Migrate to ViewPager2

app/src/main/kotlin/com.jdamcd.sudoku/browse/PuzzleChoiceActivity.kt

@@ -6,6 +6,7 @@ import android.util.Log
 import android.view.Menu
 import android.view.MenuItem
 import android.view.View
+import androidx.viewpager2.widget.MarginPageTransformer
 import com.google.android.play.core.review.ReviewManagerFactory
 import com.jdamcd.sudoku.R
 import com.jdamcd.sudoku.app.IntentFactory
@@ -77,15 +78,14 @@ class PuzzleChoiceActivity : BaseActivity(), PuzzleChoicePresenter.View {
     }
 
     private fun configurePager() {
-        val pagerAdapter = PuzzlePagerAdapter(supportFragmentManager, resources)
+        val pagerAdapter = PuzzlePagerAdapter(this)
         val pager = binding.pager
         pager.adapter = pagerAdapter
         binding.indicator.setViewPager(pager)
+        pager.offscreenPageLimit = pagerAdapter.itemCount - 1
         pager.currentItem = 1
-        pager.offscreenPageLimit = pagerAdapter.count - 1
-        pager.setPageMarginDrawable(R.drawable.divider_vertical)
-        pager.pageMargin = ViewUtil.dpToPx(resources, 5)
-        pager.addOnPageChangeListener(fabView)
+        pager.setPageTransformer(MarginPageTransformer(ViewUtil.dpToPx(resources, 5)))
+        pager.registerOnPageChangeCallback(fabView)
     }
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {

app/src/main/kotlin/com.jdamcd.sudoku/browse/PuzzlePagerAdapter.kt

@@ -1,17 +1,14 @@
 package com.jdamcd.sudoku.browse
 
-import android.content.res.Resources
-import androidx.fragment.app.FragmentManager
-import androidx.fragment.app.FragmentPagerAdapter
+import androidx.fragment.app.FragmentActivity
+import androidx.viewpager2.adapter.FragmentStateAdapter
 import com.jdamcd.sudoku.repository.Level
 
-internal class PuzzlePagerAdapter(fm: FragmentManager, private val resources: Resources) : FragmentPagerAdapter(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {
+internal class PuzzlePagerAdapter(activity: FragmentActivity) : FragmentStateAdapter(activity) {
 
-    override fun getItem(position: Int) = PuzzleListFragment.create(levels[position])
+    override fun getItemCount() = levels.size
 
-    override fun getPageTitle(position: Int): String = resources.getString(levels[position].nameId)
-
-    override fun getCount() = levels.size
+    override fun createFragment(position: Int) = PuzzleListFragment.create(levels[position])
 
     companion object {
         val levels = arrayOf(Level.EASY, Level.MEDIUM, Level.HARD, Level.EXTREME)

app/src/main/kotlin/com.jdamcd.sudoku/browse/RandomFabView.kt

@@ -3,11 +3,11 @@ package com.jdamcd.sudoku.browse
 import android.animation.ArgbEvaluator
 import android.animation.ValueAnimator
 import android.content.res.ColorStateList
-import androidx.viewpager.widget.ViewPager
+import androidx.viewpager2.widget.ViewPager2
 import com.google.android.material.floatingactionbutton.FloatingActionButton
 import com.jdamcd.sudoku.R
 
-internal class RandomFabView : ViewPager.OnPageChangeListener {
+internal class RandomFabView : ViewPager2.OnPageChangeCallback() {
 
     private lateinit var fab: FloatingActionButton
     private lateinit var fabColours: IntArray
@@ -22,10 +22,6 @@ internal class RandomFabView : ViewPager.OnPageChangeListener {
         return fabColours[position % fabColours.size]
     }
 
-    override fun onPageScrollStateChanged(state: Int) {}
-
-    override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {}
-
     override fun onPageSelected(position: Int) {
         animateBackgroundChange(position)
     }

app/src/main/kotlin/com.jdamcd.sudoku/browse/indicator/PageIndicator.kt

@@ -1,17 +1,16 @@
 package com.jdamcd.sudoku.browse.indicator
 
-import androidx.viewpager.widget.ViewPager
-import androidx.viewpager.widget.ViewPager.OnPageChangeListener
+import androidx.viewpager2.widget.ViewPager2
 
-interface PageIndicator : OnPageChangeListener {
+interface PageIndicator {
 
-    fun setViewPager(view: ViewPager)
+    fun setViewPager(view: ViewPager2)
 
-    fun setViewPager(view: ViewPager, initialPosition: Int)
+    fun setViewPager(view: ViewPager2, initialPosition: Int)
 
     fun setCurrentItem(item: Int)
 
-    fun setOnPageChangeListener(listener: OnPageChangeListener)
+    fun setOnPageChangeCallback(listener: ViewPager2.OnPageChangeCallback)
 
     fun notifyDataSetChanged()
 }

app/src/main/kotlin/com.jdamcd.sudoku/browse/indicator/PagerStripIndicator.kt

@@ -15,30 +15,32 @@ import android.widget.HorizontalScrollView
 import android.widget.LinearLayout
 import android.widget.TextView
 import androidx.core.widget.TextViewCompat
-import androidx.viewpager.widget.ViewPager
-import androidx.viewpager.widget.ViewPager.OnPageChangeListener
+import androidx.viewpager2.widget.ViewPager2
+import androidx.viewpager2.widget.ViewPager2.OnPageChangeCallback
 import com.jdamcd.sudoku.R
 import com.jdamcd.sudoku.util.ViewUtil
 
 class PagerStripIndicator @JvmOverloads constructor(context: Context, attrs: AttributeSet, defStyle: Int = 0) : HorizontalScrollView(context, attrs, defStyle), PageIndicator {
 
     private val tabLayoutParams: LinearLayout.LayoutParams
 
-    private var pager: ViewPager? = null
-    private var listener: OnPageChangeListener? = null
+    private var pager: ViewPager2? = null
+    private var listener: OnPageChangeCallback? = null
 
     private val tabsContainer: LinearLayout
 
     private var tabCount: Int = 0
     private lateinit var rectPaint: Paint
     private var tabBackground: Int = 0
     private var tabTextColour = -0x99999a
-    private val indicatorColours: IntArray
     private var tabTextSize = 12
     private var scrollOffset = 52
     private var indicatorHeight = 8
     private var tabPadding = 24
 
+    private val indicatorColours: IntArray
+    private val indicatorTitles: Array<String>
+
     private var currentPosition = 0
     private var currentPositionOffset = 0f
     private var lastScrollX = 0
@@ -59,6 +61,7 @@ class PagerStripIndicator @JvmOverloads constructor(context: Context, attrs: Att
         initSystemAttributes(context, attrs)
 
         indicatorColours = resources.getIntArray(R.array.tab_colours)
+        indicatorTitles = resources.getStringArray(R.array.tab_titles)
         tabLayoutParams = LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 1.0f)
     }
 
@@ -85,17 +88,17 @@ class PagerStripIndicator @JvmOverloads constructor(context: Context, attrs: Att
         a.recycle()
     }
 
-    override fun setViewPager(view: ViewPager) {
+    override fun setViewPager(view: ViewPager2) {
         if (pager === view) {
             return
         }
         view.adapter ?: throw IllegalStateException("ViewPager does not have adapter instance.")
         this.pager = view
-        view.addOnPageChangeListener(this)
+        view.registerOnPageChangeCallback(CallbackWrapper())
         notifyDataSetChanged()
     }
 
-    override fun setViewPager(view: ViewPager, initialPosition: Int) {
+    override fun setViewPager(view: ViewPager2, initialPosition: Int) {
         setViewPager(view)
         setCurrentItem(initialPosition)
     }
@@ -105,17 +108,17 @@ class PagerStripIndicator @JvmOverloads constructor(context: Context, attrs: Att
         requestLayout()
     }
 
-    override fun setOnPageChangeListener(listener: OnPageChangeListener) {
+    override fun setOnPageChangeCallback(listener: OnPageChangeCallback) {
         this.listener = listener
     }
 
     @SuppressLint("NewApi")
     override fun notifyDataSetChanged() {
         tabsContainer.removeAllViews()
 
-        tabCount = pager?.adapter!!.count
+        tabCount = pager?.adapter!!.itemCount
         for (i in 0 until tabCount) {
-            addTextTab(i, pager?.adapter!!.getPageTitle(i).toString())
+            addTextTab(i)
         }
 
         updateTabStyles()
@@ -132,9 +135,9 @@ class PagerStripIndicator @JvmOverloads constructor(context: Context, attrs: Att
         )
     }
 
-    private fun addTextTab(position: Int, title: String) {
+    private fun addTextTab(position: Int) {
         val tab = TextView(context)
-        tab.text = title
+        tab.text = indicatorTitles[position]
         tab.gravity = Gravity.CENTER
         TextViewCompat.setTextAppearance(tab, R.style.TabText)
         tab.setOnClickListener { pager!!.currentItem = position }
@@ -218,32 +221,6 @@ class PagerStripIndicator @JvmOverloads constructor(context: Context, attrs: Att
         return indicatorColours[position % indicatorColours.size]
     }
 
-    override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {
-        currentPosition = position
-        currentPositionOffset = positionOffset
-
-        if (currentPositionOffset == 1.0f) {
-            currentPosition++
-            currentPositionOffset = 0f
-        }
-
-        scrollToChild(position, (positionOffset * tabsContainer.getChildAt(position).width).toInt())
-        invalidate()
-
-        listener?.onPageScrolled(position, positionOffset, positionOffsetPixels)
-    }
-
-    override fun onPageScrollStateChanged(state: Int) {
-        if (state == ViewPager.SCROLL_STATE_IDLE) {
-            scrollToChild(pager!!.currentItem, 0)
-        }
-        listener?.onPageScrollStateChanged(state)
-    }
-
-    override fun onPageSelected(position: Int) {
-        listener?.onPageSelected(position)
-    }
-
     public override fun onRestoreInstanceState(state: Parcelable) {
         val savedState = state as SavedState
         super.onRestoreInstanceState(savedState.superState)
@@ -258,6 +235,34 @@ class PagerStripIndicator @JvmOverloads constructor(context: Context, attrs: Att
         return savedState
     }
 
+    private inner class CallbackWrapper : OnPageChangeCallback() {
+        override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {
+            currentPosition = position
+            currentPositionOffset = positionOffset
+
+            if (currentPositionOffset == 1.0f) {
+                currentPosition++
+                currentPositionOffset = 0f
+            }
+
+            scrollToChild(position, (positionOffset * tabsContainer.getChildAt(position).width).toInt())
+            invalidate()
+
+            listener?.onPageScrolled(position, positionOffset, positionOffsetPixels)
+        }
+
+        override fun onPageScrollStateChanged(state: Int) {
+            if (state == ViewPager2.SCROLL_STATE_IDLE) {
+                scrollToChild(pager!!.currentItem, 0)
+            }
+            listener?.onPageScrollStateChanged(state)
+        }
+
+        override fun onPageSelected(position: Int) {
+            listener?.onPageSelected(position)
+        }
+    }
+
     private class SavedState : BaseSavedState {
         var currentPosition: Int = 0
 

app/src/main/res/layout/activity_puzzle_choice.xml

@@ -21,7 +21,7 @@
         style="@style/PagerIndicator" />
   </com.google.android.material.appbar.AppBarLayout>
 
-  <androidx.viewpager.widget.ViewPager
+  <androidx.viewpager2.widget.ViewPager2
     android:id="@+id/pager"
     style="@style/Match"
     app:layout_behavior="@string/appbar_scrolling_view_behavior" />

app/src/main/res/values/array.xml

@@ -16,6 +16,13 @@
     <item>@color/extreme</item>
   </integer-array>
 
+  <integer-array name="tab_titles">
+    <item>@string/level_easy</item>
+    <item>@string/level_medium</item>
+    <item>@string/level_hard</item>
+    <item>@string/level_extreme</item>
+  </integer-array>
+
   <string-array name="complete_greetings">
     <item>@string/puzzle_complete_1</item>
     <item>@string/puzzle_complete_2</item>