ui/app: introduce DataDir for application-specific data files

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/app/GioActivity.java

@@ -12,16 +12,14 @@ import android.view.WindowManager;
 public class GioActivity extends Activity {
 	private GioView view;
 
-	static {
-		System.loadLibrary("gio");
-	}
-
 	@Override public void onCreate(Bundle state) {
 		super.onCreate(state);
+
 		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
 			Window w = getWindow();
 			w.setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
 		}
+
 		this.view = new GioView(this);
 		setContentView(view);
 	}

ui/app/GioView.java

@@ -20,18 +20,46 @@ import android.view.inputmethod.InputConnection;
 import android.view.inputmethod.InputMethodManager;
 import android.view.inputmethod.EditorInfo;
 
+import java.io.UnsupportedEncodingException;
+
 public class GioView extends SurfaceView implements Choreographer.FrameCallback {
+	private final static Object initLock = new Object();
+	private static boolean jniLoaded;
+	private static String dataDir;
+
 	private final SurfaceHolder.Callback callbacks;
 	private final InputMethodManager imm;
 	private final Handler handler;
 	private long nhandle;
 
+	private static synchronized void initialize(Context appCtx) {
+		synchronized (initLock) {
+			if (jniLoaded) {
+				return;
+			}
+			dataDir = appCtx.getFilesDir().getAbsolutePath();
+			System.loadLibrary("gio");
+			jniLoaded = true;
+		}
+	}
+
+	static byte[] dataDir() {
+		try {
+			return dataDir.getBytes("UTF-8");
+		} catch (UnsupportedEncodingException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
 	public GioView(Context context) {
 		this(context, null);
 	}
 
 	public GioView(Context context, AttributeSet attrs) {
 		super(context, attrs);
+		// Late initialization of the Go runtime to wait for a valid context.
+		initialize(context.getApplicationContext());
+
 		nhandle = onCreateView(this);
 		handler = new Handler();
 		imm = (InputMethodManager)context.getSystemService(Context.INPUT_METHOD_SERVICE);

ui/app/app.go

@@ -118,3 +118,12 @@ func init() {
 	args := strings.Split(extraArgs, "|")
 	os.Args = append(os.Args, args...)
 }
+
+// DataDir returns a path to use for application-specific
+// configuration data.
+// On desktop systems, DataDir use os.UserConfigDir.
+// On iOS NSDocumentDirectory is queried.
+// For Android Context.getFilesDir is used.
+func DataDir() (string, error) {
+	return dataDir()
+}

ui/app/datadir.go

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// +build !android
+
+package app
+
+import "os"
+
+func dataDir() (string, error) {
+	return os.UserConfigDir()
+}

ui/app/datadir_android.go

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// +build android
+
+package app
+
+import "C"
+
+var dataDir func() (string, error)
+
+//export setDataDir
+func setDataDir(cdir *C.char) {
+	dir := C.GoString(cdir)
+	dataDir = func() (string, error) {
+		return dir, nil
+	}
+}
+

ui/app/os_android.c

@@ -4,7 +4,7 @@
 #include "os_android.h"
 #include "_cgo_export.h"
 
-JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserver) {
+JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
 	JNIEnv *env;
 	if ((*vm)->GetEnv(vm, (void**)&env, JNI_VERSION_1_6) != JNI_OK) {
 		return -1;
@@ -87,6 +87,23 @@ JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserver) {
 	if ((*env)->RegisterNatives(env, viewClass, methods, sizeof(methods)/sizeof(methods[0])) != 0) {
 		return -1;
 	}
+
+	// Initialize data dir.
+	jmethodID dataDirMethod = (*env)->GetStaticMethodID(env, viewClass, "dataDir", "()[B");
+	if (dataDirMethod == NULL) {
+		return -1;
+	}
+	jbyteArray dirArr = (*env)->CallStaticObjectMethod(env, viewClass, dataDirMethod);
+	if (dirArr == NULL) {
+		return -1;
+	}
+	jbyte *dir = (*env)->GetByteArrayElements(env, dirArr, NULL);
+	if (dir == NULL) {
+		return -1;
+	}
+	setDataDir((char *)dir);
+	(*env)->ReleaseByteArrayElements(env, dirArr, dir, JNI_ABORT);
+
 	return JNI_VERSION_1_6;
 }