[Overview][Types][Classes][Procedures and functions][Index] | Reference for unit 'LazHelpHTML' (#lcl)

# THTMLHelpDatabase

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

Provides support for context-sensitive help using HTML help files.

## Declaration

Source position: lazhelphtml.pas line 52

`type THTMLHelpDatabase = class(THelpDatabase)`
`public`
`constructor Create(); override;` |  | Constructor for the class instance.
`destructor Destroy; override;` |  | Destructor for the class instance.
`function ShowURL(); virtual;` |  | Displays a help viewer for the specified HTML help topic.
`function ShowHelp(); override;` |  | Displays a context-sensitive HTML help topics in the HTML database.
`function GetNodesForKeyword(); override;` |  | Populates the list with help nodes using the KeywordPrefix for the HTML help database.
`function GetEffectiveBaseURL;` |  | Gets the effective Base URL used to access a topic in the HTML help database.
`procedure Load(); override;` |  | Loads HTML help database settings from the specified configuration storage.
`procedure Save(); override;` |  | Saves configuration settings to the specified storage.
`property DefaultBaseURL: string; [rw]` |  | Default value for the BaseURL used in the HTML help database.
`published`
`property BuiltInBaseURL: string; [rw]`
`property BaseURL: string; [rws]` |  | Protocol and Path to the directory where HTML help files are stored for the HTML help database.
`property AutoRegister: Boolean;` |  | Indicates if the HTML help database is automatically registered at run-time.
`property KeywordPrefix: string; [rw]` |  | Common prefix which identifies the related keyword topics handled in the HTML help database.
`end;`

## Inheritance

`THTMLHelpDatabase` |  | Provides support for context-sensitive help using HTML help files.
`THelpDatabase` |  | Provides support for integrating a collection of related help topics with a table of contents.
`TComponent`
?
`TObject`

## Description

THTMLHelpDatabase is a THelpDatabase descendant that provides support for using HTML files as context-sensitive help displayed when the F1 key is pressed in an application. THTMLHelpDatabase extends the ancestor class to include properties and methods needed to associate Help Keywords to specific HTML files, and to retrieve and display the help content.

The KeywordPrefix property is the value found at the start of a HelpKeyword which indicates that the topic belongs the HTML help database. BaseURL determines the path searched when accessing HTML files for the help database.

An application can create a THTMLHelpDatabase instance, assign the KeywordPrefix and BaseURL for the help database, and use AutoRegistered to enable the help database. Controls on the Form should use the value htKeyword in their HelpType property, and their HelpKeyword property must be set to a value that includes the KeyWordPrefix and the HTML file name accessed for the control.

THTMLBrowserHelpViewer is a companion component that allows the correct HTML help file to be displayed for the keyword/url in a web browser when the F1 key is pressed.

There is an example program that demonstrates usage of the components: examples/helphtml

## See also

THelpDatabase
THTMLBrowserHelpViewer |  | Implements a browser/viewer for HTML help topics.
TControl.HelpKeyword |  | The context-sensitive Help keyword for the control.
TControl.HelpType |  | Indicates whether context-sensitive Help is selected by numeric ID or keyword.