HelpProvider.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / WinForms / Managed / System / WinForms / HelpProvider.cs / 1 / HelpProvider.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

/* 
 */ 
namespace System.Windows.Forms {
    using System; 
    using System.ComponentModel;
    using System.ComponentModel.Design;
    using Microsoft.Win32;
    using Hashtable = System.Collections.Hashtable; 
    using System.Windows.Forms;
    using System.Windows.Forms.Design; 
    using System.Diagnostics; 
    using System.Drawing;
    using System.Drawing.Design; 


    /// 
    ///  
    ///    
    ///       Provides pop-up or online Help for controls. 
    ///     
    /// 
    [ 
    ProvideProperty("HelpString", typeof(Control)),
    ProvideProperty("HelpKeyword", typeof(Control)),
    ProvideProperty("HelpNavigator", typeof(Control)),
    ProvideProperty("ShowHelp", typeof(Control)), 
    ToolboxItemFilter("System.Windows.Forms"),
    SRDescription(SR.DescriptionHelpProvider) 
    ] 
    public class HelpProvider : Component, IExtenderProvider {
 
        private string helpNamespace = null;
        private Hashtable helpStrings = new Hashtable();
        private Hashtable showHelp = new Hashtable();
        private Hashtable boundControls = new Hashtable(); 
        private Hashtable keywords = new Hashtable();
        private Hashtable navigators = new Hashtable(); 
 
        private object userData;
 
        /// 
        /// 
        ///    
        ///       Initializes a new instance of the  class. 
        ///    
        ///  
        public HelpProvider() { 
        }
 
        /// 
        /// 
        ///    
        ///       Gets or sets a string indicating the name of the Help 
        ///       file associated with this  object.
        ///     
        ///  
        [
        Localizable(true), 
        DefaultValue(null),
        Editor("System.Windows.Forms.Design.HelpNamespaceEditor, " + AssemblyRef.SystemDesign, typeof(UITypeEditor)),
        SRDescription(SR.HelpProviderHelpNamespaceDescr)
        ] 
        public virtual string HelpNamespace {
            get { 
                return helpNamespace; 
            }
 
            set {
                this.helpNamespace = value;
            }
        } 

        ///  
        [ 
        SRCategory(SR.CatData),
        Localizable(false), 
        Bindable(true),
        SRDescription(SR.ControlTagDescr),
        DefaultValue(null),
        TypeConverter(typeof(StringConverter)), 
        ]
        public object Tag { 
            get { 
                return userData;
            } 
            set {
                userData = value;
            }
        } 

        ///  
        ///  
        ///    
        ///       Determines if the help provider can offer it's extender properties 
        ///       to the specified target object.
        ///    
        /// 
        public virtual bool CanExtend(object target) { 
            return(target is Control);
        } 
 
        /// 
        ///  
        ///    
        ///       Retrieves the Help Keyword displayed when the
        ///       user invokes Help for the specified control.
        ///     
        /// 
        [ 
        DefaultValue(null), 
        Localizable(true),
        SRDescription(SR.HelpProviderHelpKeywordDescr) 
        ]
        public virtual string GetHelpKeyword(Control ctl) {
            return(string)keywords[ctl];
        } 

        ///  
        ///  
        ///    
        ///       Retrieves the contents of the pop-up help window for the specified 
        ///       control.
        ///    
        /// 
        [ 
        DefaultValue(HelpNavigator.AssociateIndex),
        Localizable(true), 
        SRDescription(SR.HelpProviderNavigatorDescr) 
        ]
        public virtual HelpNavigator GetHelpNavigator(Control ctl) { 
            object nav = navigators[ctl];
            return (nav == null) ? HelpNavigator.AssociateIndex : (HelpNavigator)nav;
        }
 
        /// 
        ///  
        ///     
        ///       Retrieves the contents of the pop-up help window for the specified
        ///       control. 
        ///    
        /// 
        [
        DefaultValue(null), 
        Localizable(true),
        SRDescription(SR.HelpProviderHelpStringDescr) 
        ] 
        public virtual string GetHelpString(Control ctl) {
            return(string)helpStrings[ctl]; 
        }

        /// 
        ///  
        ///    
        ///       Retrieves a value indicating whether Help displays for 
        ///       the specified control. 
        ///    
        ///  
        [
        Localizable(true),
        SRDescription(SR.HelpProviderShowHelpDescr)
        ] 
        public virtual bool GetShowHelp(Control ctl) {
            object b = showHelp[ctl]; 
            if (b == null) { 
                return false;
            } 
            else {
                return(Boolean) b;
            }
        } 

        ///  
        ///  
        ///     Handles the help event for any bound controls.
        ///  
        /// 
        private void OnControlHelp(object sender, HelpEventArgs hevent) {
            Control ctl = (Control)sender;
            string helpString = GetHelpString(ctl); 
            string keyword = GetHelpKeyword(ctl);
            HelpNavigator navigator = GetHelpNavigator(ctl); 
            bool show = GetShowHelp(ctl); 

            if (!show) { 
                return;
            }

            // If the mouse was down, we first try whats this help 
            //
            if (Control.MouseButtons != MouseButtons.None && helpString != null) { 
                Debug.WriteLineIf(Help.WindowsFormsHelpTrace.TraceVerbose, "HelpProvider:: Mouse down w/ helpstring"); 

                if (helpString.Length > 0) { 
                    Help.ShowPopup(ctl, helpString, hevent.MousePos);
                    hevent.Handled = true;
                }
            } 

            // If we have a help file, and help keyword we try F1 help next 
            // 
            if (!hevent.Handled && helpNamespace != null) {
                Debug.WriteLineIf(Help.WindowsFormsHelpTrace.TraceVerbose, "HelpProvider:: F1 help"); 
                if (keyword != null) {
                    if (keyword.Length > 0) {
                        Help.ShowHelp(ctl, helpNamespace, navigator, keyword);
                        hevent.Handled = true; 
                    }
                } 
 
                if (!hevent.Handled) {
                    Help.ShowHelp(ctl, helpNamespace, navigator); 
                    hevent.Handled = true;
                }
            }
 
            // So at this point we don't have a help keyword, so try to display
            // the whats this help 
            // 
            if (!hevent.Handled && helpString != null) {
                Debug.WriteLineIf(Help.WindowsFormsHelpTrace.TraceVerbose, "HelpProvider:: back to helpstring"); 

                if (helpString.Length > 0) {
                    Help.ShowPopup(ctl, helpString, hevent.MousePos);
                    hevent.Handled = true; 
                }
            } 
 
            // As a last resort, just popup the contents page of the help file...
            // 
            if (!hevent.Handled && helpNamespace != null) {
                Debug.WriteLineIf(Help.WindowsFormsHelpTrace.TraceVerbose, "HelpProvider:: contents");

                Help.ShowHelp(ctl, helpNamespace); 
                hevent.Handled = true;
            } 
        } 

        ///  
        /// 
        ///     Handles the help event for any bound controls.
        /// 
        ///  
        private void OnQueryAccessibilityHelp(object sender, QueryAccessibilityHelpEventArgs e) {
            Control ctl = (Control)sender; 
 
            e.HelpString = GetHelpString(ctl);
            e.HelpKeyword = GetHelpKeyword(ctl); 
            e.HelpNamespace = HelpNamespace;
        }

        ///  
        /// 
        ///     
        ///       Specifies 
        ///       a Help string associated with a control.
        ///     
        /// 
        public virtual void SetHelpString(Control ctl, string helpString) {
            helpStrings[ctl] = helpString;
            if (helpString != null) { 
                if (helpString.Length > 0) {
                    SetShowHelp(ctl, true); 
                } 
            }
            UpdateEventBinding(ctl); 
        }

        /// 
        ///  
        ///    
        ///       Specifies the Help keyword to display when 
        ///       the user invokes Help for a control. 
        ///    
        ///  
        public virtual void SetHelpKeyword(Control ctl, string keyword) {
            keywords[ctl] = keyword;
            if (keyword != null) {
                if (keyword.Length > 0) { 
                    SetShowHelp(ctl, true);
                } 
            } 
            UpdateEventBinding(ctl);
        } 

        /// 
        /// 
        ///     
        ///       Specifies the Help keyword to display when
        ///       the user invokes Help for a control. 
        ///     
        /// 
        public virtual void SetHelpNavigator(Control ctl, HelpNavigator navigator) { 
            //valid values are 0x80000001 to 0x80000007
            if (!ClientUtils.IsEnumValid(navigator, (int)navigator, (int)HelpNavigator.Topic, (int)HelpNavigator.TopicId)){
                //validate the HelpNavigator enum
                throw new InvalidEnumArgumentException("navigator", (int)navigator, typeof(HelpNavigator)); 
            }
 
            navigators[ctl] = navigator; 
            SetShowHelp(ctl, true);
            UpdateEventBinding(ctl); 
        }
        /// 
        /// 
        ///     
        ///       Specifies whether Help is displayed for a given control.
        ///     
        ///  
        public virtual void SetShowHelp(Control ctl, bool value) {
            showHelp[ ctl] = value ; 
            UpdateEventBinding(ctl);
        }

        ///  
        /// 
        ///    Used by the designer 
        ///  
        /// 
        internal virtual bool ShouldSerializeShowHelp(Control ctl) { 
            return showHelp.ContainsKey(ctl);
        }

        ///  
        /// 
        ///    Used by the designer 
        ///  
        /// 
        public virtual void ResetShowHelp(Control ctl) { 
            showHelp.Remove(ctl);
        }

        ///  
        /// 
        ///     Binds/unbinds event handlers to ctl 
        ///  
        /// 
        private void UpdateEventBinding(Control ctl) { 
            if (GetShowHelp(ctl) && !boundControls.ContainsKey(ctl)) {
                ctl.HelpRequested += new HelpEventHandler(this.OnControlHelp);
                ctl.QueryAccessibilityHelp += new QueryAccessibilityHelpEventHandler(this.OnQueryAccessibilityHelp);
                boundControls[ctl] = ctl; 
            }
            else if (!GetShowHelp(ctl) && boundControls.ContainsKey(ctl)) { 
                ctl.HelpRequested -= new HelpEventHandler(this.OnControlHelp); 
                ctl.QueryAccessibilityHelp -= new QueryAccessibilityHelpEventHandler(this.OnQueryAccessibilityHelp);
                boundControls.Remove(ctl); 
            }
        }

        ///  
        /// 
        ///    Returns a string representation for this control. 
        ///  
        /// 
        public override string ToString() { 
            string s = base.ToString();
            return s + ", HelpNamespace: " + HelpNamespace;
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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HelpProvider.cs source code in C# .NET

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