Fix drag & drop issues in SimpleDragCallback

app/src/main/AndroidManifest.xml

@@ -88,6 +88,9 @@
         <activity
             android:name="com.mikepenz.fastadapter.app.DiffUtilActivity"
             android:label="@string/sample_diff_util" />
+        <activity
+            android:name="com.mikepenz.fastadapter.app.DragAndDropActivity"
+            android:label="Drag &amp; Drop Sample" />
 
         <!-- USED FOR THE MopubAdsActivity sample-->
         <activity

app/src/main/java/com/mikepenz/fastadapter/app/DragAndDropActivity.kt

@@ -0,0 +1,208 @@
+package com.mikepenz.fastadapter.app
+
+import android.os.Bundle
+import android.view.MenuItem
+import android.view.View
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.res.ResourcesCompat
+import androidx.recyclerview.widget.DefaultItemAnimator
+import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import com.mikepenz.fastadapter.FastAdapter
+import com.mikepenz.fastadapter.GenericItem
+import com.mikepenz.fastadapter.IAdapter
+import com.mikepenz.fastadapter.adapters.ItemAdapter
+import com.mikepenz.fastadapter.adapters.ItemAdapter.Companion.items
+import com.mikepenz.fastadapter.app.databinding.ActivitySampleBinding
+import com.mikepenz.fastadapter.app.items.DragHandleTouchEvent
+import com.mikepenz.fastadapter.app.items.DraggableSingleLineItem
+import com.mikepenz.fastadapter.app.items.SectionHeaderItem
+import com.mikepenz.fastadapter.app.items.SmallIconSingleLineItem
+import com.mikepenz.fastadapter.app.view.DraggableFrameLayout
+import com.mikepenz.fastadapter.app.view.RecyclerViewBackgroundDrawable
+import com.mikepenz.fastadapter.drag.ItemTouchCallback
+import com.mikepenz.fastadapter.drag.SimpleDragCallback
+import com.mikepenz.fastadapter.utils.DragDropUtil
+import com.mikepenz.iconics.IconicsDrawable
+import com.mikepenz.iconics.typeface.library.materialdesigniconic.MaterialDesignIconic
+
+private const val STATE_LIST_ORDER = "com.mikepenz.fastadapter.app.LIST_ORDER"
+
+class DragAndDropActivity : AppCompatActivity(), ItemTouchCallback {
+    private lateinit var binding: ActivitySampleBinding
+
+    private lateinit var fastAdapter: FastAdapter<GenericItem>
+    private lateinit var itemAdapter: ItemAdapter<GenericItem>
+
+    private lateinit var touchCallback: SimpleDragCallback
+    private lateinit var touchHelper: ItemTouchHelper
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivitySampleBinding.inflate(layoutInflater).also {
+            setContentView(it.root)
+        }
+
+        setSupportActionBar(binding.toolbar)
+        supportActionBar?.setDisplayHomeAsUpEnabled(true)
+        supportActionBar?.setHomeButtonEnabled(false)
+
+        // Create empty ItemAdapter
+        itemAdapter = items()
+
+        // Create FastAdapter instance that will manage the whole list
+        fastAdapter = FastAdapter.with(itemAdapter).apply {
+            // Add an event hook that manages touching the drag handle
+            addEventHook(
+                DragHandleTouchEvent { position ->
+                    binding.rv.findViewHolderForAdapterPosition(position)?.let { viewHolder ->
+                        // Start dragging
+                        touchHelper.startDrag(viewHolder)
+                    }
+                }
+            )
+        }
+
+        // Handle clicks on our list items
+        fastAdapter.onClickListener = { v: View?, _: IAdapter<GenericItem>, item: GenericItem, _: Int ->
+            if (v != null) {
+                // Perform an action depending on the type of the item
+                val message = when (item) {
+                    is SmallIconSingleLineItem -> item.name.getText(v.context)
+                    is DraggableSingleLineItem -> item.name.getText(v.context)
+                    is SectionHeaderItem -> null
+                    else -> "Unknown item type: $item"
+                }
+                if (message != null) {
+                    Toast.makeText(v.context, message, Toast.LENGTH_SHORT).show()
+                }
+            }
+            false
+        }
+
+        // Set up our RecyclerView
+        binding.rv.layoutManager = LinearLayoutManager(this)
+        binding.rv.itemAnimator = DefaultItemAnimator()
+        binding.rv.adapter = fastAdapter
+
+        // Set a custom background on the RecyclerView. It avoids filling the area without list items at the bottom of
+        // the RecyclerView with our background color.
+        val recyclerViewBackgroundColor = ResourcesCompat.getColor(resources, R.color.behindRecyclerView, theme)
+        RecyclerViewBackgroundDrawable(recyclerViewBackgroundColor).attachTo(binding.rv)
+
+        // Create our list and set it on the adapter
+        val items = buildSampleItemList(savedInstanceState)
+        itemAdapter.add(items)
+
+        // Add drag and drop functionality to the RecyclerView
+        touchCallback = SimpleDragCallback(itemTouchCallback = this).apply {
+            // Disable drag & drop on long-press
+            isDragEnabled = false
+        }
+        touchHelper = ItemTouchHelper(touchCallback)
+        touchHelper.attachToRecyclerView(binding.rv)
+
+        // Restore the adapter state (this has to be done after adding the items)
+        fastAdapter.withSavedInstanceState(savedInstanceState)
+    }
+
+    private fun buildSampleItemList(savedInstanceState: Bundle?): ArrayList<GenericItem> {
+        val items = ArrayList<GenericItem>()
+        items.add(
+            SmallIconSingleLineItem(
+                IconicsDrawable(this, MaterialDesignIconic.Icon.gmi_settings),
+                getString(R.string.list_item_general_settings)
+            )
+        )
+
+        items.add(SectionHeaderItem(getString(R.string.list_item_accounts_section)))
+
+        val accountIcon = IconicsDrawable(this, MaterialDesignIconic.Icon.gmi_account)
+
+        val accountItems = (1..5).map { i ->
+            val name = getString(R.string.list_item_account, i)
+            DraggableSingleLineItem(accountIcon, name).apply {
+                identifier = (100 + i).toLong()
+            }
+        }
+
+        // Use the saved state (if available) to sort the list of accounts
+        val sortedAccountItems = if (savedInstanceState != null) {
+            val listOrder = savedInstanceState.getLongArray(STATE_LIST_ORDER) ?: error("Missing saved state")
+            val orderById = listOrder.withIndex().associate { it.value to it.index }
+            accountItems.sortedBy { orderById[it.identifier] }
+        } else {
+            accountItems
+        }
+
+        items.addAll(sortedAccountItems)
+
+        items.add(SectionHeaderItem(getString(R.string.list_item_misc_section)))
+        items.add(SmallIconSingleLineItem(
+            IconicsDrawable(this, MaterialDesignIconic.Icon.gmi_info),
+            getString(R.string.list_item_about)
+        ))
+        items.add(
+            SmallIconSingleLineItem(
+                IconicsDrawable(this, MaterialDesignIconic.Icon.gmi_code),
+                getString(R.string.list_item_licenses)
+            )
+        )
+        return items
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        // Save the adapter's state
+        val newOutState = fastAdapter.saveInstanceState(outState)
+
+        // Save the current account order
+        val itemIdentifiers = itemAdapter.adapterItems
+            .filterIsInstance<DraggableSingleLineItem>()
+            .map { it.identifier }
+            .toLongArray()
+        newOutState.putLongArray(STATE_LIST_ORDER, itemIdentifiers)
+
+        super.onSaveInstanceState(newOutState)
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            android.R.id.home -> {
+                onBackPressed()
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
+    override fun itemTouchStartDrag(viewHolder: RecyclerView.ViewHolder) {
+        // Add visual highlight to the dragged item
+        (viewHolder.itemView as DraggableFrameLayout).isDragged = true
+    }
+
+    override fun itemTouchStopDrag(viewHolder: RecyclerView.ViewHolder) {
+        // Remove visual highlight from the dropped item
+        (viewHolder.itemView as DraggableFrameLayout).isDragged = false
+    }
+
+    override fun itemTouchOnMove(oldPosition: Int, newPosition: Int): Boolean {
+        // Determine the "drop area"
+        val firstDropPosition = itemAdapter.adapterItems.indexOfFirst { it is DraggableSingleLineItem }
+        val lastDropPosition = itemAdapter.adapterItems.indexOfLast { it is DraggableSingleLineItem }
+
+        // Only move the item if the new position is inside the "drop area"
+        return if (newPosition in firstDropPosition..lastDropPosition) {
+            // Change the item's position in the adapter
+            DragDropUtil.onMove(itemAdapter, oldPosition, newPosition)
+            true
+        } else {
+            false
+        }
+    }
+
+    override fun itemTouchDropped(oldPosition: Int, newPosition: Int) {
+        // Save the new item order, e.g. in your database
+    }
+}

app/src/main/java/com/mikepenz/fastadapter/app/SampleActivity.kt

@@ -88,6 +88,7 @@ class SampleActivity : AppCompatActivity() {
                     PrimaryDrawerItem().withName(R.string.sample_collapsible_multi_select_delete).withDescription(R.string.sample_collapsible_multi_select_delete_descr).withSelectable(false).withIdentifier(18).withIcon(MaterialDesignIconic.Icon.gmi_check_all),
                     PrimaryDrawerItem().withName(R.string.sample_sticky_header_mopub).withDescription(R.string.sample_sticky_header_mopub_descr).withSelectable(false).withIdentifier(19).withIcon(MaterialDesignIconic.Icon.gmi_accounts_list),
                     PrimaryDrawerItem().withName(R.string.sample_diff_util).withDescription(R.string.sample_diff_util_descr).withSelectable(false).withIdentifier(20).withIcon(MaterialDesignIconic.Icon.gmi_refresh),
+                    PrimaryDrawerItem().withName(R.string.sample_drag_and_drop).withDescription(R.string.sample_drag_and_drop_descr).withSelectable(false).withIdentifier(22).withIcon(MaterialDesignIconic.Icon.gmi_reorder),
                     DividerDrawerItem(),
                     PrimaryDrawerItem().withName(R.string.open_source).withSelectable(false).withIdentifier(100).withIcon(MaterialDesignIconic.Icon.gmi_github)
             )
@@ -114,6 +115,7 @@ class SampleActivity : AppCompatActivity() {
                     19L -> Intent(this@SampleActivity, StickyHeaderMopubAdsActivity::class.java)
                     20L -> Intent(this@SampleActivity, DiffUtilActivity::class.java)
                     21L -> Intent(this@SampleActivity, PagedActivity::class.java)
+                    22L -> Intent(this@SampleActivity, DragAndDropActivity::class.java)
                     100L -> LibsBuilder()
                             .withFields(R.string::class.java.fields)
                             .withActivityTitle(getString(R.string.open_source))

app/src/main/java/com/mikepenz/fastadapter/app/items/DraggableSingleLineItem.kt

@@ -0,0 +1,69 @@
+package com.mikepenz.fastadapter.app.items
+
+import android.graphics.drawable.Drawable
+import android.view.MotionEvent
+import android.view.View
+import android.widget.ImageView
+import android.widget.TextView
+import androidx.recyclerview.widget.RecyclerView
+import com.mikepenz.fastadapter.FastAdapter
+import com.mikepenz.fastadapter.app.R
+import com.mikepenz.fastadapter.drag.IDraggable
+import com.mikepenz.fastadapter.items.AbstractItem
+import com.mikepenz.fastadapter.listeners.TouchEventHook
+import com.mikepenz.fastadapter.ui.utils.ImageHolder
+import com.mikepenz.fastadapter.ui.utils.StringHolder
+
+class DraggableSingleLineItem(icon: Drawable, name: String) : AbstractItem<DraggableSingleLineItem.ViewHolder>(), IDraggable {
+    val icon: ImageHolder = ImageHolder(icon)
+    val name: StringHolder = StringHolder(name)
+
+    override val isDraggable: Boolean = true
+
+    override val type: Int
+        get() = R.id.fastadapter_draggable_single_line_item
+
+    override val layoutRes: Int
+        get() = R.layout.draggable_single_line_item
+
+    override fun bindView(holder: ViewHolder, payloads: List<Any>) {
+        super.bindView(holder, payloads)
+        ImageHolder.applyToOrSetGone(icon, holder.icon)
+        name.applyTo(holder.name)
+    }
+
+    override fun unbindView(holder: ViewHolder) {
+        holder.icon.setImageDrawable(null)
+        holder.name.text = null
+    }
+
+    override fun getViewHolder(v: View): ViewHolder = ViewHolder(v)
+
+    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
+        var icon: ImageView = view.findViewById(R.id.icon)
+        var name: TextView = view.findViewById(R.id.name)
+        var dragHandle: View = view.findViewById(R.id.drag_handle)
+    }
+}
+
+class DragHandleTouchEvent(val action: (position: Int) -> Unit) : TouchEventHook<DraggableSingleLineItem>() {
+    override fun onBind(viewHolder: RecyclerView.ViewHolder): View? {
+        return if (viewHolder is DraggableSingleLineItem.ViewHolder) viewHolder.dragHandle else null
+    }
+
+    override fun onTouch(
+        v: View,
+        event: MotionEvent,
+        position: Int,
+        fastAdapter: FastAdapter<DraggableSingleLineItem>,
+        item: DraggableSingleLineItem
+    ): Boolean {
+        return if (event.action == MotionEvent.ACTION_DOWN) {
+            action(position)
+            true
+        } else {
+            false
+        }
+    }
+}
+

app/src/main/java/com/mikepenz/fastadapter/app/items/SectionHeaderItem.kt

@@ -0,0 +1,33 @@
+package com.mikepenz.fastadapter.app.items
+
+import android.view.View
+import android.widget.TextView
+import androidx.recyclerview.widget.RecyclerView
+import com.mikepenz.fastadapter.app.R
+import com.mikepenz.fastadapter.items.AbstractItem
+import com.mikepenz.fastadapter.ui.utils.StringHolder
+
+class SectionHeaderItem(text: String) : AbstractItem<SectionHeaderItem.ViewHolder>() {
+    val text: StringHolder = StringHolder(text)
+
+    override val type: Int
+        get() = R.id.fastadapter_section_header_item
+
+    override val layoutRes: Int
+        get() = R.layout.section_header_item
+
+    override fun bindView(holder: ViewHolder, payloads: List<Any>) {
+        super.bindView(holder, payloads)
+        text.applyTo(holder.text)
+    }
+
+    override fun unbindView(holder: ViewHolder) {
+        holder.text.text = null
+    }
+
+    override fun getViewHolder(v: View): ViewHolder = ViewHolder(v)
+
+    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
+        var text: TextView = view.findViewById(R.id.text)
+    }
+}

app/src/main/java/com/mikepenz/fastadapter/app/items/SmallIconSingleLineItem.kt

@@ -0,0 +1,40 @@
+package com.mikepenz.fastadapter.app.items
+
+import android.graphics.drawable.Drawable
+import android.view.View
+import android.widget.ImageView
+import android.widget.TextView
+import androidx.recyclerview.widget.RecyclerView
+import com.mikepenz.fastadapter.app.R
+import com.mikepenz.fastadapter.items.AbstractItem
+import com.mikepenz.fastadapter.ui.utils.ImageHolder
+import com.mikepenz.fastadapter.ui.utils.StringHolder
+
+class SmallIconSingleLineItem(icon: Drawable, name: String) : AbstractItem<SmallIconSingleLineItem.ViewHolder>() {
+    val icon: ImageHolder = ImageHolder(icon)
+    val name: StringHolder = StringHolder(name)
+
+    override val type: Int
+        get() = R.id.fastadapter_small_icon_single_line_item
+
+    override val layoutRes: Int
+        get() = R.layout.small_single_line_item
+
+    override fun bindView(holder: ViewHolder, payloads: List<Any>) {
+        super.bindView(holder, payloads)
+        ImageHolder.applyToOrSetGone(icon, holder.icon)
+        name.applyTo(holder.name)
+    }
+
+    override fun unbindView(holder: ViewHolder) {
+        holder.icon.setImageDrawable(null)
+        holder.name.text = null
+    }
+
+    override fun getViewHolder(v: View): ViewHolder = ViewHolder(v)
+
+    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
+        var icon: ImageView = view.findViewById(R.id.icon)
+        var name: TextView = view.findViewById(R.id.name)
+    }
+}