v0.3.0: True Touch Drag & Drop Reordering & Fix OTA Auto-Install Bug

app/src/main/java/com/hotdeal/alarm/presentation/components/DragDropListState.kt

@@ -1,11 +1,6 @@
 package com.hotdeal.alarm.presentation.components
 
-import androidx.compose.animation.core.Animatable
-import androidx.compose.animation.core.Spring
-import androidx.compose.animation.core.spring
 import androidx.compose.foundation.gestures.detectDragGesturesAfterLongPress
-import androidx.compose.foundation.gestures.scrollBy
-import androidx.compose.foundation.lazy.LazyListItemInfo
 import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.runtime.*
 import androidx.compose.ui.Modifier
@@ -13,126 +8,110 @@ import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.graphicsLayer
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.zIndex
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.launch
 
 /**
- * Compose LazyColumn Drag & Drop Reordering State
+ * Key 기반 드래그 앤 드롭 Reorder 시스템
+ *
+ * - 각 아이템에 item-level long-press 제스처를 적용하여 드래그 시작
+ * - 드래그 중 다른 아이템의 중심점과 겹치면 swap 실행
+ * - swap 시 delta 보정으로 시각적 점프 방지
+ * - 비드래그 아이템은 animateItemPlacement()로 부드러운 슬라이드
  */
 @Composable
-fun rememberDragDropListState(
-    lazyListState: LazyListState,
-    onMove: (Int, Int) -> Unit,
-    onDragEnd: () -> Unit = {}
-): DragDropListState {
-    val scope = rememberCoroutineScope()
-    val state = remember(lazyListState) {
-        DragDropListState(
-            lazyListState = lazyListState,
-            onMove = onMove,
-            onDragEnd = onDragEnd,
-            scope = scope
-        )
+fun rememberReorderState(
+    listState: LazyListState,
+    onSwap: (fromListIndex: Int, toListIndex: Int) -> Boolean
+): ReorderState {
+    return remember(listState) {
+        ReorderState(listState, onSwap)
     }
-    return state
 }
 
-class DragDropListState(
-    val lazyListState: LazyListState,
-    private val onMove: (Int, Int) -> Unit,
-    private val onDragEnd: () -> Unit,
-    private val scope: CoroutineScope
+@Stable
+class ReorderState(
+    val listState: LazyListState,
+    private val onSwap: (Int, Int) -> Boolean
 ) {
-    var initiallyDraggedElement by mutableStateOf<LazyListItemInfo?>(null)
+    /** 현재 드래그 중인 아이템의 key (null이면 드래그 없음) */
+    var draggedKey by mutableStateOf<Any?>(null)
         private set
 
-    var currentIndexOfDraggedItem by mutableStateOf<Int?>(null)
+    /** 누적 드래그 Y축 오프셋 */
+    var dragDelta by mutableFloatStateOf(0f)
         private set
 
-    private val dragOffset = Animatable(0f)
+    fun startDrag(key: Any) {
+        draggedKey = key
+        dragDelta = 0f
+    }
 
-    val elementOffset: Float
-        get() = dragOffset.value
+    fun updateDrag(delta: Offset) {
+        if (draggedKey == null) return
+        dragDelta += delta.y
+        checkOverlap()
+    }
 
-    fun onDragStart(offset: Offset) {
-        lazyListState.layoutInfo.visibleItemsInfo
-            .firstOrNull { item -> offset.y.toInt() in item.offset..(item.offset + item.size) }
-            ?.also { item ->
-                currentIndexOfDraggedItem = item.index
-                initiallyDraggedElement = item
+    fun endDrag() {
+        draggedKey = null
+        dragDelta = 0f
+    }
+
+    private fun checkOverlap() {
+        val dragged = listState.layoutInfo.visibleItemsInfo
+            .firstOrNull { it.key == draggedKey } ?: return
+
+        val draggedMid = dragged.offset + dragged.size / 2f + dragDelta
+
+        val target = listState.layoutInfo.visibleItemsInfo
+            .firstOrNull { item ->
+                item.key != draggedKey &&
+                draggedMid >= item.offset.toFloat() &&
+                draggedMid < (item.offset + item.size).toFloat()
+            } ?: return
+
+        if (dragged.index == target.index) return
+
+        val swapped = onSwap(dragged.index, target.index)
+        if (swapped) {
+            // swap 후 아이템이 새 위치로 이동하므로, 시각적 점프를 막기 위해 delta 보정
+            dragDelta += if (dragged.index < target.index) {
+                -target.size.toFloat()
+            } else {
+                target.size.toFloat()
             }
-    }
-
-    fun onDragInterrupted() {
-        initiallyDraggedElement = null
-        currentIndexOfDraggedItem = null
-        scope.launch {
-            dragOffset.snapTo(0f)
-        }
-    }
-
-    fun onDrag(change: Offset) {
-        scope.launch {
-            dragOffset.snapTo(dragOffset.value + change.y)
-
-            val currentElement = initiallyDraggedElement ?: return@launch
-            val startOffset = currentElement.offset + dragOffset.value
-            val endOffset = startOffset + currentElement.size
-
-            val hoveredItem = lazyListState.layoutInfo.visibleItemsInfo
-                .firstOrNull { item ->
-                    val itemMid = item.offset + item.size / 2
-                    val isMidInRange = itemMid in startOffset.toInt()..endOffset.toInt()
-                    isMidInRange && item.index != currentIndexOfDraggedItem
-                }
-
-            if (hoveredItem != null) {
-                val currentIndex = currentIndexOfDraggedItem ?: return@launch
-                val targetIndex = hoveredItem.index
-                onMove(currentIndex, targetIndex)
-                currentIndexOfDraggedItem = targetIndex
-            }
-        }
-    }
-
-    fun onDragStop() {
-        onDragEnd()
-        scope.launch {
-            dragOffset.animateTo(0f, spring(stiffness = Spring.StiffnessMediumLow))
-            initiallyDraggedElement = null
-            currentIndexOfDraggedItem = null
         }
     }
 }
 
-fun Modifier.dragDropGesture(
-    dragDropState: DragDropListState
-): Modifier = this.pointerInput(dragDropState) {
-    detectDragGesturesAfterLongPress(
-        onDragStart = { offset -> dragDropState.onDragStart(offset) },
-        onDragEnd = { dragDropState.onDragStop() },
-        onDragCancel = { dragDropState.onDragInterrupted() },
-        onDrag = { change, dragAmount ->
-            change.consume()
-            dragDropState.onDrag(dragAmount)
-        }
-    )
-}
-
-fun Modifier.dragDropItem(
-    index: Int,
-    dragDropState: DragDropListState
-): Modifier = this.then(
-    if (index == dragDropState.currentIndexOfDraggedItem) {
-        Modifier
-            .zIndex(10f)
-            .graphicsLayer {
-                translationY = dragDropState.elementOffset
+/**
+ * 개별 아이템에 부착하는 드래그 핸들 + 시각 효과 Modifier
+ * - 길게 누르면 드래그 시작
+ * - 드래그 중 아이템이 떠오르며 그림자 및 스케일업
+ */
+fun Modifier.reorderableItem(
+    state: ReorderState,
+    key: Any
+): Modifier {
+    val isDragged = state.draggedKey == key
+    return this
+        .zIndex(if (isDragged) 10f else 0f)
+        .graphicsLayer {
+            if (isDragged) {
+                translationY = state.dragDelta
                 scaleX = 1.03f
                 scaleY = 1.03f
-                shadowElevation = 8f
+                shadowElevation = 16f
             }
-    } else {
-        Modifier
-    }
-)
+        }
+        .pointerInput(key) {
+            detectDragGesturesAfterLongPress(
+                onDragStart = { state.startDrag(key) },
+                onDrag = { change, dragAmount ->
+                    change.consume()
+                    state.updateDrag(dragAmount)
+                },
+                onDragEnd = { state.endDrag() },
+                onDragCancel = { state.endDrag() }
+            )
+        }
+}