feat: support actually sending notifications

android/NotificationHelper.java

@@ -21,4 +21,14 @@ public class NotificationHelper {
     	Log.e(tag,String.format("manager: %s",notificationManager));
         notificationManager.createNotificationChannel(channel);
     }
+    public static void sendNotification(Context ctx, String channelID, int notificationID, String title, String text) {
+        Notification.Builder builder = new Notification.Builder(ctx, channelID)
+                .setContentTitle(title)
+                .setSmallIcon(Icon.createWithBitmap(Bitmap.createBitmap(1,1,Bitmap.Config.ALPHA_8)))
+                .setContentText(text)
+                .setPriority(Notification.PRIORITY_DEFAULT);
+
+        NotificationManager notificationManager = ctx.getSystemService(NotificationManager.class);
+        notificationManager.notify(notificationID, builder.build());
+    }
 }

android/notify_android.go

@@ -2,11 +2,25 @@ package android
 
 import (
 	"fmt"
+	"sync"
 
 	"gioui.org/app"
 	"github.com/tailscale/tailscale-android/jni"
 )
 
+var (
+	idlock             sync.Mutex
+	nextNotificationID int32
+)
+
+func nextID() int32 {
+	idlock.Lock()
+	defer idlock.Unlock()
+	id := nextNotificationID
+	nextNotificationID++
+	return id
+}
+
 type NotificationChannel struct {
 	id string
 }
@@ -36,3 +50,33 @@ func NewChannel(id, name, description string) (*NotificationChannel, error) {
 	}
 	return nc, nil
 }
+
+type Notification struct {
+	id int32
+}
+
+func (nc *NotificationChannel) Send(title, text string) (*Notification, error) {
+	notificationID := nextID()
+	if err := jni.Do(jni.JVMFor(app.JavaVM()), func(env jni.Env) error {
+		appCtx := jni.Object(app.AppContext())
+		classLoader := jni.ClassLoaderFor(env, appCtx)
+		notifyClass, err := jni.LoadClass(env, classLoader, "ht/sr/git/whereswaldon/niotify/NotificationHelper")
+		if err != nil {
+			return err
+		}
+		newChannelMethod := jni.GetStaticMethodID(env, notifyClass, "sendNotification", "(Landroid/content/Context;Ljava/lang/String;ILjava/lang/String;Ljava/lang/String;)V")
+		jtitle := jni.Value(jni.JavaString(env, title))
+		jtext := jni.Value(jni.JavaString(env, text))
+		jID := jni.Value(jni.JavaString(env, nc.id))
+		err = jni.CallStaticVoidMethod(env, notifyClass, newChannelMethod, jni.Value(app.AppContext()), jID, jni.Value(notificationID), jtitle, jtext)
+		if err != nil {
+			return err
+		}
+		return nil
+	}); err != nil {
+		return nil, fmt.Errorf("failed creating notification channel: %w", err)
+	}
+	return &Notification{
+		id: notificationID,
+	}, nil
+}

example/hello.go

@@ -21,7 +21,6 @@ import (
 
 //go:generate javac -target 1.8 -source 1.8 -bootclasspath $ANDROID_HOME/platforms/android-29/android.jar ../android/NotificationHelper.java
 //go:generate jar cf NotificationHelper.jar ../android/NotificationHelper.class
-//go:generate rm ../android/NotificationHelper.class
 
 func main() {
 	go func() {
@@ -30,19 +29,13 @@ func main() {
 			log.Fatal(err)
 		}
 	}()
-	go func() {
-		channel, err := android.NewChannel("CHANNEL", "hello", "description")
-		if err != nil {
-			log.Printf("channel creation failed: %v", err)
-		}
-		log.Println(channel)
-	}()
 	app.Main()
 }
 
 func loop(w *app.Window) error {
 	th := material.NewTheme(gofont.Collection())
 	var ops op.Ops
+	first := true
 	for {
 		e := <-w.Events()
 		switch e := e.(type) {
@@ -56,6 +49,21 @@ func loop(w *app.Window) error {
 			l.Alignment = text.Middle
 			l.Layout(gtx)
 			e.Frame(gtx.Ops)
+			if first {
+				first = false
+				go func() {
+					channel, err := android.NewChannel("CHANNEL", "hello", "description")
+					if err != nil {
+						log.Printf("channel creation failed: %v", err)
+					}
+					log.Println(channel)
+					notif, err := channel.Send("hello!", "IS GIO OUT THERE?")
+					if err != nil {
+						log.Printf("notification send failed: %v", err)
+					}
+					log.Println(notif)
+				}()
+			}
 		}
 	}
 }