In case anyone else might run into this, I found out the cause of my problems with the DLLs is simple and general and not specific to these libraries.
It turns out that vcpkg defaults to downloading 32-bit libraries. So to my great embarrassment, all the libraries I have installed are 32-bits. Once I found this out, I changed the Xojo build settings to 32-bits and tested my app, and it worked.
Well, I want 64-bits for this project, so I am now installing the right libraries with vcpkg. I expected that since I’m running 64-bit installation of Windows 10, then the microsoft tool vcpkg would know this and default to installing 64-bit libraries, but it does not do this. To me that is really not at all logical. Anyway, the trick I did not know I needed is to add the option “–triplet x64-windows” to the install command:
.\vcpkg install library_name --triplet x64-windows
The environment variable for vcpkg default behaviour can also be changed to get 64-bit libraries without having to type in the option. The steps needed to do this in Windows 10 seem a bit ridiculous to me, but I did it anyway and maybe you will want to do it too, so here they are:
- Click Windows Start and then click on “Settings” (this used to be “Control Panels”)
- Click on “System”, and type in the word “environment” into the search field
- Select the option that reads “Edit the System Environment Variables”
- in the window that appears, click the “Advanced” tab
- at the bottom right, click the “Environment Variables” button
- Under the “System Variables” pane, click the “New…” button
- create a new variable with this info:
name: VCPKG_DEFAULT_TRIPLET
value: x64-windows
Now when you use vcpkg at the Power Shell command prompt, you do not need to type --triplet x64-windows to get 64-bit libraries 