CustomOnPageChangeCallback

import androidx.viewpager2.widget.ViewPager2;

import com.aiyiqi.base.util.LogUtil;

import java.util.function.BiConsumer;

public class CustomOnPageChangeCallback extends ViewPager2.OnPageChangeCallback {

    /**
     * 页面位置偏移回调
     * Boolean    当前滑动页面是和上次滑动页面是否是同一页面  默认滑初始动页面是 0
     * Integer    滑动偏移量 范围 0-1
     **/
    private BiConsumer<Boolean, Float> pageScrolledCallback;

    public CustomOnPageChangeCallback(BiConsumer<Boolean, Float> pageScrolledCallback) {
        this.pageScrolledCallback = pageScrolledCallback;
    }

    /**
     * 上次滑动的页面
     **/
    private int previousPosition = 0;
    /**
     * 当前ViewPager2选中的页面
     **/
    private int currentPosition = 0;

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        super.onPageScrolled(position, positionOffset, positionOffsetPixels);
        boolean b = false;
        if (position == previousPosition) {
            b = true;
        } else if (position < previousPosition) {
            b = false;
        }
        if (pageScrolledCallback != null && positionOffset > 0) {
            pageScrolledCallback.accept(b, positionOffset);
        }
    }

    @Override
    public void onPageSelected(int position) {
        super.onPageSelected(position);
        // 记录当选择新页面时。
        currentPosition = position;
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        super.onPageScrollStateChanged(state);
        if (state == ViewPager2.SCROLL_STATE_IDLE) {
            // 滑动结束
            previousPosition = currentPosition;
        }
    }
}