仿IOS效果 带弹簧动画的ListView

最近项目打算做一个界面,类似于dayone首页的界面效果,dayone 是一款付费应用,目前只有ios端。作为一个资深懒惰的程序员，奉行的宗旨是绝对不重复造一个*。于是乎，去网上找一大堆开源项目，发现没有找到合适的，然后，只能硬着头皮自己来了。先看看效果：

效果图

其实写起来也比较简单，就是控制listview的头部和底部的高度就可以了, 如果用recycleview实现起来也是一样,只是recycleview添加头和尾巴稍微麻烦一点,处理点击事件也不是很方便,所以就基于listview去实现了。实现的代码， 我已经上传到github上了。

1、使用方法

compile 'com.a520wcf.yllistview:yllistview:1.0.1

2、使用介绍:
1）、布局:
布局注意一个小细节android:layout_height 最好是match_parent, 否则listview每次滑动的时候都有可能需要重新计算条目高度,比较耗费cpu;

 <com.a520wcf.yllistview.yllistview 
 android:divider="@android:color/transparent"
 android:id="@+id/listview" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" />

2）、代码:

 private yllistview listview;
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);
  listview = (yllistview) findviewbyid(r.id.listview);
  // 不添加也有默认的头和底
  view topview=view.inflate(this,r.layout.top,null);
  listview.addheaderview(topview);
  view bottomview=new view(getapplicationcontext());
  listview.addfooterview(bottomview);

  // 顶部和底部也可以固定最终的高度 不固定就使用布局本身的高度
  listview.setfinalbottomheight(100);
  listview.setfinaltopheight(100);

  listview.setadapter(new demoadapter());

  //yllistview默认有头和底 处理点击事件位置注意减去
  listview.setonitemclicklistener(new adapterview.onitemclicklistener() {
   @override
   public void onitemclick(adapterview<?> parent, view view, int position, long id) {
    position=position-listview.getheaderviewscount();
   }
  });
 }

3、源码介绍
其实这个项目里面只有一个类,大家不需要依赖,直接把这个类复制到项目中就可以了,来看看源码:

package com.a520wcf.yllistview;

import android.content.context;
import android.util.attributeset;
import android.view.motionevent;
import android.view.view;
import android.view.viewtreeobserver.ongloballayoutlistener;
import android.view.animation.decelerateinterpolator;
import android.widget.abslistview;
import android.widget.listview;
import android.widget.scroller;

public class yllistview extends listview implements abslistview.onscrolllistener {
 private scroller mscroller; // used for scroll back
 private float mlasty = -1;

 private int mscrollback;
 private final static int scrollback_header = 0;
 private final static int scrollback_footer = 1;

 private final static int scroll_duration = 400; // scroll back duration
 private final static float offset_radio = 1.8f;
 // total list items, used to detect is at the bottom of listview.
 private int mtotalitemcount;
 private view mheaderview; // 顶部图片
 private view mfooterview; // 底部图片
 private int finaltopheight;
 private int finalbottomheight;

 public yllistview(context context) {
  super(context);
  initwithcontext(context);
 }

 public yllistview(context context, attributeset attrs) {
  super(context, attrs);
  initwithcontext(context);
 }

 public yllistview(context context, attributeset attrs, int defstyle) {
  super(context, attrs, defstyle);
  initwithcontext(context);
 }

 private void initwithcontext(context context) {
  mscroller = new scroller(context, new decelerateinterpolator());
  super.setonscrolllistener(this);

  this.getviewtreeobserver().addongloballayoutlistener(
    new ongloballayoutlistener() {
     @override
     public void ongloballayout() {
      if(mheaderview==null){
       view view=new view(getcontext());
       addheaderview(view);
      }
      if(mfooterview==null){
       view view=new view(getcontext());
       addfooterview(view);
      }
      getviewtreeobserver()
        .removeglobalonlayoutlistener(this);
     }
    });
 }

 @override
 public boolean ontouchevent(motionevent ev) {
  if (mlasty == -1) {
   mlasty = ev.getrawy();
  }
  switch (ev.getaction()) {
   case motionevent.action_down:
    mlasty = ev.getrawy();
    break;
   case motionevent.action_move:
    final float deltay = ev.getrawy() - mlasty;
    mlasty = ev.getrawy();
    if (getfirstvisibleposition() == 0 && (mheaderview.getheight() > finaltopheight || deltay > 0)
      && mheaderview.gettop() >= 0) {
     // the first item is showing, header has shown or pull down.
     updateheaderheight(deltay / offset_radio);
    } else if (getlastvisibleposition() == mtotalitemcount - 1
      && (getfootheight() >finalbottomheight || deltay < 0)) {
     updatefooterheight(-deltay / offset_radio);
    }
    break;
   default:
    mlasty = -1; // reset
    if (getfirstvisibleposition() == 0 && getheaderheight() > finaltopheight) {
     resetheaderheight();
    }
    if (getlastvisibleposition() == mtotalitemcount - 1 ){
      if(getfootheight() > finalbottomheight) {
       resetfooterheight();
      }
    }
    break;
  }
  return super.ontouchevent(ev);
 }

 /**
  * 重置底部高度
  */
 private void resetfooterheight() {
  int bottomheight = getfootheight();
  if (bottomheight > finalbottomheight) {
   mscrollback = scrollback_footer;
   mscroller.startscroll(0, bottomheight, 0, -bottomheight+finalbottomheight,
     scroll_duration);
   invalidate();
  }
 }
 // 计算滑动 当invalidate()后 系统会自动调用
 @override
 public void computescroll() {
  if (mscroller.computescrolloffset()) {
   if (mscrollback == scrollback_header) {
    setheaderheight(mscroller.getcurry());
   } else {
    setfooterviewheight(mscroller.getcurry());
   }
   postinvalidate();
  }
  super.computescroll();
 }
 // 设置顶部高度
 private void setheaderheight(int height) {
  layoutparams layoutparams = (layoutparams) mheaderview.getlayoutparams();
  layoutparams.height = height;
  mheaderview.setlayoutparams(layoutparams);
 }
 // 设置底部高度
 private void setfooterviewheight(int height) {
  layoutparams layoutparams =
    (layoutparams) mfooterview.getlayoutparams();
  layoutparams.height =height;
  mfooterview.setlayoutparams(layoutparams);
 }
 // 获取顶部高度
 public int getheaderheight() {
  abslistview.layoutparams layoutparams =
    (abslistview.layoutparams) mheaderview.getlayoutparams();
  return layoutparams.height;
 }
 // 获取底部高度
 public int getfootheight() {
  abslistview.layoutparams layoutparams =
    (abslistview.layoutparams) mfooterview.getlayoutparams();
  return layoutparams.height;
 }

 private void resetheaderheight() {
  int height = getheaderheight();
  if (height == 0) // not visible.
   return;
  mscrollback = scrollback_header;
  mscroller.startscroll(0, height, 0, finaltopheight - height,
    scroll_duration);
  invalidate();
 }

 /**
  * 设置顶部高度 如果不设置高度,默认就是布局本身的高度
  * @param height 顶部高度
  */
 public void setfinaltopheight(int height) {
  this.finaltopheight = height;
 }
 /**
  * 设置底部高度 如果不设置高度,默认就是布局本身的高度
  * @param height 底部高度
  */
 public void setfinalbottomheight(int height){
  this.finalbottomheight=height;
 }
 @override
 public void addheaderview(view v) {
  mheaderview = v;
  super.addheaderview(mheaderview);
  mheaderview.getviewtreeobserver().addongloballayoutlistener(
    new ongloballayoutlistener() {
     @override
     public void ongloballayout() {
      if(finaltopheight==0) {
       finaltopheight = mheaderview.getmeasuredheight();
      }
      setheaderheight(finaltopheight);
      getviewtreeobserver()
        .removeglobalonlayoutlistener(this);
     }
    });
 }

 @override
 public void addfooterview(view v) {
  mfooterview = v;
  super.addfooterview(mfooterview);

  mfooterview.getviewtreeobserver().addongloballayoutlistener(
    new ongloballayoutlistener() {
     @override
     public void ongloballayout() {
      if(finalbottomheight==0) {
       finalbottomheight = mfooterview.getmeasuredheight();
      }
      setfooterviewheight(finalbottomheight);
      getviewtreeobserver()
        .removeglobalonlayoutlistener(this);
     }
    });
 }

 private onscrolllistener mscrolllistener; // user's scroll listener

 @override
 public void setonscrolllistener(onscrolllistener l) {
  mscrolllistener = l;
 }

 @override
 public void onscrollstatechanged(abslistview view, int scrollstate) {
  if (mscrolllistener != null) {
   mscrolllistener.onscrollstatechanged(view, scrollstate);
  }
 }

 @override
 public void onscroll(abslistview view, int firstvisibleitem,
       int visibleitemcount, int totalitemcount) {
  // send to user's listener
  mtotalitemcount = totalitemcount;
  if (mscrolllistener != null) {
   mscrolllistener.onscroll(view, firstvisibleitem, visibleitemcount,
     totalitemcount);
  }
 }

 private void updateheaderheight(float delta) {
  setheaderheight((int) (getheaderheight()+delta));
  setselection(0); // scroll to top each time
 }

 private void updatefooterheight(float delta) {
  setfooterviewheight((int) (getfootheight()+delta));

 }
}

以上就是本文的全部内容，希望对大家的学习有所帮助。