perf: improve MarkerComposable rendering performance

Author: brucemok8

maps-compose/src/main/java/com/google/maps/android/compose/Marker.kt

@@ -341,27 +341,28 @@ public fun MarkerComposable(
     content: @UiComposable @Composable () -> Unit,
 ) {
     val icon = rememberComposeBitmapDescriptor(*keys) { content() }
-
-    MarkerImpl(
-        state = state,
-        contentDescription = contentDescription,
-        alpha = alpha,
-        anchor = anchor,
-        draggable = draggable,
-        flat = flat,
-        icon = icon,
-        infoWindowAnchor = infoWindowAnchor,
-        rotation = rotation,
-        snippet = snippet,
-        tag = tag,
-        title = title,
-        visible = visible,
-        zIndex = zIndex,
-        onClick = onClick,
-        onInfoWindowClick = onInfoWindowClick,
-        onInfoWindowClose = onInfoWindowClose,
-        onInfoWindowLongClick = onInfoWindowLongClick,
-    )
+    if (icon != null) {
+        MarkerImpl(
+            state = state,
+            contentDescription = contentDescription,
+            alpha = alpha,
+            anchor = anchor,
+            draggable = draggable,
+            flat = flat,
+            icon = icon,
+            infoWindowAnchor = infoWindowAnchor,
+            rotation = rotation,
+            snippet = snippet,
+            tag = tag,
+            title = title,
+            visible = visible,
+            zIndex = zIndex,
+            onClick = onClick,
+            onInfoWindowClick = onInfoWindowClick,
+            onInfoWindowClose = onInfoWindowClose,
+            onInfoWindowLongClick = onInfoWindowLongClick,
+        )
+    }
 }
 
 /**
@@ -489,27 +490,28 @@ public fun MarkerInfoWindowComposable(
     content: @UiComposable @Composable () -> Unit,
 ) {
     val icon = rememberComposeBitmapDescriptor(*keys) { content() }
-
-    MarkerImpl(
-        state = state,
-        alpha = alpha,
-        anchor = anchor,
-        draggable = draggable,
-        flat = flat,
-        icon = icon,
-        infoWindowAnchor = infoWindowAnchor,
-        rotation = rotation,
-        snippet = snippet,
-        tag = tag,
-        title = title,
-        visible = visible,
-        zIndex = zIndex,
-        onClick = onClick,
-        onInfoWindowClick = onInfoWindowClick,
-        onInfoWindowClose = onInfoWindowClose,
-        onInfoWindowLongClick = onInfoWindowLongClick,
-        infoWindow = infoContent,
-    )
+    if (icon != null) {
+        MarkerImpl(
+            state = state,
+            alpha = alpha,
+            anchor = anchor,
+            draggable = draggable,
+            flat = flat,
+            icon = icon,
+            infoWindowAnchor = infoWindowAnchor,
+            rotation = rotation,
+            snippet = snippet,
+            tag = tag,
+            title = title,
+            visible = visible,
+            zIndex = zIndex,
+            onClick = onClick,
+            onInfoWindowClick = onInfoWindowClick,
+            onInfoWindowClose = onInfoWindowClose,
+            onInfoWindowLongClick = onInfoWindowLongClick,
+            infoWindow = infoContent,
+        )
+    }
 }
 
 /**

maps-compose/src/main/java/com/google/maps/android/compose/RememberComposeBitmapDescriptor.kt

@@ -19,52 +19,65 @@ package com.google.maps.android.compose
 import android.view.View
 import android.view.ViewGroup
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.CompositionContext
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCompositionContext
 import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.platform.ComposeView
 import androidx.compose.ui.platform.LocalView
 import androidx.core.graphics.applyCanvas
+import androidx.core.graphics.createBitmap
 import com.google.android.gms.maps.model.BitmapDescriptor
 import com.google.android.gms.maps.model.BitmapDescriptorFactory
-import androidx.core.graphics.createBitmap
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
 
 @MapsComposeExperimentalApi
 @Composable
 public fun rememberComposeBitmapDescriptor(
     vararg keys: Any,
     content: @Composable () -> Unit,
-): BitmapDescriptor {
+): BitmapDescriptor? {
+    var bitmapDescriptor by remember { mutableStateOf<BitmapDescriptor?>(null) }
     val parent = LocalView.current as ViewGroup
     val compositionContext = rememberCompositionContext()
     val currentContent by rememberUpdatedState(content)
+    val composeView = remember { ComposeView(parent.context) }
 
-    return remember(parent, compositionContext, currentContent, *keys) {
-        renderComposableToBitmapDescriptor(parent, compositionContext, currentContent)
-    }
-}
-
-private val measureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED)
-
-private fun renderComposableToBitmapDescriptor(
-    parent: ViewGroup,
-    compositionContext: CompositionContext,
-    content: @Composable () -> Unit,
-): BitmapDescriptor {
-    val composeView =
-        ComposeView(parent.context)
+    DisposableEffect(Unit) {
+        composeView
             .apply {
                 layoutParams = ViewGroup.LayoutParams(
                     ViewGroup.LayoutParams.WRAP_CONTENT,
                     ViewGroup.LayoutParams.WRAP_CONTENT,
                 )
                 setParentCompositionContext(compositionContext)
-                setContent(content)
+                setContent(currentContent)
             }
             .also(parent::addView)
+        onDispose {
+            parent.removeView(composeView)
+        }
+    }
+
+    LaunchedEffect(*keys) {
+        bitmapDescriptor = withContext(Dispatchers.IO) {
+            renderComposableToBitmapDescriptor(composeView)
+        }
+    }
+
+    return bitmapDescriptor
+}
 
+private val measureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED)
+
+private fun renderComposableToBitmapDescriptor(
+    composeView: ComposeView,
+): BitmapDescriptor {
     composeView.measure(measureSpec, measureSpec)
 
     if (composeView.measuredWidth == 0 || composeView.measuredHeight == 0) {
@@ -79,7 +92,5 @@ private fun renderComposableToBitmapDescriptor(
 
     bitmap.applyCanvas { composeView.draw(this) }
 
-    parent.removeView(composeView)
-
     return BitmapDescriptorFactory.fromBitmap(bitmap)
 }