OnScrollListenerPro

OnScrollListenerPro

————OnScrollListener 增強版

@[Android|ListView|OnScrollListener]

---

在寫listview的時候很時候咱們都會遇到一些場景

1. 判斷當前是向上滾動，精確到px
2. 判斷是否滾動到最後一個

可是Android提供給咱們的OnScrollView不能給咱們提供這些功能
因而我寫了一個OnScrollListenerPro來完成這樣的事情

package org.hangox.test;

import android.view.View;
import android.widget.AbsListView;

/**
 * Created With Android Studio
 * User 47
 * Date 2014-11-03
 * Time 17:42
 * 一個增強板的OnScrollListener
 * 能夠提供向上滑動向下活動檢測
 * 是不是最後一個檢測
 */
public class OnScrollListenerPro implements AbsListView.OnScrollListener {
    private AbsListView mAbsListView;
    private int mLimit = 40;
    private int mLastScroll;
    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        mAbsListView = view;
    }

    /**
     * 設定最少滾動多少纔算是滾動
     * @param mLimit
     */
    public void setLimit(int mLimit){
        this.mLimit = mLimit;
    }
    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        mAbsListView = view;
        int currentScrollY = getScrollY();
        int dValue = currentScrollY - mLastScroll;
        if(dValue < -mLimit){//向上滾
            onScrollUp(mLastScroll,currentScrollY);
            mLastScroll = currentScrollY;
        }else if(dValue > mLimit ){//向下滾
            onScrollDown(mLastScroll,currentScrollY);
            mLastScroll = currentScrollY;
        }
        if(((totalItemCount > 0) && (firstVisibleItem + visibleItemCount >= totalItemCount - 1)))
            onLastItemShow();
    }

    /**
     * 向上滾動
     * @param lastScroll
     * @param currentScroll
     */
    public void onScrollUp(int lastScroll,int currentScroll){

    }


    /**
     * 向下滾動
     * @param lastScroll 上一次滾動值
     * @param currentScroll 這一次
     */
    public void onScrollDown(int lastScroll,int currentScroll){

    }

    public void onLastItemShow(){

    }



    public int getScrollY() {//獲取滾動距離
        View c = mAbsListView.getChildAt(0);
        if (c == null) {
            return 0;
        }

        int firstVisiblePosition = mAbsListView.getFirstVisiblePosition();
        int top = c.getTop();

        int headerHeight = 0;
        if (firstVisiblePosition >= 1) {
            headerHeight = mAbsListView.getHeight();
        }
        return -top + firstVisiblePosition * c.getHeight() + headerHeight;
    }
}

使用很簡單，重寫其中的函數就能夠了