feat(library): Improve category tab selection when searching/filtering library or adding/removing categories (#1233)

* feat(library): Improve category tab selection when searching/filtering library or adding/removing categories

* Improve active category index handling in LibraryScreenModel

app/src/main/java/eu/kanade/presentation/library/components/LibraryContent.kt

@@ -28,6 +28,9 @@ import kotlin.time.Duration.Companion.seconds
 @Composable
 fun LibraryContent(
     categories: List<Category>,
+    // KMK -->
+    activeCategoryIndex: Int,
+    // KMK <--
     searchQuery: String?,
     selection: Set<Long>,
     contentPadding: PaddingValues,
@@ -60,9 +63,17 @@ fun LibraryContent(
 
         if (showPageTabs && categories.isNotEmpty() && (categories.size > 1 || !categories.first().isSystemCategory)) {
             LaunchedEffect(categories) {
-                if (categories.size <= pagerState.currentPage) {
-                    pagerState.scrollToPage(categories.size - 1)
+                // KMK -->
+                val targetPage = when {
+                    categories.isEmpty() -> 0
+                    activeCategoryIndex != pagerState.currentPage -> activeCategoryIndex.coerceAtMost(categories.size - 1)
+                    pagerState.currentPage >= categories.size -> categories.size - 1
+                    else -> pagerState.currentPage
                 }
+                if (targetPage != pagerState.currentPage) {
+                    pagerState.scrollToPage(targetPage)
+                }
+                // KMK <--
             }
             LibraryTabs(
                 categories = categories,

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryScreenModel.kt

@@ -1386,7 +1386,12 @@ class LibraryScreenModel(
 
     fun updateActiveCategoryIndex(index: Int) {
         val newIndex = mutableState.updateAndGet { state ->
-            state.copy(activeCategoryIndex = index)
+            state.copy(
+                activeCategoryIndex = index,
+                // KMK -->
+                activeCategoryId = state.displayedCategories.getOrNull(index)?.id,
+                // KMK <--
+            )
         }
             .coercedActiveCategoryIndex
 
@@ -1653,6 +1658,9 @@ class LibraryScreenModel(
         val dialog: Dialog? = null,
         val libraryData: LibraryData = LibraryData(),
         private val activeCategoryIndex: Int = 0,
+        // KMK -->
+        private val activeCategoryId: Long? = null,
+        // KMK <--
         private val groupedFavorites: Map<Category, List</* LibraryItem */ Long>> = emptyMap(),
         // SY -->
         val showSyncExh: Boolean = false,
@@ -1671,10 +1679,13 @@ class LibraryScreenModel(
          */
         val displayedCategories: List<Category> = groupedFavorites.keys.toList()
 
-        val coercedActiveCategoryIndex = activeCategoryIndex.coerceIn(
-            minimumValue = 0,
-            maximumValue = displayedCategories.lastIndex.coerceAtLeast(0),
-        )
+        val coercedActiveCategoryIndex = /* KMK --> */ displayedCategories.indexOfFirst { it.id == activeCategoryId }
+            .takeIf { it != -1 } ?: activeCategoryIndex
+            // KMK <--
+            .coerceIn(
+                minimumValue = 0,
+                maximumValue = displayedCategories.lastIndex.coerceAtLeast(0),
+            )
 
         val activeCategory: Category? = displayedCategories.getOrNull(coercedActiveCategoryIndex)
 

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryTab.kt

@@ -302,6 +302,9 @@ data object LibraryTab : Tab {
                 else -> {
                     LibraryContent(
                         categories = state.displayedCategories,
+                        // KMK -->
+                        activeCategoryIndex = state.coercedActiveCategoryIndex,
+                        // KMK <--
                         searchQuery = state.searchQuery,
                         selection = state.selection,
                         contentPadding = contentPadding,