package com.contrarywind.timer;
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import com.contrarywind.view.WheelView;
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import java.util.TimerTask;
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/**
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* 平滑滚动的实现
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*
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* @author 小嵩
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*/
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public final class SmoothScrollTimerTask extends TimerTask {
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private int realTotalOffset;
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private int realOffset;
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private int offset;
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private final WheelView wheelView;
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public SmoothScrollTimerTask(WheelView wheelView, int offset) {
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this.wheelView = wheelView;
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this.offset = offset;
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realTotalOffset = Integer.MAX_VALUE;
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realOffset = 0;
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}
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@Override
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public final void run() {
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if (realTotalOffset == Integer.MAX_VALUE) {
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realTotalOffset = offset;
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}
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//把要滚动的范围细分成10小份，按10小份单位来重绘
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realOffset = (int) ((float) realTotalOffset * 0.1F);
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if (realOffset == 0) {
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if (realTotalOffset < 0) {
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realOffset = -1;
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} else {
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realOffset = 1;
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}
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}
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if (Math.abs(realTotalOffset) <= 1) {
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wheelView.cancelFuture();
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wheelView.getHandler().sendEmptyMessage(MessageHandler.WHAT_ITEM_SELECTED);
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} else {
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wheelView.setTotalScrollY(wheelView.getTotalScrollY() + realOffset);
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//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
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if (!wheelView.isLoop()) {
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float itemHeight = wheelView.getItemHeight();
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float top = (float) (-wheelView.getInitPosition()) * itemHeight;
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float bottom = (float) (wheelView.getItemsCount() - 1 - wheelView.getInitPosition()) * itemHeight;
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if (wheelView.getTotalScrollY() <= top || wheelView.getTotalScrollY() >= bottom) {
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wheelView.setTotalScrollY(wheelView.getTotalScrollY() - realOffset);
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wheelView.cancelFuture();
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wheelView.getHandler().sendEmptyMessage(MessageHandler.WHAT_ITEM_SELECTED);
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return;
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}
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}
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wheelView.getHandler().sendEmptyMessage(MessageHandler.WHAT_INVALIDATE_LOOP_VIEW);
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realTotalOffset = realTotalOffset - realOffset;
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}
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}
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}
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