[FEATURE] Installer: Prompt for downgrading and prompt for uninstall if Odamex is already installed

[bcahue]

This change to the Inno Setup file is a pascal script that first checks if the version of Odamex you are installing is a downgrade to an already installed version of Odamex, and another prompt to ask the user if they want to uninstall the current version of Odamex before installing the new one, which would in effect free up the user to install Odamex to a different directory if wanted, or to change the install to a User install rather than a Computer-wide install, or vice versa.

Since it would notify the user what to do to change the path, I would consider this as solving #768

The script is skipped if the install is marked /SILENT or /VERYSILENT.

Attached is an example installer created using this script. It's of a fictitious (at the moment) version of 10.3.0. You can play around with the logic by changing the DisplayVersion in HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{2E517BBB-916F-4AB6-80E0-D4A292513F7A}_is1

Odamex-Installer.zip

[AlexMax]

I like the idea, however I have two issues with it.

First off, I don't get the "select install mode" screen after uninstalling Odamex. That probably has to be fixed.

Secondly, I think the message is unclear and front-loads the idea of uninstalling Odamex, which really should only be done in exceptional circumstances. There's also no way to cancel the installation at that point.

Try this copy on for size:

Odamex has been detected on this machine. Would you like to do an in-place upgrade?

If you want to upgrade your copy of Odamex in-place, press "Yes." This is the suggested choice.
If you want to do a fresh installation of Odamex, in order to change your installation directory or permissionss, press "No."
If you want to exit the installation, press "Cancel."

[Yes} [No] [Cancel]

[bcahue]

@AlexMax

I like the idea, however I have two issues with it.

First off, I don't get the "select install mode" screen after uninstalling Odamex. That probably has to be fixed.

I will likely need to just simply exit after uninstall and the user should simply launch the installer again to get the system-wide/user-wide prompt. I am not able to control this, as far as I can tell.

Secondly, I think the message is unclear and front-loads the idea of uninstalling Odamex, which really should only be done in exceptional circumstances. There's also no way to cancel the installation at that point.

Try this copy on for size:

Odamex has been detected on this machine. Would you like to do an in-place upgrade?
If you want to upgrade your copy of Odamex in-place, press "Yes." This is the suggested choice.
If you want to do a fresh installation of Odamex, in order to change your installation directory or permissionss, press "No."
If you want to exit the installation, press "Cancel."
[Yes} [No] [Cancel]

Agreed, this prompt is doable and does make more sense in a flow sense. I'll update when these are implemented.