View.setSystemUiVisibility(): implement fullscreen

For now we only allow fullscreen for maximized windows

src/api-impl-jni/generated_headers/android_view_View.h

@@ -311,6 +311,14 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1drawBackground
 JNIEXPORT void JNICALL Java_android_view_View_native_1drawContent
   (JNIEnv *, jobject, jlong, jlong);
 
+/*
+ * Class:     android_view_View
+ * Method:    nativeSetFullscreen
+ * Signature: (JZ)V
+ */
+JNIEXPORT void JNICALL Java_android_view_View_nativeSetFullscreen
+  (JNIEnv *, jobject, jlong, jboolean);
+
 /*
  * Class:     android_view_View
  * Method:    nativeInvalidate

src/api-impl-jni/views/android_view_View.c

@@ -577,3 +577,17 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1drawContent(JNIEnv *env, j
 	GdkSnapshot *snapshot = GDK_SNAPSHOT(_PTR(snapshot_ptr));
 	gtk_widget_snapshot_child(&wrapper->parent_instance, wrapper->child, snapshot);
 }
+
+JNIEXPORT void JNICALL Java_android_view_View_nativeSetFullscreen(JNIEnv *env, jobject this, jlong widget_ptr, jboolean fullscreen)
+{
+	GtkWidget *widget = GTK_WIDGET(_PTR(widget_ptr));
+	GtkWindow *window = GTK_WINDOW(gtk_widget_get_native(widget));
+	if (fullscreen) {
+		if (gtk_window_is_maximized(window))
+			gtk_window_fullscreen(window);
+		else
+			printf("blocking fullscreen request, because window is not maximized\n");
+	} else {
+		gtk_window_unfullscreen(window);
+	}
+}

src/api-impl/android/view/View.java

@@ -1038,7 +1038,10 @@ public class View implements Drawable.Callback {
 		return true;
 	}
 
+	private native void nativeSetFullscreen(long widget, boolean fullscreen);
+
 	public void setSystemUiVisibility(int visibility) {
+		nativeSetFullscreen(widget, (visibility & View.SYSTEM_UI_FLAG_FULLSCREEN) != 0);
 		system_ui_visibility = visibility;
 	}
 	public int getSystemUiVisibility() {