Can the Help.ShowHelp API be modified to simply invoke the CHM file?

Question

This is my primary way for displaying help topics from within my WinForm button click handlers:

Handler:

private void buttonHelp_Click(object sender, EventArgs e)
{
    CutTools.DisplayHelpTopic(this, "create-new-viewport.htm");
}

Base method:

public static void DisplayHelpTopic(Control parent, string topic)
{
    try
    {
        // Use an empty form as the parent so that the help file will not block the CAD software
        Form mHelpParent = new Form();

        // Use location of this DLL file
        System.Reflection.Module mod = parent.GetType().Module;
        string path = Path.GetDirectoryName(mod.FullyQualifiedName);

        Help.ShowHelp(mHelpParent,
            Path.Combine(path, "cut-tools-help.chm"), HelpNavigator.Topic, topic);
    }
    catch (System.Exception ex)
    {
        _AcAp.Application.ShowAlertDialog(
                            string.Format("\nError: {0}\nStackTrace: {1}", ex.Message, ex.StackTrace));
    }
}

The forms are displaid inside AutoCAD, BricsCAD or ZWCAD. The about is fine and great. But if I want to simply display the CHM file itself (so no actual form is available) I have to do this:

[CommandMethod("TS_DisplayHelp")]
public void TS_DisplayHelp()
{
    // Use location of this DLL file
    System.Reflection.Module mod = GetType().Module;
    System.Diagnostics.Process.Start(
        Path.Combine(Path.GetDirectoryName(mod.FullyQualifiedName), "cut-tools-help.chm"));
}

It works but has one drawback. It spawns a new instance of the help and does not use the same instance.

For example:

You start one of the other commands and show the help via button click. You cancel.
You start a different command and show the help via button click. Help.ShowHelp uses same instance.
You can command and start help via TS_DISPLAYHELP and it starts new instance.

Given the context of TS_DISPLAYHELP I can't work out how to directly use Help.ShowHelp as I can in my button click handlers.

score 1 · Accepted Answer · answered Sep 29 '21 at 07:18

At the moment I have managed to get around this issue by duplicating the DisplayHelpTopic code directly in the command TS_DISPLAYHELP method:

[CommandMethod("TS_DisplayHelp")]
public void TS_DisplayHelp()
{
    try
    {
        // Use an empty form as the parent so that the help file will not block the CAD software
        Form mHelpParent = new Form();

        // Use location of this DLL file
        System.Reflection.Module mod = GetType().Module;
        string path = Path.GetDirectoryName(mod.FullyQualifiedName);

        Help.ShowHelp(mHelpParent,
            Path.Combine(path, "cut-tools-help.chm"), HelpNavigator.Topic, "command-index.htm");
    }
    catch (System.Exception ex)
    {
        _AcAp.Application.ShowAlertDialog(
                            string.Format("\nError: {0}\nStackTrace: {1}", ex.Message, ex.StackTrace));
    }
}

I know that my default topic is "command-index.htm".

I am happy with the above resolution.

Can the Help.ShowHelp API be modified to simply invoke the CHM file?

1 Answers1