ui/app: (android) relay system focus events

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

ui/app/GioView.java

@@ -32,10 +32,16 @@ public class GioView extends SurfaceView implements Choreographer.FrameCallback
 
 	public GioView(Context context, AttributeSet attrs) {
 		super(context, attrs);
+		nhandle = onCreateView(this);
 		handler = new Handler();
 		imm = (InputMethodManager)context.getSystemService(Context.INPUT_METHOD_SERVICE);
 		setFocusable(true);
 		setFocusableInTouchMode(true);
+		setOnFocusChangeListener(new View.OnFocusChangeListener() {
+			@Override public void onFocusChange(View v, boolean focus) {
+				GioView.this.onFocusChange(nhandle, focus);
+			}
+		});
 		callbacks = new SurfaceHolder.Callback() {
 			@Override public void surfaceCreated(SurfaceHolder holder) {
 				// Ignore; surfaceChanged is guaranteed to be called immediately after this.
@@ -48,7 +54,6 @@ public class GioView extends SurfaceView implements Choreographer.FrameCallback
 			}
 		};
 		getHolder().addCallback(callbacks);
-		nhandle = onCreateView(this);
 	}
 
 	@Override public boolean onKeyDown(int keyCode, KeyEvent event) {
@@ -179,6 +184,7 @@ public class GioView extends SurfaceView implements Choreographer.FrameCallback
 	static private native void onKeyEvent(long handle, int code, int character, long time);
 	static private native void onFrameCallback(long handle, long nanos);
 	static private native boolean onBack(long handle);
+	static private native void onFocusChange(long handle, boolean focus);
 
 	private static class InputConnection extends BaseInputConnection {
 		private final Editable editable;

ui/app/os_android.c

@@ -77,6 +77,11 @@ JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserver) {
 			.name = "onBack",
 			.signature = "(J)Z",
 			.fnPtr = onBack
+		},
+		{
+			.name = "onFocusChange",
+			.signature = "(JZ)V",
+			.fnPtr = onFocusChange
 		}
 	};
 	if ((*env)->RegisterNatives(env, viewClass, methods, sizeof(methods)/sizeof(methods[0])) != 0) {

ui/app/os_android.go

@@ -191,6 +191,12 @@ func onBack(env *C.JNIEnv, class C.jclass, view C.jlong) C.jboolean {
 	return C.JNI_FALSE
 }
 
+//export onFocusChange
+func onFocusChange(env *C.JNIEnv, class C.jclass, view C.jlong, focus C.jboolean) {
+	w := views[view]
+	w.event(key.Focus{Focus: focus == C.JNI_TRUE})
+}
+
 func (w *window) setVisible() {
 	win := w.aNativeWindow()
 	width, height := C.ANativeWindow_getWidth(win), C.ANativeWindow_getHeight(win)