Use Shader instead of RenderEffect for highlight

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

@@ -166,8 +166,6 @@ half4 main(float2 coord) {
 
 @Language("AGSL")
 internal const val DefaultHighlightShaderString = """
-uniform shader content;
-
 uniform float2 size;
 uniform float4 cornerRadii;
 uniform float angle;
@@ -184,13 +182,11 @@ half4 main(float2 coord) {
     float2 grad = gradSdRoundedRectangle(centeredCoord, halfSize, gradRadius);
     float2 normal = float2(-cos(angle), -sin(angle));
     float intensity = pow(abs(dot(normal, grad)), falloff);
-    return content.eval(coord) * intensity;
+    return half4(intensity);
 }"""
 
 @Language("AGSL")
 internal const val AmbientHighlightShaderString = """
-uniform shader content;
-
 uniform float2 size;
 uniform float4 cornerRadii;
 uniform float angle;
@@ -207,16 +203,13 @@ half4 main(float2 coord) {
     float2 grad = gradSdRoundedRectangle(centeredCoord, halfSize, gradRadius);
     float2 normal = float2(-cos(angle), -sin(angle));
     float d = dot(normal, grad);
-    float alpha = content.eval(coord).a;
     float intensity = pow(abs(d), falloff);
     
     if (d > 0.0) {
-        return half4(0.0, 0.0, 0.0, 1.0) * intensity * alpha;
+        return half4(0.0, 0.0, 0.0, 1.0) * intensity;
+    } else {
+        return half4(1.0) * intensity;
     }
-    if (d < 0.0) {
-        return half4(1.0) * intensity * alpha;
-    }
-    return half4(0.0);
 }"""
 
 @Language("AGSL")

backdrop/src/main/java/com/kyant/backdrop/highlight/HighlightModifier.kt

@@ -11,7 +11,6 @@ import androidx.compose.ui.graphics.drawOutline
 import androidx.compose.ui.graphics.drawscope.ContentDrawScope
 import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.graphics.drawscope.translate
-import androidx.compose.ui.graphics.layer.CompositingStrategy
 import androidx.compose.ui.graphics.layer.GraphicsLayer
 import androidx.compose.ui.graphics.layer.drawLayer
 import androidx.compose.ui.node.DrawModifierNode
@@ -73,7 +72,6 @@ internal class HighlightNode(
     override val shouldAutoInvalidate: Boolean = false
 
     private var highlightLayer: GraphicsLayer? = null
-    private var maskLayer: GraphicsLayer? = null
 
     private val paint =
         Paint().apply {
@@ -94,8 +92,7 @@ internal class HighlightNode(
         drawContent()
 
         val highlightLayer = highlightLayer
-        val maskLayer = maskLayer
-        if (highlightLayer != null && maskLayer != null) {
+        if (highlightLayer != null) {
             val size = size
             val density: Density = this
             val layoutDirection = layoutDirection
@@ -116,18 +113,8 @@ internal class HighlightNode(
 
             configurePaint(highlight)
 
-            val style = highlight.style
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-                if (prevStyle != style) {
-                    highlightLayer.renderEffect = with(style) {
-                        createRenderEffect(
-                            shape = shapeProvider.shape,
-                            runtimeShaderCache = runtimeShaderCache
-                        )
-                    }
-                    prevStyle = style
-                }
-            }
+            highlightLayer.alpha = highlight.alpha
+            highlightLayer.blendMode = highlight.style.blendMode
             highlightLayer.record(safeSize) {
                 translate(1f, 1f) {
                     val canvas = drawContext.canvas
@@ -138,14 +125,8 @@ internal class HighlightNode(
                 }
             }
 
-            maskLayer.alpha = highlight.alpha
-            maskLayer.blendMode = style.blendMode
-            maskLayer.record(safeSize) {
-                drawLayer(highlightLayer)
-            }
-
             translate(-1f, -1f) {
-                drawLayer(maskLayer)
+                drawLayer(highlightLayer)
             }
         }
     }
@@ -153,10 +134,6 @@ internal class HighlightNode(
     override fun onAttach() {
         val graphicsContext = requireGraphicsContext()
         highlightLayer = graphicsContext.createGraphicsLayer()
-        maskLayer =
-            graphicsContext.createGraphicsLayer().apply {
-                compositingStrategy = CompositingStrategy.Offscreen
-            }
     }
 
     override fun onDetach() {
@@ -165,10 +142,6 @@ internal class HighlightNode(
             graphicsContext.releaseGraphicsLayer(layer)
             highlightLayer = null
         }
-        maskLayer?.let { layer ->
-            graphicsContext.releaseGraphicsLayer(layer)
-            maskLayer = null
-        }
         clipPath = null
         runtimeShaderCache.clear()
         prevStyle = null
@@ -185,5 +158,13 @@ internal class HighlightNode(
             } else {
                 null
             }
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+            paint.shader = with(highlight.style) {
+                createShader(
+                    shape = shapeProvider.shape,
+                    runtimeShaderCache = runtimeShaderCache
+                )
+            }
+        }
     }
 }

backdrop/src/main/java/com/kyant/backdrop/highlight/HighlightStyle.kt

@@ -8,9 +8,8 @@ import androidx.compose.runtime.Immutable
 import androidx.compose.runtime.Stable
 import androidx.compose.ui.graphics.BlendMode
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.RenderEffect
+import androidx.compose.ui.graphics.Shader
 import androidx.compose.ui.graphics.Shape
-import androidx.compose.ui.graphics.asComposeRenderEffect
 import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.util.fastCoerceAtMost
@@ -27,10 +26,10 @@ interface HighlightStyle {
     val blendMode: BlendMode
 
     @RequiresApi(Build.VERSION_CODES.S)
-    fun DrawScope.createRenderEffect(
+    fun DrawScope.createShader(
         shape: Shape,
         runtimeShaderCache: RuntimeShaderCache
-    ): RenderEffect?
+    ): Shader?
 
     @Immutable
     data class Plain(
@@ -39,10 +38,10 @@ interface HighlightStyle {
     ) : HighlightStyle {
 
         @RequiresApi(Build.VERSION_CODES.S)
-        override fun DrawScope.createRenderEffect(
+        override fun DrawScope.createShader(
             shape: Shape,
             runtimeShaderCache: RuntimeShaderCache
-        ): RenderEffect? = null
+        ): Shader? = null
     }
 
     @Immutable
@@ -57,20 +56,20 @@ interface HighlightStyle {
         override val blendMode: BlendMode = BlendMode.Plus
 
         @RequiresApi(Build.VERSION_CODES.S)
-        override fun DrawScope.createRenderEffect(
+        override fun DrawScope.createShader(
             shape: Shape,
             runtimeShaderCache: RuntimeShaderCache
-        ): RenderEffect? {
+        ): Shader? {
             return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
-                val shader = runtimeShaderCache.obtainRuntimeShader("Default", DefaultHighlightShaderString)
-                shader.apply {
+                runtimeShaderCache.obtainRuntimeShader(
+                    "Default",
+                    DefaultHighlightShaderString
+                ).apply {
                     setFloatUniform("size", size.width, size.height)
                     setFloatUniform("cornerRadii", getCornerRadii(shape))
                     setFloatUniform("angle", angle * (PI / 180f).toFloat())
                     setFloatUniform("falloff", falloff)
                 }
-                android.graphics.RenderEffect.createRuntimeShaderEffect(shader, "content")
-                    .asComposeRenderEffect()
             } else {
                 null
             }
@@ -87,20 +86,20 @@ interface HighlightStyle {
         override val blendMode: BlendMode = DrawScope.DefaultBlendMode
 
         @RequiresApi(Build.VERSION_CODES.S)
-        override fun DrawScope.createRenderEffect(
+        override fun DrawScope.createShader(
             shape: Shape,
             runtimeShaderCache: RuntimeShaderCache
-        ): RenderEffect? {
+        ): Shader? {
             return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
-                val shader = runtimeShaderCache.obtainRuntimeShader("Ambient", AmbientHighlightShaderString)
-                shader.apply {
+                runtimeShaderCache.obtainRuntimeShader(
+                    "Ambient",
+                    AmbientHighlightShaderString
+                ).apply {
                     setFloatUniform("size", size.width, size.height)
                     setFloatUniform("cornerRadii", getCornerRadii(shape))
                     setFloatUniform("angle", 45f * (PI / 180f).toFloat())
                     setFloatUniform("falloff", 1f)
                 }
-                android.graphics.RenderEffect.createRuntimeShaderEffect(shader, "content")
-                    .asComposeRenderEffect()
             } else {
                 null
             }
@@ -121,9 +120,9 @@ interface HighlightStyle {
 }
 
 private fun DrawScope.getCornerRadii(shape: Shape): FloatArray {
-    val shape = shape as? CornerBasedShape ?: return FloatArray(4) { size.minDimension / 2f }
     val size = size
     val maxRadius = size.minDimension / 2f
+    val shape = shape as? CornerBasedShape ?: return FloatArray(4) { maxRadius }
     val isLtr = layoutDirection == LayoutDirection.Ltr
     val topLeft =
         if (isLtr) shape.topStart.toPx(size, this)