Re: HTML help

From: Martin Strand (marstr2(RemoveThis)_at_online.no)
Date: 01/25/04 

Date: Sun, 25 Jan 2004 20:07:27 +0100

Christakis John wrote:

> I have got HTML help working nicely when you click a button,
> including going to certain pages etc. But, when I press F1 it still
> tries to launch WinHelp with the .CHM file and errors. How can I
> intercept the F1?

Use this unit, and just go on as it was .hlp

dmHTMLHelp.pas

unit dmHTMLHelp;
{Unit to translate WinHelp requests into HTML Help and call the API.}
{Written by Dave Murray, October 2001. dmurray@worldmark.com}
{NOTES:
This unit assigns its own handler to the Application.OnHelp event.
DO NOT assign your own handler to Application.OnHelp.
Also, this unit ignores any form's HelpFile property. (Delphi 4+)}

interface

uses
  Windows, Messages, SysUtils, Forms;

const
  {commands to pass to HtmlHelp(), see HTML Help API Reference}
  HH_DISPLAY_TOPIC = $0000; {open help topic}
  HH_HELP_FINDER = $0000; {backwards compatibility,use
HH_DISPLAY_TOPIC instead}
  HH_DISPLAY_TOC = $0001; {select Contents tab in nav pane}
  HH_DISPLAY_INDEX = $0002; {select Index tab + search for keyword}
  HH_DISPLAY_SEARCH = $0003; {select Search tab in nav pane}
  HH_SET_WIN_TYPE = $0004;
  HH_GET_WIN_TYPE = $0005;
  HH_GET_WIN_HANDLE = $0006;
  HH_ENUM_INFO_TYPE = $0007;
  HH_SET_INFO_TYPE = $0008;
  HH_SYNC = $0009;
  HH_RESERVED1 = $000A; {not currently implemented}
  HH_RESERVED2 = $000B; {not currently implemented}
  HH_RESERVED3 = $000C; {not currently implemented}
  HH_KEYWORD_LOOKUP = $000D;
  HH_DISPLAY_TEXT_POPUP = $000E; {display string resource/text in a popup}
  HH_HELP_CONTEXT = $000F; {display topic for context number}
  HH_TP_HELP_CONTEXTMENU = $0010; {text popup help, same as
HELP_CONTEXTMENU}
  HH_TP_HELP_WM_HELP = $0011; {text popup help, same as HELP_WM_HELP}
  HH_CLOSE_ALL = $0012; {close all windows opened by caller}
  HH_ALINK_LOOKUP = $0013; {ALink version of HH_KEYWORD_LOOKUP}
  HH_GET_LAST_ERROR = $0014; {not currently implemented}
  HH_ENUM_CATEGORY = $0015;
  HH_ENUM_CATEGORY_IT = $0016;
  HH_RESET_IT_FILTER = $0017;
  HH_SET_INCLUSIVE_FILTER = $0018;
  HH_SET_EXCLUSIVE_FILTER = $0019;
  HH_INITIALIZE = $001C;
  HH_UNINITIALIZE = $001D;
  HH_PRETRANSLATEMESSAGE = $00FD;
  HH_SET_GLOBAL_PROPERTY = $00FC;

function HtmlHelp(hwndCaller: THandle; pszFile: PChar; uCommand: cardinal;
dwData: longint): THandle; stdcall;

implementation

function HtmlHelp(hwndCaller: THandle; pszFile: PChar; uCommand: cardinal;
dwData: longint): THandle; stdcall; external 'hhctrl.ocx' name 'HtmlHelpA';
{external API call}

type
  TdmHTMLHelp = class(TObject) {encapsulates function}
    function ApplicationHelp(Command: Word; Data: Longint; var CallHelp:
Boolean): Boolean;
  end; {TdmHTMLHelp..}

function TdmHTMLHelp.ApplicationHelp(Command: Word; Data: Longint; var
CallHelp: Boolean): Boolean;
{translates WinHelp commands to HTMLHelp commands + calls API}
var
  HCommand : word;
begin
  {make sure VCL doesn't activate WinHelp + function succeeds}
  CallHelp := false;
  result := true;
  {translate WinHelp > HTMLHelp}
  case Command of
    HELP_CONTENTS : begin
      HCommand := HH_DISPLAY_TOC;
      Data := 0;
      end; {HELP_CONTENTS..}
  HELP_CONTEXT : HCommand := HH_HELP_CONTEXT;
    HELP_CONTEXTPOPUP : HCommand := HH_HELP_CONTEXT;
    HELP_FINDER : HCommand := HH_DISPLAY_TOPIC;
    HELP_KEY : HCommand := HH_DISPLAY_INDEX;
    HELP_QUIT : begin
      HCommand := HH_CLOSE_ALL;
      Data := 0;
      end; {HELP_QUIT..}
  else begin {default}
    HCommand := HH_DISPLAY_TOPIC;
    Data := 0;
    end; {default..}
  end; {case Command..}
  {call HTML Help API}
  HtmlHelp(Application.MainForm.Handle, PChar(Application.HelpFile),
HCommand, Data);
end; {function TdmHTMLHelp.ApplicationHelp}

var
  HTMLHelper: TdmHTMLHelp;

initialization
  {create object + assign event handler}
  HTMLHelper := TdmHTMLHelp.Create;
  Application.OnHelp := HTMLHelper.ApplicationHelp;
finalization
  {free event handler + object}
  Application.OnHelp := nil;
  HTMLHelper.Free;
end. 

-- 
I didn't intend to do a thing today
and so far I'm right on schedule!