lhelp using HelpType set to htContext
lazarus / 21-General

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Tdecnj · 2023-11-24 14:14

Hello,
Is it possible to use a chm help file (made with Ms_Windows hhw) with
lhelp (Lazarus 2.2.6 and FPC 3.2.2) with  HelpType set to htContext?
I am trying for several days and the only thing i got it's an error
windows with 2 messages :
'A help database was found for this topic, but this topic was not
found...' and below 'Help context 4 not found.' (4 is the number of my
Context help)
The first one is rsHelpContextNotFound and the second is
shrContextNotFound but looking at the code referencing this 2 messages
(helpintfs.pas, lazhelpchm.pas, lazhelphtml.pas and lazhelpintf.pas ) 
I was not able to understand the problem.
If I set HelpType  to htKeyword I got the help file on summary (it's
better than the error message but it is not that I want). Alls my try
were on Windows 10.
I have read all the documents I have found on lhelp (chm, etc). It is
possible that I missed something (english is not my mother tongue).

Thanks.

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balazsszekely · 2023-11-24 14:27

Quote from: Tdecnj on November 24, 2023, 03:14:06 pmHello,
Is it possible to use a chm help file (made with Ms_Windows hhw) with
lhelp (Lazarus 2.2.6 and FPC 3.2.2) with  HelpType set to htContext?
I am trying for several days and the only thing i got it's an error
windows with 2 messages :
'A help database was found for this topic, but this topic was not
found...' and below 'Help context 4 not found.' (4 is the number of my
Context help)
The first one is rsHelpContextNotFound and the second is
shrContextNotFound but looking at the code referencing this 2 messages
(helpintfs.pas, lazhelpchm.pas, lazhelphtml.pas and lazhelpintf.pas ) 
I was not able to understand the problem.
If I set HelpType  to htKeyword I got the help file on summary (it's
better than the error message but it is not that I want). Alls my try
were on Windows 10.
I have read all the documents I have found on lhelp (chm, etc). It is
possible that I missed something (english is not my mother tongue).

Thanks.
Not exactly what you need, but very similar.
https://wiki.lazarus.freepascal.org/Add_Help_to_Your_Application
https://forum.lazarus.freepascal.org/index.php/topic,38487.msg261731.h
tml#msg261731

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Tdecnj · 2023-11-24 19:58

Thanks,
I have readed these docs and they do not answer my initial question.

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wp · 2023-11-24 22:22

Created a little demo with a few controls (Edit HelpCtx = 2, Combobox
HelpCtx = 3, Button HelpCtx = 4, ?-button calling HelpCtx 1) and wrote
a chm file with HelpNDoc, to have something for testing.

Never worked much with the internal help system, therefore, I started
with what I have done before: Call help based on the htmlhelp unit
which comes with FPC. I am attaching the project in this state
demonstrating that help is working this way and the chm file is
correct.

Of course, this is a windows-only solution, and I'll try to look into
the LCL Help database system in the next step. But cannot promise
anything...

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Tdecnj · 2023-11-25 11:30

I knew this one and the code (in relation to help) in Lazstats : its
works but only on Ms_Windows and I am looking for a solution for Linux
that's why i wanted to use lhelp.
Anyway, thanks for trying to help me.

By the way i have an another question : who is responsible for closing
lhelp? In my application (on Ms_Windows) when I quit with lhelp
running, lhelp is not closed;  in Lazarus Ide when I quit with lhelp
running, lhelp is closed. So the responsible is the application using
lhelp.
In my application, I am using LHelpConnector and CHMHelpDatabase, I
suppose that is LHelpConnector the candidate to stop lhelp, but how?
Or do I need to search lhelp in the running tasks and stop it running
when I close the application?
Thanks.

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wp · 2023-11-25 15:41

In the meantime, after some more experiments, I got the impression
that TCHMHelpDatabase does not fully support the way of identifying
help items by means of the HelpContext numbers. Switching to Help
Keywords, on the other hand, works, also with LHelp.

There is an issue, though, in my help files created by HelpNDoc: This
authoring system puts the html files in the root of the chm file
structure. Therefore the KeywordPrefix property needed by the
CHMHelpdatabase must be empty - and this causes trouble in unit
LazHelpCHM where the condition "(KeywordPrefix <> '')" inhibits
further processing; after commenting this out I got my demo working
correctly:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
TCHMHelpDatabase.GetNodesForKeyword(const HelpKeyword: string;  var
ListOfNodes: THelpNodeQueryList; var ErrMsg: string):
TShowHelpResult;...  if not (csDesigning in ComponentState) and//  
 (KeywordPrefix<>'') and     // <---- MUST BE COMMENTED OUT   
(LeftStr(HelpKeyword,length(KeywordPrefix))=KeywordPrefix) then  begin
                   ...
I found a way how to terminate LHelp with the main application: Add a
handler to the form's OnDestroy and send an "mrClose" command to LHelp
via IPC:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses 
LHelpControl;  // for "mrClose" procedure TForm1.FormDestroy(Sender:
TObject);begin  if (LHelpConnector1.Connection <> nil) and
LHelpConnector1.Connection.ServerRunning then   
LHelpConnector1.Connection.RunMiscCommand(LHelpControl.mrClose);end;

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Tdecnj · 2023-11-25 18:39

Hello wp,
I tried, on Ms_Windows 10, your code to close lhelp, it's work fine.
Thank you very much for this help. (I will try it later on Linux-
Ubuntu)

I tried again to get a context help via htKeyword (I think that
htContext is not implemented...) but i got only the summary of my help
file not the page of the context help. I am probably doing something
wrong.
Thank you again for your help.

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wp · 2023-11-25 22:21

Quote from: Tdecnj on November 25, 2023, 07:39:45 pmI tried again to
get a context help via htKeyword (I think that htContext is not
implemented...) but i got only the summary of my help file not the
page of the context help. I am probably doing something wrong.
Strange... I assume that the controls have the correct help keywords
for the pages that you want to see. Do you see the correct help pages
when you replace LHelpConnector/CHMHelpDatabase by the htmlhelp unit
that I mentioned in the other thread? I am attaching a modified
version of one of the previous demos to show how to work with help
keywords in the htmlhelp unit. I know this is for Windows only, but it
is an easy check whether keywords are correct.

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wp · 2023-11-25 22:24

Another idea for Linux: There is a great chm viewer, kchmviewer, and
of course, you can invoke it to display the help windows for you:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses 
Process; procedure TForm1.FormCreate(Sender: TObject);var  chmfile:
String;begin  chmFile := ChangeFileExt(Application.ExeName, '.chm'); 
if FileExists(chmfile) then begin    Application.HelpFile := chmfile; 
  Application.OnHelp := @HelpHandler;  end;end; // Call HTML help
(.chm file)function TForm1.HelpHandler(Command:word; Data:PtrInt;  var
CallHelp:Boolean): Boolean;var  topic: String;  process:
TProcess;begin  topic := PChar(Data);  process :=
TProcess.Create(Self);  try    process.Executable := 'kchmviewer';   
process.Parameters.Add('-showPage');   
process.Parameters.Add(topic);   
process.Parameters.Add(Application.HelpFile);    process.Execute; 
finally    process.Free;  end;   // Don't call regular help  CallHelp
:= False;end;
Unfortunately, this example displays a modal help window, but you
certainly can fiddle with the TProcess options to make it non-modal,
and it requires some book-keeping to make sure that the window is
updated when F1 is pressed the next time.

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Tdecnj · 2023-11-26 15:46

Hello,
I found why I could not obtain context help with htKeyword. The
document wiki.lazarus.freepascal.org/Add_Help_to_Your_Application say
in its example for chm, I quote :

"Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
 CHMHelpDatabase1.Filename := ChangeFileExt(Application.ExeName,
'.chm');    CHMHelpDatabase1.KeywordPrefix := 'html/';   
CHMHelpDatabase1.AutoRegister:=True;"
I followed the example but there was an error :
CHMHelpDatabase1.KeywordPrefix := 'html/'; should have been 
 CHMHelpDatabase1.KeywordPrefix := 'html'; without trailing slash.
So if your help file is 'helpApplication.chm', 
CHMHelpDatabase1.KeywordPrefix will be set to 'helpApplication' and in
your control's HelpKeyword you will put 'helpApplication/topic1.htlm'
: the context help with htKeyword will work.

to wp : I knew kchmviewer (yes, it's great), I didn't think that i
could use it in the same way we can use the MS_Windows help.
Thanks.

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wp · 2023-11-26 16:23

Quote from: Tdecnj on November 26, 2023, 04:46:02
pmCHMHelpDatabase1.KeywordPrefix := 'html/'; should have been 
 CHMHelpDatabase1.KeywordPrefix := 'html'; without trailing slash.