同步使用OnPageChangeListener 2 ViewPagers [英] Synchronizing two ViewPagers using OnPageChangeListener

问题描述

我想同步两个 ViewPager S，因为我之前显然有相当多的人了，我得尽可能的：

I'm trying to synchronize two ViewPagers, as apparently have quite a lot of people before me, and I've got as far as this:

private ViewPager mNavPager;

private ViewPager mMainPager;

private final OnPageChangeListener mNavPagerListener = new OnPageChangeListener() {

    private boolean mNavDragging;
    private int mScrollPosition;

    @Override
    public void onPageSelected(int position) {
        mScrollPosition = position;
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        if(mNavDragging)
            mMainPager.scrollTo(positionOffsetPixels, 0);
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        switch(state) {
        case ViewPager.SCROLL_STATE_DRAGGING:
        case ViewPager.SCROLL_STATE_SETTLING:
            mNavDragging = true;
            break;
        case ViewPager.SCROLL_STATE_IDLE:
            mNavDragging = false;
            break;
        }
    }
};

private OnPageChangeListener mMainPagerListener = new OnPageChangeListener() {

    private boolean mMainDragging;
    private int mScrollPosition;

    @Override
    public void onPageSelected(int position) {
        mScrollPosition = position;
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        if(mMainDragging)
            mNavPager.scrollTo(positionOffsetPixels, 0);
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        switch(state) {
        case ViewPager.SCROLL_STATE_DRAGGING:
        case ViewPager.SCROLL_STATE_SETTLING:
            mMainDragging = true;
            break;
        case ViewPager.SCROLL_STATE_IDLE:
            mMainDragging = false;
            break;
        }
    }
};

如果其中任何一个手动滚动，另一种是采用滚动国家财产从属于它。它精美的作品，直到项目达到其最终位置;在这点上，从属寻呼机笔触即刻回pviously选择的项目，仿佛滚动没有发生的$ P $

If either one is scrolled manually, the other is slaved to it using the scroll state property. It works beautifully till the items reach their final position; at this point, the slaved pager flicks instantly back to the previously selected item, as though the scrolling hadn't taken place.

我已经打过电话 ViewPager＃setCurrentItem（mScrolledPosition）与各种不同的逻辑约束，但是这也不行，尽管它偶尔使情况变得更糟。我觉得好像一定有​​东西，可以与该做，但我不知道是什么。

I have tried calling ViewPager#setCurrentItem(mScrolledPosition) with a variety of different logic constraints but that doesn't work either, though it does occasionally make it worse. I feel as though there must be something that can be done with that but I'm not sure what.

我怎样才能获得从属于寻呼机保持在正确的位置？

How can I get the slaved pager to remain in the correct position?

推荐答案

我使用OnPageChangeListener在一个更容易（和更清洁的）的方式解决了这个问题：

I solved this problem in a much easier (and cleaner) way using the OnPageChangeListener:

mViewPager1.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

      private int mScrollState = ViewPager.SCROLL_STATE_IDLE;

      @Override
      public void onPageScrolled(final int position, final float positionOffset, final int positionOffsetPixels) {
        if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
          return;
        }
        mViewPager2.scrollTo(mViewPager1.getScrollX(), mViewPager2.getScrollY());
      }

      @Override
      public void onPageSelected(final int position) {

      }

      @Override
      public void onPageScrollStateChanged(final int state) {
        mScrollState = state;
        if (state == ViewPager.SCROLL_STATE_IDLE) {
          mViewPager2.setCurrentItem(mViewPager1.getCurrentItem(), false);
        }
      }
});

mViewPager2.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

      private int mScrollState = ViewPager.SCROLL_STATE_IDLE;

      @Override
      public void onPageScrolled(final int position, final float positionOffset, final int positionOffsetPixels) {
        if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
          return;
        }
        mViewPager1.scrollTo(mViewPager2.getScrollX(), mViewPager1.getScrollY());
      }

      @Override
      public void onPageSelected(final int position) {

      }

      @Override
      public void onPageScrollStateChanged(final int state) {
        mScrollState = state;
        if (state == ViewPager.SCROLL_STATE_IDLE) {
          mViewPager1.setCurrentItem(mViewPager2.getCurrentItem(), false);
        }
      }
});

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