Listbox.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / WebControls / Listbox.cs / 1 / Listbox.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

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

 

    /// 
    ///    Constructs a list box and defines its
    ///       properties. 
    /// 
    [ 
    ValidationProperty("SelectedItem"), 
    SupportsEventValidation
    ] 
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    public class ListBox : ListControl, IPostBackDataHandler {
 

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


        ///  
        ///    [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;
            }
        } 

        internal override bool IsMultiSelectInternal  { 
            get  { 
                return SelectionMode == ListSelectionMode.Multiple;
            } 
        }


        ///  
        ///     Gets or
        ///       sets the display height (in rows) of the list box. 
        ///  
        [
        WebCategory("Appearance"), 
        DefaultValue(4),
        WebSysDescription(SR.ListBox_Rows)
        ]
        public virtual int Rows { 
            get {
                object n = ViewState["Rows"]; 
                return((n == null) ? 4 : (int)n); 
            }
            set { 
                if (value < 1) {
                    throw new ArgumentOutOfRangeException("value");
                }
                ViewState["Rows"] = value; 
            }
        } 
 

        ///  
        ///    Gets or sets
        ///       the selection behavior of the list box.
        /// 
        [ 
        WebCategory("Behavior"),
        DefaultValue(ListSelectionMode.Single), 
        WebSysDescription(SR.ListBox_SelectionMode) 
        ]
        public virtual ListSelectionMode SelectionMode { 
            get {
                object sm = ViewState["SelectionMode"];
                return((sm == null) ? ListSelectionMode.Single : (ListSelectionMode)sm);
            } 
            set {
                if (value < ListSelectionMode.Single || value > ListSelectionMode.Multiple) { 
                    throw new ArgumentOutOfRangeException("value"); 
                }
                ViewState["SelectionMode"] = value; 
            }
        }

 
        /// 
        protected override void AddAttributesToRender(HtmlTextWriter writer) { 
            writer.AddAttribute(HtmlTextWriterAttribute.Size, 
                                        Rows.ToString(NumberFormatInfo.InvariantInfo));
 
            string uniqueID = UniqueID;
            if (uniqueID != null) {
                writer.AddAttribute(HtmlTextWriterAttribute.Name, uniqueID);
            } 

            base.AddAttributesToRender(writer); 
        } 

 
        public virtual int[] GetSelectedIndices() {
            return (int[])SelectedIndicesInternal.ToArray(typeof(int));
        }
 

        ///  
        ///  
        /// 
        protected internal override void OnPreRender(EventArgs e) { 
            base.OnPreRender(e);
            if (Page != null && SelectionMode == ListSelectionMode.Multiple && Enabled) {

                // ensure postback when no item is selected 
                Page.RegisterRequiresPostBack(this);
            } 
        } 

 
        /// 
        /// 
        /// Loads the posted content of the list control if it is different from the last
        /// posting. 
        /// 
        bool IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection) { 
            return LoadPostData(postDataKey, postCollection); 
        }
 

        /// 
        /// 
        /// Loads the posted content of the list control if it is different from the last 
        /// posting.
        ///  
        protected virtual bool LoadPostData(String postDataKey, NameValueCollection postCollection) { 
            if (IsEnabled == false) {
                // When a ListBox is disabled, then there is no postback 
                // data for it. Any checked state information has been loaded
                // via view state.
                return false;
            } 

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

            EnsureDataBound(); 
            if (selectedItems != null) {
                if (SelectionMode == ListSelectionMode.Single) {

                    ValidateEvent(postDataKey, selectedItems[0]); 

                    int n = Items.FindByValueInternal(selectedItems[0], false); 
                    if (SelectedIndex != n) { 
                        SetPostDataSelection(n);
                        selectionChanged = true; 
                    }
                }
                else { // multiple selection
                    int count = selectedItems.Length; 
                    ArrayList oldSelectedIndices = SelectedIndicesInternal;
                    ArrayList newSelectedIndices = new ArrayList(count); 
                    for (int i=0; i < count; i++) { 

                        ValidateEvent(postDataKey, selectedItems[i]); 

                        // create array of new indices from posted values
                        newSelectedIndices.Add(Items.FindByValueInternal(selectedItems[i], false));
                    } 

                    int oldcount = 0; 
                    if (oldSelectedIndices != null) 
                        oldcount = oldSelectedIndices.Count;
 
                    if (oldcount == count) {
                        // check new indices against old indices
                        // assumes selected values are posted in order
                        for (int i=0; i < count; i++) { 
                            if (((int)newSelectedIndices[i]) != ((int)oldSelectedIndices[i])) {
                                selectionChanged = true; 
                                break; 
                            }
                        } 
                    }
                    else {
                        // indices must have changed if count is different
                        selectionChanged = true; 
                    }
 
                    if (selectionChanged) { 
                        // select new indices
                        SelectInternal(newSelectedIndices); 
                    }
                }
            }
            else { // no items selected 
                if (SelectedIndex != -1) {
                    SetPostDataSelection(-1); 
                    selectionChanged = true; 
                }
            } 

            return selectionChanged;
        }
 

        ///  
        ///  
        /// Invokes the OnSelectedIndexChanged method whenever posted data
        /// for the  control has changed. 
        /// 
        void IPostBackDataHandler.RaisePostDataChangedEvent() {
            RaisePostDataChangedEvent();
        } 

 
        ///  
        /// 
        /// Invokes the OnSelectedIndexChanged method whenever posted data 
        /// for the  control has changed.
        /// 
        protected virtual void RaisePostDataChangedEvent() {
            if (AutoPostBack && !Page.IsPostBackEventControlRegistered) { 
                // VSWhidbey 204824
                Page.AutoPostBackControl = this; 
 
                if (CausesValidation) {
                    Page.Validate(ValidationGroup); 
                }
            }
            OnSelectedIndexChanged(EventArgs.Empty);
        } 
    }
}

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