Observe UserDefaults values

build.gradle.kts

@@ -22,7 +22,11 @@ kotlin {
  }
 
  sourceSets {
- val nativeMain by creating
+ val nativeMain by creating {
+ dependencies {
+ implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.7.3")
+ }
+ }
  val macosX64Main by getting {
  dependsOn(nativeMain)
  }

src/nativeMain/kotlin/Debouncer.kt

@@ -0,0 +1,18 @@
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlin.coroutines.EmptyCoroutineContext
+
+class Debouncer(private val delayMs: Long) {
+ private val scope = CoroutineScope(EmptyCoroutineContext)
+ private var job: Job? = null
+
+ fun execute(task: () -> Unit) {
+ job?.cancel()
+ job = scope.launch {
+ delay(delayMs)
+ task()
+ }
+ }
+}

src/nativeMain/kotlin/Main.kt

@@ -4,9 +4,7 @@ import kotlinx.cinterop.CPointer
 import kotlinx.cinterop.ExperimentalForeignApi
 import kotlinx.cinterop.useContents
 import platform.AppKit.*
-import platform.Foundation.NSBundle
-import platform.Foundation.NSMakeRect
-import platform.Foundation.NSRect
+import platform.Foundation.*
 import platform.ScreenSaver.ScreenSaverView
 import kotlin.math.pow
 import kotlin.math.sqrt
@@ -35,17 +33,16 @@ abstract class KotlinScreenSaverView {
 }
 
 class KotlinLogosViewImpl : KotlinScreenSaverView() {
- private val logos: List<BouncingLogo> by lazy {
- List(Preferences.LOGO_COUNT) { BouncingLogo(view, bundle) }
- }
+ private var logos: List<BouncingLogo> = emptyList()
 
  override fun init(screenSaverView: ScreenSaverView, isPreview: Boolean, bundle: NSBundle) {
  super.init(screenSaverView, isPreview, bundle)
  screenSaverView.animationTimeInterval = 1 / 120.0
+ setupUserDefaultsObserver()
+ initLogos()
  }
 
  override fun draw(rect: CPointer<NSRect>) {
- clearStage()
  logos.forEach(BouncingLogo::draw)
  }
 
@@ -54,9 +51,20 @@ class KotlinLogosViewImpl : KotlinScreenSaverView() {
  view.setNeedsDisplayInRect(view.frame)
  }
 
- private fun clearStage() {
- NSColor.blackColor.setFill()
- NSRectFill(view.frame)
+ private val debouncer = Debouncer(500)
+
+ private fun setupUserDefaultsObserver() {
+ NSNotificationCenter.defaultCenter
+ .addObserverForName(NSUserDefaultsDidChangeNotification, null, null) {
+ debouncer.execute {
+ initLogos()
+ }
+ }
+ }
+
+ private fun initLogos() {
+ logos.forEach(BouncingLogo::dispose)
+ logos = List(Preferences.LOGO_COUNT) { BouncingLogo(view, bundle) }
  }
 }
 
@@ -171,4 +179,8 @@ class BouncingLogo(
  logoWidth = area / logoHeight
  }
  }
+
+ fun dispose() {
+ imageView.removeFromSuperview()
+ }
 }