HelpDisplay Class

Create a link to the help system in use.

Inheritance Hierarchy

Object
VObject
HelpDisplay

Namespace: VO
Assembly: VOGUIClasses (in VOGUIClasses.dll) Version: 2.21

Syntax

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 CLASS HelpDisplay INHERIT VObject

public class HelpDisplay : VObject

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The HelpDisplay type exposes the following members.

Constructors

	Name	Description
	HelpDisplay	Construct a help display to be used for a specified help database.

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Methods

	Name	Description
	HelpError	Determine if the previous HelpDisplay operation was successful.
	Show	Instruct the help system to provide the help topic associated with a given keyword.

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Fields

	Name	Description
	DefaultPageOnContents
	oCargo	Cargo slot. (Inherited from VObject.)
	Win32Processing

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Remarks

The HelpDisplay class allows you to easily provide online help for your applications. The help system resource provided by the GUI can remain in memory until the HelpDisplay object is deleted. Therefore, before the application terminates, ensure that the HelpDisplay object is either deleted or goes out of scope. HelpDisplay provides a way to display help on a given topic. However, the application still needs a means of determining which topic help is required. For large applications, most GUI style guides recommend that help commands be made available from the menu bar. These commands can be trapped using the MenuCommandEvent handler, and the appropriate help information displayed in response. Another approach is to use push buttons to obtain help on specific topics. Using a push button and the ButtonClick() event handler, you can program the application to display the relevant help information when the Help button is pressed. In practice, an application's Help facility should combine menu commands and buttons to provide help. Context-sensitive help means the user receives help specific to the current activity when the help key or mouse sequence is chosen. For example, when responding to a dialog window, the user can want help for the control with the focus. X# applications can provide context-sensitive help for: Particular areas of the screen (such as the caption bar and canvas area) Menu commands Controls (like push buttons, edit controls, and toolbar buttons) To support a portable context-sensitive help system, X# provides the HelpRequestEvent class, the Window:HelpDisplay property, and the Window:HelpRequest() event handler method. (HelpRequest() determines the source of the help trigger—that is, the particular item for which help is requested—and passes this information on to the GUI's help system.) Refer to the "GUI Classes" chapter in the Programmer's Guide for more information on programming an online help system for your application.

Tip
The EXPORTed variable DefaultPageOnContents is a LOGIC which defaults to TRUE. It is used to determine whether the default page should be shown when HelpContents is requested. If set to FALSE, 'HelpContents' will display the Contents tab but leave the current topic displayed. For HTML Help only.

Examples

The following example handles two common menu commands, Help Index and Help Using Help:

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 1CLASS MyWindow INHERIT TopAppWindow
 2METHOD Init() CLASS MyWindow
 3SUPER:Init()
 4SELF:HelpDisplay := HelpDisplay{"mywind.hlp"}
 5METHOD MenuCommand(oMCE) CLASS MyWindow
 6LOCAL nItemID := oMCE:ItemID
 7DO CASE
 8CASE nItemID = IDM_MENU_HELP_INDEX_ID
 9SELF:HelpDisplay:Show("HelpIndex")
10CASE nItemID = IDM_MENU_HELP_USINGHELP_ID
11SELF:HelpDisplay:Show("HelpOnHelp")
12OTHERWISE
13SUPER:MenuCommand(oMCE)
14ENDCASE

Reference

VO Namespace