ignore .idea

.gitignore

@@ -5,3 +5,4 @@ gradlew*
 
 # Ignore Gradle build output directory
 build
+.idea

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 Stephen Byrne
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,79 @@
+# obsdc
+
+OBS control from D-Bus messages
+
+Send a D-Bus signal to perform an operation with `src/obsdc-signal`, which takes a single operation command
+as an argument, and performs an action in OBS.
+
+## Operations
+
+* `SCENE_NEXT` - switch to the next scene
+* `SCENE_PREV` - switch to the previous scene
+* `SCENE_#` - switch to the indicated scene
+  * replace `#` with scene index, starting with 1.
+* `STUDIO_TRANSITION` - transition the studio preview and program
+* `STUDIO_MODE_TOGGLE` - toggle studio mode
+* `PAN_UP` - move the top unlocked source up 50px
+* `PAN_DOWN` - move the top unlocked source down 50px
+* `PAN_LEFT` - move the top unlocked source left 50px
+* `PAN_RIGHT` - move the top unlocked source right 50pxt
+
+## Configuration
+
+Configuration is read from `$XDG_CONFIG_HOME/net.eksb.obsdc/config.properties`
+
+### Configuration options
+
+* `host` - OBS websocket host (default: `localhost`)
+* `port` - OBS websocket port (default: `4455`)
+* `password` - OBS websocket password (required)
+
+### systemd
+
+A systemd unit file ([obsdc.service](src/main/dist/obsdc.service)) is included.
+
+1. Copy the file to `~/.config/systemd/user/`.
+2. Edit the `ExecStart` line for where you have installed obsdc.
+3. `systemctl --user enable obsdc`
+4. `systemctl --user start obsdc`
+
+## Build
+
+`gradle build`
+
+## Run
+
+1. `tar xf build/distributions/obsdc.tar`
+2. `cd obsdc`
+3. Create config file. See [#Configuration].
+4. `bin/obsdc`
+5. `bin/obsdc-signal` to send an op.
+
+## Code
+
+Start at [Main](src/main/kotlin/net/eksb/obsdc/Main.kt).
+
+[Obs](src/main/kotlin/net/eksb/obsdc/Obs.kt) is a wrapper around
+[obs-websocket-java](https://github.com/obs-websocket-community-projects/obs-websocket-java)
+that handles reconnects and queuing operations until the websocket it ready.
+
+[OpRunner](src/main/kotlin/net/eksb/obsdc/OpRunner.kt) has the logic to run [Op](src/main/kotlin/net/eksb/obsdc/Op.kt)s
+using an `Obs`.
+
+[DBus](src/main/kotlin/net/eksb/obsdc/DBus.kt) listens for the `D-Bus` signals and calls `OpRunner`.
+
+## History/Rationale
+
+I usually code on a 4k monitor in portrait mode. To show what I am doing on video calls,
+I use OBS to share that monitor, but it is a 2160x4096 source in a 1920x1080 scene.
+
+I have
+[a macropad](https://keeb.io/collections/bdn9-collection/products/bdn9-rev-2-3x3-9-key-macropad-rotary-encoder-and-rgb)
+with three knobs.
+My [window manager](https://swaywm.org/) is configured to call `obsdc-signal` with
+`PAN_UP`/`PAN_DOWN` for the keys emitted by the left knob,
+`PAN_RIGHT`/`PAN_LEFT` for the keys emitted by the right knob, and
+`SCENE_NEXT`/`SCENE_PREV` for the keys emitted by the center knob.
+The regular keys on the macropad are mapped to the other actions.
+
+So now I can quickly control what people can see without having to focus (or even make visible) the OBS window.

build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    id("org.jetbrains.kotlin.jvm") version "1.9.0"
+    id("org.jetbrains.kotlin.jvm") version "2.0.0"
     application
 }
 
@@ -7,8 +7,8 @@ dependencies {
     testImplementation("org.jetbrains.kotlin:kotlin-test-junit5")
     testImplementation("org.junit.jupiter:junit-jupiter-engine:5.9.3")
 
-    implementation("com.github.hypfvieh:dbus-java-core:4.3.1")
+    implementation("com.github.hypfvieh:dbus-java-core:5.0.0")
-    runtimeOnly("com.github.hypfvieh:dbus-java-transport-native-unixsocket:4.3.1")
+    runtimeOnly("com.github.hypfvieh:dbus-java-transport-native-unixsocket:5.0.0")
 
     implementation("io.obs-websocket.community:client:2.0.0")
 

src/main/dist/obsdc.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=OBSDC
+
+[Service]
+Type=dbus
+BusName=net.eksb.obsdc
+ExecStart=/opt/obsdc/bin/obsdc
+
+[Install]
+WantedBy=default.target

src/main/kotlin/net/eksb/obsdc/DBus.kt

@@ -3,55 +3,55 @@ package net.eksb.obsdc
 import org.freedesktop.dbus.annotations.DBusInterfaceName
 import org.freedesktop.dbus.connections.impl.DBusConnection
 import org.freedesktop.dbus.connections.impl.DBusConnectionBuilder
+import org.freedesktop.dbus.exceptions.DBusException
 import org.freedesktop.dbus.interfaces.DBusInterface
 import org.freedesktop.dbus.interfaces.DBusSigHandler
 import org.freedesktop.dbus.messages.DBusSignal
 import org.slf4j.LoggerFactory
-import java.util.concurrent.BlockingQueue
-import java.util.concurrent.TimeUnit
-import kotlin.concurrent.thread
 
-class DBus(private val q: BlockingQueue<Op>) {
+/**
+ * Listen to signals on the session DBUS, and send the ops to [q].
+ *
+ * To send an op signal:
+ * `dbus-send --session --type=signal --dest=net.eksb.obsdc / net.eksb.Obsdc.Signal string:{OP_NAME}`
+ *
+ * `{OP_NAME}` is the name of an [Op].
+ *
+ * `src/scripts/obsdc-signal` takes an [Op] name and sends the signal.
+ */
+class DBus(private val opHandler:(String)->Unit): AutoCloseable {
 
-	private val thread = thread(
+	// To monitor DBUS: `dbus-monitor`
-		start = true,
+  // To see what is registered: `qdbus net.eksb.obsdc /`
-		isDaemon = true,
-		name = "dbus",
-	) {
-		DBusConnectionBuilder.forSessionBus().build().use { dbus ->
 
+	val dbus = DBusConnectionBuilder.forSessionBus().build()
+
+	init {
 		// These lines are not necessary to handle signals, but are necessary to register methods.
-			dbus.requestBusName("net.eksb.obsdc")
+		try {
+			dbus.requestBusName(BUS_NAME)
+		} catch (e:DBusException) {
+			error("Error requesting bus. Already running?")
+		}
 		dbus.exportObject("/", ObsdcDBusInterfaceImpl())
 
 		dbus.addSigHandler<ObsdcDBusInterface.Signal> { signal ->
-				log.info("signal: ${signal.op}")
+			log.debug("signal: ${signal.op}")
-				val op = Op.valueOf(signal.op)
+			opHandler.invoke(signal.op)
-				log.info("op: ${op}")
-				try {
-					q.offer(op, 1, TimeUnit.SECONDS)
-				} catch (e:InterruptedException) {
-					log.debug("queue offer interrupted")
 		}
-			}
+		log.debug("DBUS initialized")
-			while (true) {
-				try {
-					Thread.sleep(60_000)
-				} catch (e:InterruptedException) {
-					log.info("interrupted")
-					break
-				}
-			}
-		}
-		log.info("done")
 	}
 
-	fun stop() {
+	override fun close() {
-		thread.interrupt()
+		dbus.releaseBusName(BUS_NAME)
+		dbus.close()
 	}
 
+	companion object {
+		private const val BUS_NAME = "net.eksb.obsdc"
 		private val log = LoggerFactory.getLogger(DBus::class.java)
 	}
+}
 
 inline fun <reified T: DBusSignal> DBusConnection.addSigHandler(handler: DBusSigHandler<T>) {
 	addSigHandler(T::class.java, handler)
@@ -62,24 +62,10 @@ interface ObsdcDBusInterface: DBusInterface {
 	fun echo(message:String): String
 	class Signal(path:String, val op:String): DBusSignal(path, op)
 }
+
 class ObsdcDBusInterfaceImpl: ObsdcDBusInterface {
 	override fun echo(message: String):String {
 		return message
 	}
 	override fun getObjectPath(): String = "/"
 }
-
-/*
-Monitor:
-`dbus-monitor`
-
-See what is registered:
-`qdbus net.eksb.obsdc /`
-
-Send signal:
-`dbus-send --session --type=signal --dest=net.eksb.obsdc / net.eksb.Obsdc.Signal string:a`
-
-Call method:
-`dbus-send --session --type=method_call --print-reply --dest=net.eksb.obsdc / net.eksb.Obsdc.echo string:b`
-`qdbus net.eksb.obsdc / net.eksb.Obsdc.echo hello`
- */

src/main/kotlin/net/eksb/obsdc/Gate.kt

@@ -0,0 +1,50 @@
+package net.eksb.obsdc
+
+import java.util.concurrent.atomic.AtomicBoolean
+import java.util.concurrent.locks.Lock
+import java.util.concurrent.locks.ReentrantLock
+
+/**
+ * A Gate blocks [enter] until the gate is opened by [open].
+ */
+class Gate {
+
+	private val lock:Lock = ReentrantLock()
+	private val open = AtomicBoolean(false)
+	private val condition = lock.newCondition()
+
+	/**
+	 * Open the gate; allow all waiting [enter]s to run.
+	 */
+	fun open() {
+		lock.lock()
+		try {
+			open.set(true)
+			condition.signalAll()
+		} finally {
+			lock.unlock()
+		}
+	}
+
+	/**
+	 * Close the gate; any subsequent calls to [enter] will block until [open] is called.
+	 */
+	fun close() {
+		open.set(false)
+	}
+
+	/**
+	 * Enter the gate: run the specified [block] as soon as the gate is open.
+	 */
+	fun <R> enter(block:()->R): R {
+		lock.lock()
+		try {
+			while(!open.get()) {
+				condition.await()
+			}
+			return block()
+		} finally {
+			lock.unlock()
+		}
+	}
+}

src/main/kotlin/net/eksb/obsdc/Main.kt

@@ -1,13 +1,26 @@
 package net.eksb.obsdc
 
-import java.util.concurrent.BlockingQueue
+import org.slf4j.LoggerFactory
-import java.util.concurrent.LinkedBlockingQueue
 
 object Main {
     @JvmStatic
     fun main(args: Array<String>) {
-        val q:BlockingQueue<Op> = LinkedBlockingQueue()
+        try {
-        DBus(q) // forks daemon thread
+            val config = CONFIG_FILE.properties()
-        Obs(q).run() // blocks
+            Obs(
+                host = config.getProperty("host") ?: "localhost",
+                port = config.getProperty("port")?.toInt() ?: 4455,
+                password = config.getProperty("password") ?: error("config missing \"password\""),
+                connectionTimeout = config.getProperty("connectionTimeout")?.toInt() ?: 5
+            ).use { obs ->
+                DBus(OpRunner(obs)).use { dbus ->
+                    waitForShutdown()
                 }
             }
+        } catch (e:Exception) {
+            log.error(e.message, e)
+        }
+    }
+
+    private val log = LoggerFactory.getLogger(Main::class.java)
+}

src/main/kotlin/net/eksb/obsdc/Obs.kt

@@ -1,129 +1,186 @@
 package net.eksb.obsdc
 
 import io.obswebsocket.community.client.OBSRemoteController
-import io.obswebsocket.community.client.message.event.ui.StudioModeStateChangedEvent
+import io.obswebsocket.community.client.WebSocketCloseCode
-import io.obswebsocket.community.client.model.Scene
+import io.obswebsocket.community.client.listener.lifecycle.ReasonThrowable
-import io.obswebsocket.community.client.model.SceneItem.Transform
-import io.obswebsocket.community.client.model.SceneItem.Transform.TransformBuilder
-import org.slf4j.LoggerFactory
 import java.util.concurrent.BlockingQueue
-import java.util.concurrent.TimeUnit
+import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.concurrent.thread
+import org.slf4j.LoggerFactory
+import java.util.concurrent.LinkedBlockingQueue
+import kotlin.time.Duration
 
-// protocol docs: https://github.com/obsproject/obs-websocket/blob/master/docs/generated/protocol.md
+/**
-class Obs(private val q:BlockingQueue<Op>): AutoCloseable {
+ * Wrapper for an [OBSRemoteController] that handles connecting, reconnecting, and queuing operations
+ * until ready.
+ *
+ * Call [submit] to submit a request.
+ *
+ * protocol docs: https://github.com/obsproject/obs-websocket/blob/master/docs/generated/protocol.md
+ */
+class Obs(
+	host:String = "localhost",
+	port:Int = 4455,
+	password:String,
+	connectionTimeout:Int = 5 // seconds
+): AutoCloseable {
 
-	private val panAmount = 50F
+	/** Queue of requests to run. */
+	private val q:BlockingQueue<Req> = LinkedBlockingQueue()
 
-	private val controller = OBSRemoteController.builder()
+	/** Flag to set when closed to stop queue poll loop. */
-		.host("localhost")
+	private val closed = AtomicBoolean(false)
-		.port(4455)
+
-		.password("R3tRkVXhFofJ2wRF") // TODO put this in a file
+	/**
+	 * Flag set when we start trying to connect, unset when disconnected.
+	 * Used to determine if we should reconnect on controller error.
+	 */
+	private val connectingOrConnected = AtomicBoolean(false)
+	/**
+	 * Flag to set when connected, unset when disconnected.
+	 * Used to determine if we should reconnect on controller error.
+	 */
+	private val connected = AtomicBoolean(false)
+
+	/** Gate to block queue poll loop when not ready. */
+	private val ready:Gate = Gate()
+
+	/** The OBS controller. */
+	val controller:OBSRemoteController = OBSRemoteController.builder()
+		.host(host)
+		.port(port)
+		.password(password)
 		.autoConnect(false)
-		.connectionTimeout(3)
+		.connectionTimeout(connectionTimeout)
 		.lifecycle()
-			.onReady(::ready)
+			.onReady(::onReady)
-			.onClose { code -> log.error("closed:${code}")}
+			.onClose(::onClose)
-			.onControllerError { e ->  log.error("controller error", e ) }
+			.onControllerError(::onControllerError)
-			.onCommunicatorError { e -> log.error("comm error", e ) }
+			.onCommunicatorError(::onCommError)
-			.onDisconnect { log.info("disconnected") }
+			.onDisconnect(::onDisconnect)
-			.and()
+			.onConnect {
-		.registerEventListener(StudioModeStateChangedEvent::class.java) {
+				log.debug("connected")
-			log.info("studio mode state change: ${it}")
+				connected.set(true)
 			}
+			.and()
 		.build()
 
-	private var alive = true
-
 	init {
-		Runtime.getRuntime().addShutdownHook(thread(start=false) {
+		// OBSRemoteController starts a non-daemon thread. It probably should not do that.
-			log.info("shutdown")
+		// Kill it on shutdown.
-			alive = false
+		addShutdownHook {
-			controller.stop()
+			close()
-		})
+		}
+		// Thread that connects if we are not connected/connecting.
+		thread(name="obs-connect", isDaemon=true, start=true) {
+			while(!closed.get()) {
+				if (connectingOrConnected.compareAndSet(false,true)) {
+					log.debug("Not closed, not connected. Try to connect...")
+					try {
+						// Only call connect from here; if you try to call connect from [onControllerError] or [onDisconnect]
+						// eventually you will get stack overflow.
+						controller.connect()
+					} catch (e:Exception) {
+						log.warn("failed to connect: ${e.message}", e)
+					}
+				}
+				Thread.sleep(connectionTimeout.toLong() * 1000L) // in case the error was immediate
+			}
+		}
 	}
 
-	fun run() {
+	private fun onClose(e:WebSocketCloseCode) {
-		controller.connect()
+		log.debug("closed: ${e.code}")
+		ready.close()
+	}
+
+	private fun onControllerError(e:ReasonThrowable) {
+		log.debug("controller error - ${e.reason}",e.throwable)
+		// If we are not connected, a controller error means that connection failed and we will not connect.
+		// If we are connected, it does not mean we are/will be disconnected.
+		if (!connected.get()) {
+			connectingOrConnected.set(false)
+		}
+	}
+	private fun onCommError(e:ReasonThrowable) {
+		log.debug("comm error - ${e.reason}",e.throwable)
+	}
+	private fun onDisconnect() {
+		log.debug("disconnected")
+		connectingOrConnected.set(false)
+		connected.set(false)
+	}
+
+	private fun onReady() {
+		log.debug("ready")
+		ready.open()
+		// The docs say that you are only supposed to send requests from the [onReady] handler,
+		// but you cannot block the [onReady] handler.
+		// (If you block the [onReady] handler other handlers are not called. [onDisconnect] is not called so you
+		// cannot reconnect if OBS is restarted.)
+		// This would be fine if `onReady` was called after each response, but it is not.
+		// So we keep track of if it is ready, and make requests from another thread ([opThread]).
+	}
+
+	/**
+	 * Thread that runs submitted requests from [q] when [ready].
+	 */
+	private val opThread = thread(name="obs-op", isDaemon=false, start=true) {
+		while(!closed.get()) {
+			val req = try {
+				q.take()
+			} catch (e:InterruptedException) {
+				log.debug("interrupted taking req")
+				continue
+			}
+			log.debug("got req: ${req}, wait for ready")
+			try {
+				ready.enter {
+					log.debug("ready")
+					if (!req.expired()) {
+							req.block.invoke(controller)
+					}
+				}
+			} catch (e:Exception) {
+				log.error("req ${req} failed", e )
+			}
+		}
+		log.debug("done")
+	}
+
+	/**
+	 * Submit a request to run when ready.
+	 *
+	 * @param timeout If this time has elapsed before ready, do not run. Always run if null.
+	 * @param block the request to run
+	 */
+	fun submit(
+		timeout:Duration? = null,
+		block:(OBSRemoteController)->Unit,
+	) {
+		q.put(Req(block, timeout?.inWholeNanoseconds))
 	}
 
 	override fun close() {
+		closed.set(true)
+		opThread.interrupt()
 		controller.disconnect()
-	}
+		controller.stop()
-
-	private fun ready() {
-		log.info("ready")
-		while(alive) {
-			val op: Op? = q.poll(1, TimeUnit.SECONDS) // blocks
-			if (op != null) {
-				log.info("op: ${op}")
-				op(op)
-				break
-			}
-		}
-	}
-
-	private fun op(op:Op) {
-		when(op) {
-			Op.SCENE_1 -> scene { scenes -> scenes.firstOrNull() }
-			Op.SCENE_2 -> scene { scenes -> scenes.asSequence().drop(1).firstOrNull() }
-			Op.STUDIO_TRANSITION -> {
-				controller.triggerStudioModeTransition { response ->
-					// This does not get called?
-					log.info("Response successful: ${response.isSuccessful}")
-					ready()
-				}
-			}
-			Op.PAN_UP -> pan { old -> positionY(old.positionY - panAmount ) }
-			Op.PAN_DOWN -> pan { old -> positionY(old.positionY + panAmount ) }
-			Op.PAN_LEFT -> pan { old -> positionX(old.positionX - panAmount ) }
-			Op.PAN_RIGHT -> pan { old -> positionX(old.positionX + panAmount ) }
-			Op.TODO -> {
-				log.info("OP=TODO")
-				ready()
-			}
-		}
-	}
-
-	private fun scene(selector:(List<Scene>)->Scene?) {
-		controller.getSceneList { response ->
-			val scene = selector(response.scenes.sortedBy(Scene::getSceneIndex).reversed())
-			log.info("select scene ${scene?.sceneName} index:${scene?.sceneIndex}")
-			if (scene != null) {
-				controller.setCurrentProgramScene(scene.sceneName) { response ->
-					ready()
-				}
-			} else {
-				ready()
-			}
-		}
-	}
-
-	private fun pan(block:TransformBuilder.(Transform)->TransformBuilder) {
-		controller.getCurrentProgramScene { response ->
-			val sceneName = response.currentProgramSceneName
-			log.info("scene name: ${sceneName}")
-			controller.getSceneItemList(sceneName) { response ->
-				val item = response.sceneItems.last()
-				val itemId = item.sceneItemId
-				log.info("last item id: ${itemId}")
-				controller.getSceneItemTransform(sceneName, itemId) { response ->
-					val transform = response.sceneItemTransform
-					log.info("position: ${transform.positionX} x ${transform.positionY}")
-					val newTransform = block(Transform.builder(), transform).build()
-					controller.setSceneItemTransform(sceneName, itemId, newTransform) { response ->
-						log.info("transform successful: ${response.isSuccessful}")
-						// Have to set the current scene to take effect if in studio mode.
-						controller.setCurrentProgramScene(sceneName) { response ->
-							ready()
-						}
-					}
-				}
-			}
-		}
 	}
 
 	companion object {
 		private val log = LoggerFactory.getLogger(Obs::class.java)
+
+		/**
+		 * Wrap a request and keep track of timeout.
+		 */
+		private class Req(
+			val block:(OBSRemoteController)->Unit,
+			val timeout:Long?,
+		) {
+			val submitTime = System.nanoTime()
+			fun expired():Boolean = timeout != null && System.nanoTime() - submitTime > timeout
 		}
 	}
+}
+

src/main/kotlin/net/eksb/obsdc/Op.kt

@@ -1,13 +0,0 @@
-package net.eksb.obsdc
-
-enum class Op {
-	STUDIO_TRANSITION,
-	SCENE_1,
-	SCENE_2,
-	PAN_UP,
-	PAN_DOWN,
-	PAN_LEFT,
-	PAN_RIGHT,
-	TODO,
-	;
-}

src/main/kotlin/net/eksb/obsdc/OpRunner.kt

@@ -0,0 +1,166 @@
+package net.eksb.obsdc
+
+import io.obswebsocket.community.client.message.request.RequestBatch
+import io.obswebsocket.community.client.message.request.sceneitems.GetSceneItemLockedRequest
+import io.obswebsocket.community.client.message.response.sceneitems.GetSceneItemLockedResponse
+import io.obswebsocket.community.client.model.Scene
+import io.obswebsocket.community.client.model.SceneItem.Transform
+import io.obswebsocket.community.client.model.SceneItem.Transform.TransformBuilder
+import org.slf4j.LoggerFactory
+
+/**
+ * Use an [obs] to run an operation.
+ *
+ * Call [invoke] to run an OBS operation.
+ */
+class OpRunner(private val obs:Obs): (String)->Unit {
+
+	/** How much to pan. */
+	private val panAmount = 50F
+
+	private val controller = obs.controller
+
+	/**
+	 * Run the specified [op].
+	 *
+	 * @param op Operation to run.
+	 */
+	override fun invoke(op:String) {
+		obs.submit { controller ->
+			when {
+				op == "SCENE_NEXT" -> scene { scenes, current ->
+					if (current != null) {
+						scenes.asSequence()
+							.dropWhile { scene -> scene != current }
+							.drop(1)
+							.firstOrNull()
+							?: scenes.firstOrNull()
+					} else {
+						null
+					}
+				}
+				op == "SCENE_PREV" -> scene { scenes, current ->
+					if (current != null) {
+						scenes.reversed().asSequence()
+							.dropWhile { scene -> scene != current }
+							.drop(1)
+							.firstOrNull()
+							?: scenes.lastOrNull()
+					} else {
+						null
+					}
+				}
+				op.startsWith("SCENE_") -> scene { scenes, current ->
+					val drop = op.drop("SCENE_".length).toInt() - 1
+					scenes.asSequence().drop(drop).firstOrNull()
+				}
+				op == "STUDIO_TRANSITION" -> {
+					controller.triggerStudioModeTransition { response ->
+						log.debug("studio transitioned: ${response.isSuccessful}")
+					}
+				}
+				op == "STUDIO_MODE_TOGGLE" -> studioModeToggle()
+				op == "PAN_UP" -> transform { old -> positionY(old.positionY - panAmount ) }
+				op == "PAN_DOWN" -> transform { old -> positionY(old.positionY + panAmount ) }
+				op == "PAN_LEFT" -> transform { old -> positionX(old.positionX - panAmount ) }
+				op == "PAN_RIGHT" -> transform { old -> positionX(old.positionX + panAmount ) }
+				else -> log.error("Unhandled op \"${op}\"")
+			}
+		}
+	}
+
+	private fun studioModeToggle() {
+		controller.getStudioModeEnabled { response ->
+			if (response.isSuccessful) {
+				val enable = !response.studioModeEnabled
+				log.debug("toggle studio mode: ${!enable}")
+				controller.setStudioModeEnabled(enable) { response ->
+					log.debug("toggled studio mode: ${enable}")
+				}
+			}
+		}
+	}
+
+	/**
+	 * Select a scene from the scene list with the supplied [selector] and set the selected scene (if any)
+	 * as the current program scene.
+	 *
+	 * @param selector Lambda that takes as arguments the list of scenes and the current scene (or null if the current
+	 * scene is unknown), and returns the scene to select, or null to not change the scene.
+	 */
+	private fun scene(selector:(List<Scene>,Scene?)->Scene?) {
+		controller.getCurrentProgramScene { response ->
+			val currentSceneName = response.currentProgramSceneName
+			controller.getSceneList { response ->
+				val scenes = response.scenes.sortedBy(Scene::getSceneIndex).reversed()
+				val currentScene = scenes.find { scene -> scene.sceneName == currentSceneName }
+				val scene = selector(response.scenes.sortedBy(Scene::getSceneIndex).reversed(), currentScene)
+				log.debug("select scene ${scene?.sceneName} index:${scene?.sceneIndex}")
+				if (scene != null) {
+					controller.setCurrentProgramScene(scene.sceneName) { response ->
+						log.debug("selected scene ${scene.sceneName}: ${response.isSuccessful}")
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Generate a transform for the lowest non-locked item in the current program scene with the
+	 * supplied [transformBuilder], and apply that transform to the item.
+	 */
+	private fun transform(transformBuilder:TransformBuilder.(Transform)->TransformBuilder) {
+		controller.getCurrentProgramScene { response ->
+			val sceneName = response.currentProgramSceneName
+			log.debug("scene name: ${sceneName}")
+			controller.getSceneItemList(sceneName) { response ->
+				val items = response.sceneItems
+				// Even though locked status is in the response from OBS, the library does not parse it.
+				// So we have to ask for it explicitly:
+				controller.sendRequestBatch(
+					RequestBatch.builder()
+						.requests(
+							response.sceneItems.map { item ->
+								GetSceneItemLockedRequest.builder()
+									.sceneName(sceneName)
+									.sceneItemId(item.sceneItemId)
+									.build()
+							}
+						)
+						.build()
+				) { response ->
+					val item = response.data.results
+						.map { result ->
+							(result.responseData as GetSceneItemLockedResponse.SpecificData).sceneItemLocked
+						}
+						.zip(items)
+						.asSequence()
+						.filter { (locked,item) -> ! locked }
+						.map { (locked,item) -> item }
+						.sortedBy { item -> item.sceneItemIndex }
+						.firstOrNull()
+					log.debug("item to pan: ${item?.sceneItemId}")
+					if (item != null) {
+						controller.getSceneItemTransform(sceneName, item.sceneItemId) { response ->
+							val transform = response.sceneItemTransform
+							log.debug("position: ${transform.positionX} x ${transform.positionY}")
+							val newTransform = transformBuilder(Transform.builder(), transform).build()
+							controller.setSceneItemTransform(sceneName, item.sceneItemId, newTransform) { response ->
+								log.debug("transform successful: ${response.isSuccessful}")
+								// Have to set the current scene to take effect if in studio mode.
+								controller.setCurrentProgramScene(sceneName) { response ->
+									log.debug("set current program to ${sceneName}: ${response.isSuccessful}")
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+
+	companion object {
+		private val log = LoggerFactory.getLogger(OpRunner::class.java)
+	}
+}
+

src/main/kotlin/net/eksb/obsdc/Util.kt

@@ -0,0 +1,27 @@
+package net.eksb.obsdc
+
+import java.io.File
+import java.util.Properties
+import java.util.concurrent.CountDownLatch
+import kotlin.concurrent.thread
+
+val HOME:File = System.getProperty("user.home")?.let(::File) ?: error("No user.home")
+val CONFIG_HOME:File = System.getenv("XDG_CONFIG_HOME")?.let(::File) ?: File(HOME, ".config")
+val CONFIG_FILE:File = File(CONFIG_HOME,"net.eksb.obsdc/config.properties")
+
+fun File.properties(): Properties = Properties()
+	.also { properties ->
+		if (isFile) {
+			inputStream().use(properties::load)
+		}
+	}
+
+fun addShutdownHook(block:()->Unit) = Runtime.getRuntime().addShutdownHook(thread(start=false) { block() })
+
+fun waitForShutdown() {
+	val latch = CountDownLatch(1)
+	addShutdownHook {
+		latch.countDown()
+	}
+	latch.await()
+}

src/main/resources/simplelogger.properties

@@ -0,0 +1,2 @@
+org.slf4j.simpleLogger.log.net.eksb=debug
+org.slf4j.simpleLogger.log.org.freedesktop.dbus=debug