wpf Listbox 实现按住ctrl键来取消选中

1. 首先继承一个listbox，来获得按住ctrl键时，点击的item

  public class listboxex : listbox
   {
      public beattemplatewave getanitem()
        {           
            var obj = this.anchoritem;
            if (obj != null)
            {
                type type = obj.gettype();
                system.reflection.propertyinfo propertyinfo = type.getproperty("item", bindingflags.instance | bindingflags.nonpublic);
                system.reflection.propertyinfo propertyinfo2 = type.getproperty("index", bindingflags.instance| bindingflags.nonpublic);
                beattemplatewave value_old = (beattemplatewave)propertyinfo.getvalue(obj, null); //获取属性值
                return value_old;
            }
            else
            {
                return null;
            }
        }

//重写选中
public void setlist(list<beattemplatewave> list)
{
this.setselecteditems(list);
}

   }

2 在listbox 的调用处： 获得listbox 的选中项：selecteditemslist

3 在mouseleftdown事件里面添加处理程序

   private void mouseleftbuttonuphandler(elementmousebuttoneventmerge embem)
        {
           
            listboxex listbox = (embem.sender as listboxex);
            if (keyboard.iskeydown(key.leftctrl) || keyboard.iskeydown(key.rightctrl))
            {
                list<beattemplatewave> selectlist = new list<beattemplatewave>();
                var obj = (embem.sender as listboxnowheelex).getanitem();
                if (selecteditemslist != null)
                {
                    var templist = selecteditemslist.ilisttocollection<beattemplatewave>();
                    if (obj != null)
                    {
                        //判断鼠标点击的项在不在选中的里面，如果不在，则加入临时集合，如果在选中项里面，则不加入临时集合， 
                        if (templist.any(p => p.r == obj.r))
                        {
                            foreach (beattemplatewave a in templist)
                            {
                                if (a.r == obj.r)
                                {
                                }
                                else
                                {
                                    selectlist.add(a);
                                }
                            }
                        }
                        else
                        {
                            selectlist.add(obj);
                            selectlist.addrange(templist);
                        }
                    }
                    else
                    {
                        selectlist.addrange(templist);
                    }
                    listbox.setlist(selectlist);    //重新选中              
                    selecteditemslist = selectlist;//将临时集合赋值给选中项 重写选中
                }
                return;
            }
            else
            {
                if (listbox.selecteditems != null)
                {
                    selecteditemslist = listbox.selecteditems;
                    var item = selecteditemslist;
                    if (item.count == 0)
                        return;
                   
                }
            }
         
        }