Android弹性滑动

1、View使用Scroller滑动

/**

*在scroller.startScroll()方法中，会将scrollX和deltaX相加存入mFinalX中

*invalidate()方法会调用draw()方法，draw()会调用computeScroll()方法，而在View

*中computeScroll()方法是空实现，所以要复写该方法，在方法中调用

*scrollTo(scroller.getCurrX(),scroller.getCurrY()),又因为getCurrX()方法返回的是mFinalX

*的值，调用postInvalidate()方法进行第二次重绘实现view的刷新

*/

Scrollerscroller=newScroller(mContext);

privatevoidsmoothScrollTo(intdestX,intdestY){

intscrollX=getScrollX();

intdeltaX=destX-scrollX;

//1000ms内滑向destX，效果就是慢慢滑动

scroller.startScroll(scrollX,0,deltaX,0,1000);

invalidate();

}

@Override

publicvoidcomputeScroll(){

if(scroller.computeScrollOffset()){

scrollTo(scroller.getCurrX(),scroller.getCurrY());

postInvalidate();

}

}

2、使用动画

finalintstartX=0;

finalintdeltaX=100;

finalButtonmButton=newButton(mContext);

ValueAnimatoranimator=ValueAnimator.ofInt(0,1).setDuration(1000);

animator.addUpdateListener(newValueAnimator.AnimatorUpdateListener(){

@Override

publicvoidonAnimationUpdate(ValueAnimatoranimator){

floatfraction=animator.getAnimatedFraction();

mButton.scrollTo(startX+(int)(deltaX*fraction),0);

}

});

animator.start();

3、使用延时加载Handler

privatestaticfinalintMESSAGE_SCROLL_TO=1;

privatestaticfinalintFRAME_COUNT=30;

privatestaticfinalintDELAYED_TIME=33;

privateintmCount=0;

privateButtonmButton;

privateHandlermHandler=newHandler(){

@Override

publicvoidhandleMessage(Messagemsg){

switch(msg.what){

caseMESSAGE_SCROLL_TO:

mCount++;

if(mCount<=FRAME_COUNT){

floatfraction=mCount/(float)FRAME_COUNT;

intscrollX=(int)(fraction*100);

mButton.scrollTo(scrollX,0);

mHandler.sendEmptyMessageDelayed(MESSAGE_SCROLL_TO,DELAYED_TIME);

}

break;

}

}

};