Using Office Interop Application Object to get the PowerPoint version during installation with Inno Setup - vb.net

Question

During the installation of our PowerPoint add-in using Inno Setup installer, I need to get the currently used version of PowerPoint by querying an Application.PowerPoint object itself – instead of relying on registry entries which can't be guaranteed to give the correct value.
I have successfully implemented this for an MSI installer written with WIX based on this answer using this code:
Imports Microsoft.Office.Interop.PowerPoint
Public Class Environment
Public Shared Function GetPowerPointVersion() As String
Dim CurVer As String
Dim thisPowerPoint As Object
thisPowerPoint = New Application()
CurVer = thisPowerPoint.Version
thisPowerPoint.Quit()
Return CurVer
End Function
End Class
I don't entirely trust this to work in all situations (maybe paranoid), so will put in try/catch blocks and use the registry method if this fails.
I haven't been able to work out how to do a similar thing with Inno Setup installer. There are some examples of using DLLs – https://jrsoftware.org/ishelp/index.php?topic=scriptdll – but I can't see how I could create a function callable from Inno Setup from this which would return the version number.

Answer 1

You can use CreateOleObject to call PowerPoint and return the version:
[Code]
function GetPowerPointVersion(): string;
var
MyPowerPoint: Variant;
begin
MyPowerPoint := CreateOleObject('PowerPoint.Application');
Result := MyPowerPoint.Version;
MyPowerPoint.Quit;
end;

Answer 2

For completeness, this is the Pascal Script code which I am now using to get the PowerPoint version – based on Matej's answer, with a fallback to checking the registry if that fails:
function PowerPointVersion(): String;
var
key: String;
versionToUse: String;
installedPowerPoint: Variant;
begin
versionToUse := '';
try
installedPowerPoint := CreateOleObject('PowerPoint.Application');
versionToUse := installedPowerPoint.Version;
installedPowerPoint.Quit;
except
versionToUse := '';
end;
if versionToUse = '' then
begin
if RegQueryStringValue(GetHKLM, 'SOFTWARE\Microsoft\Office\ClickToRun\Configuration','VersionToReport', key) then
begin
versionToUse := key;
Delete(versionToUse, Pos('.', key), Length(key));
versionToUse := versionToUse + '.0';
end;
end;
if versionToUse = '' then
begin
if RegQueryStringValue(HKCR, 'PowerPoint.Application\CurVer\','', key) then
begin
StringChangeEx(key, 'PowerPoint.Application.', '', True);
versionToUse := key;
versionToUse := versionToUse + '.0';
end;
end;
try
// Check to see if versionToUse string can convert to a float:
StrToFloat(versionToUse);
Result := versionToUse;
except
Result := '';
end;
end;

Answer 3

It turns out that using Microsoft.Office.Interop.PowerPoint which is a NuGet package is not a good idea as it is not supported and will be prone to failure. See this discussion.
This external C# code will work and can be set up to be called from Inno Setup. However, using CreateOleObject within Inno Setup Pascal code as described in the accepted answer is far simpler.
[SupportedOSPlatform("windows")]
public class PowerPointEnvironment
{
public static string GetPowerPointVersion()
{
string CurVer = "";
Type? PowerPointType = Type.GetTypeFromProgID("PowerPoint.Application");
if (PowerPointType != null)
{
dynamic? thisPowerPoint = Activator.CreateInstance(PowerPointType);
if (thisPowerPoint != null)
{
CurVer = thisPowerPoint.version();
}
}
return CurVer;
}
}