Manage save file on Android an PC

[alejandro-a]

Hi,

I was trying to create a file in order to save some game progress, various settings, etc...
Can someone suggest me some strategy/library in order to manage a save file on android and pc?

Thanks

[hajimehoshi]

I'm not familiar with mobile APIs but I'd define a Go interface like this, expose it, and add an implementation in Java and Objective-C.

type Storage interface {
  Save(path string, data []byte) error
  Load(path string) ([]byte, error)
}

[kendfss]

I figured out a work around for android. The fundamental problem is that android apps run from the / root directory, but only have write permission in a sandboxed directory whose path looks something like /data/user/0/com.your.app/files.

You could just hard-code that path, but what I did is create a binding function that accepts a string which I can call from the onCreate method in my main activity to pass the directory (which I obtain with this.getFilesDir().getPath(), where this is the main activity) which is slightly more of a cross platform solution than hard-coding.

Fwiw, here's a chat I had that helped me figure out a workflow. It starts with intercepting the back button and it ultimately reaches a slightly different approach in which I'm just passing the config json blob to java which handles the saving.

my final binding file:

package mob

import (
	"github.com/charmbracelet/log"
	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/mobile"
	"github.com/kendfss/shunt/gui"
)

var game ebiten.Game

func init() {
	game = gui.NewGame()
	mobile.SetGame(game)
}

func Dummy() {}

func OnBack() bool {
	return game.(*gui.App).OnBack()
}

func ConfDir(s string) {
	log.Info("setting conf dir", "path", s)
	game.(*gui.App).Conf.Dir(s)
	game.(*gui.App).Conf.Load()
}

my main activity:

package io.github.kendfss.shunt;

import android.os.Bundle;

import go.Seq;


public class MainActivity extends android.app.Activity {
    private EbitenViewWithErrorHandling view;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        io.github.kendfss.shunt.mob.Mob.confDir(this.getFilesDir().getPath());
        super.onCreate(savedInstanceState);
        Seq.setContext(getApplicationContext());
        view = new EbitenViewWithErrorHandling(this);
        setContentView(view);
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (view!=null) {
            view.suspendGame();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (view!=null) {
            view.resumeGame();
        }
    }

    @Override
    public void onBackPressed() {
        if (io.github.kendfss.shunt.mob.Mob.onBack()) {
            super.onBackPressed();
        }
    }
}