## wxHelpController

This is a family of classes by which applications may invoke a help viewer to provide on-line help.

A help controller allows an application to display help, at the contents or at a particular topic, and shut the help program down on termination. This avoids proliferation of many instances of the help viewer whenever the user requests a different topic via the application's menus or buttons.

Typically, an application will create a help controller instance when it starts, and immediately call Initialize to associate a filename with it. The help viewer will only get run, however, just before the first call to display something.

Most help controller classes actually derive from wxHelpControllerBase and have names of the form wxXXXHelpController or wxHelpControllerXXX. An appropriate class is aliased to the name wxHelpController for each platform, as follows:

- On Windows, wxWinHelpController is used.
- On all other platforms, wxHelpControllerHtml is used if wxHTML is compiled into wxWindows; otherwise wxExtHelpController is used (for invoking an external browser).

The remaining help controller classess need to be named explicitly by an application that wishes to make use of them.

There are currently the following help controller classes defined:

- wxWinHelpController, for controlling Windows Help.
- wxCHMHelpController, for controlling MS HTML Help. To use this, you need to set wxUSE_MS_HTML_HELP to 0 in setup.h, and link your application with Microsoft's htmlhelp.lib. Currently VC++ only.
- wxExtHelpController, for controlling external browsers under Unix. The default browser is Netscape Navigator. The 'help' sample shows its use.
- wxHelpControllerHtml, using wxHTML (REF NOT FOUND) to display help. See `wx/helpwxht.h` for details of use.
- wxHtmlHelpController, a more sophisticated help controller using wxHTML (REF NOT FOUND), in a similar style to the Microsoft HTML Help viewer and using some of the same files. Although it has an API compatible with other help controllers, it has more advanced features, so it is recommended that you use the specific API for this class instead.

Derived from

wxHelpControllerBase
wxObject

Include files

<wx/help.h> (wxWindows chooses the appropriate help controller class)
<wx/helpbase.h> (wxHelpControllerBase class)
<wx/helpwin.h> (Windows Help controller)
<wx/msw/helpchm.h> (MS HTML Help controller)
<wx/generic/helpext.h> (external HTML browser controller)
<wx/generic/helpwxht.h> (simple wxHTML-based help controller)
<wx/html/helpctrl.h> (advanced wxHTML based help controller: wxHtmlHelpController)

See also

wxHtmlHelpController, wxHTML (REF NOT FOUND)

Members

wxHelpController::wxHelpController
wxHelpController::~wxHelpController
wxHelpController::Initialize
wxHelpController::DisplayBlock
wxHelpController::DisplayContents
wxHelpController::DisplaySection
wxHelpController::GetFrameParameters
wxHelpController::KeywordSearch
wxHelpController::LoadFile
wxHelpController::OnQuit
wxHelpController::SetFrameParameters
wxHelpController::SetViewer
wxHelpController::Quit

### wxHelpController::wxHelpController

wxHelpController()

Constructs a help instance object, but does not invoke the help viewer.

### wxHelpController::~wxHelpController

~wxHelpController()

Destroys the help instance, closing down the viewer if it is running.

### wxHelpController::Initialize

virtual void Initialize(const wxString& file)

virtual void Initialize(const wxString& file, int server)

Initializes the help instance with a help filename, and optionally a server socket number if using wxHelp (now obsolete). Does not invoke the help viewer. This must be called directly after the help instance object is created and before any attempts to communicate with the viewer.

You may omit the file extension and a suitable one will be chosen. For wxHtmlHelpController, the extensions zip, htb and hhp will be appended while searching for a suitable file. For WinHelp, the hlp extension is appended. For wxHelpControllerHtml (the standard HTML help controller), the filename is assumed to be a directory containing the HTML files.

### wxHelpController::DisplayBlock

virtual bool DisplayBlock(long blockNo)

If the help viewer is not running, runs it and displays the file at the given block number.

WinHelp: Refers to the context number.

MS HTML Help: Refers to the context number.

External HTML help: the same as for wxHelpController::DisplaySection.

wxHtmlHelpController: sectionNo is an identifier as specified in the `.hhc` file. See Help files format.

This function is for backward compatibility only, and applications should use wxHelpController instead.

### wxHelpController::DisplayContents

virtual bool DisplayContents()

If the help viewer is not running, runs it and displays the contents.

### wxHelpController::DisplaySection

virtual bool DisplaySection(const wxString& section)

If the help viewer is not running, runs it and displays the given section.

The interpretation of section differs between help viewers. For most viewers, this call is equivalent to KeywordSearch. For MS HTML Help, external HTML help and simple wxHTML help, if section has a .htm or .html extension, that HTML file will be displayed; otherwise a keyword search is done.

virtual bool DisplaySection(int sectionNo)

If the help viewer is not running, runs it and displays the given section.

WinHelp, MS HTML Help: sectionNo is a context id.

External HTML help/simple wxHTML help: wxExtHelpController and wxHelpControllerHtml implement sectionNo as an id in a map file, which is of the form:

    0  wx.html             ; Index
    1  wx34.html#classref  ; Class reference
    2  wx204.html          ; Function reference

wxHtmlHelpController: sectionNo is an identifier as specified in the `.hhc` file. See Help files format.

See also the help sample for notes on how to specify section numbers for various help file formats.

### wxHelpController::GetFrameParameters

virtual wxFrame * GetFrameParameters(const wxSize * size = NULL, const wxPoint * pos = NULL, bool *newFrameEachTime = NULL)

This reads the current settings for the help frame in the case of the wxHelpControllerHtml, setting the frame size, position and the newFrameEachTime parameters to the last values used. It also returns the pointer to the last opened help frame. This can be used for example, to automatically close the help frame on program shutdown.

wxHtmlHelpController returns the frame, size and position.

For all other help controllers, this function does nothing and just returns NULL.

Parameters

viewer

This defaults to "netscape" for wxExtHelpController.

flags

This defaults to wxHELP_NETSCAPE for wxExtHelpController, indicating that the viewer is a variant of Netscape Navigator.

### wxHelpController::KeywordSearch

virtual bool KeywordSearch(const wxString& keyWord)

If the help viewer is not running, runs it, and searches for sections matching the given keyword. If one match is found, the file is displayed at this section.

WinHelp, MS HTML Help: If more than one match is found, the first topic is displayed.

External HTML help, simple wxHTML help: If more than one match is found, a choice of topics is displayed.

wxHtmlHelpController: see wxHtmlHelpController::KeywordSearch.

### wxHelpController::LoadFile

virtual bool LoadFile(const wxString& file = "")

If the help viewer is not running, runs it and loads the given file. If the filename is not supplied or is empty, the file specified in Initialize is used. If the viewer is already displaying the specified file, it will not be reloaded. This member function may be used before each display call in case the user has opened another file.

wxHtmlHelpController ignores this call.

### wxHelpController::OnQuit

virtual bool OnQuit()

Overridable member called when this application's viewer is quit by the user.

This does not work for all help controllers.

### wxHelpController::SetFrameParameters

virtual void SetFrameParameters(const wxString & title, const wxSize & size, const wxPoint & pos = wxDefaultPosition, bool newFrameEachTime = FALSE)

For wxHelpControllerHtml, this allows the application to set the default frame title, size and position for the frame. If the title contains %s, this will be replaced with the page title. If the parameter newFrameEachTime is set, the controller will open a new help frame each time it is called.

For wxHtmlHelpController, the title is set (again with %s indicating the page title) and also the size and position of the frame if the frame is already open. newFrameEachTime is ignored.

For all other help controllers this function has no effect.

### wxHelpController::SetViewer

virtual void SetViewer(const wxString& viewer, long flags)

Sets detailed viewer information. So far this is only relevant to wxExtHelpController.

Some examples of usage:

      m_help.SetViewer("kdehelp");
      m_help.SetViewer("gnome-help-browser");
      m_help.SetViewer("netscape", wxHELP_NETSCAPE);

### wxHelpController::Quit

virtual bool Quit()

If the viewer is running, quits it by disconnecting.

For Windows Help, the viewer will only close if no other application is using it.