C#实现带搜索功能的ComboBox

带搜索的combobox就是给combobox一个依赖属性的itemsource，然后通过数据源中是否包含要查询的值，重新给combobox绑定数据源。

public class editcombobox : combobox
  {
    private bool t = true;//首次获取焦点标志位
    private observablecollection<object> bindinglist = new observablecollection<object>();//数据源绑定list
    private string edittext = "";//编辑文本内容

    /// <summary>
    /// 注册依赖事件
    /// </summary>
    public static readonly dependencyproperty itemssourcepropertynew = dependencyproperty.register("myitemssource", typeof(ienumerable), typeof(editcombobox), new frameworkpropertymetadata(new propertychangedcallback(valuechanged)));
    /// <summary>
    /// 数据源改变，添加数据源到绑定数据源
    /// </summary>
    /// <param name="d"></param>
    /// <param name="e"></param>
    private static void valuechanged(dependencyobject d, dependencypropertychangedeventargs e)
    {
      editcombobox ecb = d as editcombobox;
      ecb.bindinglist.clear();
      //遍历循环操作
      foreach (var item in ecb.myitemssource)
      {
        ecb.bindinglist.add(item);
      }
    }
    /// <summary>
    /// 设置或获取combobox的数据源
    /// </summary>
    public ienumerable myitemssource
    {
      get
      {
        return (ienumerable)getvalue(itemssourcepropertynew);
      }

      set
      {
        if (value == null)
          clearvalue(itemssourcepropertynew);
        else
          setvalue(itemssourcepropertynew, value);
      }
    }
    /// <summary>
    /// 重写初始化
    /// </summary>
    /// <param name="e"></param>
    protected override void oninitialized(eventargs e)
    {
      base.oninitialized(e);
      this.iseditable = true;
      this.istextsearchenabled = false;
      this.itemssource = bindinglist;
    }
    /// <summary>
    /// 下拉框获取焦点，首次搜索文本编辑框
    /// </summary>
    /// <param name="e"></param>
    protected override void ongotfocus(routedeventargs e)
    {
      if (t)
        findtextbox(this);
      else
        t = false;
    }
    /// <summary>
    /// 搜索编辑文本框，添加文本改变事件
    /// </summary>
    /// <param name="obj"></param>
    private void findtextbox(dependencyobject obj)
    {
      for (int i = 0; i < visualtreehelper.getchildrencount(obj); i++)
      {
        dependencyobject child = visualtreehelper.getchild(obj, i);
        if (child!=null && child is textbox)
        {
          //注册文本改变事件
          (child as textbox).textchanged += editcombobox_textchanged;
        }
        else
        {
          findtextbox(child);
        }
      }
    }
    /// <summary>
    /// 文本改变，动态控制下拉条数据源
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void editcombobox_textchanged(object sender, textchangedeventargs e)
    {
      textbox tb = sender as textbox;
      if(tb.isfocused)
      {
        this.isdropdownopen = true;
        if (edittext == this.text)
          return;
        edittext = this.text;
        setlist(edittext);
      }
    }
    /// <summary>
    /// 组合框关闭，数据源恢复
    /// </summary>
    /// <param name="e"></param>
    protected override void ondropdownclosed(eventargs e)
    {
      base.ondropdownclosed(e);
      if (myitemssource == null)
        return;
      foreach (var item in myitemssource)
      {
        if (!bindinglist.contains(item))
          bindinglist.add(item);
      }
    }
    /// <summary>
    /// 过滤符合条件的数据项，添加到数据源项中
    /// </summary>
    /// <param name="txt"></param>
    private void setlist(string txt)
    {
      try
      {
        string temp1 = "";
        string temp2 = "";
        if (myitemssource == null)
          return;
        foreach (var item in myitemssource)
        {
          temp1 = item.gettype().getproperty(this.displaymemberpath).getvalue(item, null).tostring();
          if (string.isnullorempty(this.selectedvaluepath))
          {
            temp2 = "";
          }
          else
          {
            temp2 = item.gettype().getproperty(this.selectedvaluepath).getvalue(item, null).tostring();
          }
          if(temp1.contains(txt)||temp2.startswith(txt))
          {
            if (!bindinglist.contains(item))
              bindinglist.add(item);
          }
          else if (bindinglist.contains(item))
          {
            bindinglist.remove(item);
          }
        }
      }
      catch (exception ex)
      {
        messagebox.show(ex.tostring());
      }
    }
  }

调用方法就是将数据源绑定到myitemssource上，剩下的就和原有的combobox用法一样了。

<local:editcombobox myitemssource="{binding prolist,mode=twoway}" selecteditem="{binding selpro,mode=twoway}" selectedvaluepath="id" displaymemberpath="name"/>

效果演示

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