內部解決法：
重寫ViewPager的dispatchTouchEvent方法判斷滑動傾向

import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;

public class HorizontalViewPager extends ViewPager {
    int lastX = -1;
    int lastY = -1;

    public HorizontalViewPager(Context context) {
        super(context);
    }

    public HorizontalViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        int x = (int) ev.getRawX();
        int y = (int) ev.getRawY();
        int dealtX = 0;
        int dealtY = 0;

        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                getParent().requestDisallowInterceptTouchEvent(true);
                break;
            case MotionEvent.ACTION_MOVE:
                dealtX += Math.abs(x - lastX);
                dealtY += Math.abs(y - lastY);
                lastX = x;
                lastY = y;
                if (dealtX >= dealtY) { // 左右滑動請求父不要需要攔截
                    getParent().requestDisallowInterceptTouchEvent(true);
                } else {
                    getParent().requestDisallowInterceptTouchEvent(false);
                    return false;
                }
                break;
            case MotionEvent.ACTION_CANCEL:
                break;
            case MotionEvent.ACTION_UP:
                break;

        }
        return super.dispatchTouchEvent(ev);
    }