Merge pull request #441 from PhilKes/feat/list-drag-scroll

Add auto-scroll when dragging ListItem to top/bottom

app/src/main/java/androidx/recyclerview/widget/NestedScrollViewItemTouchHelper.kt

@@ -0,0 +1,118 @@
+package androidx.recyclerview.widget
+
+import android.graphics.Rect
+import android.view.View
+import android.view.ViewGroup
+import androidx.core.view.children
+import androidx.core.widget.NestedScrollView
+import kotlin.math.abs
+
+class NestedScrollViewItemTouchHelper(
+    callback: Callback,
+    private val scrollView: NestedScrollView,
+) : ItemTouchHelper(callback) {
+    private var selectedStartY: Int = -1
+    private var selectedStartScrollY: Float = -1f
+    private var selectedView: View? = null
+    private var dragScrollStartTimeInMs: Long = 0
+
+    private var lastmDy = 0f
+    private var lastScrollY = 0
+    private var tmpRect: Rect? = null
+
+    override fun select(selected: RecyclerView.ViewHolder?, actionState: Int) {
+        super.select(selected, actionState)
+        if (selected != null) {
+            selectedView = selected.itemView
+            selectedStartY = selected.itemView.top
+            selectedStartScrollY = scrollView!!.scrollY.toFloat()
+        }
+    }
+
+    /**
+     * Scrolls [scrollView] when an item in [mRecyclerView] is dragged to the top or bottom of the
+     * [scrollView].
+     *
+     * Inspired by
+     * [https://stackoverflow.com/a/70699988/9748566](https://stackoverflow.com/a/70699988/9748566)
+     */
+    override fun scrollIfNecessary(): Boolean {
+        if (mSelected == null) {
+            dragScrollStartTimeInMs = Long.MIN_VALUE
+            return false
+        }
+        val now = System.currentTimeMillis()
+        val scrollDuration =
+            if (dragScrollStartTimeInMs == Long.MIN_VALUE) 0 else now - dragScrollStartTimeInMs
+        val lm = mRecyclerView.layoutManager
+        if (tmpRect == null) {
+            tmpRect = Rect()
+        }
+        var scrollY = 0
+        val currentScrollY = scrollView.scrollY
+
+        // We need to use the height of NestedScrollView, not RecyclerView's!
+        val actualShowingHeight =
+            scrollView.height - mRecyclerView.top - mRecyclerView.paddingBottom
+
+        lm!!.calculateItemDecorationsForChild(mSelected.itemView, tmpRect!!)
+        if (lm.canScrollVertically()) {
+            // Keep scrolling if the user didnt change the drag direction
+            if (lastScrollY != 0 && abs(lastmDy) >= abs(mDy)) {
+                scrollY = lastScrollY
+            } else {
+                // The true current Y of the item in NestedScrollView, not in RecyclerView!
+                val curY = (selectedStartY + mDy - currentScrollY).toInt()
+                // The true mDy should plus the initial scrollY and minus current scrollY of
+                // NestedScrollView
+                val checkDy = (mDy + selectedStartScrollY - currentScrollY).toInt()
+                val topDiff = curY - tmpRect!!.top - mRecyclerView.paddingTop
+                if (checkDy < 0 && topDiff < 0) { // User is draging the item out of the top edge.
+                    scrollY = topDiff
+                } else if (checkDy > 0) { // User is draging the item out of the bottom edge.
+                    val bottomDiff = (curY + mSelected.itemView.height - actualShowingHeight) + 10
+                    if (bottomDiff >= 0) {
+                        scrollY = bottomDiff
+                    }
+                } else {
+                    scrollY = 0
+                }
+            }
+        }
+        lastScrollY = scrollY
+        lastmDy = mDy
+        if (scrollY != 0) {
+            scrollY =
+                mCallback.interpolateOutOfBoundsScroll(
+                    mRecyclerView,
+                    mSelected.itemView.height,
+                    scrollY,
+                    actualShowingHeight,
+                    scrollDuration,
+                )
+        }
+        if (scrollY != 0) {
+            val maxScrollY = scrollView.childrenHeightsSum - scrollView.height
+            // Check if we can scroll further before applying the scroll
+            if (
+                (scrollY < 0 && scrollView.scrollY > 0) ||
+                    (scrollY > 0 && scrollView.scrollY < maxScrollY)
+            ) {
+                if (dragScrollStartTimeInMs == Long.MIN_VALUE) {
+                    dragScrollStartTimeInMs = now
+                }
+                scrollView.scrollBy(0, scrollY)
+                // Update the dragged item position as well
+                selectedView?.translationY = selectedView!!.translationY + scrollY
+                return true
+            }
+        }
+        dragScrollStartTimeInMs = Long.MIN_VALUE
+        lastScrollY = 0
+        lastmDy = 0f
+        return false
+    }
+
+    private val ViewGroup.childrenHeightsSum
+        get() = children.map { it.measuredHeight }.sum()
+}

app/src/main/java/com/philkes/notallyx/presentation/activity/note/EditListActivity.kt

@@ -230,6 +230,7 @@ class EditListActivity : EditActivity(Type.LIST), MoreListActions {
                 NotallyXPreferences.getInstance(application),
                 listManager,
                 false,
+                binding.ScrollView,
             )
         val initializedItems = notallyModel.items.init(true)
         if (preferences.autoSortByCheckedEnabled) {
@@ -243,6 +244,7 @@ class EditListActivity : EditActivity(Type.LIST), MoreListActions {
                     NotallyXPreferences.getInstance(application),
                     listManager,
                     true,
+                    binding.ScrollView,
                 )
             itemsChecked =
                 SortedItemsList(ListItemParentSortCallback(adapterChecked!!)).apply {

app/src/main/java/com/philkes/notallyx/presentation/view/note/listitem/ListItemDragCallback.kt

@@ -44,7 +44,7 @@ class ListItemDragCallback(private val elevation: Float, internal val listManage
     internal fun move(from: Int, to: Int): Boolean {
         if (positionFrom == null) {
             positionFrom = from
-            stateBefore = listManager.getState()
+            stateBefore = listManager.getState(selectedPos = from)
             val item = listManager.getItem(from)
             parentBefore = if (item.isChild) listManager.findParent(item)?.second else null
         }
@@ -142,6 +142,6 @@ class ListItemDragCallback(private val elevation: Float, internal val listManage
     }
 
     companion object {
-        private const val TAG = "DragCallback"
+        private const val TAG = "ListItemDragCallback"
     }
 }

app/src/main/java/com/philkes/notallyx/presentation/view/note/listitem/ListManager.kt

@@ -72,38 +72,40 @@ class ListManager(
         this.itemsChecked?.let { Log.d(TAG, "itemsChecked:\n${it}") }
     }
 
-    internal fun getState(): ListState {
+    internal fun getState(selectedPos: Int? = null): ListState {
         val (pos, cursorPos) = recyclerView.getFocusedPositionAndCursor()
         return ListState(
             items.cloneList(),
             itemsChecked?.toMutableList()?.cloneList(),
-            pos,
+            selectedPos ?: pos,
             cursorPos,
         )
     }
 
     internal fun setState(state: ListState) {
-        adapter.submitList(state.items)
+        adapter.submitList(state.items) {
-        this.itemsChecked?.setItems(state.checkedItems!!)
+            // Focus item's EditText and set cursor position
-        // Focus item's EditText and set cursor position
+            state.focusedItemPos?.let { itemPos ->
-        state.focusedItemPos?.let { itemPos ->
+                recyclerView.post {
-            recyclerView.postDelayed(
+                    if (itemPos in 0..items.size) {
-                {
+                        recyclerView.smoothScrollToPosition(itemPos)
-                    (recyclerView.findViewHolderForAdapterPosition(itemPos) as? ListItemVH?)?.let {
+                        (recyclerView.findViewHolderForAdapterPosition(itemPos) as? ListItemVH?)
-                        viewHolder ->
+                            ?.let { viewHolder ->
-                        inputMethodManager?.let { inputManager ->
+                                inputMethodManager?.let { inputManager ->
-                            val maxCursorPos = viewHolder.binding.EditText.length()
+                                    val maxCursorPos = viewHolder.binding.EditText.length()
-                            viewHolder.focusEditText(
+                                    viewHolder.focusEditText(
-                                selectionStart =
+                                        selectionStart =
-                                    state.cursorPos?.coerceIn(0, maxCursorPos) ?: maxCursorPos,
+                                            state.cursorPos?.coerceIn(0, maxCursorPos)
-                                inputMethodManager = inputManager,
+                                                ?: maxCursorPos,
-                            )
+                                        inputMethodManager = inputManager,
-                        }
+                                    )
+                                }
+                            }
                     }
-                },
+                }
-                20,
+            }
-            ) // Delay is needed, otherwise focus is overwritten by submitList()
         }
+        this.itemsChecked?.setItems(state.checkedItems!!)
     }
 
     fun add(
@@ -141,7 +143,7 @@ class ListManager(
         adapter.notifyItemRangeInserted(insertPos, count)
         items.notifyPreviousFirstItem(insertPos, count)
         if (pushChange) {
-            changeHistory.push(ListAddChange(stateBefore, getState(), this))
+            changeHistory.push(ListAddChange(stateBefore, getState(selectedPos = insertPos), this))
         }
 
         recyclerView.post {
@@ -205,7 +207,7 @@ class ListManager(
 
     /** @return position of the moved item afterwards and the moved item count. */
     fun move(positionFrom: Int, positionTo: Int): Pair<Int, Int> {
-        val stateBefore = getState()
+        val itemsCheckedBefore = itemsChecked?.toMutableList()?.cloneList()
         val list = items.toMutableList()
         val movedItem = list[positionFrom]
         // Do not allow to move parent into its own children
@@ -229,7 +231,7 @@ class ListManager(
                 Pair(toOrder until fromOrder, itemCount)
             }
         shiftItemOrders(orderRange, valueToAdd, items = list)
-        stateBefore.checkedItems?.shiftItemOrders(orderRange, valueToAdd)
+        itemsCheckedBefore?.shiftItemOrders(orderRange, valueToAdd)
 
         list.removeFromParent(movedItem)
         list.removeWithChildren(movedItem)

app/src/main/java/com/philkes/notallyx/presentation/view/note/listitem/adapter/CheckedListItemAdapter.kt

@@ -2,6 +2,7 @@ package com.philkes.notallyx.presentation.view.note.listitem.adapter
 
 import android.view.ViewGroup
 import androidx.annotation.ColorInt
+import androidx.core.widget.NestedScrollView
 import androidx.recyclerview.widget.RecyclerView
 import androidx.recyclerview.widget.SortedList
 import com.philkes.notallyx.data.model.ListItem
@@ -17,6 +18,7 @@ class CheckedListItemAdapter(
     private val preferences: NotallyXPreferences,
     private val listManager: ListManager,
     private val isCheckedListAdapter: Boolean,
+    scrollView: NestedScrollView,
 ) : RecyclerView.Adapter<ListItemVH>(), HighlightText {
 
     private lateinit var list: SortedList<ListItem>
@@ -31,6 +33,7 @@ class CheckedListItemAdapter(
                 preferences,
                 listManager,
                 isCheckedListAdapter,
+                scrollView,
             ) {
             override fun getItem(position: Int): ListItem = list[position]
         }

app/src/main/java/com/philkes/notallyx/presentation/view/note/listitem/adapter/ListItemAdapter.kt

@@ -2,6 +2,7 @@ package com.philkes.notallyx.presentation.view.note.listitem.adapter
 
 import android.view.ViewGroup
 import androidx.annotation.ColorInt
+import androidx.core.widget.NestedScrollView
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListAdapter
 import androidx.recyclerview.widget.RecyclerView
@@ -18,6 +19,7 @@ class ListItemAdapter(
     private val preferences: NotallyXPreferences,
     private val listManager: ListManager,
     private val isCheckedListAdapter: Boolean,
+    scrollView: NestedScrollView,
 ) : ListAdapter<ListItem, ListItemVH>(DIFF_CALLBACK), HighlightText {
 
     private val itemAdapterBase =
@@ -30,6 +32,7 @@ class ListItemAdapter(
                 preferences,
                 listManager,
                 isCheckedListAdapter,
+                scrollView,
             ) {
             override fun getItem(position: Int): ListItem = this@ListItemAdapter.getItem(position)
         }

app/src/main/java/com/philkes/notallyx/presentation/view/note/listitem/adapter/ListItemAdapterBase.kt

@@ -3,7 +3,8 @@ package com.philkes.notallyx.presentation.view.note.listitem.adapter
 import android.view.LayoutInflater
 import android.view.ViewGroup
 import androidx.annotation.ColorInt
-import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.core.widget.NestedScrollView
+import androidx.recyclerview.widget.NestedScrollViewItemTouchHelper
 import androidx.recyclerview.widget.RecyclerView
 import com.philkes.notallyx.data.model.ListItem
 import com.philkes.notallyx.databinding.RecyclerListItemBinding
@@ -28,10 +29,11 @@ abstract class ListItemAdapterBase(
     private val preferences: NotallyXPreferences,
     private val listManager: ListManager,
     private val isCheckedListAdapter: Boolean,
+    scrollView: NestedScrollView,
 ) {
 
     private val callback = ListItemDragCallback(elevation, listManager)
-    private val touchHelper = ItemTouchHelper(callback)
+    private val touchHelper = NestedScrollViewItemTouchHelper(callback, scrollView)
     private val highlights = mutableMapOf<Int, MutableList<ListItemHighlight>>()
 
     fun onAttachedToRecyclerView(recyclerView: RecyclerView) {

app/src/test/kotlin/com/philkes/notallyx/recyclerview/listmanager/ListManagerTestBase.kt

@@ -88,6 +88,12 @@ open class ListManagerTestBase {
             }
             .`when`(adapter)
             .submitList(any())
+        doAnswer { invocation ->
+                val listArgument = invocation.getArgument<MutableList<ListItem>>(0)
+                itemsInternal = listArgument
+            }
+            .`when`(adapter)
+            .submitList(any(), any())
 
         listManager.init(adapter, itemsChecked, adapterChecked)
         adapter.submitList(items)