Add swiping between posts in PostActivity

app/build.gradle.kts

@@ -154,6 +154,8 @@ dependencies {
     implementation("net.engawapg.lib:zoomable:1.4.3")
     implementation("androidx.browser:browser:1.5.0")
 
+    implementation("me.saket.swipe:swipe:1.2.0")
+
     implementation("androidx.profileinstaller:profileinstaller:1.3.1")
     baselineProfile(project(":benchmarks"))
 }

app/src/main/java/com/jerboa/MainActivity.kt

@@ -49,9 +49,9 @@ import com.jerboa.ui.components.comment.edit.CommentEditViewModel
 import com.jerboa.ui.components.comment.reply.CommentReplyActivity
 import com.jerboa.ui.components.comment.reply.CommentReplyViewModel
 import com.jerboa.ui.components.common.MarkdownHelper
+import com.jerboa.ui.components.common.PostSwipeWrapper
 import com.jerboa.ui.components.common.ShowChangelog
 import com.jerboa.ui.components.common.ShowOutdatedServerDialog
-import com.jerboa.ui.components.common.SwipeToNavigateBack
 import com.jerboa.ui.components.common.getCurrentAccount
 import com.jerboa.ui.components.common.getCurrentAccountSync
 import com.jerboa.ui.components.community.CommunityActivity
@@ -501,7 +501,13 @@ class MainActivity : ComponentActivity() {
                             postViewModel.initialize(id = Either.Left(postId))
                             postViewModel.getData(account)
                         }
-                        SwipeToNavigateBack(navController = navController) {
+                        PostSwipeWrapper(
+                            navController = navController,
+                            account = account,
+                            homeViewModel = homeViewModel,
+                            postViewModel = postViewModel,
+                            appSettingsViewModel = appSettingsViewModel,
+                        ) {
                             PostActivity(
                                 postViewModel = postViewModel,
                                 accountViewModel = accountViewModel,

app/src/main/java/com/jerboa/db/AppDB.kt

@@ -118,6 +118,11 @@ data class AppSettings(
         defaultValue = "0",
     )
     val secureWindow: Boolean,
+    @ColumnInfo(
+        name = "swipe_between_posts",
+        defaultValue = "0",
+    )
+    val swipeBetweenPosts: Boolean,
 )
 
 @Dao
@@ -436,8 +441,17 @@ val MIGRATION_15_16 = object : Migration(15, 16) {
     }
 }
 
+val MIGRATION_16_17 = object : Migration(16, 17) {
+    override fun migrate(database: SupportSQLiteDatabase) {
+        database.execSQL(UPDATE_APP_CHANGELOG_UNVIEWED)
+        database.execSQL(
+            "ALTER TABLE AppSettings add column swipe_between_posts INTEGER NOT NULL default 0",
+        )
+    }
+}
+
 @Database(
-    version = 16,
+    version = 17,
     entities = [Account::class, AppSettings::class],
     exportSchema = true,
 )
@@ -477,6 +491,7 @@ abstract class AppDB : RoomDatabase() {
                         MIGRATION_13_14,
                         MIGRATION_14_15,
                         MIGRATION_15_16,
+                        MIGRATION_16_17,
                     )
                     // Necessary because it can't insert data on creation
                     .addCallback(object : Callback() {

app/src/main/java/com/jerboa/ui/components/common/PostSwipeWrapper.kt

@@ -0,0 +1,29 @@
+package com.jerboa.ui.components.common
+
+import androidx.compose.runtime.Composable
+import androidx.navigation.NavController
+import com.jerboa.db.Account
+import com.jerboa.db.AppSettingsViewModel
+import com.jerboa.ui.components.home.HomeViewModel
+import com.jerboa.ui.components.post.PostViewModel
+
+@Composable
+fun PostSwipeWrapper(
+    navController: NavController,
+    homeViewModel: HomeViewModel,
+    postViewModel: PostViewModel,
+    appSettingsViewModel: AppSettingsViewModel,
+    account: Account?,
+    content: @Composable () -> Unit,
+) {
+    if (appSettingsViewModel.appSettings.value?.swipeBetweenPosts == true) {
+        SwipeBetweenPosts(
+            homeViewModel = homeViewModel,
+            postViewModel = postViewModel,
+            account = account,
+            content = content,
+        )
+    } else {
+        SwipeToNavigateBack(navController = navController, content = content)
+    }
+}

app/src/main/java/com/jerboa/ui/components/common/SwipeBetweenPosts.kt

@@ -0,0 +1,84 @@
+package com.jerboa.ui.components.common
+
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.graphics.Color
+import arrow.core.left
+import com.jerboa.api.ApiState
+import com.jerboa.datatypes.types.GetPosts
+import com.jerboa.db.Account
+import com.jerboa.ui.components.home.HomeViewModel
+import com.jerboa.ui.components.post.PostViewModel
+import me.saket.swipe.SwipeAction
+import me.saket.swipe.SwipeableActionsBox
+
+@Composable
+fun SwipeBetweenPosts(
+    homeViewModel: HomeViewModel,
+    postViewModel: PostViewModel,
+    account: Account?,
+    content: @Composable () -> Unit,
+) {
+    val forward = SwipeAction(
+        icon = { Text("Next") },
+        onSwipe = {
+            val res = homeViewModel.postsRes
+            if (res is ApiState.Success) {
+                res.data.posts
+                    .mapIndexed { index, postView -> index to postView }
+                    .firstOrNull { it.second.post.id == postViewModel.id?.swap()?.getOrNull() }
+                    ?.first?.let { currIndex ->
+                        if (currIndex + 1 >= res.data.posts.size - 1) {
+                            val nextIndex = res.data.posts.size
+                            homeViewModel.nextPage()
+                            homeViewModel.appendPosts(
+                                GetPosts(
+                                    page = homeViewModel.page,
+                                    sort = homeViewModel.sortType,
+                                    type_ = homeViewModel.listingType,
+                                    auth = account?.jwt,
+                                ),
+                            ).invokeOnCompletion {
+                                val newRes = homeViewModel.postsRes
+                                if (newRes is ApiState.Success && newRes.data.posts.size > nextIndex) {
+                                    postViewModel.initialize(newRes.data.posts[nextIndex].post.id.left())
+                                    postViewModel.getData(account)
+                                }
+                            }
+                        } else if (currIndex >= 0) {
+                            postViewModel.initialize(res.data.posts[currIndex + 1].post.id.left())
+                            postViewModel.getData(account)
+                        }
+                        Unit
+                    }
+            }
+        },
+        background = Color.Transparent,
+    )
+
+    val backward = SwipeAction(
+        icon = { Text("Next") },
+        onSwipe = {
+            val res = homeViewModel.postsRes
+            if (res is ApiState.Success) {
+                val currIndex = res.data.posts
+                    .mapIndexed { index, postView -> index to postView }
+                    .firstOrNull { it.second.post.id == postViewModel.id?.swap()?.getOrNull() }
+                    ?.first
+                if (currIndex != null && currIndex > 0 && currIndex < res.data.posts.size) {
+                    val nextId = res.data.posts[currIndex - 1].post.id
+                    postViewModel.initialize(nextId.left())
+                    postViewModel.getData(account)
+                }
+            }
+        },
+        background = Color.Transparent,
+    )
+
+    SwipeableActionsBox(
+        startActions = listOf(backward),
+        endActions = listOf(forward),
+    ) {
+        content()
+    }
+}

app/src/main/java/com/jerboa/ui/components/home/HomeViewModel.kt

@@ -77,7 +77,7 @@ class HomeViewModel : ViewModel() {
         }
     }
 
-    fun appendPosts(form: GetPosts) {
+    fun appendPosts(form: GetPosts) =
         viewModelScope.launch {
             fetchingMore = true
             val more = apiWrapper(API.getInstance().getPosts(form.serializeToMap()))
@@ -104,7 +104,6 @@ class HomeViewModel : ViewModel() {
                 else -> {}
             }
         }
-    }
 
     fun likePost(form: CreatePostLike) {
         viewModelScope.launch {
@@ -168,7 +167,9 @@ class HomeViewModel : ViewModel() {
 
     fun updateFromAccount(account: Account) {
         updateSortType(SortType.values().getOrElse(account.defaultSortType) { sortType })
-        updateListingType(ListingType.values().getOrElse(account.defaultListingType) { listingType })
+        updateListingType(
+            ListingType.values().getOrElse(account.defaultListingType) { listingType },
+        )
     }
 
     fun updatePost(postView: PostView) {
@@ -178,6 +179,7 @@ class HomeViewModel : ViewModel() {
                 val newRes = ApiState.Success(existing.data.copy(posts = newPosts))
                 postsRes = newRes
             }
+
             else -> {}
         }
     }

app/src/main/java/com/jerboa/ui/components/settings/lookandfeel/LookAndFeelActivity.kt

@@ -68,6 +68,8 @@ fun LookAndFeelActivity(
     val useCustomTabsState = rememberBooleanSettingState(settings?.useCustomTabs ?: true)
     val usePrivateTabsState = rememberBooleanSettingState(settings?.usePrivateTabs ?: false)
 
+    val swipeBetweenPosts = rememberBooleanSettingState(settings?.swipeBetweenPosts ?: false)
+
     val secureWindowState = rememberBooleanSettingState(settings?.secureWindow ?: false)
 
     val snackbarHostState = remember { SnackbarHostState() }
@@ -92,6 +94,7 @@ fun LookAndFeelActivity(
                 useCustomTabs = useCustomTabsState.value,
                 usePrivateTabs = usePrivateTabsState.value,
                 secureWindow = secureWindowState.value,
+                swipeBetweenPosts = swipeBetweenPosts.value,
             ),
         )
     }
@@ -241,6 +244,13 @@ fun LookAndFeelActivity(
                     },
                     onCheckedChange = { updateAppSettings() },
                 )
+                SettingsCheckbox(
+                    state = swipeBetweenPosts,
+                    title = {
+                        Text(text = stringResource(id = R.string.look_and_feel_swipe_between_posts))
+                    },
+                    onCheckedChange = { updateAppSettings() },
+                )
             }
         },
     )

app/src/main/res/values/strings.xml

@@ -214,6 +214,7 @@
     <string name="look_and_feel_theme_color_pink">Pink</string>
     <string name="look_and_feel_theme_color_purple">Purple</string>
     <string name="look_and_feel_theme_color_woodland">Woodland</string>
+    <string name="look_and_feel_swipe_between_posts">Swipe between posts</string>
     <string name="look_and_feel_use_custom_tabs">Use custom tabs</string>
     <string name="look_and_feel_use_private_tabs">Use private custom tabs if available</string>
     <string name="markRead">Mark as read</string>