Add item type builder and enable drag to reorder

compose-recyclerview/src/main/java/com/example/compose_recyclerview/ComposeRecyclerView.kt

@@ -1,6 +1,5 @@
 package com.example.compose_recyclerview
 
-import android.os.Parcelable
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.getValue
@@ -12,11 +11,16 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.viewinterop.AndroidView
 import androidx.core.os.bundleOf
+import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.ItemTouchHelper.DOWN
+import androidx.recyclerview.widget.ItemTouchHelper.END
+import androidx.recyclerview.widget.ItemTouchHelper.START
+import androidx.recyclerview.widget.ItemTouchHelper.UP
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.example.compose_recyclerview.adapter.ComposeRecyclerViewAdapter
 import com.example.compose_recyclerview.data.LayoutOrientation
-
+import com.example.compose_recyclerview.utils.InfiniteScrollListener
 
 /**
  * Composable function to display a RecyclerView with dynamically generated Compose items.
@@ -26,6 +30,12 @@ import com.example.compose_recyclerview.data.LayoutOrientation
  * @param itemBuilder The lambda function responsible for creating the Compose content for each item at the specified index.
  * @param onScrollEnd Callback triggered when the user reaches the end of the list during scrolling.
  * @param orientation The layout direction of the RecyclerView.
+ * @param itemTypeBuilder The optional lambda function to determine the type of each item.
+ *  * Required for effective drag and drop. Provide a non-null [ComposeRecyclerViewAdapter.ItemTypeBuilder] when enabling drag and drop functionality.
+ *  * Useful when dealing with multiple item types, ensuring proper handling and layout customization for each type.
+ * @param onDragCompleted Callback triggered when an item drag operation is completed.
+ * @param onItemMove Callback triggered when an item is moved within the RecyclerView.
+ * @param onCreate Callback to customize the RecyclerView after its creation.
  */
 @Composable
 fun ComposeRecyclerView(
@@ -34,14 +44,17 @@ fun ComposeRecyclerView(
     itemBuilder: @Composable (index: Int) -> Unit,
     onScrollEnd: () -> Unit = {},
     orientation: LayoutOrientation = LayoutOrientation.Vertical,
-    onCreate: (RecyclerView) -> Unit? = {}
+    itemTypeBuilder: ComposeRecyclerViewAdapter.ItemTypeBuilder? = null,
+    onDragCompleted: (position: Int) -> Unit = { _ -> },
+    onItemMove: (fromPosition: Int, toPosition: Int, itemType: Int) -> Unit = { _, _, _ -> },
+    onCreate: (RecyclerView) -> Unit = {}
 ) {
     val context = LocalContext.current
     var scrollState by rememberSaveable { mutableStateOf(bundleOf()) }
+
     val layoutManager = remember {
         val layoutManager = LinearLayoutManager(context)
-        val parcelableState = scrollState.getParcelable<Parcelable?>("RecyclerviewState")
-        layoutManager.onRestoreInstanceState(parcelableState)
+        layoutManager.onRestoreInstanceState(scrollState.getParcelable("RecyclerviewState"))
         layoutManager.orientation = when (orientation) {
             LayoutOrientation.Horizontal -> RecyclerView.HORIZONTAL
             LayoutOrientation.Vertical -> RecyclerView.VERTICAL
@@ -53,13 +66,15 @@ fun ComposeRecyclerView(
         ComposeRecyclerViewAdapter().apply {
             this.totalItems = itemCount
             this.itemBuilder = itemBuilder
+            itemTypeBuilder?.let {
+                this.itemTypeBuilder = itemTypeBuilder
+            }
             this.layoutOrientation = orientation
         }
     }
 
     val composeRecyclerView = remember {
         RecyclerView(context).apply {
-            onCreate.invoke(this)
             this.layoutManager = layoutManager
             addOnScrollListener(object : InfiniteScrollListener() {
                 override fun onScrollEnd() {
@@ -70,46 +85,71 @@ fun ComposeRecyclerView(
         }
     }
 
+    val itemTouchHelper = remember {
+        ItemTouchHelper(object : ItemTouchHelper.SimpleCallback(UP or DOWN or START or END, 0) {
+            override fun onMove(
+                recyclerView: RecyclerView,
+                viewHolder: RecyclerView.ViewHolder,
+                target: RecyclerView.ViewHolder
+            ): Boolean {
+                val fromType = adapter.getItemViewType(viewHolder.bindingAdapterPosition)
+                val toType = adapter.getItemViewType(target.bindingAdapterPosition)
+
+                if (fromType != toType) {
+                    return false
+                }
+
+                adapter.onItemMove(viewHolder.bindingAdapterPosition, target.bindingAdapterPosition)
+                onItemMove.invoke(
+                    viewHolder.bindingAdapterPosition,
+                    target.bindingAdapterPosition,
+                    fromType
+                )
+                return true
+            }
+
+            override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {  }
+
+            override fun clearView(
+                recyclerView: RecyclerView,
+                viewHolder: RecyclerView.ViewHolder
+            ) {
+                viewHolder.itemView.alpha = 1f
+                onDragCompleted.invoke(viewHolder.bindingAdapterPosition)
+            }
+
+            override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
+                super.onSelectedChanged(viewHolder, actionState)
+                if (actionState == ItemTouchHelper.ACTION_STATE_DRAG) {
+                    viewHolder?.itemView?.alpha = 0.5f
+                }
+            }
+
+            override fun isLongPressDragEnabled(): Boolean {
+                return true
+            }
+        })
+    }
+
     // Use AndroidView to embed the RecyclerView in the Compose UI
     AndroidView(
-        factory = { composeRecyclerView },
+        factory = {
+            composeRecyclerView.apply {
+                onCreate.invoke(this)
+                itemTypeBuilder?.let {
+                    itemTouchHelper.attachToRecyclerView(this)
+                }
+            }
+        },
         modifier = modifier,
         update = {
-            adapter.totalItems = itemCount
-            adapter.itemBuilder = itemBuilder
-            adapter.layoutOrientation = orientation
+            adapter.update(itemCount, itemBuilder, orientation, itemTypeBuilder)
         }
     )
 
-
     DisposableEffect(key1 = Unit, effect = {
         onDispose {
             scrollState = bundleOf("RecyclerviewState" to layoutManager.onSaveInstanceState())
         }
     })
-}
-
-/**
- * Abstract class for handling infinite scrolling events in a RecyclerView.
- */
-abstract class InfiniteScrollListener : RecyclerView.OnScrollListener() {
-    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
-        super.onScrolled(recyclerView, dx, dy)
-        if (dy > 0 || dx > 0) {
-            val layoutManager = recyclerView.layoutManager
-            if (layoutManager is LinearLayoutManager) {
-                val visibleItemCount = layoutManager.childCount
-                val totalItemCount = layoutManager.itemCount
-                val pastVisibleItems = layoutManager.findFirstVisibleItemPosition()
-                if (visibleItemCount + pastVisibleItems >= totalItemCount) {
-                    onScrollEnd()
-                }
-            }
-        }
-    }
-
-    /**
-     * Callback triggered when the user reaches the end of the list during scrolling.
-     */
-    protected abstract fun onScrollEnd()
-}
+}

compose-recyclerview/src/main/java/com/example/compose_recyclerview/adapter/ComposeRecyclerViewAdapter.kt

@@ -11,8 +11,12 @@ import com.example.compose_recyclerview.data.LayoutOrientation
 /**
  * RecyclerView adapter for handling dynamically generated Compose items.
  */
-internal class ComposeRecyclerViewAdapter :
-    RecyclerView.Adapter<ComposeRecyclerViewAdapter.ComposeRecyclerViewHolder>() {
+class ComposeRecyclerViewAdapter :
+    RecyclerView.Adapter<ComposeRecyclerViewAdapter.ComposeRecyclerViewHolder>(){
+
+    interface ItemTypeBuilder {
+        fun getItemType(position: Int): Int
+    }
 
     var totalItems: Int = 0
         set(value) {
@@ -25,7 +29,10 @@ internal class ComposeRecyclerViewAdapter :
             }
         }
 
-    var itemBuilder: (@Composable (index: Int) -> Unit)? = null
+    var itemBuilder: (@Composable (index: Int) -> Unit)? =
+        null
+
+    var itemTypeBuilder: ItemTypeBuilder? = null
 
     var layoutOrientation: LayoutOrientation = LayoutOrientation.Vertical
         set(value) {
@@ -34,6 +41,7 @@ internal class ComposeRecyclerViewAdapter :
             notifyItemChanged(0)
         }
 
+
     inner class ComposeRecyclerViewHolder(val composeView: ComposeView) :
         RecyclerView.ViewHolder(composeView)
 
@@ -44,17 +52,20 @@ internal class ComposeRecyclerViewAdapter :
     }
 
     override fun onBindViewHolder(holder: ComposeRecyclerViewHolder, position: Int) {
-        holder.composeView.setContent {
-            when (layoutOrientation) {
-                LayoutOrientation.Horizontal -> {
-                    Row {
-                        itemBuilder?.invoke(position)
+        holder.composeView.apply {
+            tag = holder
+            setContent {
+                when (layoutOrientation) {
+                    LayoutOrientation.Horizontal -> {
+                        Row {
+                            itemBuilder?.invoke(position)
+                        }
                     }
-                }
 
-                LayoutOrientation.Vertical -> {
-                    Column {
-                        itemBuilder?.invoke(position)
+                    LayoutOrientation.Vertical -> {
+                        Column {
+                            itemBuilder?.invoke(position)
+                        }
                     }
                 }
             }
@@ -64,6 +75,24 @@ internal class ComposeRecyclerViewAdapter :
     override fun getItemCount(): Int = totalItems
 
     override fun getItemViewType(position: Int): Int {
-        return position
+        return itemTypeBuilder?.getItemType(position) ?: 0
+    }
+
+    fun onItemMove(fromPosition: Int, toPosition: Int) {
+        notifyItemMoved(fromPosition, toPosition)
+    }
+
+    fun update(
+        itemCount: Int,
+        itemBuilder: @Composable (index: Int) -> Unit,
+        layoutOrientation: LayoutOrientation,
+        itemTypeBuilder: ItemTypeBuilder?
+    ) {
+        this.totalItems = itemCount
+        this.itemBuilder = itemBuilder
+        this.layoutOrientation = layoutOrientation
+        itemTypeBuilder?.let {
+            this.itemTypeBuilder = it
+        }
     }
-}
+}

compose-recyclerview/src/main/java/com/example/compose_recyclerview/utils/InfiniteScrollListener.kt

@@ -0,0 +1,29 @@
+package com.example.compose_recyclerview.utils
+
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+
+/**
+ * Abstract class for handling infinite scrolling events in a RecyclerView.
+ */
+abstract class InfiniteScrollListener : RecyclerView.OnScrollListener() {
+    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
+        super.onScrolled(recyclerView, dx, dy)
+        if (dy > 0 || dx > 0) {
+            val layoutManager = recyclerView.layoutManager
+            if (layoutManager is LinearLayoutManager) {
+                val visibleItemCount = layoutManager.childCount
+                val totalItemCount = layoutManager.itemCount
+                val pastVisibleItems = layoutManager.findFirstVisibleItemPosition()
+                if (visibleItemCount + pastVisibleItems >= totalItemCount) {
+                    onScrollEnd()
+                }
+            }
+        }
+    }
+
+    /**
+     * Callback triggered when the user reaches the end of the list during scrolling.
+     */
+    protected abstract fun onScrollEnd()
+}