Android实现滑动删除操作（PopupWindow）

参考android仿腾讯qq实现滑动删除这篇文章进行学习，文章实现的功能是:在listview的item上从右向左滑时，出现删除按钮，点击删除按钮把item删除，效果

看过文章后，感觉没有必要把dispatchtouchevent()和ontouchevent()两个方法都重写，只要重写ontouchevent就好了。于是对代码作了一些调整： 

public class mylistview extends listview {
 private static final string tag = "mylistview";
 private int mtouchslop;
 private int mxdown;
 private int mydown;
 private int mcurrentposition;
 private view mcurrentview;
 private popupwindow mpopupwindow;
 private layoutinflater minflater;
 private boolean issliding = false;
 // 为删除按钮提供一个回调接口
 private delbuttonclicklistener mlistener;
 private button mdelbtn;
 private int mpopupwindowheight;
 private int mpopupwindowwidth;

 public mylistview(context context, attributeset attrs) {
  super(context, attrs);
  minflater = layoutinflater.from(context);
  mtouchslop = viewconfiguration.get(context).getscaledtouchslop();

  view view = minflater.inflate(r.layout.delete_btn, null);
  mdelbtn = (button) view.findviewbyid(r.id.id_item_btn);
  mpopupwindow = new popupwindow(view, linearlayout.layoutparams.wrap_content,
    linearlayout.layoutparams.wrap_content);
  // 如果需要通过点击popupwindow之外的地方使其消失，则需要setfocusable(true).
  mpopupwindow.setfocusable(true);
  // android 6.0以前的版本需要setbackgrounddrawable()，
  // 才能实现通过点击popupwindow之外的地方使其消失的功能。
  mpopupwindow.setbackgrounddrawable(new colordrawable(0));
  // 先调用下measure，否则拿不到宽和高
  mpopupwindow.getcontentview().measure(0, 0);
  mpopupwindowheight = mpopupwindow.getcontentview().getmeasuredheight();
  mpopupwindowwidth = mpopupwindow.getcontentview().getmeasuredwidth();
 }

 @override
 public boolean ontouchevent(motionevent ev) {
  int action = ev.getaction();
  int x = (int) ev.getx();
  int y = (int) ev.gety();

  switch (action){
   case motionevent.action_down:
    issliding = false;
    mxdown = x;
    mydown = y;
    mcurrentposition = pointtoposition(mxdown, mydown);
    view view = getchildat(mcurrentposition - getfirstvisibleposition());
    mcurrentview = view;
    break;
   case motionevent.action_move:
    int dx = x - mxdown;
    int dy = y - mydown;

    log.d(tag, "mtouchslop = " + mtouchslop + ", dx = " + dx + ", dy = " + dy);

    if(mxdown > x && math.abs(dx) > mtouchslop && math.abs(dy) < mtouchslop){
     log.d(tag, "issliding");
     issliding = true;
     int[] location = new int[2];
     mcurrentview.getlocationonscreen(location);
     mpopupwindow.setanimationstyle(r.style.popwindow_delete_btn_anim_style);
     mpopupwindow.update();
     log.d(tag, "height: " + mcurrentview.getheight() + "," + mpopupwindow.getheight());
     mpopupwindow.showatlocation(mcurrentview, gravity.no_gravity,
       location[0] + mcurrentview.getwidth(),
       location[1] + mcurrentview.getheight() / 2 - mpopupwindowheight / 2);
     mdelbtn.setonclicklistener(new onclicklistener() {
      @override
      public void onclick(view v) {
       mlistener.clickhappend(mcurrentposition);
       mpopupwindow.dismiss();
      }
     });
    }
   case motionevent.action_up:
    // issliding 如果这里恢复为false,则后面会执行super.ontouchevent事件，
    // 而abslistview的ontouchevent调用了ontouchup方法，在ontouchup方法中有可能执行
    // performclick.run() --> performitemclick() --> super.performitemclick
    // --> monitemclicklistener.onitemclick，这样最终触发item的点击。
    // 因此此处依旧保持issliding为true的状态，而在action_down事件中恢复issliding为false，
    // 毕竟每个事件都以action_down开始。
    //issliding = false;
  }

  if(issliding){
   return true;
  }

  return super.ontouchevent(ev);
 }

 public void setdelbuttonclicklistener(delbuttonclicklistener listener){
  mlistener = listener;
 }

 interface delbuttonclicklistener{
  public void clickhappend(int position);
 }
} 

通过这个例子学习到：
 1、listview的item点击事件的触发过程：
 自定义listview的ontouchevent()  ---调用super.ontouchevent()---> abslistview.ontouchevent() ---motionevent.action_up---> abslistview.ontouchup() 
---(有可能)调用performclick.run()---> abslistview.performclick.run() ---调用performitemclick()---> abslistview.performitemclick()

---(有可能)调用super.performitemclick()---> adapterview.performitemclick() ---monitemclicklistener.onitemclick---> onitemclicklistener.onitemclick() 
也就是item的点击事件是在motionevent.action_up事件完成的，这样在自定义listview的ontouchevent()中，对motionevent.action_up直接return true消费掉事件，而不要调用super.ontouchevent。这样就避免了删除按钮与item点击事件的冲突。 

2、popupwindow--通过点击popupwindow之外的地方使其消失 
a、需要调用setfocusable()方法（popupwindow中showatlocation() --> createpopuplayoutparams() --> computeflags() --> 设置flag_not_focusable）； 
b、android 6.0以前的版本需要setbackgrounddrawable()（具体原因见：popupwindow的使用）。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。