This article will explain how to fully integrate HTMLHelp (.chm) with C# WinForm application. The standard .NET
HelpProvider can only show topics out of .chm file or show static context help. Here, we will show how to display context sensitive help and tooltips out of the .chm as well.
HTMLHelp was designed to ship with C++ applications so a standard C++ application can make full use of a .chm file. Through
HtmlHelp API, it displays topics and can automatically assign controls to
stringIds allowing context sensitive help to be shown when requested. All was working on C++
controlIds mapped to
HTMLHelp stringIds and shared .h files used from both
HTMLHelp compiler and C++ application to help the mapping. The C# use of .chm file in that respect is very limited. Through
HelpProvider, one can assign only topics or static text to be show when help is requested for the control. The controls don't have the C++ IDs any more that can be mapped to an
stringIds for automatic context help display. To solve the lack of context sensitive help, we can still use
HtmlHelp API through
InteropServices and hhctrl.ocx. We can use this function with
HH_DISPLAY_TEXT_POPUP and passing the marshaled
HH_POPUP structure from C# filled with the necessary information. The only problem is that it needs
idString which is the numeric id of the
string for the context help text in the
HTMLHelp file. In C++, these numeric IDs were coming from the shared .h file, but here we don't have it ...... well then, add it to the project as a resource and parse it ourselves. We can "Add as Link" this .h file which originally should be in the
HTMLHelp project and set its build action as "Embedded Resource". The .h file consists of defines like:
#define ButtonHelp 1001
#define ButtonHelp.TT 1002
#define MainForm.tbKW 1003
#define MainForm.tbKW.TT 1004
#define MainForm 1005
#define MainForm.TT 1006
#define MainForm.cbHC 1007
#define MainForm.tvHF 1008
so we can read the resource at runtime:
and create a dictionary mapping
strings to numbers. But then still how to map these numbers to the controls in the C# application. Well, we can come up with some automatic recursive naming convention which constructs the
HTMLHelp name from gluing the names of the control and its parent back in the hierarchy.
String GetControlName(Control ctrl)
if (ctrl.Parent == null)
return GetControlName(ctrl.Parent) + "." + ctrl.Name;
For example, if we have a
MainForm and control on it named
tbKW, we can automatically workout that the
stringId matching this control is in the
dictionary under key "
MainForm.tbKW" . So if we construct the .h file defines with that in mind, everything will hook up when we use it with C#. The
HtmlHelp API is called on the control's
HelpRequested event, automatically filling up
HH_POPUP with the right
stringId taken from the .h dictionary with key the "recursive naming convention control name" -
To get the tooltips from the .chm file is another matter. It was not available even with C++ application so we have to use some trick to do it. The idea came from another CodeProject article Decompiling CHM (help) files with C# which explains how to browse through a content of a .chm file. Basically, all the files that are included in the
HMLHelp project are compiled as
IStreams in the .chm file which is kind of Compound Document File but not one you can open with Ole32.dll
StgOpenStorage, but for which we have to use undocumented interface
ITStorage (itss.dll) and its
StgOpenStorage. So basically, we can create a .txt file with the same syntax as the .txt file for the context sensitive help (even use the same one) and add the tooltips text there. Then, name the
stringIds with the same naming convention as the context sensitive help, but adding ".TT" at the end to separate them as tooltips. So when the application runs, we can read this
stream from the .chm storage and parse it and create dictionary of
stringId and tooltip text. Then, we can set C#
ToolTip object to be associated with each control and automatically assign the text for the control name.
Using the Code
The code that comes with the article is a C# WinForms project and a Library file which implements the .chm help interactions.
HTMLHelp Workshop project as well which works with the C# app:
It demonstrates the described ideas and can give you a good start.
The WinForms application makes use of the .chm help file through the class library
WinHtmlLib through class
WinHelpEx. So first of all, create an object of this class:
WinHelpEx s_help = new WinHelpEx();
This object can be
static and used throughout the whole application or per form depending on the needs and the structure of the .chm file. If you define separate context sensitive .txt file and tooltip .txt file and .h map file for every form in the .chm file has to have object per form. If all the context sensitive help is in one file and tooltip text is in one file and map .h is only one file, you can use only one
WinHelpEx static object for the whole project.
WinHelpEx has two main functions:
public void Load(
public void AttachForm(
Please take a look at the attached example for more details or just ask.
The code was updated to work on Win7 64 bit as per wvd_vegt remarks in the message section.
The code was updated to output a .h file with the
#defines of the
To unable it, uncomment these lines in Program.cs:
On that occasion, you don't need to call the
s_help.Load( ...... );