api-impl: implement vibrator using evdev

we use the first vibrator that is marked for use with feedbackd in udev

meson.build

@@ -80,6 +80,7 @@ libtranslationlayer_so = shared_library('translation_layer_main', [
                                                                   	'src/api-impl-jni/android_os_Environment.c',
                                                                   	'src/api-impl-jni/android_os_MessageQueue.c',
                                                                   	'src/api-impl-jni/android_os_SystemClock.c',
+                                                                  	'src/api-impl-jni/android_os_Vibrator.c',
                                                                   	'src/api-impl-jni/android_util_Log.c',
                                                                   	'src/api-impl-jni/android_view_Window.c',
                                                                   	'src/api-impl-jni/app/android_app_Activity.c',
@@ -136,6 +137,7 @@ libtranslationlayer_so = shared_library('translation_layer_main', [
                                                                   dependencies: [
                                                                   	dependency('gtk4', version: '>=4.8'), dependency('gl'), dependency('egl'), dependency('wayland-client'), dependency('jni'),
                                                                   	dependency('libportal'), dependency('sqlite3'), libskia_dep, dependency('libavcodec', version: '>=59'), dependency('libdrm'),
+                                                                  	dependency('gudev-1.0'),
                                                                   	libandroidfw_dep
                                                                   ],
                                                                   link_with: [ libandroid_so ],

src/api-impl-jni/android_os_Vibrator.c

@@ -0,0 +1,114 @@
+#include <gudev/gudev.h>
+
+#include <fcntl.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+#include <linux/input.h>
+
+#include "defines.h"
+#include "util.h"
+#include "generated_headers/android_hardware_SensorManager.h"
+
+/* finds a feedbackd-recognized vibrator */
+char *find_vibrator(void)
+{
+	char *device_file = NULL;
+
+	GUdevClient *udev_client = g_udev_client_new(NULL);
+	GList *udev_devices = g_udev_client_query_by_subsystem(udev_client, "input");
+	for(GList *l = udev_devices; l != NULL; l = l->next) {
+		GUdevDevice *device = l->data;
+		if(!g_strcmp0(g_udev_device_get_property(device, "FEEDBACKD_TYPE"), "vibra")) {
+			device_file = strdup(g_udev_device_get_device_file(device));
+			break;
+		}
+	}
+
+	g_list_free_full(udev_devices, g_object_unref);
+	g_object_unref(udev_client);
+
+	return device_file;
+}
+
+JNIEXPORT jint JNICALL Java_android_os_Vibrator_native_1constructor(JNIEnv *env, jobject this) {
+	char *device_file;
+
+	/* if there are multiple instances of Vibrator for some reason, reuse the fd */
+	static int fd = -1;
+	if(fd != -1)
+		return fd;
+
+	device_file = find_vibrator();
+	if(!device_file) {
+		g_log(NULL, G_LOG_LEVEL_WARNING, "no feedbackd-recognized vibrator found");
+		return -1;
+	}
+
+
+
+	fd = open(device_file, O_RDWR);
+	if(fd < 0) {
+		g_log(NULL, G_LOG_LEVEL_WARNING, "cannot open vibrator device '%s': %m", device_file);
+		free(device_file);
+		return -1;
+	}
+	free(device_file);
+
+	struct input_event set_gain = {
+		.type = EV_FF,
+		.code = FF_GAIN,
+		/* arbitrary, could possibly be improved */
+		.value = 0xFFFFUL * 80 / 100,
+	};
+
+
+	if (write(fd, &set_gain, sizeof(set_gain)) < 0) {
+		g_log(NULL, G_LOG_LEVEL_WARNING, "failed to set gain on vibrator: %m");
+	}
+
+	return fd;
+}
+
+JNIEXPORT void JNICALL Java_android_os_Vibrator_native_1vibrate(JNIEnv *env, jobject this, jint fd, jlong duration) {
+	/* FIXME: not thread-safe */
+	static struct ff_effect effect = { .id = -1 };
+
+	if(effect.id != -1 && effect.replay.length != duration) {
+		ioctl(fd, EVIOCRMFF, effect.id);
+		effect.id = -1;
+	}
+
+	if(effect.id == -1) {
+		/* arbitrary, could possibly be improved */
+		effect.type = FF_PERIODIC;
+		effect.id = -1;
+		effect.u.periodic.waveform = FF_SINE;
+		effect.u.periodic.period = 10;
+		effect.u.periodic.magnitude = 0x7fff;
+		effect.u.periodic.offset = 0;
+		effect.u.periodic.phase = 0;
+		effect.direction = 0x4000;
+		effect.u.periodic.envelope.attack_length = 1000;
+		effect.u.periodic.envelope.attack_level = 0x7fff;
+		effect.u.periodic.envelope.fade_length = 1000;
+		effect.u.periodic.envelope.fade_level = 0x7fff;
+		effect.trigger.button = 0;
+		effect.trigger.interval = 0;
+
+		effect.replay.length = duration;
+		effect.replay.delay = 0;
+
+		ioctl(fd, EVIOCSFF, &effect);
+	}
+
+	struct input_event play = {
+		.type = EV_FF,
+		.code = effect.id,
+		.value = 1,
+	};
+
+	if(write(fd, (const void*)&play, sizeof(play)) < 0) {
+		g_log(NULL, G_LOG_LEVEL_WARNING, "failed to play vibraton: %m");
+	}
+}

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

@@ -0,0 +1,29 @@
+/* DO NOT EDIT THIS FILE - it is machine generated */
+#include <jni.h>
+/* Header for class android_os_Vibrator */
+
+#ifndef _Included_android_os_Vibrator
+#define _Included_android_os_Vibrator
+#ifdef __cplusplus
+extern "C" {
+#endif
+/*
+ * Class:     android_os_Vibrator
+ * Method:    native_vibrate
+ * Signature: (IJ)V
+ */
+JNIEXPORT void JNICALL Java_android_os_Vibrator_native_1vibrate
+  (JNIEnv *, jobject, jint, jlong);
+
+/*
+ * Class:     android_os_Vibrator
+ * Method:    native_constructor
+ * Signature: ()I
+ */
+JNIEXPORT jint JNICALL Java_android_os_Vibrator_native_1constructor
+  (JNIEnv *, jobject);
+
+#ifdef __cplusplus
+}
+#endif
+#endif

src/api-impl/android/os/Vibrator.java

@@ -3,9 +3,19 @@ package android.os;
 import android.util.Slog;
 
 public class Vibrator {
-	public void vibrate(long millis) {
-		Slog.v("Vibrator", "vibration motor go burrrr for "+millis+"ms");
+	int fd; // vibrator /dev/input/eventX
+
+	public Vibrator() {
+		fd = native_constructor();
 	}
+
+	public void vibrate(long millis) {
+		if(fd != -1)
+			native_vibrate(fd, millis);
+		else
+			Slog.v("Vibrator", "vibration motor go burrrr for "+millis+"ms");
+	}
+
 	public void vibrate (final long[] pattern, int repeat) {
 		Thread t = new Thread(new Runnable() {
 			public void run() {
@@ -19,4 +29,7 @@ public class Vibrator {
 		});
 		t.start();
 	}
+
+	private native void native_vibrate(int fd, long millis);
+	private native int native_constructor();
 }