DropDownList.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / WebControls / DropDownList.cs / 2 / DropDownList.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.UI.WebControls { 
 
    using System;
    using System.Collections; 
    using System.ComponentModel;
    using System.Collections.Specialized;
    using System.Drawing;
    using System.Web; 
    using System.Web.UI;
    using System.Web.UI.WebControls.Adapters; 
    using System.Security.Permissions; 

 
    /// 
    ///    Creates a control that allows the user to select a single item from a
    ///       drop-down list.
    ///  
    [
    SupportsEventValidation, 
    ValidationProperty("SelectedItem") 
    ]
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    public class DropDownList : ListControl, IPostBackDataHandler {

 
        /// 
        /// Initializes a new instance of the  class. 
        ///  
        public DropDownList() {
        } 


        /// 
        ///    [To be supplied.] 
        /// 
        [ 
        Browsable(false) 
        ]
        public override Color BorderColor { 
            get {
                return base.BorderColor;
            }
            set { 
                base.BorderColor = value;
            } 
        } 

 
        /// 
        ///    [To be supplied.]
        /// 
        [ 
        Browsable(false)
        ] 
        public override BorderStyle BorderStyle { 
            get {
                return base.BorderStyle; 
            }
            set {
                base.BorderStyle = value;
            } 
        }
 
 
        /// 
        ///    [To be supplied.] 
        /// 
        [
        Browsable(false)
        ] 
        public override Unit BorderWidth {
            get { 
                return base.BorderWidth; 
            }
            set { 
                base.BorderWidth = value;
            }
        }
 

        ///  
        ///    Gets or sets the index of the item selected by the user 
        ///       from the 
        ///       control. 
        /// 
        [
        WebCategory("Behavior"),
        DefaultValue(0), 
        WebSysDescription(SR.WebControl_SelectedIndex),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden) 
        ] 
        public override int SelectedIndex {
            get { 
                int selectedIndex = base.SelectedIndex;
                if (selectedIndex < 0 && Items.Count > 0) {
                    Items[0].Selected = true;
                    selectedIndex = 0; 
                }
                return selectedIndex; 
            } 
            set {
                base.SelectedIndex = value; 
            }
        }

        internal override ArrayList SelectedIndicesInternal { 
            get {
                int sideEffect = SelectedIndex; 
                return base.SelectedIndicesInternal; 
            }
        } 


        protected override void AddAttributesToRender(HtmlTextWriter writer) {
            string uniqueID = UniqueID; 
            if (uniqueID != null) {
                writer.AddAttribute(HtmlTextWriterAttribute.Name, uniqueID); 
            } 

            base.AddAttributesToRender(writer); 
        }


        protected override ControlCollection CreateControlCollection() { 
            return new EmptyControlCollection(this);
        } 
 
        /// 
        ///  
        /// Process posted data for the  control.
        /// 
        bool IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection) {
            return LoadPostData(postDataKey, postCollection); 
        }
 
 
        /// 
        ///  
        /// Process posted data for the  control.
        /// 
        protected virtual bool LoadPostData(String postDataKey, NameValueCollection postCollection) {
 
            // When a DropDownList is disabled, then there is no postback data for it.
            // Since DropDownList doesn't call RegisterRequiresPostBack, this method will 
            // never be called, so we don't need to worry about ignoring empty postback data. 

            string [] selectedItems = postCollection.GetValues(postDataKey); 

            EnsureDataBound();
            if (selectedItems != null) {
 
                ValidateEvent(postDataKey, selectedItems[0]);
 
                int n = Items.FindByValueInternal(selectedItems[0], false); 

                if (SelectedIndex != n) { 
                    SetPostDataSelection(n);
                    return true;
                }
            } 

            return false; 
        } 

 
        /// 
        /// 
        /// Raises events for the  control on post back.
        ///  
        void IPostBackDataHandler.RaisePostDataChangedEvent() {
            RaisePostDataChangedEvent(); 
        } 

 
        /// 
        /// 
        /// Raises events for the  control on post back.
        ///  
        protected virtual void RaisePostDataChangedEvent() {
            if (AutoPostBack && !Page.IsPostBackEventControlRegistered) { 
                // VSWhidbey 204824 
                Page.AutoPostBackControl = this;
 
                if (CausesValidation) {
                    Page.Validate(ValidationGroup);
                }
            } 
            OnSelectedIndexChanged(EventArgs.Empty);
        } 
 

        protected internal override void VerifyMultiSelect() { 
            throw new HttpException(SR.GetString(SR.Cant_Multiselect, "DropDownList"));
        }
    }
}
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DropDownList.cs source code in C# .NET

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