handle drag-and-drop events as ACTION_SEND Intents

src/api-impl-jni/handle_cache.c

@@ -99,6 +99,7 @@ void set_up_handle_cache(JNIEnv *env)
 		(*env)->ExceptionDescribe(env);
 	handle_cache.context.sendBroadcast = _METHOD(handle_cache.context.class, "sendBroadcast", "(Landroid/content/Intent;)V");
 	handle_cache.context.startActivity = _METHOD(handle_cache.context.class, "startActivity", "(Landroid/content/Intent;)V");
+	handle_cache.context.resolveActivityInternal = _STATIC_METHOD(handle_cache.context.class, "resolveActivityInternal", "(Landroid/content/Intent;)Landroid/app/Activity;");
 	handle_cache.context.startService = _METHOD(handle_cache.context.class, "startService", "(Landroid/content/Intent;)Landroid/content/ComponentName;");
 
 	handle_cache.application.class = _REF((*env)->FindClass(env, "android/app/Application"));

src/api-impl-jni/handle_cache.h

@@ -97,6 +97,7 @@ struct handle_cache {
 		jmethodID get_package_name;
 		jmethodID sendBroadcast;
 		jmethodID startActivity;
+		jmethodID resolveActivityInternal;
 		jmethodID startService;
 	} context;
 	struct {

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

@@ -158,6 +158,8 @@ static gboolean on_event(GtkEventControllerLegacy *event_controller, GdkEvent *e
 	}
 
 	uintptr_t id = (uintptr_t)gdk_event_get_event_sequence(event);
+	if (id > MAX_POINTERS-1)  // sequence id is a real pointer for drag and drop events
+		return false;
 
 	/* FIXME: this will clash with touchscreen */
 	if(id == 0)

src/api-impl/android/content/Context.java

@@ -547,6 +547,30 @@ public class Context extends Object {
 		return true;
 	}
 
+	/* For use from native code */
+	static Activity resolveActivityInternal(Intent intent) throws ReflectiveOperationException {
+		String className = null;
+		if (intent.getComponent() != null) {
+			className = intent.getComponent().getClassName();
+		} else {
+			int best_score = -5;
+			for (PackageParser.Activity activity: pkg.activities) {
+				for (PackageParser.IntentInfo intentInfo: activity.intents) {
+					int score = intentInfo.match(intent.getAction(), intent.getType(), intent.getScheme(), intent.getData(), intent.getCategories(), "Context");
+					if (score > best_score && score > 0) {
+						className = activity.className;
+						best_score = score;
+					}
+				}
+			}
+		}
+		if (className != null) {
+			return Activity.internalCreateActivity(className, this_application.native_window, intent);
+		} else {
+			return null;
+		}
+	}
+
 	public void startActivity(Intent intent) {
 		Slog.i(TAG, "startActivity(" + intent + ") called");
 		if (intent.getAction() != null && intent.getAction().equals("android.intent.action.CHOOSER")) {

src/main-executable/main.c

@@ -236,6 +236,31 @@ static void parse_string_extras(JNIEnv *env, char **extra_string_keys, jobject i
 	g_regex_unref(regex);
 }
 
+/* Drag and drop callback to simulate ACTION_SEND intents */
+static gboolean on_drop(GtkDropTarget *target, const GValue *value, double x, double y, gpointer user_data)
+{
+	const char *data = g_value_get_string(value);
+	if (!data || !*data) {
+		return FALSE;
+	}
+
+	JNIEnv *env = get_jni_env();
+	jobject intent = (*env)->NewObject(env, handle_cache.intent.class, handle_cache.intent.constructor);
+	_SET_OBJ_FIELD(intent, "action", "Ljava/lang/String;", _JSTRING("android.intent.action.SEND"));
+	_SET_OBJ_FIELD(intent, "data", "Landroid/net/Uri;", (*env)->CallStaticObjectMethod(env, handle_cache.uri.class, handle_cache.uri.parse, _JSTRING(data)));
+
+	jobject activity = (*env)->CallStaticObjectMethod(env, handle_cache.context.class, handle_cache.context.resolveActivityInternal, intent);
+	if ((*env)->ExceptionCheck(env)) {
+		(*env)->ExceptionDescribe(env);
+	}
+	if (!activity) {
+		printf("failed to resolve activity to handle URI: %s\n", data);
+		return FALSE;
+	}
+	activity_start(env, activity);
+	return TRUE;
+}
+
 static void open(GtkApplication *app, GFile **files, gint nfiles, const gchar *hint, struct jni_callback_data *d)
 {
 // TODO: pass all files to classpath
@@ -668,6 +693,9 @@ static void open(GtkApplication *app, GFile **files, gint nfiles, const gchar *h
 
 	gtk_header_bar_pack_start(GTK_HEADER_BAR(header_bar), back_button);
 	gtk_window_set_titlebar(GTK_WINDOW(window), header_bar);
+	GtkDropTarget *drop_target = gtk_drop_target_new(G_TYPE_STRING, GDK_ACTION_COPY);
+	g_signal_connect(drop_target, "drop", G_CALLBACK(on_drop), NULL);
+	gtk_widget_add_controller(window, GTK_EVENT_CONTROLLER(drop_target));
 	gtk_window_present(GTK_WINDOW(window));
 
 	// set package name as application id for window icon on Wayland. Needs a {package_name}.desktop file defining the icon