Android程序开发之ListView 与PopupWindow实现从左向右滑动删除功能

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。

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；

b、android 6.0以前的版本需要setbackgrounddrawable()（具体原因见：popupwindow的使用）。

以上所述是小编给大家介绍的android程序开发之listview 与popupwindow实现滑动删除功能