DropDownList.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / xsp / System / Web / UI / WebControls / DropDownList.cs / 1305376 / 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; 
 
    /// 
    ///    Creates a control that allows the user to select a single item from a 
    ///       drop-down list.
    /// 
    [
    SupportsEventValidation, 
    ValidationProperty("SelectedItem")
    ] 
    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; 
            } 
        }
 
        public override bool SupportsDisabledAttribute {
            get {
                return true;
            } 
        }
 
        ///  
        ///    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"));
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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DropDownList.cs source code in C# .NET

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