How can I view a specific chm help file topic in an edge browser (inside a WebView2 control)

Question

How can I view a specific chm help file topic in an edge browser (inside a WebView2 control)

Jim Ward 6

I am converting a VB.Net Winforms application that targets .Net framework 4.8 using WebBrowser controls to use WebView2 controls

The Winforms application has a chm help file which is installed with the application and in the IE/WebBrowser world I can view a specific context sensitive help topic using the ms-its protocol

e.g. ms-its:C:/Program%20Files%20(x86)/Smart%20Communications%20Client%2026.0.0.1/SmartCommunications.chm::/BCSDocumentIntro.htm

This doesn't work with Edge/WebView2 and I get the message

Failed to launch 'ms-its:C:/Program%20Files%20(x86)/Smart%20Communications%20Client%2026.0.0.1/SmartCommunications.chm::/BCSDocumentIntro.htm' because the scheme does not have a registered handler.

How can I view a specific chm help file topic in an edge browser within a chm file (with navigation to previous, next and linked topics working)?

Jim Ward 6 Reputation points

2022-01-06T11:37:41.8+00:00

I have tried using

file:///C:\Program%20Files%20(x86)\Smart%20Communications%20Client%2026.0.0.1\SmartCommunications.chm

This resulted in edge downloading the chm file (it's already on my hard drive) and I had to click on Open file to open the help file outside edge as if I had clicked on the chm directly
That's not what I need as I need to open the chm on a specific topic within the browser itself and not in another windows application.
The ms-its protocol lets you specify the topic following the chm file, if I try that using the file protocol it doesn't recognize the file name
Jim Ward 6 Reputation points

2022-01-06T12:07:43.14+00:00

I know that if I de-compile the chm file I can use the file protocol to display the specific file but that's a poor solution as my setup program would need to be changed to install the de-compiled stuff as well as the chm file

The chm file is a compressed version of all the help files; it's not elegant to have to de-compile it, duplicating the information and tripling the amount of disk space used.
Castorix31 90,521 Reputation points

2022-01-06T12:26:47.96+00:00

Do you really need to use WebView2 to display it ?
Because they are other methods, like ShowHTMLDialogEx, from Mshtml.dll, which is used by Edge (for IE Mode), and supported to at least 2029, according to docs
Jim Ward 6 Reputation points

2022-01-06T12:32:14.847+00:00

If that displays html then I still need to de-compile the chm file to use it. (it seems to me that it's a double whammy if I need to install help files and the chm file containing them)
Does it work with chm files too?
If so do you have an example?
Castorix31 90,521 Reputation points

2022-01-06T12:38:11.113+00:00

Yes, I tested with a MS help file from SDK (SHELLCC.CHM) and a random Topic
I quickly tested in C#, but I can convert it into VB if your code is in VB.NET
Jim Ward 6 Reputation points

2022-01-06T13:57:05.887+00:00

Does that allow navigation through the help file from that page as well?
I also don't want it as a separate dialogue, I need a control containing the result in existing forms as shown
Jim Ward 6 Reputation points

2022-01-06T14:14:36.397+00:00
Castorix31 90,521 Reputation points

2022-01-06T15:17:23.71+00:00

Does that allow navigation through the help file from that page as well?

This seems to be a problem : If I click on links in the .CHM page, they are opened in a new window
Jim Ward 6 Reputation points

2022-01-07T09:37:44.183+00:00

I've updated the issue description to clarify that I need navigation links in the help file to work too
Castorix31 90,521 Reputation points

2022-01-08T09:31:06.17+00:00

Then my method is not a good solution (I tried to intercept new windows from links with IDocHostUIHandler, but too complicated...)
Otherwise, you could keep the WebBrowser control if the goal is just to display .CHM
I found this from a MS employee (champnic) who works on MS Edge in this thread : Is Compatibility mode an option in WebView2

"the WebBrowser control will continue to work after the IE Desktop Browser end of life in 2022, until about 2029. We do have #440 tracking adding IE mode support, but I don't anticipate we will get to that work anytime soon, and our recommendation is to switch between using WebView2 and WebBrowser if you still need IE support.
"

Your answer

Jim Ward 6 Reputation points

2022-01-06T11:37:41.8+00:00

I have tried using

file:///C:\Program%20Files%20(x86)\Smart%20Communications%20Client%2026.0.0.1\SmartCommunications.chm

This resulted in edge downloading the chm file (it's already on my hard drive) and I had to click on Open file to open the help file outside edge as if I had clicked on the chm directly
That's not what I need as I need to open the chm on a specific topic within the browser itself and not in another windows application.
The ms-its protocol lets you specify the topic following the chm file, if I try that using the file protocol it doesn't recognize the file name
Jim Ward 6 Reputation points

2022-01-06T12:07:43.14+00:00

I know that if I de-compile the chm file I can use the file protocol to display the specific file but that's a poor solution as my setup program would need to be changed to install the de-compiled stuff as well as the chm file

The chm file is a compressed version of all the help files; it's not elegant to have to de-compile it, duplicating the information and tripling the amount of disk space used.
Castorix31 90,521 Reputation points

2022-01-06T12:26:47.96+00:00

Do you really need to use WebView2 to display it ?
Because they are other methods, like ShowHTMLDialogEx, from Mshtml.dll, which is used by Edge (for IE Mode), and supported to at least 2029, according to docs
Jim Ward 6 Reputation points

2022-01-06T12:32:14.847+00:00

If that displays html then I still need to de-compile the chm file to use it. (it seems to me that it's a double whammy if I need to install help files and the chm file containing them)
Does it work with chm files too?
If so do you have an example?
Castorix31 90,521 Reputation points

2022-01-06T12:38:11.113+00:00

Yes, I tested with a MS help file from SDK (SHELLCC.CHM) and a random Topic
I quickly tested in C#, but I can convert it into VB if your code is in VB.NET
Jim Ward 6 Reputation points

2022-01-06T13:57:05.887+00:00

Does that allow navigation through the help file from that page as well?
I also don't want it as a separate dialogue, I need a control containing the result in existing forms as shown
Castorix31 90,521 Reputation points

2022-01-06T15:17:23.71+00:00

Does that allow navigation through the help file from that page as well?

This seems to be a problem : If I click on links in the .CHM page, they are opened in a new window
Jim Ward 6 Reputation points

2022-01-07T09:37:44.183+00:00

I've updated the issue description to clarify that I need navigation links in the help file to work too
Castorix31 90,521 Reputation points

2022-01-08T09:31:06.17+00:00

Then my method is not a good solution (I tried to intercept new windows from links with IDocHostUIHandler, but too complicated...)
Otherwise, you could keep the WebBrowser control if the goal is just to display .CHM
I found this from a MS employee (champnic) who works on MS Edge in this thread : Is Compatibility mode an option in WebView2

"the WebBrowser control will continue to work after the IE Desktop Browser end of life in 2022, until about 2029. We do have #440 tracking adding IE mode support, but I don't anticipate we will get to that work anytime soon, and our recommendation is to switch between using WebView2 and WebBrowser if you still need IE support.
"

Share via

How can I view a specific chm help file topic in an edge browser (inside a WebView2 control)

Your answer