SmoothScrollTimerTask.java
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package com.contrarywind.timer;
import com.contrarywind.view.WheelView;
import java.util.TimerTask;
/**
* 平滑滚动的实现
*
* @author 小嵩
*/
public final class SmoothScrollTimerTask extends TimerTask {
private int realTotalOffset;
private int realOffset;
private int offset;
private final WheelView wheelView;
public SmoothScrollTimerTask(WheelView wheelView, int offset) {
this.wheelView = wheelView;
this.offset = offset;
realTotalOffset = Integer.MAX_VALUE;
realOffset = 0;
}
@Override
public final void run() {
if (realTotalOffset == Integer.MAX_VALUE) {
realTotalOffset = offset;
}
//把要滚动的范围细分成10小份，按10小份单位来重绘
realOffset = (int) ((float) realTotalOffset * 0.1F);
if (realOffset == 0) {
if (realTotalOffset < 0) {
realOffset = -1;
} else {
realOffset = 1;
}
}
if (Math.abs(realTotalOffset) <= 1) {
wheelView.cancelFuture();
wheelView.getHandler().sendEmptyMessage(MessageHandler.WHAT_ITEM_SELECTED);
} else {
wheelView.setTotalScrollY(wheelView.getTotalScrollY() + realOffset);
//这里如果不是循环模式，则点击空白位置需要回滚，不然就会出现选到－1 item的 情况
if (!wheelView.isLoop()) {
float itemHeight = wheelView.getItemHeight();
float top = (float) (-wheelView.getInitPosition()) * itemHeight;
float bottom = (float) (wheelView.getItemsCount() - 1 - wheelView.getInitPosition()) * itemHeight;
if (wheelView.getTotalScrollY() <= top || wheelView.getTotalScrollY() >= bottom) {
wheelView.setTotalScrollY(wheelView.getTotalScrollY() - realOffset);
wheelView.cancelFuture();
wheelView.getHandler().sendEmptyMessage(MessageHandler.WHAT_ITEM_SELECTED);
return;
}
}
wheelView.getHandler().sendEmptyMessage(MessageHandler.WHAT_INVALIDATE_LOOP_VIEW);
realTotalOffset = realTotalOffset - realOffset;
}
}
}