mmaximumvelocity = configuration.getscaledmaximumflingvelocity (); }
Configuration.getscaledtouchslop ()//Get the distance you can swipe with gestures
configuration.getscaledminimumflingvelocity ()//Get the minimum speed value allowed to perform a fling gesture action
configuration.getscaledmaximumflingvelocity ()//Get the maximum speed value allowed to perform a fling gesture action
2. Handling In touch events:@Override Public boolean ontouchevent(motionevent event) { Obtainvelocitytracker (event); InitializeMvelocitytracker int action = event.getaction (); Switch (action) {Case motionevent. Action_down: Starty = event.gety (); if (mscroller. isfinished ()) { mscroller. abortanimation (); }Break ; Case motionevent. action_move: //pseudo-instantaneous speed float movey = event.gety ();scrollTo (0, (int) (getscrolly () + (starty -Movey)); Starty = event.gety ();Break ; Case motionevent. action_up: final velocitytracker velocitytracker = Mvelocitytracker; velocitytracker.computecurrentvelocity ( mmaximumvelocity); int initialvelocity = (int) velocitytracker.getyvelocity (); Get the speed of the y-axis if (Math. ABS(initialvelocity) > mminimumvelocity) && getchildcount () > 0) {Fling (-initialvelocity); Start scrolling } Case motionevent. action_cancel:Releasevelocitytracker (); To releaseBreak ; } return true; }
/*** ReleaseMvelocitytracker */ private void releasevelocitytracker () { if(null ! = Mvelocitytracker) { Mvelocitytracker. Clear (); mvelocitytracker. Recycle (); Mvelocitytracker = null; } }
/*** Release Initialization */ private void Obtainvelocitytracker (motionevent event) { if(null = = Mvelocitytracker) { Mvelocitytracker = Velocitytracker. obtain (); } mvelocitytracker. Addmovement (event); }
The down and move events are simple follow gestures moving, and the main event handling is in the up. The scrolling event handling is in the Fling method: public void Fling (int velocityy) { Mscroller. Fling (Getscrollx (), getscrolly (), 0, velocityy, 0, 0,-1080, 0); is a way of scroller, very simple. awakenscrollbars (mscroller. getduration ()); invalidate (); }
Fling (Getscrollx (), getscrolly (), 0, velocityy, 0, 0, -1080, 0);
Min y Max y
My demo is just a simple scroll on the y-axis, so I set the minimum maximum movement distance on the y axis. The minimum y Max y is said to be scrolly this property. There are scroller this class. The Computscroll method is indispensable. public void computescroll () { if (mscroller. Computescrolloffset ()) { int x = mscroller. Getcurrx (); int y = mscroller. Getcurry (); scrollTo (x, y); postinvalidate (); } }
My github address: https://github.com/flyme2012 My blog address: http://www.cnblogs.com/flyme2012/
From for notes (Wiz)
The Velocitytracker of Android learning
