Question

I am able to open a CHM file by passing a ShortInteger and casting it as a Word for the dwData parameter. I.E.

Unit Help;   //this is where the Id's are set with their description
 Interface
 Const

Address_File = 35;  //delphi identifies Address_File as a shortint
etc..

Call get help pass my ID

GetHelp(Address_File); //call get help pass my ID to open to the Address_File topic

GetHelp procedure

procedure GetHelp(HelpID : Word);
begin
  Application.HelpFile := ProgramPath + 'help.chm';
  HtmlHelpW(0, PWideChar(Application.HelpFile),HH_HELP_CONTEXT , HelpID);
end;

HtmlHelpW function

function HtmlHelpW(hwndCaller : HWND; pszFile: PWideChar; uCommand : Integer;
         dwData : DWORD) : HWND; stdcall; external 'hhctrl.ocx' name 'HtmlHelpW';

As I pass different ShortIntegers I am able to initialize the help file at different sections.
However I can’t figure out how the values are mapped. There are some sections in the chm file that I want to be able to map to but the short Integer or context ID associated with them is not documented in the program or is not mapped.

Answer 1

Free Pascal comes with a chmls.exe util that has a command that tries to recover the alias (context) data:

chmls, a CHM utility. (c) 2010 Free Pascal core.

Usage: chmls [switches] [command] [command specific parameters]

Switches :
 -h, --help     : this screen
 -p, --no-page  : do not page list output
 -n,--name-only : only show "name" column in list output

Where command is one of the following or if omitted, equal to LIST.
 list       <filename> [section number]
            Shows contents of the archive's directory
 extract    <chm filename> <filename to extract> [saveasname]
            Extracts file "filename to get" from archive "filename",
            and, if specified, saves it to [saveasname]
 extractall <chm filename> [directory]
            Extracts all files from archive "filename" to directory
            "directory"
 unblockchm <filespec1> [filespec2] ..
            Mass unblocks (XPsp2+) the relevant CHMs. Multiple files
            and wildcards allowed
 extractalias <chmfilename> [basefilename] [symbolprefix]
            Extracts context info from file "chmfilename"
            to a "basefilename".h and "basefilename".ali,
            using symbols "symbolprefix"contextnr
 extracttoc <chmfilename> [filename]
            Extracts the toc (mainly to check binary TOC)
 extractindex <chmfilename> [filename]
            Extracts the index (mainly to check binary index)

This might be a start, since at least you’ll know which pages are exported using an ID, and maybe the URL names will give some information.

The util is in recent releases (make sure you get 2.6.0) and also available in Free Pascal source, which should be convertable to Delphi with relatively minor effort.

Basically the chmls tool was created out of various test codebases. The testprograms decompiled and printed contents of different CHM sections and were used while creating the helpfile compiler, chmcmd, which is also part of FPC.