fix(android): free decoded images on the new backend

android/src/new/java/com/margelo/nitro/rive/HybridViewModelImageProperty.kt

@@ -9,28 +9,43 @@ import com.facebook.proguard.annotations.DoNotStrip
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
+import java.util.concurrent.atomic.AtomicInteger
+
+// Shared by every wrapper for one instance path, since JS may look the property up again per set.
+internal class ImagePropertySequencer {
+  // Single-threaded so a clear cannot run between the generation check and setImage.
+  val scope = CoroutineScope(Dispatchers.Default.limitedParallelism(1))
+
+  // Decoding suspends, so a decode that finishes after a newer set or clear must be dropped.
+  val generation = AtomicInteger()
+}
 
 @Keep
 @DoNotStrip
-class HybridViewModelImageProperty(
+class HybridViewModelImageProperty internal constructor(
   private val instance: ViewModelInstance,
   private val path: String,
-  private val riveWorker: CommandQueue
+  private val riveWorker: CommandQueue,
+  private val sequencer: ImagePropertySequencer
 ) : HybridViewModelImagePropertySpec(),
   BaseHybridViewModelProperty<Unit> by BaseHybridViewModelPropertyImpl() {
   companion object {
     private const val TAG = "HybridViewModelImageProperty"
   }
 
-  private val imageScope = CoroutineScope(Dispatchers.Default)
-
   override fun set(image: HybridRiveImageSpec?) {
-    val hybridImage = image as? HybridRiveImage ?: return
-    imageScope.launch {
+    val hybridImage = image as? HybridRiveImage
+    val gen = sequencer.generation.incrementAndGet()
+    sequencer.scope.launch {
       try {
+        if (hybridImage == null) {
+          instance.setImage(path, null)
+          return@launch
+        }
         val result = ImageAsset.fromBytes(riveWorker, hybridImage.rawData)
         if (result is app.rive.Result.Success) {
-          instance.setImage(path, result.value)
+          // The property keeps its own ref, so close ours right away.
+          result.value.use { if (sequencer.generation.get() == gen) instance.setImage(path, it) }
         } else {
           Log.e(TAG, "Failed to decode image for path '$path'")
         }

android/src/new/java/com/margelo/nitro/rive/HybridViewModelInstance.kt

@@ -7,6 +7,7 @@ import app.rive.ViewModelInstanceSource
 import app.rive.core.CommandQueue
 import com.facebook.proguard.annotations.DoNotStrip
 import com.margelo.nitro.core.Promise
+import java.util.concurrent.ConcurrentHashMap
 
 @Keep
 @DoNotStrip
@@ -24,6 +25,8 @@ class HybridViewModelInstance(
     private const val TAG = "HybridViewModelInstance"
   }
 
+  private val imageSequencers = ConcurrentHashMap<String, ImagePropertySequencer>()
+
   override fun dispose() {
     if (ownsInstance) {
       runCatching { viewModelInstance.close() }
@@ -78,7 +81,8 @@ class HybridViewModelInstance(
 
   override fun imageProperty(path: String): HybridViewModelImagePropertySpec? {
     return try {
-      HybridViewModelImageProperty(viewModelInstance, path, riveWorker)
+      val sequencer = imageSequencers.getOrPut(path) { ImagePropertySequencer() }
+      HybridViewModelImageProperty(viewModelInstance, path, riveWorker, sequencer)
     } catch (e: Exception) {
       Log.e(TAG, "imageProperty failed for path '$path'", e)
       null

example/__tests__/image-property-clear.harness.ts

@@ -0,0 +1,44 @@
+import { describe, it, expect } from 'react-native-harness';
+import { Platform } from 'react-native';
+import { RiveFileFactory, RiveImages } from '@rive-app/react-native';
+
+const DATABINDING_IMAGES = require('../assets/rive/databinding_images.riv');
+
+// 1x1 red PNG
+const PNG_BASE64 =
+  'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVR4nGP4z8AAAAMBAQDJ/pLvAAAAAElFTkSuQmCC';
+
+function pngBytes(): ArrayBuffer {
+  const binary = atob(PNG_BASE64);
+  const bytes = new Uint8Array(binary.length);
+  for (let i = 0; i < binary.length; i++) bytes[i] = binary.charCodeAt(i);
+  return bytes.buffer;
+}
+
+describe('ViewModelImageProperty', () => {
+  it('repeated set(image) and set(undefined) do not throw', async () => {
+    const file = await RiveFileFactory.fromSource(
+      DATABINDING_IMAGES,
+      undefined
+    );
+    const instance = file
+      .viewModelByName('MyViewModel')
+      ?.createInstanceByIndex(0);
+    const prop = instance?.imageProperty('bound_image');
+    expect(prop).toBeDefined();
+
+    // The new iOS runtime can't clear image properties yet (#360)
+    const canClear =
+      Platform.OS !== 'ios' || RiveFileFactory.getBackend() !== 'experimental';
+
+    const image = await RiveImages.loadFromBytesAsync(pngBytes());
+    for (let i = 0; i < 10; i++) prop!.set(image);
+    if (canClear) prop!.set(undefined);
+    prop!.set(image);
+    if (canClear) prop!.set(undefined);
+
+    prop!.dispose();
+    instance!.dispose();
+    file.dispose();
+  });
+});