Fix effects are failed to be observed

backdrop/src/main/java/com/kyant/backdrop/BackdropEffectScope.kt

@@ -4,10 +4,6 @@ import android.graphics.RenderEffect
 import android.graphics.RuntimeShader
 import android.os.Build
 import androidx.annotation.RequiresApi
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableFloatStateOf
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.setValue
 import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Shape
 import androidx.compose.ui.graphics.drawscope.DrawScope
@@ -27,10 +23,10 @@ interface BackdropEffectScope : Density, RuntimeShaderCacheScope {
 
 internal abstract class BackdropEffectScopeImpl : BackdropEffectScope {
 
-    override var density: Float by mutableFloatStateOf(1f)
-    override var fontScale: Float by mutableFloatStateOf(1f)
-    override var size: Size by mutableStateOf(Size.Unspecified)
-    override var layoutDirection: LayoutDirection by mutableStateOf(LayoutDirection.Ltr)
+    override var density: Float = 1f
+    override var fontScale: Float = 1f
+    override var size: Size = Size.Unspecified
+    override var layoutDirection: LayoutDirection = LayoutDirection.Ltr
     override var renderEffect: RenderEffect? = null
 
     private val runtimeShaders = mutableMapOf<String, RuntimeShader>()
@@ -40,11 +36,32 @@ internal abstract class BackdropEffectScopeImpl : BackdropEffectScope {
         return runtimeShaders.getOrPut(key) { RuntimeShader(string) }
     }
 
-    fun applyDrawScope(scope: DrawScope) {
-        density = scope.density
-        fontScale = scope.fontScale
-        size = scope.size
-        layoutDirection = scope.layoutDirection
+    fun update(scope: DrawScope): Boolean {
+        val newDensity = scope.density
+        val newFontScale = scope.fontScale
+        val newSize = scope.size
+        val newLayoutDirection = scope.layoutDirection
+
+        val changed = newDensity != density ||
+                newFontScale != fontScale ||
+                newSize != size ||
+                newLayoutDirection != layoutDirection
+
+        if (changed) {
+            density = newDensity
+            fontScale = newFontScale
+            size = newSize
+            layoutDirection = newLayoutDirection
+        }
+
+        return changed
+    }
+
+    fun reset() {
+        density = 1f
+        fontScale = 1f
+        size = Size.Unspecified
+        layoutDirection = LayoutDirection.Ltr
         renderEffect = null
     }
 }

backdrop/src/main/java/com/kyant/backdrop/ContentBackdropModifier.kt

@@ -159,15 +159,6 @@ private class ContentBackdropNode(
             null
         }
 
-    private var isCacheValid = false
-    private val cacheDrawBlock: DrawScope.() -> Unit = {
-        if (effectScope != null) {
-            effectScope.applyDrawScope(this)
-            effects(effectScope)
-            graphicsLayer?.renderEffect = effectScope.renderEffect?.asComposeRenderEffect()
-        }
-    }
-
     private val layoutLayerBlock: GraphicsLayerScope.() -> Unit = {
         clip = true
         shape = shapeProvider.shape
@@ -188,9 +179,8 @@ private class ContentBackdropNode(
 
     override fun ContentDrawScope.draw() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-            if (!isCacheValid) {
-                observeReads { cacheDrawBlock() }
-                isCacheValid = true
+            if (effectScope != null && effectScope.update(this)) {
+                updateEffects()
             }
         }
 
@@ -227,13 +217,28 @@ private class ContentBackdropNode(
     }
 
     fun invalidateDrawCache() {
-        isCacheValid = false
+        observeEffects()
         invalidateDraw()
     }
 
+    private fun observeEffects() {
+        if (effectScope != null) {
+            observeReads { updateEffects() }
+        }
+    }
+
+    private fun updateEffects() {
+        if (effectScope != null) {
+            effectScope.renderEffect = null
+            effects(effectScope)
+            graphicsLayer?.renderEffect = effectScope.renderEffect?.asComposeRenderEffect()
+        }
+    }
+
     override fun onAttach() {
         val graphicsContext = requireGraphicsContext()
         graphicsLayer = graphicsContext.createGraphicsLayer()
+        observeEffects()
     }
 
     override fun onDetach() {
@@ -242,5 +247,7 @@ private class ContentBackdropNode(
             graphicsContext.releaseGraphicsLayer(layer)
             graphicsLayer = null
         }
+        inverseLayerScope = null
+        effectScope?.reset()
     }
 }

backdrop/src/main/java/com/kyant/backdrop/DrawBackdropModifier.kt

@@ -197,15 +197,6 @@ private class DrawBackdropNode(
             null
         }
 
-    private var isCacheValid = false
-    private val cacheDrawBlock: DrawScope.() -> Unit = {
-        if (effectScope != null) {
-            effectScope.applyDrawScope(this)
-            effects(effectScope)
-            graphicsLayer?.renderEffect = effectScope.renderEffect?.asComposeRenderEffect()
-        }
-    }
-
     private val layoutLayerBlock: GraphicsLayerScope.() -> Unit = {
         clip = true
         shape = shapeProvider.shape
@@ -231,9 +222,8 @@ private class DrawBackdropNode(
 
     override fun ContentDrawScope.draw() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-            if (!isCacheValid) {
-                observeReads { cacheDrawBlock() }
-                isCacheValid = true
+            if (effectScope != null && effectScope.update(this)) {
+                updateEffects()
             }
         }
 
@@ -283,13 +273,28 @@ private class DrawBackdropNode(
     }
 
     fun invalidateDrawCache() {
-        isCacheValid = false
+        observeEffects()
         invalidateDraw()
     }
 
+    private fun observeEffects() {
+        if (effectScope != null) {
+            observeReads { updateEffects() }
+        }
+    }
+
+    private fun updateEffects() {
+        if (effectScope != null) {
+            effectScope.renderEffect = null
+            effects(effectScope)
+            graphicsLayer?.renderEffect = effectScope.renderEffect?.asComposeRenderEffect()
+        }
+    }
+
     override fun onAttach() {
         val graphicsContext = requireGraphicsContext()
         graphicsLayer = graphicsContext.createGraphicsLayer()
+        observeEffects()
     }
 
     override fun onDetach() {
@@ -299,5 +304,6 @@ private class DrawBackdropNode(
             graphicsLayer = null
         }
         recordBlock = null
+        effectScope?.reset()
     }
 }