feat(ui): read/resume button movable

* material3: update scaffold to support FabPosition.Start

also fix fab's width calculation with inset

* Moveable Read button & sticky to either size of screen

app/src/main/java/eu/kanade/domain/ui/UiPreferences.kt

@@ -1,5 +1,6 @@
 package eu.kanade.domain.ui
 
+import androidx.compose.material3.FabPosition
 import com.materialkolor.PaletteStyle
 import eu.kanade.domain.ui.model.AppTheme
 import eu.kanade.domain.ui.model.TabletUiMode
@@ -61,6 +62,8 @@ class UiPreferences(
     fun relatedMangasInOverflow() = preferenceStore.getBoolean("related_mangas_in_overflow", false)
 
     fun showHomeOnRelatedMangas() = preferenceStore.getBoolean("show_home_on_related_mangas", true)
+
+    fun readButtonPosition() = preferenceStore.getString("reading_button_position", FabPosition.End.toString())
     // KMK <--
 
     fun recommendsInOverflow() = preferenceStore.getBoolean("recommends_in_overflow", false)

app/src/main/java/eu/kanade/presentation/manga/MangaScreen.kt

@@ -5,6 +5,7 @@ import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.core.animateFloatAsState
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
+import androidx.compose.foundation.gestures.detectHorizontalDragGestures
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
@@ -15,6 +16,7 @@ import androidx.compose.foundation.layout.calculateEndPadding
 import androidx.compose.foundation.layout.calculateStartPadding
 import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.only
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.systemBars
@@ -26,6 +28,7 @@ import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.PlayArrow
+import androidx.compose.material3.FabPosition
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
@@ -36,19 +39,26 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.State
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
 import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.hapticfeedback.HapticFeedbackType
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.layout.onGloballyPositioned
 import androidx.compose.ui.layout.onSizeChanged
+import androidx.compose.ui.layout.positionOnScreen
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.platform.LocalHapticFeedback
 import androidx.compose.ui.platform.LocalLayoutDirection
 import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.util.fastAll
 import androidx.compose.ui.util.fastAny
@@ -128,6 +138,7 @@ import uy.kohesive.injekt.api.get
 import java.time.Instant
 import java.time.ZoneId
 import java.time.ZonedDateTime
+import kotlin.math.roundToInt
 
 @Composable
 fun MangaScreen(
@@ -416,6 +427,13 @@ private fun MangaScreenSmallImpl(
     val expandRelatedMangas by uiPreferences.expandRelatedMangas().collectAsState()
     val showRelatedMangasInOverflow by uiPreferences.relatedMangasInOverflow().collectAsState()
     val fullCoverBackground = MaterialTheme.colorScheme.surfaceTint.blend(MaterialTheme.colorScheme.surface)
+
+    var layoutSize by remember { mutableStateOf(IntSize.Zero) }
+    var fabSize by remember { mutableStateOf(IntSize.Zero) }
+    var positionOnScreen by remember { mutableStateOf(Offset.Zero) }
+    var offsetX by remember { mutableFloatStateOf(0f) }
+    val fabPosition by uiPreferences.readButtonPosition().collectAsState()
+    val readButtonPosition = uiPreferences.readButtonPosition()
     // KMK <--
 
     val internalOnBackPressed = {
@@ -502,6 +520,29 @@ private fun MangaScreenSmallImpl(
                 visible = isFABVisible,
                 enter = fadeIn(),
                 exit = fadeOut(),
+                // KMK -->
+                modifier = Modifier
+                    .offset { IntOffset(offsetX.roundToInt(), 0) }
+                    .onGloballyPositioned { coordinates ->
+                        fabSize = coordinates.size
+                        positionOnScreen = coordinates.positionOnScreen()
+                    }
+                    .pointerInput(Unit) {
+                        detectHorizontalDragGestures(
+                            onDragEnd = {
+                                if (positionOnScreen.x + fabSize.width / 2 >= layoutSize.width / 2) {
+                                    readButtonPosition.set(FabPosition.End.toString())
+                                } else {
+                                    readButtonPosition.set(FabPosition.Start.toString())
+                                }
+                                offsetX = 0f
+                            },
+                        ) { change, dragAmount ->
+                            change.consume()
+                            offsetX += dragAmount
+                        }
+                    },
+                // KMK <--
             ) {
                 ExtendedFloatingActionButton(
                     text = {
@@ -522,7 +563,15 @@ private fun MangaScreenSmallImpl(
             }
         },
         // KMK -->
+        floatingActionButtonPosition = if (fabPosition == FabPosition.End.toString()) {
+            FabPosition.End
+        } else {
+            FabPosition.Start
+        },
         modifier = Modifier
+            .onGloballyPositioned { coordinates ->
+                layoutSize = coordinates.size
+            }
             .haze(
                 state = hazeState,
                 style = HazeStyle(
@@ -835,6 +884,13 @@ private fun MangaScreenLargeImpl(
     val expandRelatedMangas by uiPreferences.expandRelatedMangas().collectAsState()
     val showRelatedMangasInOverflow by uiPreferences.relatedMangasInOverflow().collectAsState()
     val fullCoverBackground = MaterialTheme.colorScheme.surfaceTint.blend(MaterialTheme.colorScheme.surface)
+
+    var layoutSize by remember { mutableStateOf(IntSize.Zero) }
+    var fabSize by remember { mutableStateOf(IntSize.Zero) }
+    var positionOnScreen by remember { mutableStateOf(Offset.Zero) }
+    var offsetX by remember { mutableFloatStateOf(0f) }
+    val fabPosition by uiPreferences.readButtonPosition().collectAsState()
+    val readButtonPosition = uiPreferences.readButtonPosition()
     // KMK <--
 
     val insetPadding = WindowInsets.systemBars.only(WindowInsetsSides.Horizontal).asPaddingValues()
@@ -918,6 +974,29 @@ private fun MangaScreenLargeImpl(
                 visible = isFABVisible,
                 enter = fadeIn(),
                 exit = fadeOut(),
+                // KMK -->
+                modifier = Modifier
+                    .offset { IntOffset(offsetX.roundToInt(), 0) }
+                    .onGloballyPositioned { coordinates ->
+                        fabSize = coordinates.size
+                        positionOnScreen = coordinates.positionOnScreen()
+                    }
+                    .pointerInput(Unit) {
+                        detectHorizontalDragGestures(
+                            onDragEnd = {
+                                if (positionOnScreen.x + fabSize.width / 2 >= layoutSize.width / 2) {
+                                    readButtonPosition.set(FabPosition.End.toString())
+                                } else {
+                                    readButtonPosition.set(FabPosition.Start.toString())
+                                }
+                                offsetX = 0f
+                            },
+                        ) { change, dragAmount ->
+                            change.consume()
+                            offsetX += dragAmount
+                        }
+                    },
+                // KMK <--
             ) {
                 ExtendedFloatingActionButton(
                     text = {
@@ -940,7 +1019,15 @@ private fun MangaScreenLargeImpl(
             }
         },
         // KMK -->
+        floatingActionButtonPosition = if (fabPosition == FabPosition.End.toString()) {
+            FabPosition.End
+        } else {
+            FabPosition.Start
+        },
         modifier = Modifier
+            .onGloballyPositioned { coordinates ->
+                layoutSize = coordinates.size
+            }
             .haze(
                 state = hazeState,
                 style = HazeStyle(

presentation-core/src/main/java/tachiyomi/presentation/core/components/material/Scaffold.kt

@@ -27,7 +27,11 @@ import androidx.compose.foundation.layout.calculateStartPadding
 import androidx.compose.foundation.layout.exclude
 import androidx.compose.foundation.layout.onConsumedWindowInsetsChanged
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FabPosition
+import androidx.compose.material3.FloatingActionButton
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.Scaffold
 import androidx.compose.material3.ScaffoldDefaults
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.material3.TopAppBarScrollBehavior
@@ -44,8 +48,10 @@ import androidx.compose.ui.unit.Constraints
 import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.max
+import androidx.compose.ui.unit.offset
 import androidx.compose.ui.util.fastForEach
 import androidx.compose.ui.util.fastMap
+import androidx.compose.ui.util.fastMapNotNull
 import androidx.compose.ui.util.fastMaxBy
 import kotlin.math.max
 
@@ -152,7 +158,6 @@ fun Scaffold(
  * @param bottomBar the content to place at the bottom of the [Scaffold], on top of the
  * [content], typically a [NavigationBar].
  */
-@OptIn(ExperimentalMaterial3Api::class)
 @Composable
 private fun ScaffoldLayout(
     fabPosition: FabPosition,
@@ -210,8 +215,12 @@ private fun ScaffoldLayout(
             }
 
             val fabPlaceables =
-                subcompose(ScaffoldLayoutContent.Fab, fab).fastMap { measurable ->
-                    measurable.measure(looseConstraints)
+                subcompose(ScaffoldLayoutContent.Fab, fab).fastMapNotNull { measurable ->
+                    measurable
+                        // KMK -->
+                        .measure(looseConstraints.offset(-leftInset - rightInset, -bottomInset))
+                        .takeIf { it.height != 0 && it.width != 0 }
+                    // KMK <--
                 }
 
             val fabWidth = fabPlaceables.fastMaxBy { it.width }?.width ?: 0
@@ -220,14 +229,28 @@ private fun ScaffoldLayout(
             val fabPlacement = if (fabPlaceables.isNotEmpty() && fabWidth != 0 && fabHeight != 0) {
                 // FAB distance from the left of the layout, taking into account LTR / RTL
                 // Tachiyomi: Calculate insets for fab placement offset
-                val fabLeftOffset = if (fabPosition == FabPosition.End) {
-                    if (layoutDirection == LayoutDirection.Ltr) {
-                        layoutWidth - FabSpacing.roundToPx() - fabWidth - rightInset
-                    } else {
-                        FabSpacing.roundToPx() + leftInset
+                val fabLeftOffset = when (fabPosition) {
+                    // KMK -->
+                    FabPosition.Start -> {
+                        if (layoutDirection == LayoutDirection.Ltr) {
+                            FabSpacing.roundToPx() + leftInset
+                        } else {
+                            layoutWidth - FabSpacing.roundToPx() - fabWidth - rightInset
+                        }
+                    }
+                    FabPosition.EndOverlay,
+                    // KMK <--
+                    FabPosition.End,
+                    -> {
+                        if (layoutDirection == LayoutDirection.Ltr) {
+                            layoutWidth - FabSpacing.roundToPx() - fabWidth - rightInset
+                        } else {
+                            FabSpacing.roundToPx() + leftInset
+                        }
+                    }
+                    else -> {
+                        leftInset + ((insetLayoutWidth - fabWidth) / 2)
                     }
-                } else {
-                    leftInset + ((insetLayoutWidth - fabWidth) / 2)
                 }
 
                 FabPlacement(
@@ -311,34 +334,6 @@ private fun ScaffoldLayout(
     }
 }
 
-/**
- * The possible positions for a [FloatingActionButton] attached to a [Scaffold].
- */
-@ExperimentalMaterial3Api
-@JvmInline
-value class FabPosition internal constructor(@Suppress("unused") private val value: Int) {
-    companion object {
-        /**
-         * Position FAB at the bottom of the screen in the center, above the [NavigationBar] (if it
-         * exists)
-         */
-        val Center = FabPosition(0)
-
-        /**
-         * Position FAB at the bottom of the screen at the end, above the [NavigationBar] (if it
-         * exists)
-         */
-        val End = FabPosition(1)
-    }
-
-    override fun toString(): String {
-        return when (this) {
-            Center -> "FabPosition.Center"
-            else -> "FabPosition.End"
-        }
-    }
-}
-
 /**
  * Placement information for a [FloatingActionButton] inside a [Scaffold].
  *