Refine FavouriteStatusRouter observable stateFlow

app/src/main/kotlin/com/hippo/ehviewer/ui/main/GalleryInfo.kt

@@ -67,11 +67,8 @@ fun GalleryInfoListItem(
                     modifier = Modifier.aspectRatio(DEFAULT_ASPECT).fillMaxSize(),
                 )
             }
-            val showFav by produceState(false, info.gid) {
-                value = info.favoriteSlot != NOT_FAVORITED && !isInFavScene
-                FavouriteStatusRouter.stateFlow(info.gid).collect {
-                    value = it != NOT_FAVORITED && !isInFavScene
-                }
+            val showFav by FavouriteStatusRouter.collectAsState(info) {
+                it != NOT_FAVORITED && !isInFavScene
             }
             ConstraintLayout(modifier = Modifier.padding(8.dp, 4.dp).fillMaxSize()) {
                 val (titleRef, uploaderRef, ratingRef, categoryRef, postedRef, favRef, iconsRef) = createRefs()

app/src/main/kotlin/com/hippo/ehviewer/ui/scene/GalleryDetailScene.kt

@@ -79,7 +79,6 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
@@ -715,9 +714,8 @@ class GalleryDetailScene : BaseScene() {
                 .horizontalScroll(rememberScrollState()),
             horizontalArrangement = Arrangement.spacedBy(12.dp, Alignment.CenterHorizontally),
         ) {
-            val favored by produceState(initialValue = false) {
-                value = galleryDetail.favoriteSlot != NOT_FAVORITED
-                FavouriteStatusRouter.stateFlow(galleryDetail.gid).collect { value = it != NOT_FAVORITED }
+            val favored by FavouriteStatusRouter.collectAsState(galleryDetail) {
+                it != NOT_FAVORITED
             }
             val favButtonText = if (favored) {
                 galleryDetail.favoriteName ?: stringResource(id = R.string.local_favorites)

app/src/main/kotlin/com/hippo/ehviewer/util/FavouriteStatusRouter.kt

@@ -15,11 +15,16 @@
  */
 package com.hippo.ehviewer.util
 
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.remember
 import com.hippo.ehviewer.EhDB
+import com.hippo.ehviewer.client.data.GalleryInfo
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.asSharedFlow
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.transform
 import kotlinx.coroutines.launch
 
@@ -40,5 +45,8 @@ object FavouriteStatusRouter {
 
     val globalFlow = _globalFlow.asSharedFlow()
 
-    fun stateFlow(targetGid: Long) = globalFlow.transform { (gid, slot) -> if (targetGid == gid) emit(slot) }
+    @Composable
+    inline fun <R> collectAsState(initial: GalleryInfo, crossinline transform: (Int) -> R) = remember(initial) {
+        globalFlow.transform { (gid, slot) -> if (initial.gid == gid) emit(slot) }.map(transform)
+    }.collectAsState(transform(initial.favoriteSlot))
 }