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DropDownList下拉框多选

最近弄完个项目、项目需要支持多选功能、找了很多例子没找到合适的，最后自己开发了个控件：

DropDownCheckBoxList 控件继承 DropDownList ；

整个控件由四部分组成：一个文本框、两个图标（向下|向上）、一个隐藏的 DIV 、两个隐藏域。控件示意图

收缩状态：

展开状态：

先介绍些关键属性：

1. DisplayMode 有两个值 Label,Value；分别表示显示文本、显示值。

2. Splitor 多选时，多个值间的分隔符。

3. ShowSelectAllOption 是否显示" 全选 " 选项、一般多项选择都会有个" 全选 " 功能。

4. SelectAllOptionLabel 全选选项显示的文本，默认值："全选"。

重写了 OnInit 事件，在 OnInit 事件里面创建控件：

protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);

            if (!DesignMode)
            {
                CreateControls();
            }
        }

CreateControls()

 1  protected void CreateControls()
 2         {
 3             txt = new TextBox();
 4             txt.ID = this.ClientID + "_txtMain";
 5             txt.ReadOnly = true;
 6             txt.Width = (Unit)(this.Width.Value - 20);
 7             txt.Style.Add(HtmlTextWriterStyle.Padding, "0");
 8             txt.Style.Add(HtmlTextWriterStyle.Margin, "0");
 9             txt.Height = this.Height;
10 
11             if (txt.Height.IsEmpty)
12             { txt.Height = 15; }
13 
14             hfValueText = new HiddenField();
15             hfValueText.ID = string.Format("{0}_{1}", this.ClientID, "selectItemValueText");
16             hfValue = new HiddenField();
17             hfValue.ID = string.Format("{0}_{1}", this.ClientID, "selectItemValue");
18 
19             txt.Enabled = this.Enabled;
20         }

在预呈现 OnPreRender 事件里面注册客户端脚本：

protected override void OnPreRender(EventArgs e)
        {
            base.OnPreRender(e);

            if (!DesignMode)
            {
                DoRegisterScript();
            }
        }

DoRegisterScript

 1 ClientScriptManager sc = this.Page.Page.ClientScript;
 2 
 3             string scriptString = sc.GetWebResourceUrl(this.GetType(), "DevControl.Resources.DropDownCheckBoxList.js");
 4 
 5             if (!sc.IsClientScriptIncludeRegistered("DropDownGridScriptKey"))
 6             { sc.RegisterClientScriptInclude(this.GetType(), "DropDownGridScriptKey", scriptString); }
 7 
 8             scriptString = Page.Form.Attributes["onclick"];
 9             if (string.IsNullOrEmpty(scriptString))
10             { scriptString = string.Format("responseOnFormClick(event,'{0}');", this.ClientID); }
11             else
12             { scriptString = string.Format("{0} responseOnFormClick(event,'{1}');", scriptString, this.ClientID); }
13 
14             Page.Form.Attributes.Add("onclick", scriptString);
15 
16             this.Page.RegisterRequiresPostBack(this);

重写 TagKey 设置为：Table

protected override HtmlTextWriterTag TagKey
        {
            get
            {
                if (!DesignMode)
                {
                    return HtmlTextWriterTag.Table;
                }

                return base.TagKey;
            }
        }

在 AddAttributesToRender 事件中设置 table 的属性

protected override void AddAttributesToRender(HtmlTextWriter writer)
        {
            if (!DesignMode)
            { AddCustomAttribute(writer); }
            else
            { base.AddAttributesToRender(writer); }
        }

AddCustomAttribute

1 writer.AddAttribute(HtmlTextWriterAttribute.Width, this.Width.ToString());
2             writer.AddAttribute(HtmlTextWriterAttribute.Border, "0");
3             writer.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID + "_displaytable");
4             writer.AddAttribute(HtmlTextWriterAttribute.Cellpadding, "0");
5             writer.AddAttribute(HtmlTextWriterAttribute.Cellspacing, "0");
6             writer.AddStyleAttribute(HtmlTextWriterStyle.Position, "relative");
7             writer.AddStyleAttribute(HtmlTextWriterStyle.ZIndex, "1");
8             writer.AddStyleAttribute(HtmlTextWriterStyle.Left, "-5px");

在 GetDivWidth 方法里面动态算出 DIV 宽度，避免当某项内容长度超出 DIV 的默认宽度时，动态调整DIV 的宽度。

GetDivWidth()

 1 int itemWidth = 0;
 2             int byteCount = 0;
 3             foreach (ListItem item in this.Items)
 4             {
 5                 byteCount = System.Text.UnicodeEncoding.Default.GetByteCount(item.Text);
 6                 if (byteCount > itemWidth)
 7                 { itemWidth = byteCount; }
 8             }
 9 
10             itemWidth = itemWidth * 8 + 20;
11             itemWidth = itemWidth + 16; //加上checkbox 宽度
12 
13             if (itemWidth > this.Width.Value)
14             { this.Width = itemWidth; }

在 RenderContents 事件里面呈现默认显示(文本框、图标)的内容：

protected override void RenderContents(HtmlTextWriter writer)
        {
            if (DesignMode)
            {
                base.RenderContents(writer);
                return;
            }

            RenderCustomContent(writer);
        }

RenderCustomContent

 1 void RenderCustomContent(HtmlTextWriter writer)
 2         {
 3             GetDivWidth();
 4             string divId = this.ClientID + "_div";
 5             string cmbDown = this.ClientID + "_imgDown";
 6             string cmbUp = this.ClientID + "_imgUp";
 7 
 8             // base.RenderContents(writer);
 9             ////控件显示主体
10             writer.AddAttribute(HtmlTextWriterAttribute.Align, "left");
11             writer.RenderBeginTag(HtmlTextWriterTag.Tr);
12             writer.RenderBeginTag(HtmlTextWriterTag.Td);
13             writer.AddStyleAttribute(HtmlTextWriterStyle.Cursor, "default");
14             if (this.Enabled)
15             { writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("toggleDivShowState('{0}','{1}','{2}');", this.ClientID, Splitor, this.Items.Count)); }
16             ////控件主体文本框 
17             txt.RenderControl(writer);
18 
19             writer.Write("<br/>");
20             ////隐藏下拉面板
21             writer.AddAttribute(HtmlTextWriterAttribute.Id, divId);
22             writer.AddStyleAttribute(HtmlTextWriterStyle.Display, "none");
23             writer.AddStyleAttribute(HtmlTextWriterStyle.BackgroundColor, "#ECECE3");
24             writer.AddStyleAttribute(HtmlTextWriterStyle.Position, "absolute");
25             writer.AddStyleAttribute(HtmlTextWriterStyle.ZIndex, "32766");
26             writer.AddStyleAttribute(HtmlTextWriterStyle.BorderColor, "Gray");
27             writer.AddStyleAttribute(HtmlTextWriterStyle.BorderWidth, "thin");
28             writer.AddStyleAttribute(HtmlTextWriterStyle.BorderStyle, "double");
29             writer.AddStyleAttribute(HtmlTextWriterStyle.VerticalAlign, "top");
30             writer.AddStyleAttribute(HtmlTextWriterStyle.Width, this.Width.ToString());
31             writer.RenderBeginTag(HtmlTextWriterTag.Div);
32             ////呈现 item 列表
33             ModifyRenderedCheckboxes(writer);
34             writer.RenderEndTag();//end div
35 
36             writer.RenderEndTag();//end td
37             ////下拉图标
38             writer.AddAttribute(HtmlTextWriterAttribute.Border, "0");
39             writer.RenderBeginTag(HtmlTextWriterTag.Td);
40             writer.AddStyleAttribute(HtmlTextWriterStyle.Margin, "0");
41             writer.AddStyleAttribute(HtmlTextWriterStyle.Padding, "0");
42             writer.AddStyleAttribute(HtmlTextWriterStyle.Position, "relative");
43             writer.AddStyleAttribute(HtmlTextWriterStyle.Left, "-8px");
44             writer.AddAttribute(HtmlTextWriterAttribute.Src, this.Page.ClientScript.GetWebResourceUrl(this.GetType(), "DevControl.Resources.cmb_down.jpg"));
45 
46             if (this.Enabled)
47             { writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("toggleDivShowState('{0}','{1}','{2}');", this.ClientID, Splitor, this.Items.Count)); }
48 
49             writer.AddAttribute(HtmlTextWriterAttribute.Id, cmbDown);
50             writer.RenderBeginTag(HtmlTextWriterTag.Img);
51             writer.RenderEndTag();//end img
52             writer.AddStyleAttribute(HtmlTextWriterStyle.Margin, "0");
53             writer.AddStyleAttribute(HtmlTextWriterStyle.Padding, "0");
54             writer.AddStyleAttribute(HtmlTextWriterStyle.Position, "relative");
55             writer.AddStyleAttribute(HtmlTextWriterStyle.Left, "-8px");
56             writer.AddAttribute(HtmlTextWriterAttribute.Src, this.Page.ClientScript.GetWebResourceUrl(this.GetType(), "DevControl.Resources.cmb_up.jpg"));
57             if (this.Enabled)
58             { writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("toggleDivShowState('{0}','{1}','{2}');", this.ClientID, Splitor, this.Items.Count)); }
59             writer.AddStyleAttribute(HtmlTextWriterStyle.Display, "none");
60             writer.AddAttribute(HtmlTextWriterAttribute.Id, cmbUp);
61             writer.RenderBeginTag(HtmlTextWriterTag.Img);
62             writer.RenderEndTag();//end img
63 
64             writer.RenderEndTag();//end td
65             writer.RenderEndTag();//end tr 
66         }

在 ModifyRenderedCheckboxes 方法里面呈现 DIV 的内容：

ModifyRenderedCheckboxes

  1 protected void ModifyRenderedCheckboxes(HtmlTextWriter writer)
  2         {
  3             int index = 0;
  4 
  5             string spanId = "";
  6             string wapperId = "";
  7             string allChkId = "";
  8 
  9             writer.AddAttribute(HtmlTextWriterAttribute.Width, this.Width.ToString());
 10             writer.AddAttribute(HtmlTextWriterAttribute.Border, "0");
 11             writer.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID + "_Optiontable");
 12             writer.AddAttribute(HtmlTextWriterAttribute.Cellpadding, "0");
 13             writer.AddAttribute(HtmlTextWriterAttribute.Cellspacing, "0");
 14             writer.AddStyleAttribute(HtmlTextWriterStyle.Position, "relative");
 15             writer.AddStyleAttribute(HtmlTextWriterStyle.Left, "0px");
 16             writer.RenderBeginTag(HtmlTextWriterTag.Table);
 17 
 18             #region 首选项
 19             if (ShowSelectAllOption)
 20             {
 21                 writer.RenderBeginTag(HtmlTextWriterTag.Tr);
 22                 wapperId = string.Format("{0}_{1}", this.ClientID, "chkAllItemWapper");
 23                 allChkId = string.Format("{0}_{1}", this.ClientID, "chkAllItemValue");
 24                 spanId = string.Format("{0}_{1}", this.ClientID, "chkAllItemText");
 25 
 26                 writer.AddAttribute("onmouseover", string.Format("setStyleOnMouseOver('{0}');", wapperId));
 27                 writer.AddAttribute("onmouseout", string.Format("setStyleOnMouseOut('{0}');", wapperId));
 28 
 29                 writer.AddStyleAttribute(HtmlTextWriterStyle.Width, (this.Width.Value - 10).ToString());
 30                 writer.AddStyleAttribute(HtmlTextWriterStyle.Height, "20px");
 31                 writer.AddAttribute(HtmlTextWriterAttribute.Id, wapperId);
 32                 writer.AddStyleAttribute("cursor", "pointer");
 33                 writer.AddStyleAttribute("cursor", "hand");
 34                 writer.AddStyleAttribute(HtmlTextWriterStyle.VerticalAlign, "middle");
 35                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingLeft, "5px");
 36                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingRight, "5px");
 37                 writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("return clickChangeValueWhenCheckAllCheckBox(event,'{0}','{1}');", allChkId, this.ClientID));
 38                 writer.RenderBeginTag(HtmlTextWriterTag.Td);
 39                 writer.AddAttribute(HtmlTextWriterAttribute.Id, allChkId);
 40                 writer.AddStyleAttribute("cursor", "pointer");
 41                 writer.AddStyleAttribute("cursor", "hand");
 42                 writer.AddAttribute(HtmlTextWriterAttribute.Value, "");
 43                 writer.AddStyleAttribute(HtmlTextWriterStyle.VerticalAlign, "middle");
 44                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingBottom, "5px");
 45                 writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("return mouseUpdateValueWhenSelectAllStateChanged(event,this,'{0}');", this.ClientID));
 46                 writer.AddAttribute(HtmlTextWriterAttribute.Type, "checkbox");
 47                 writer.RenderBeginTag(HtmlTextWriterTag.Input);
 48                 writer.RenderEndTag();//end input
 49 
 50                 writer.AddAttribute(HtmlTextWriterAttribute.Id, spanId);
 51                 writer.AddStyleAttribute(HtmlTextWriterStyle.FontSize, "small");
 52                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingTop, "5px");
 53                 writer.AddStyleAttribute(HtmlTextWriterStyle.VerticalAlign, "middle");
 54                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingBottom, "5px");
 55                 writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("return mouseUpdateValueWhenCheckAllCheckBox(event,'{0}','{1}');", allChkId, this.ClientID));
 56                 writer.RenderBeginTag(HtmlTextWriterTag.Span);
 57                 writer.Write(SelectAllOptionLabel);
 58                 writer.RenderEndTag();//end span
 59 
 60                 writer.RenderEndTag();//td
 61                 writer.RenderEndTag();//tr
 62             }
 63             #endregion
 64 
 65             #region 内容选项
 66             string chkId = "";
 67             foreach (ListItem item in this.Items)
 68             {
 69                 writer.RenderBeginTag(HtmlTextWriterTag.Tr);
 70                 wapperId = string.Format("{0}_{1}{2}", this.ClientID, "chkItemWapper", index.ToString());
 71                 chkId = string.Format("{0}_{1}{2}", this.ClientID, "chkItemValue", index.ToString());
 72                 spanId = string.Format("{0}_{1}{2}", this.ClientID, "chkItemText", index.ToString());
 73 
 74                 writer.AddAttribute("onmouseover", string.Format("setStyleOnMouseOver('{0}');", wapperId));
 75                 writer.AddAttribute("onmouseout", string.Format("setStyleOnMouseOut('{0}');", wapperId));
 76 
 77                 writer.AddStyleAttribute(HtmlTextWriterStyle.Width, (this.Width.Value - 10).ToString());
 78                 writer.AddStyleAttribute(HtmlTextWriterStyle.Height, "20px");
 79                 writer.AddAttribute(HtmlTextWriterAttribute.Id, wapperId);
 80                 writer.AddStyleAttribute("cursor", "pointer");
 81                 writer.AddStyleAttribute("cursor", "hand");
 82                 writer.AddStyleAttribute(HtmlTextWriterStyle.VerticalAlign, "middle");
 83                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingLeft, "5px");
 84                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingRight, "5px");
 85 
 86                 writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("return clickChangeValueWhenCheckItemCheckBox(event,'{0}','{1}','{2}','{3}');", chkId, spanId, allChkId, this.ClientID));
 87                 writer.RenderBeginTag(HtmlTextWriterTag.Td);
 88                 writer.AddAttribute(HtmlTextWriterAttribute.Id, chkId);
 89                 writer.AddStyleAttribute("cursor", "pointer");
 90                 writer.AddStyleAttribute("cursor", "hand");
 91                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingTop, "5px");
 92                 writer.AddStyleAttribute(HtmlTextWriterStyle.VerticalAlign, "middle");
 93                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingBottom, "5px");
 94                 writer.AddAttribute(HtmlTextWriterAttribute.Width, "16px");
 95                 writer.AddAttribute(HtmlTextWriterAttribute.Value, item.Value);
 96                 writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("return mouseUpdateValueWhenCheckItemStateChanged(event,'{0}','{1}','{2}','{3}');", chkId, spanId, allChkId, this.ClientID));
 97                 writer.AddAttribute(HtmlTextWriterAttribute.Type, "checkbox");
 98                 writer.RenderBeginTag(HtmlTextWriterTag.Input);
 99                 writer.RenderEndTag();//end input
100 
101                 writer.AddAttribute(HtmlTextWriterAttribute.Id, spanId);
102                 writer.AddStyleAttribute(HtmlTextWriterStyle.FontSize, "small");
103                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingTop, "5px");
104                 writer.AddStyleAttribute(HtmlTextWriterStyle.VerticalAlign, "middle");
105                 writer.AddStyleAttribute(HtmlTextWriterStyle.PaddingBottom, "5px");
106                 writer.AddAttribute(HtmlTextWriterAttribute.Onclick, string.Format("return mouseUpdateValueWhenCheckItemCheckBox(event,'{0}','{1}','{2}','{3}');", chkId, spanId, allChkId, this.ClientID));
107                 writer.RenderBeginTag(HtmlTextWriterTag.Span);
108                 if (DisplayMode == DevControl.DisplayMode.Label)
109                 { writer.Write(item.Text); }
110                 else
111                 { writer.Write(item.Value); }
112 
113                 writer.RenderEndTag();//end span
114 
115                 writer.RenderEndTag();//td
116                 writer.RenderEndTag();//tr
117                 index++;
118             }
119             #endregion
120 
121             writer.RenderBeginTag(HtmlTextWriterTag.Tr);
122             writer.RenderBeginTag(HtmlTextWriterTag.Td);
123             hfValue.RenderControl(writer);
124             hfValueText.RenderControl(writer);
125             writer.RenderEndTag();//end td
126             writer.RenderEndTag();//end tr
127             writer.RenderEndTag();//end table
128         }

在 LoadPostData 事件里面获取选择的内容：

protected override bool LoadPostData(string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
        {
            if (!DesignMode)
            {
                this.txt.Text = postCollection[txt.ID];
                this.hfValue.Value = postCollection[hfValue.ID];
                this.hfValueText.Value = postCollection[hfValueText.ID];
                return true;
            }

            return base.LoadPostData(postDataKey, postCollection);
        }

定义个枚举类型 DisplayMode 表示显示"文本或值"

[Serializable]
    public enum DisplayMode
    {
        /// <summary>
        /// 显示文本
        /// </summary>
        Label,
        /// <summary>
        /// 显示值
        /// </summary>
        Value
    }

客户端脚本 DropDownCheckBoxList.js 利用 JQuery 来处理：

扩展了 Array ：

Array.prototype.initItem

Array.prototype.hasItem

Array.prototype.addItem

Array.prototype.removeItem

Array.prototype.joinItem

函数responseOnFormClick 检测当前点击是否在弹出的DIV 范围;否则隐藏弹出的DIV
function (e, prefix);

responseOnFormClick

 1 //<!--检测当前点击是否在弹出的DIV 范围;否则隐藏弹出的DIV-->
 2 function responseOnFormClick(e, prefix) {
 3     idPrefix = prefix;
 4     $divObj = $("#" + idPrefix + "_div");
 5     if ($divObj.css("display") == "none") {
 6         return false;
 7     }
 8     var $imgDownObj = $("#" + idPrefix + "_imgDown");
 9     var $imgUpObj = $("#" + idPrefix + "_imgUp");
10     var targetId;
11     if ($.browser.msie) { targetId = e.srcElement.id; }
12     else { targetId = e.target.id; }
13     if (targetId == undefined || targetId.indexOf(idPrefix) < 0) {
14         $divObj.css("display", "none");
15         $imgDownObj.css("display", "inline");
16         $imgUpObj.css("display", "none");
17     }
18     return false;
19 }

函数 toggleDivShowState 显示或者隐藏弹出的DIV

toggleDivShowState

 1 ////显示或者隐藏弹出的DIV
 2 function toggleDivShowState(prefix, splitorString, iCount) {
 3     idPrefix = prefix;
 4     splitor = splitorString;
 5     itemCount = iCount;
 6     vItems = new Array(iCount);
 7     vItems.initItem();
 8     tItems = new Array(iCount);
 9     tItems.initItem();
10     vtItems = new Array(iCount);
11     vtItems.initItem();
12     $hfTextObj = $("#" + idPrefix + "_selectItemValueText");
13     $hfValueObj = $("#" + idPrefix + "_selectItemValue");
14     $divObj = $("#" + idPrefix + "_div");
15     $txtObj = $("#" + idPrefix + "_txtMain");
16     setObjectState(idPrefix + "_div");
17     if ($divObj.css("display") == "inline") {
18         selectDefaultItem(idPrefix + "_selectItemValue", idPrefix);
19     }
20     setObjectState(idPrefix + "_imgDown");
21     setObjectState(idPrefix + "_imgUp");
22 }

函数 selectDefaultItem 弹出DIV 时设置上次选择的值

selectDefaultItem

 1 function selectDefaultItem(hfValueId, prefix) {
 2     $hfValueObj = $("#" + hfValueId);
 3     if (!$hfValueObj.val())
 4     { return; }
 5     var arr = $hfValueObj.val().split(splitor);
 6     if (!arr)
 7     { return; }
 8     vItems.initItem();
 9     tItems.initItem();
10     vtItems.initItem();
11     var subNodes;
12     var firstNode;
13     var lastNode;
14     var nodeValue;
15     var nodeText;
16     var $tdNodes;
17     $divObj = $("#" + prefix + "_div");
18     var $tableNodes = $divObj.children('table');
19     var tableId = $tableNodes.get(0).id;
20     $("#" + tableId + " tr").each(function () {
21         $tdNodes = $(this).children('td');
22         $tdNodes.each(function () {
23             subNodes = this;
24             firstNode = subNodes.children[0];
25             lastNode = subNodes.children[1];
26             nodeValue = firstNode.value;
27             if (nodeValue) {
28                 if (lastNode.innerText)
29                 { nodeText = lastNode.innerText; }
30                 else
31                 { nodeText = lastNode.textContent; }
32                 if (arr.hasItem(nodeValue)) {
33                     if (!vItems.hasItem(nodeValue))
34                     { vItems.addItem(nodeValue); }
35                     if (!tItems.hasItem(nodeText))
36                     { tItems.addItem(nodeText); }
37                     if (!vtItems.hasItem(nodeValue + "|" + nodeText))
38                     { vtItems.addItem(nodeValue + "|" + nodeText); }
39                     if (!tItems.hasItem(nodeText))
40                     { tItems.addItem(nodeText); }
41                     if (!vtItems.hasItem(nodeValue + "|" + nodeText))
42                     { vtItems.addItem(nodeValue + "|" + nodeText); }
43                     firstNode.checked = true;
44                 }
45             }
46         });
47     });
48 
49     $txtObj.val(tItems.joinItem(splitor));
50     $hfTextObj.val(vtItems.joinItem(splitor));
51     $hfValueObj.val(vItems.joinItem(splitor));
52 }

控件支持主流浏览器 IE 7+,FF3.5+，Chrome 9+,Safari 5 等浏览器。但在 IE6中与与浏览器自身的 select 冲突。

点击下载本例源码

转自：http://www.soaspx.com/dotnet/asp.net/Control/control_20111011_8134.html

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原文地址：https://www.cnblogs.com/xiurui12345/p/2480686.html