Is it possible to add a callback when the user saves in-game

[KobeOne2]

Hello, and thank you for your fantastic project. I've been using it a lot recently due to my current circumstances.

Anyway, I was wondering if it was possible (to prevent forgetting to download the save😅) to trigger an automatic download prompt or even upload the save to a server whenever a player saved in-game. I tried to add this capability myself, but I couldn't find a way to detect when the save game changed. So, do you know if it is even doable with WASM mGBA? As far as I can tell, mGBA should have a callback "saveDataUpdated".

[thenick775]

I didn't know that functionality existed, which is what has so far prevented me from implementing auto-persistence features.

I might just have to figure out how to bind it in my fork of mGBA, hopefully it doesn't require threading (which I haven't gotten to a full implementation with web workers).

I'll investigate this one as I free up!

For context:

• nothing like that is exposed so far in the wasm contract
• historically, I wasn't able to figure that out as I'm pretty new to the mGBA codebase as a whole (and as a user)
• I can see this is used in _mCoreThreadAddCallbacks, which may preclude this type of functionality until I can work out threading in wasm for mGBA
• This might be nice to add to Extended settings UI #151, adding specified actions that can occur on any of the mGBA callback states in mCoreCallbacks
  • prefer opt in most likely, as I definitely do intentionally rely on the current behavior sometimes, others might too

[thenick775]

And just in case I've done a bad job at disseminating information, you should never have to download your safe files unless you want backups!

The File System has a SAVE FILE SYSTEM button, when clicked this will save all your roms/saves/save states to your browsers local indexeddb, ready for use when you close/reopen the emulator 😎

[thenick775]

@KobeOne2 How'd you learn about the saveDataUpdated method in mGBA's core callbacks?

[thenick775]

Just wanted to say I've got a tentative POC up here:

Demo link (see file system modal and console output)

gbajs3 changes

mGBA wasm changes

I'll try to polish this up as I'm available!

[KobeOne2]

Thank you for your hard work.

How'd you learn about the saveDataUpdated method in mGBA's core callbacks?

They seem to be listed here https://mgba.io/docs/scripting.html#class-CallbackManager.

[thenick775]

They seem to be listed here https://mgba.io/docs/scripting.html#class-CallbackManager.

Nice! I really need to dig deeper into mGBA docs 😂

[thenick775]

Just noting that this is still in progress!

Running into some issues adding a function to the wasm table immediately after emulator initialization/game startup, but should be able to work through that 😎

[thenick775]

@KobeOne2 I've extended the mGBA core functionality to add user defined callbacks, at least all of the ones I could prove were accessible!

You can find the work done to add callbacks on the mGBA wasm core side here

And an example of how I use them on the js side here

I may add a few more callbacks as time goes on and I make the UI a little more conducive for actual emulator settings, but feel free to submit a PR here if you want to add some functionality!

This should give you a template for adding your own callbacks, but feel free to create another issue, discussion, or comment here if you need any assistance! 😎