Refactor GalleryPreviewsScene with Paging Compose

app/src/main/java/com/hippo/widget/ComposeContentLayout.kt

@@ -5,29 +5,26 @@ import androidx.compose.foundation.layout.Box
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
-import androidx.compose.runtime.saveable.listSaver
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
-import androidx.compose.runtime.snapshots.SnapshotStateList
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.paging.PagingSource
+import androidx.paging.compose.LazyPagingItems
 import com.hippo.widget.pullrefresh.PullRefreshIndicator
 import com.hippo.widget.pullrefresh.pullRefresh
 import com.hippo.widget.pullrefresh.rememberPullRefreshState
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
-import moe.tarsin.coroutines.runSuspendCatching
 
 @Composable
 inline fun <reified T : Parcelable> ContentLayout(
     state: ContentState<T>,
-    noinline getData: suspend (Int) -> List<T>,
     modifier: Modifier = Modifier,
-    content: @Composable (Array<T>) -> Unit,
+    content: @Composable (LazyPagingItems<T>) -> Unit,
 ) {
     var refreshing by rememberSaveable { mutableStateOf(false) }
     val coroutineScope = rememberCoroutineScope { Dispatchers.IO }
@@ -35,24 +32,18 @@ inline fun <reified T : Parcelable> ContentLayout(
         refreshing = true
         if (state.startPage == 0) {
             coroutineScope.launch {
-                val result = runSuspendCatching { getData(0) }.getOrNull()
-                result?.let {
-                    state.data.clear()
-                    state.data.addAll(it)
-                }
             }.invokeOnCompletion { refreshing = false }
         } else {
             TODO()
         }
     })
     Box(modifier = Modifier.pullRefresh(refreshState)) {
-        content(state.data.toTypedArray())
         PullRefreshIndicator(refreshing = refreshing, state = refreshState, modifier = modifier.align(Alignment.TopCenter))
     }
 }
 
-class ContentState<T>(
-    val data: SnapshotStateList<T>,
+class ContentState<T : Any>(
+    val data: PagingSource<Int, T>,
     _startPage: MutableState<Int>,
     _endPage: MutableState<Int>,
 ) {
@@ -61,17 +52,10 @@ class ContentState<T>(
 }
 
 @Composable
-fun <T> rememberContentState(
-    initialData: List<T>,
+fun <T : Any> rememberContentState(
+    source: PagingSource<Int, T>,
 ): ContentState<T> {
-    val snapshotStateListSaver = remember {
-        listSaver(
-            save = { it.toList() },
-            restore = { mutableStateListOf<T>().apply { addAll(it) } },
-        )
-    }
-    val data = rememberSaveable(saver = snapshotStateListSaver) { mutableStateListOf<T>().apply { addAll(initialData) } }
     val startPage = rememberSaveable { mutableStateOf(0) }
     val endPage = rememberSaveable { mutableStateOf(0) }
-    return remember { ContentState(data, startPage, endPage) }
+    return remember { ContentState(source, startPage, endPage) }
 }