fix(ui): disable pull to load when no articles available

app/src/main/java/me/ash/reader/ui/page/home/reading/PullToLoad.kt

@@ -2,8 +2,10 @@ package me.ash.reader.ui.page.home.reading
 
 
 import androidx.compose.animation.core.FloatExponentialDecaySpec
+import androidx.compose.animation.core.Spring
 import androidx.compose.animation.core.animate
 import androidx.compose.animation.core.animateDecay
+import androidx.compose.animation.core.spring
 import androidx.compose.foundation.MutatorMutex
 import androidx.compose.foundation.layout.offset
 import androidx.compose.material.ExperimentalMaterialApi
@@ -33,7 +35,7 @@ import me.ash.reader.ui.page.home.reading.PullToLoadDefaults.ContentOffsetMultip
 import kotlin.math.abs
 import kotlin.math.sqrt
 
-private const val TAG = "PullRelease"
+private const val TAG = "PullToLoad"
 
 /**
  * A [NestedScrollConnection] that provides scroll events to a hoisted [state].
@@ -51,7 +53,7 @@ private class ReaderNestedScrollConnection(
     private val enabled: Boolean,
     private val onPreScroll: (Float) -> Float,
     private val onPostScroll: (Float) -> Float,
-    private val onRelease: (Float) -> Unit,
+    private val onRelease: () -> Unit,
     private val onScroll: ((Float) -> Unit)? = null
 ) : NestedScrollConnection {
 
@@ -81,7 +83,7 @@ private class ReaderNestedScrollConnection(
     }
 
     override suspend fun onPreFling(available: Velocity): Velocity {
-        onRelease(available.y)
+        onRelease()
         return Velocity.Zero
     }
 }
@@ -217,21 +219,22 @@ class PullToLoadState internal constructor(
         return if (offsetPulled.signOpposites(pullDelta)) onPull(pullDelta) else 0f
     }
 
-    internal fun onRelease(velocity: Float): Float {
+    internal fun onRelease(): Float {
+        // Snap to 0f and hide the indicator
+        animateDistanceTo(0f)
+
         when (status) {
-            // We don't change the pull offset here because the animation for loading another content
-            // should be handled outside, and this state will be soon disposed
             Status.PulledDown -> {
                 onLoadPrevious.value()
             }
 
             Status.PulledUp -> {
+                animateDistanceTo(0f)
                 onLoadNext.value()
             }
 
             else -> {
-                // Snap to 0f and hide the indicator
-                animateDistanceTo(0f)
+
             }
         }
         return 0f
@@ -247,7 +250,8 @@ class PullToLoadState internal constructor(
                 animate(
                     initialValue = offsetPulled,
                     targetValue = float,
-                    initialVelocity = velocity
+                    initialVelocity = velocity,
+                    animationSpec = spring(dampingRatio = Spring.DampingRatioNoBouncy)
                 ) { value, _ ->
                     offsetPulled = value
                 }
@@ -310,7 +314,7 @@ fun Modifier.pullToLoad(
     state: PullToLoadState,
     contentOffsetMultiple: Int = ContentOffsetMultiple,
     onScroll: ((Float) -> Unit)? = null,
-    enabled: Boolean = true
+    enabled: Boolean = true,
 ): Modifier =
     nestedScroll(
         ReaderNestedScrollConnection(

app/src/main/java/me/ash/reader/ui/page/home/reading/PullToLoadIndicator.kt

@@ -20,70 +20,117 @@ import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.hapticfeedback.HapticFeedbackType
+import androidx.compose.ui.platform.LocalHapticFeedback
 import androidx.compose.ui.unit.dp
+import me.ash.reader.ui.page.home.reading.PullToLoadState.Status.Idle
+import me.ash.reader.ui.page.home.reading.PullToLoadState.Status.PulledDown
+import me.ash.reader.ui.page.home.reading.PullToLoadState.Status.PulledUp
+import me.ash.reader.ui.page.home.reading.PullToLoadState.Status.PullingDown
+import me.ash.reader.ui.page.home.reading.PullToLoadState.Status.PullingUp
 import kotlin.math.abs
 
 @Composable
-fun BoxScope.PullToLoadIndicator(state:PullToLoadState) {
-    state.status.run {
-        val fraction = state.offsetFraction
-        val absFraction = abs(fraction)
-        val imageVector = when (this) {
-            PullToLoadState.Status.PulledDown -> Icons.Outlined.KeyboardArrowUp
-            PullToLoadState.Status.PulledUp -> Icons.Outlined.KeyboardArrowDown
-            else -> null
-        }
+fun BoxScope.PullToLoadIndicator(
+    state: PullToLoadState,
+    canLoadPrevious: Boolean = true,
+    canLoadNext: Boolean = true
+) {
+    val hapticFeedback = LocalHapticFeedback.current
+    val status = state.status
 
-        val alignment = if (fraction < 0f) {
-            Alignment.BottomCenter
-        } else {
-            Alignment.TopCenter
-        }
-        if (this != PullToLoadState.Status.Idle) {
-            Surface(
-                modifier = Modifier
-                    .align(alignment)
-                    .padding(vertical = 80.dp)
-                    .offset(y = (fraction * 48).dp)
-                    .width(36.dp),
-                color = MaterialTheme.colorScheme.primary,
-                shape = MaterialTheme.shapes.extraLarge
-            ) {
-                Column(
-                    modifier = Modifier
-                        .align(Alignment.Center),
-                ) {
-                    AnimatedContent(
-                        targetState = imageVector, modifier = Modifier.align(
-                            Alignment.CenterHorizontally
-                        ), transitionSpec = {
-                            (fadeIn(animationSpec = tween(220, delayMillis = 0)))
-                                .togetherWith(fadeOut(animationSpec = tween(90)))
-                        }, label = ""
-                    ) {
-                        if (it != null) {
-                            Icon(
-                                imageVector = it,
-                                contentDescription = null,
-                                tint = MaterialTheme.colorScheme.onPrimary,
-                                modifier = Modifier
-                                    .padding(horizontal = 4.dp)
-                                    .padding(vertical = (2 * absFraction).dp)
-                                    .size(32.dp)
-                            )
-                        } else {
-                            Spacer(
-                                modifier = Modifier
-                                    .width(36.dp)
-                                    .height((12 * absFraction).dp)
-                            )
-                        }
-                    }
+    LaunchedEffect(status) {
+        when {
+            canLoadPrevious && status == PulledDown -> {
+                hapticFeedback.performHapticFeedback(HapticFeedbackType.LongPress)
+            }
 
-                }
+            canLoadNext && status == PulledUp -> {
+                hapticFeedback.performHapticFeedback(HapticFeedbackType.LongPress)
+            }
+
+            else -> {}
+        }
+    }
+
+    val fraction = state.offsetFraction
+    val absFraction = abs(fraction)
+
+    val imageVector = when (status) {
+        PulledDown -> Icons.Outlined.KeyboardArrowUp
+        PulledUp -> Icons.Outlined.KeyboardArrowDown
+        else -> null
+    }
+
+    val alignment = if (fraction < 0f) {
+        Alignment.BottomCenter
+    } else {
+        Alignment.TopCenter
+    }
+
+    val visible = remember(status, canLoadPrevious, canLoadNext) {
+        when (status) {
+            Idle -> {
+                false
+            }
+
+            PullingUp, PulledUp -> {
+                canLoadNext
+            }
+
+            PulledDown, PullingDown -> {
+                canLoadPrevious
             }
         }
     }
+
+    if (visible) {
+        Surface(
+            modifier = Modifier
+                .align(alignment)
+                .padding(vertical = 80.dp)
+                .offset(y = (fraction * 48).dp)
+                .width(36.dp),
+            color = MaterialTheme.colorScheme.primary,
+            shape = MaterialTheme.shapes.extraLarge
+        ) {
+            Column(
+                modifier = Modifier
+                    .align(Alignment.Center),
+            ) {
+                AnimatedContent(
+                    targetState = imageVector, modifier = Modifier.align(
+                        Alignment.CenterHorizontally
+                    ), transitionSpec = {
+                        (fadeIn(animationSpec = tween(220, delayMillis = 0)))
+                            .togetherWith(fadeOut(animationSpec = tween(90)))
+                    }, label = ""
+                ) {
+                    if (it != null) {
+                        Icon(
+                            imageVector = it,
+                            contentDescription = null,
+                            tint = MaterialTheme.colorScheme.onPrimary,
+                            modifier = Modifier
+                                .padding(horizontal = 4.dp)
+                                .padding(vertical = (2 * absFraction).dp)
+                                .size(32.dp)
+                        )
+                    } else {
+                        Spacer(
+                            modifier = Modifier
+                                .width(36.dp)
+                                .height((12 * absFraction).dp)
+                        )
+                    }
+                }
+
+            }
+        }
+    }
+
 }

app/src/main/java/me/ash/reader/ui/page/home/reading/ReadingPage.kt

@@ -23,7 +23,6 @@ import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.hapticfeedback.HapticFeedbackType
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalHapticFeedback
 import androidx.compose.ui.unit.TextUnit
@@ -115,10 +114,10 @@ fun ReadingPage(
                         navController.popBackStack()
                     },
                 )
-                val context = LocalContext.current
-                val hapticFeedback = LocalHapticFeedback.current
 
                 val isNextArticleAvailable = !readerState.nextArticleId.isNullOrEmpty()
+                val isPreviousArticleAvailable = !readerState.previousArticleId.isNullOrEmpty()
+
 
                 if (readerState.articleId != null) {
                     // Content
@@ -159,16 +158,6 @@ fun ReadingPage(
                                 )
 
 
-                            LaunchedEffect(state.status) {
-                                when (state.status) {
-                                    PullToLoadState.Status.PulledDown, PullToLoadState.Status.PulledUp -> {
-                                        hapticFeedback.performHapticFeedback(HapticFeedbackType.LongPress)
-                                    }
-
-                                    else -> {}
-                                }
-                            }
-
                             val listState = rememberSaveable(
                                 inputs = arrayOf(content),
                                 saver = LazyListState.Saver
@@ -210,7 +199,11 @@ fun ReadingPage(
                                             showFullScreenImageViewer = true
                                         }
                                     )
-                                    PullToLoadIndicator(state = state)
+                                    PullToLoadIndicator(
+                                        state = state,
+                                        canLoadPrevious = isPreviousArticleAvailable,
+                                        canLoadNext = isNextArticleAvailable
+                                    )
                                 }
                             }
                         }
@@ -252,7 +245,8 @@ fun ReadingPage(
                     onSuccess = { context.showToast(context.getString(R.string.image_saved)) },
                     onFailure = {
                         // FIXME: crash the app for error report
-                        th -> throw th
+                            th ->
+                        throw th
                     }
                 )
             },