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IHelpService Interface

  • Reference

Definition

Namespace:
System.ComponentModel.Design
Assembly:
System.ComponentModel.TypeConverter.dll
Assembly:
System.dll
Assembly:
netstandard.dll

Provides methods for showing Help topics and adding and removing Help keywords at design time.

public interface class IHelpService
public interface IHelpService
type IHelpService = interface
Public Interface IHelpService

Examples

The following example demonstrates a designer that uses the IHelpService to add and remove Help context attributes for the included control. To use this sample, compile it to a class library and add an instance of the control to a Form. In design view, selecting the component and pressing F1 attempts to look up relevant Help topics based on the current Help context keyword or keywords. Right-click the component and the shortcut menu displays commands, including two custom DesignerVerb commands named Add IHelpService Help Keyword and Remove IHelpService Help Keyword. These commands can be used to add or remove a Help context keyword of the value "IHelpService", which attempts to raise the IHelpService topic when F1 is pressed.

#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>
#using <System.Design.dll>
#using <System.dll>

using namespace System;
using namespace System::ComponentModel;
using namespace System::ComponentModel::Design;
using namespace System::Drawing;
using namespace System::IO;
using namespace System::Windows::Forms;
using namespace System::Windows::Forms::Design;

public ref class HelpDesigner: public System::Windows::Forms::Design::ControlDesigner
{
public:
   HelpDesigner(){}

   property System::ComponentModel::Design::DesignerVerbCollection^ Verbs 
   {
      virtual System::ComponentModel::Design::DesignerVerbCollection^ get() override
      {
         array<DesignerVerb^>^temp0 = {gcnew DesignerVerb( "Add IHelpService Help Keyword",gcnew EventHandler( this, &HelpDesigner::addKeyword ) ),gcnew DesignerVerb( "Remove IHelpService Help Keyword",gcnew EventHandler( this, &HelpDesigner::removeKeyword ) )};
         return gcnew DesignerVerbCollection( temp0 );
      }
   }

private:
   void addKeyword( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      IHelpService^ hs = dynamic_cast<IHelpService^>(this->Control->Site->GetService( IHelpService::typeid ));
      hs->AddContextAttribute( "keyword", "IHelpService", HelpKeywordType::F1Keyword );
   }

   void removeKeyword( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      IHelpService^ hs = dynamic_cast<IHelpService^>(this->Control->Site->GetService( IHelpService::typeid ));
      hs->RemoveContextAttribute( "keyword", "IHelpService" );
   }
};


[Designer(HelpDesigner::typeid)]
public ref class HelpTestControl: public System::Windows::Forms::UserControl
{
public:
   HelpTestControl()
   {
      this->Size = System::Drawing::Size( 320, 100 );
      this->BackColor = Color::White;
   }

protected:
   virtual void OnPaint( System::Windows::Forms::PaintEventArgs^ e ) override
   {
      Brush^ brush = gcnew SolidBrush( Color::Blue );
      e->Graphics->DrawString( "IHelpService Example Designer Control", gcnew System::Drawing::Font( FontFamily::GenericMonospace,10 ), brush, 5, 5 );
      e->Graphics->DrawString( "Right-click this component for", gcnew System::Drawing::Font( FontFamily::GenericMonospace,8 ), brush, 5, 25 );
      e->Graphics->DrawString( "add/remove Help context keyword commands.", gcnew System::Drawing::Font( FontFamily::GenericMonospace,8 ), brush, 5, 35 );
      e->Graphics->DrawString( "Press F1 while this component is", gcnew System::Drawing::Font( FontFamily::GenericMonospace,8 ), brush, 5, 55 );
      e->Graphics->DrawString( "selected to raise Help topics for", gcnew System::Drawing::Font( FontFamily::GenericMonospace,8 ), brush, 5, 65 );
      e->Graphics->DrawString( "the current keyword or keywords", gcnew System::Drawing::Font( FontFamily::GenericMonospace,8 ), brush, 5, 75 );
   }
};

using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.IO;
using System.Windows.Forms;
using System.Windows.Forms.Design;

namespace IHelpServiceSample
{
    public class HelpDesigner : System.Windows.Forms.Design.ControlDesigner
    {
        public HelpDesigner()
        {			
        }

        public override System.ComponentModel.Design.DesignerVerbCollection Verbs
        {
            get
            {
                return new DesignerVerbCollection( new DesignerVerb[] { 
                        new DesignerVerb("Add IHelpService Help Keyword", new EventHandler(this.addKeyword)),
                        new DesignerVerb("Remove IHelpService Help Keyword", new EventHandler(this.removeKeyword))
                } );
            }
        }
        
        private void addKeyword(object sender, EventArgs e)
        {
            IHelpService hs = (IHelpService) this.Control.Site.GetService(typeof(IHelpService));			
            hs.AddContextAttribute("keyword", "IHelpService", HelpKeywordType.F1Keyword);	
        }
        
        private void removeKeyword(object sender, EventArgs e)
        {
            IHelpService hs = (IHelpService) this.Control.Site.GetService(typeof(IHelpService));			
            hs.RemoveContextAttribute("keyword", "IHelpService");
        }
    }

    [Designer(typeof(HelpDesigner))]
    public class HelpTestControl : System.Windows.Forms.UserControl
    {
        public HelpTestControl()
        {
            this.Size = new Size(320, 100);
            this.BackColor = Color.White;
        }

        protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
        {			
            Brush brush = new SolidBrush(Color.Blue);
            e.Graphics.DrawString("IHelpService Example Designer Control", new Font( FontFamily.GenericMonospace, 10 ), brush, 5, 5);
            e.Graphics.DrawString("Right-click this component for", new Font( FontFamily.GenericMonospace, 8 ), brush, 5, 25);
            e.Graphics.DrawString("add/remove Help context keyword commands.", new Font( FontFamily.GenericMonospace, 8 ), brush, 5, 35);			
            e.Graphics.DrawString("Press F1 while this component is", new Font( FontFamily.GenericMonospace, 8 ), brush, 5, 55);
            e.Graphics.DrawString("selected to raise Help topics for", new Font( FontFamily.GenericMonospace, 8 ), brush, 5, 65);			
            e.Graphics.DrawString("the current keyword or keywords", new Font( FontFamily.GenericMonospace, 8 ), brush, 5, 75);			
        }		
    }
}

Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Drawing
Imports System.IO
Imports System.Windows.Forms
Imports System.Windows.Forms.Design

Namespace IHelpServiceSample

    Public Class HelpDesigner
        Inherits System.Windows.Forms.Design.ControlDesigner

        Public Sub New()
        End Sub

        Public Overrides ReadOnly Property Verbs() As System.ComponentModel.Design.DesignerVerbCollection
            Get
                Return New DesignerVerbCollection(New DesignerVerb() {New DesignerVerb("Add IHelpService Help Keyword", AddressOf Me.addKeyword), New DesignerVerb("Remove IHelpService Help Keyword", AddressOf Me.removeKeyword)})
            End Get
        End Property

        Private Sub addKeyword(ByVal sender As Object, ByVal e As EventArgs)
            Dim hs As IHelpService = CType(Me.Control.Site.GetService(GetType(IHelpService)), IHelpService)
            hs.AddContextAttribute("keyword", "IHelpService", HelpKeywordType.F1Keyword)
        End Sub

        Private Sub removeKeyword(ByVal sender As Object, ByVal e As EventArgs)
            Dim hs As IHelpService = CType(Me.Control.Site.GetService(GetType(IHelpService)), IHelpService)
            hs.RemoveContextAttribute("keyword", "IHelpService")
        End Sub
    End Class

    <Designer(GetType(HelpDesigner))> _
    Public Class HelpTestControl
        Inherits System.Windows.Forms.UserControl

        Public Sub New()
            Me.Size = New Size(320, 100)
            Me.BackColor = Color.White
        End Sub

        Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
            Dim brush As New SolidBrush(Color.Blue)
            e.Graphics.DrawString("IHelpService Example Designer Control", New Font(FontFamily.GenericMonospace, 10), brush, 5, 5)
            e.Graphics.DrawString("Right-click this component for", New Font(FontFamily.GenericMonospace, 8), brush, 5, 25)
            e.Graphics.DrawString("add/remove Help context keyword commands.", New Font(FontFamily.GenericMonospace, 8), brush, 5, 35)
            e.Graphics.DrawString("Press F1 while this component is", New Font(FontFamily.GenericMonospace, 8), brush, 5, 55)
            e.Graphics.DrawString("selected to raise Help topics for", New Font(FontFamily.GenericMonospace, 8), brush, 5, 65)
            e.Graphics.DrawString("the current keyword or keywords", New Font(FontFamily.GenericMonospace, 8), brush, 5, 75)
        End Sub
    End Class
End Namespace 'IHelpServiceSample

Remarks

The design-time environment provides a Help system that attempts to locate relevant Help topics to display when a user presses F1. The Help system maintains a set of current context keywords that are used to identify relevant topics if Help is requested. By default, keywords are associated with selected class objects and properties of objects in the design time environment. The default keyword for a component or property is its fully qualified class or property name. Specific keywords are also associated with certain modes, such as when multiple objects are selected. If a custom Help collection is integrated with the design-time environment by configuring it for an external help provider, a documentation provider can associate a topic for a specific component class or property with a keyword consisting of the item's fully qualified type or member name.

The IHelpService can be used to invoke the help service with a specified keyword using the ShowHelpFromKeyword method, or to invoke a help topic from a specified URL using the ShowHelpFromUrl method.

The IHelpService can also be used to add or remove Help keywords at design time. Selecting a component or property at design time sets a default context keyword consisting of the fully qualified type or member name of the selection, and removes the keywords for any previously selected and no longer selected components or properties.

Because the Help system does not automatically remove custom Help keywords, you must explicitly remove a custom keyword when it no longer applies. You can monitor the events defined by the ISelectionService interface to determine when a component selection changes. Based on those events, you can add a Help context attribute for a component when it is selected and then remove the Help context attribute when the selection no longer includes the component.

Methods

AddContextAttribute(String, String, HelpKeywordType)

Adds a context attribute to the document.
ClearContextAttributes()

Removes all existing context attributes from the document.
CreateLocalContext(HelpContextType)

Creates a local IHelpService to manage subcontexts.
RemoveContextAttribute(String, String)

Removes a previously added context attribute.
RemoveLocalContext(IHelpService)

Removes a context created with CreateLocalContext(HelpContextType).
ShowHelpFromKeyword(String)

Shows the Help topic that corresponds to the specified keyword.
ShowHelpFromUrl(String)

Shows the Help topic that corresponds to the specified URL.

Applies to

See also