Core: Launcher: can drag-and-drop patch on Launcher window

[beauxq]

What is this fixing or adding?

Many people come to discord for help when they try dragging their patch file onto the window, instead of dragging it onto the executable.

(This is mostly for unsupported worlds, so there is no file-type association.)

So let's support dragging the patch file onto the window.

(I've seen the problem more with people dragging patches into the SNIClient window. Maybe I'll add this to SNIClient in a different PR later.)

How was this tested?

I generated a game with an unsupported SNES game, then opened the Launcher window and dragged the patch file into the Launcher window. It patched the rom and opened up SNIClient.

[Zunawe]

For the record, it's entirely possible for unsupported worlds to associate extensions with components, including with both BizHawkClient and SNIClient. I'm not arguing against this change, but in my opinion the instruction to players should already be to use the Open Patch button in the launcher or to associate the patch file extension with the launcher, since drag and drop has these clarity problems.

[black-sliver]

We use the same thing (drag file onto main window) in a lot of applications these days, and even a lot of websites allow that, so I am all for it.

Is there any need for more feedback to the user? Is it clear enough if only the mouse cursor changes to "accept drop" (or does not change to "deny drop")? Should we only accept drop if it can be identified? (Is this even possible with kivy?)

[beauxq]

For the record, it's entirely possible for unsupported worlds to associate extensions with components, including with both BizHawkClient and SNIClient.

Indeed, this drag-and-drop won't work if the component association isn't there.
The association that I was referring to is the Windows OS association that is made by the installer automatically for supported worlds, but is not made automatically for unsupported worlds.

the instruction to players should already be to use the Open Patch button in the launcher or to associate the patch file extension with the launcher, since drag and drop has these clarity problems.

In my opinion, these are both inferior user experiences - having to navigate to find a file in the window that opens up after pressing the "Open Patch" button (when the player is often already looking at the file in a different window) - or having to manually create a Windows file association.
I think being able to drag and drop the file onto something is a better user experience than both of these.

[beauxq]

Is there any need for more feedback to the user? Is it clear enough if only the mouse cursor changes to "accept drop" (or does not change to "deny drop")? Should we only accept drop if it can be identified? (Is this even possible with kivy?)

I don't see a kivy interface to change the indication for whether the file drop will succeed. There might be a way to do it, but I don't see a big need for it. Maybe it could be added in the future.

(Even without this PR, in our current main branch, there is an indicator that a file can be dragged onto the Launcher window, and it looks like it will do something (but it won't do anything).

[black-sliver]

Thanks!

While I think this could use some user feedback (patching may take a while, opening the client may take a while), it works as advertised.