LinkButton.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 / LinkButton.cs / 1305376 / LinkButton.cs
                        

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

namespace System.Web.UI.WebControls { 
 
    using System;
    using System.ComponentModel; 
    using System.Drawing.Design;
    using System.Web;
    using System.Web.UI;
    using System.Web.Util; 

    ///  
    /// Interacts with the parser to build a  control. 
    /// 
    public class LinkButtonControlBuilder : ControlBuilder { 


        /// 
        ///  
        ///    Specifies whether white space literals are allowed.
        ///  
        public override bool AllowWhitespaceLiterals() { 
            return false;
        } 
    }


 
    /// 
    ///    Constructs a link button and defines its properties. 
    ///  
    [
    ControlBuilderAttribute(typeof(LinkButtonControlBuilder)), 
    DataBindingHandler("System.Web.UI.Design.TextDataBindingHandler, " + AssemblyRef.SystemDesign),
    DefaultEvent("Click"),
    DefaultProperty("Text"),
    ToolboxData("<{0}:LinkButton runat=\"server\">LinkButton"), 
    Designer("System.Web.UI.Design.WebControls.LinkButtonDesigner, " + AssemblyRef.SystemDesign),
    ParseChildren(false), 
    SupportsEventValidation 
    ]
    public class LinkButton : WebControl, IButtonControl, IPostBackEventHandler { 

        private bool _textSetByAddParsedSubObject = false;
        private static readonly object EventClick = new object();
        private static readonly object EventCommand = new object(); 

 
        ///  
        /// Initializes a new instance of the  class.
        ///  
        public LinkButton() : base(HtmlTextWriterTag.A) {
        }

 
        /// 
        ///    Specifies the command name that is propagated in the 
        ///    event along with the associated  
        ///    property.
        ///  
        [
        DefaultValue(""),
        Themeable(false),
        WebCategory("Behavior"), 
        WebSysDescription(SR.WebControl_CommandName)
        ] 
        public string CommandName { 
            get {
                string s = (string)ViewState["CommandName"]; 
                return((s == null) ? String.Empty : s);
            }
            set {
                ViewState["CommandName"] = value; 
            }
        } 
 

 
        /// 
        ///    Specifies the command argument that is propagated in the
        ///    event along with the associated 
        ///    property. 
        /// 
        [ 
        Bindable(true), 
        DefaultValue(""),
        Themeable(false), 
        WebCategory("Behavior"),
        WebSysDescription(SR.WebControl_CommandArgument)
        ]
        public string CommandArgument { 
            get {
                string s = (string)ViewState["CommandArgument"]; 
                return((s == null) ? String.Empty : s); 
            }
            set { 
                ViewState["CommandArgument"] = value;
            }
        }
 

        ///  
        ///    Gets or sets whether pressing the button causes page validation to fire. This defaults to True so that when 
        ///          using validation controls, the validation state of all controls are updated when the button is clicked, both
        ///          on the client and the server. Setting this to False is useful when defining a cancel or reset button on a page 
        ///          that has validators.
        /// 
        [
        DefaultValue(true), 
        Themeable(false),
        WebCategory("Behavior"), 
        WebSysDescription(SR.Button_CausesValidation) 
        ]
        public virtual bool CausesValidation { 
            get {
                object b = ViewState["CausesValidation"];
                return((b == null) ? true : (bool)b);
            } 
            set {
                ViewState["CausesValidation"] = value; 
            } 
        }
 
        /// 
        ///    The script that is executed on a client-side click.
        /// 
        [ 
        DefaultValue(""),
        Themeable(false), 
        WebCategory("Behavior"), 
        WebSysDescription(SR.Button_OnClientClick)
        ] 
        public virtual string OnClientClick {
            get {
                string s = (string)ViewState["OnClientClick"];
                if (s == null) { 
                    return String.Empty;
                } 
                return s; 
            }
            set { 
                ViewState["OnClientClick"] = value;
            }
        }
 
        public override bool SupportsDisabledAttribute {
            get { 
                return RenderingCompatibility < VersionUtil.Framework40; 
            }
        } 

        internal override bool RequiresLegacyRendering {
            get {
                return true; 
            }
        } 
 

        ///  
        ///    Gets or sets the text display for the link button.
        /// 
        [
        Localizable(true), 
        Bindable(true),
        WebCategory("Appearance"), 
        DefaultValue(""), 
        WebSysDescription(SR.LinkButton_Text),
        PersistenceMode(PersistenceMode.InnerDefaultProperty) 
        ]
        public virtual string Text {
            get {
                object o = ViewState["Text"]; 
                return((o == null) ? String.Empty : (string)o);
            } 
            set { 
                if (HasControls()) {
                    Controls.Clear(); 
                }
                ViewState["Text"] = value;
            }
        } 

 
        [ 
        DefaultValue(""),
        Editor("System.Web.UI.Design.UrlEditor, " + AssemblyRef.SystemDesign, typeof(UITypeEditor)), 
        Themeable(false),
        UrlProperty("*.aspx"),
        WebCategory("Behavior"),
        WebSysDescription(SR.Button_PostBackUrl) 
        ]
        public virtual string PostBackUrl { 
            get { 
                string s = (string)ViewState["PostBackUrl"];
                return s == null? String.Empty : s; 
            }
            set {
                ViewState["PostBackUrl"] = value;
            } 
        }
 
        [ 
        WebCategory("Behavior"),
        Themeable(false), 
        DefaultValue(""),
        WebSysDescription(SR.PostBackControl_ValidationGroup)
        ]
        public virtual string ValidationGroup { 
            get {
                string s = (string)ViewState["ValidationGroup"]; 
                return((s == null) ? String.Empty : s); 
            }
            set { 
                ViewState["ValidationGroup"] = value;
            }
        }
 

        ///  
        ///    Occurs when the link button is clicked. 
        /// 
        [ 
        WebCategory("Action"),
        WebSysDescription(SR.LinkButton_OnClick)
        ]
        public event EventHandler Click { 
            add {
                Events.AddHandler(EventClick, value); 
            } 
            remove {
                Events.RemoveHandler(EventClick, value); 
            }
        }

 

        ///  
        /// Occurs when any item is clicked within the  control tree. 
        /// 
        [ 
        WebCategory("Action"),
        WebSysDescription(SR.Button_OnCommand)
        ]
        public event CommandEventHandler Command { 
            add {
                Events.AddHandler(EventCommand, value); 
            } 
            remove {
                Events.RemoveHandler(EventCommand, value); 
            }
        }

 
        /// 
        ///  
        ///    Render the attributes on the begin tag. 
        /// 
        protected override void AddAttributesToRender(HtmlTextWriter writer) { 
            // Make sure we are in a form tag with runat=server.
            if (Page != null) {
                Page.VerifyRenderingInServerForm(this);
            } 

            // Need to merge the onclick attribute with the OnClientClick 
            string onClick = Util.EnsureEndWithSemiColon(OnClientClick); 

            if (HasAttributes) { 
                string userOnClick = Attributes["onclick"];
                if (userOnClick != null) {
                    // We don't use Util.MergeScript because OnClientClick or
                    // onclick attribute are set by page developer directly.  We 
                    // should preserve the value without adding javascript prefix.
                    onClick += Util.EnsureEndWithSemiColon(userOnClick); 
                    Attributes.Remove("onclick"); 
                }
            } 

            if (onClick.Length > 0) {
                writer.AddAttribute(HtmlTextWriterAttribute.Onclick, onClick);
            } 

            bool effectiveEnabled = IsEnabled; 
            if (Enabled && !effectiveEnabled && SupportsDisabledAttribute) { 
                // We need to do the cascade effect on the server, because the browser
                // only renders as disabled, but doesn't disable the functionality. 
                writer.AddAttribute(HtmlTextWriterAttribute.Disabled, "disabled");
            }

            base.AddAttributesToRender(writer); 

            if (effectiveEnabled && Page != null) { 
                // 

                PostBackOptions options = GetPostBackOptions(); 
                string postBackEventReference = null;
                if (options != null) {
                    postBackEventReference = Page.ClientScript.GetPostBackEventReference(options, true);
                } 

                // If the postBackEventReference is empty, use a javascript no-op instead, since 
                //  is a link to the root of the current directory. 
                if (String.IsNullOrEmpty(postBackEventReference)) {
                    postBackEventReference = "javascript:void(0)"; 
                }

                writer.AddAttribute(HtmlTextWriterAttribute.Href, postBackEventReference);
            } 
        }
 
 
        /// 
        ///  
        /// 
        protected override void AddParsedSubObject(object obj) {
            if (HasControls()) {
                base.AddParsedSubObject(obj); 
            }
            else { 
                if (obj is LiteralControl) { 
                    if (_textSetByAddParsedSubObject) {
                        Text += ((LiteralControl)obj).Text; 
                    }
                    else {
                        Text = ((LiteralControl)obj).Text;
                    } 
                    _textSetByAddParsedSubObject = true;
                } 
                else { 
                    string currentText = Text;
                    if (currentText.Length != 0) { 
                        Text = String.Empty;
                        base.AddParsedSubObject(new LiteralControl(currentText));
                    }
                    base.AddParsedSubObject(obj); 
                }
            } 
        } 

        // Returns the client post back options. 
        protected virtual PostBackOptions GetPostBackOptions() {
            PostBackOptions options = new PostBackOptions(this, String.Empty);
            options.RequiresJavaScriptProtocol = true;
 
            if (!String.IsNullOrEmpty(PostBackUrl)) {
                // VSWhidbey 424614: Since the url is embedded as javascript in attribute, 
                // we should match the same encoding as done on HyperLink.NavigateUrl value. 
                options.ActionUrl = HttpUtility.UrlPathEncode(ResolveClientUrl(PostBackUrl));
 
                // Also, there is a specific behavior in IE that when the script
                // is triggered in href attribute, the whole string will be
                // decoded once before the code is run.  This doesn't happen to
                // onclick or other event attributes.  So here we do an extra 
                // encoding to compensate the weird behavior on IE.
                if (!DesignMode && Page != null && 
                    String.Equals(Page.Request.Browser.Browser, "IE", StringComparison.OrdinalIgnoreCase)) { 
                    options.ActionUrl = Util.QuoteJScriptString(options.ActionUrl, true);
                } 
            }

            if (CausesValidation && Page.GetValidators(ValidationGroup).Count > 0) {
                options.PerformValidation = true; 
                options.ValidationGroup = ValidationGroup;
            } 
 
            return options;
        } 


        /// 
        ///  
        ///    Load previously saved state.
        ///    Overridden to synchronize Text property with LiteralContent. 
        ///  
        protected override void LoadViewState(object savedState) {
            if (savedState != null) { 
                base.LoadViewState(savedState);
                string s = (string)ViewState["Text"];
                // Dev10 703061 If Text is set, we want to clear out any child controls, but not dirty viewstate
                if (s != null && HasControls()) { 
                    Controls.Clear();
                } 
            } 
        }
 

        /// 
        /// Raises the  event.
        ///  
        protected virtual void OnClick(EventArgs e) {
            EventHandler onClickHandler = (EventHandler)Events[EventClick]; 
            if (onClickHandler != null) onClickHandler(this,e); 
        }
 

        /// 
        /// Raises the  event.
        ///  
        protected virtual void OnCommand(CommandEventArgs e) {
            CommandEventHandler onCommandHandler = (CommandEventHandler)Events[EventCommand]; 
            if (onCommandHandler != null) 
                onCommandHandler(this,e);
 
            // Command events are bubbled up the control heirarchy
            RaiseBubbleEvent(this, e);
        }
 

        ///  
        ///  
        /// Raises a event upon postback
        /// to the server, and a  event if the  
        /// is defined.
        /// 
        void IPostBackEventHandler.RaisePostBackEvent(string eventArgument) {
            RaisePostBackEvent(eventArgument); 
        }
 
 
        /// 
        ///  
        /// Raises a event upon postback
        /// to the server, and a  event if the 
        /// is defined.
        ///  
        protected virtual void RaisePostBackEvent(string eventArgument) {
            ValidateEvent(this.UniqueID, eventArgument); 
            if (CausesValidation) { 
                Page.Validate(ValidationGroup);
            } 
            OnClick(EventArgs.Empty);
            OnCommand(new CommandEventArgs(CommandName, CommandArgument));
        }
 

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

                if ((CausesValidation && Page.GetValidators(ValidationGroup).Count > 0) ||
                     !String.IsNullOrEmpty(PostBackUrl)) { 
                    Page.RegisterWebFormsScript();  // VSWhidbey 489577
                } 
            } 
        }
 

        /// 
        /// 
        ///  
        protected internal override void RenderContents(HtmlTextWriter writer) {
            if (HasRenderingData()) { 
                base.RenderContents(writer); 
            }
            else { 
                writer.Write(Text);
            }
        }
    } 
}
 

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