[UI] Implement RecyclerTabLayout, enable swipe-to-refresh in timetable (#209)

* Enable swipe-to-refresh in timetable

* Add basic RecyclerTabLayout view

* Implement tab scrolling in RecyclerTabLayout

* Implement tab clicking in RecyclerTabLayout

* Add selected tab indicator to RecyclerTabLayout

* Add ProGuard rules for RecyclerTabLayout

* Set RecyclerTabLayout background

app/proguard-rules.pro

@@ -55,6 +55,18 @@
     setIcons(android.widget.TextView);
 }
 
+# for RecyclerTabView
+-keepclassmembernames class com.google.android.material.tabs.TabLayout {
+    tabIndicatorInterpolator;
+}
+-keepclassmembernames class com.google.android.material.tabs.TabLayout$TabView {
+    tab;
+    updateTab();
+}
+-keepclassmembernames class com.google.android.material.tabs.TabIndicatorInterpolator {
+    updateIndicatorForOffset(com.google.android.material.tabs.TabLayout, android.view.View, android.view.View, float, android.graphics.drawable.Drawable);
+}
+
 -keep class .R
 -keep class **.R$* {
     <fields>;

app/src/main/java/pl/szczodrzynski/edziennik/ext/ReflectionExtensions.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) Kuba Szczodrzyński 2024-7-6.
+ */
+
+@file:Suppress("UNCHECKED_CAST")
+
+package pl.szczodrzynski.edziennik.ext
+
+fun <T> Any.getDeclaredField(name: String): T? = this::class.java.getDeclaredField(name).run {
+    isAccessible = true
+    get(this@getDeclaredField) as? T
+}
+
+fun Any.setDeclaredField(name: String, value: Any?) = this::class.java.getDeclaredField(name).run {
+    isAccessible = true
+    set(this@setDeclaredField, value)
+}
+
+fun Any.invokeDeclaredMethod(name: String, vararg args: Pair<Class<*>, Any?>): Any? =
+    this::class.java.getDeclaredMethod(name, *args.map { (k, _) -> k }.toTypedArray()).run {
+        isAccessible = true
+        invoke(this@invokeDeclaredMethod, *args.map { (_, v) -> v }.toTypedArray())
+    }
+
+fun <T> Class<T>.invokeDeclaredConstructor(vararg args: Pair<Class<*>, Any>): T =
+    getDeclaredConstructor(*args.map { (k, _) -> k }.toTypedArray()).run {
+        isAccessible = true
+        newInstance(*args.map { (_, v) -> v }.toTypedArray())
+    }
+
+fun <T> Class<*>.getDeclaredClass(name: String): Class<T> =
+    declaredClasses.first { it.simpleName == name } as Class<T>

app/src/main/java/pl/szczodrzynski/edziennik/ui/attendance/AttendanceSummaryFragment.kt

@@ -43,7 +43,7 @@ class AttendanceSummaryFragment : BaseFragment<AttendanceSummaryFragmentBinding,
         private var periodSelection = 0
     }
 
-    override fun getRefreshScrollingView() = b.list
+    override fun getRefreshScrollingView() = b.scrollView
 
     private val manager
         get() = app.attendanceManager
@@ -149,7 +149,6 @@ class AttendanceSummaryFragment : BaseFragment<AttendanceSummaryFragmentBinding,
         }
     }
 
-    @Suppress("SuspendFunctionOnCoroutineScope")
     private fun processAttendance(): MutableList<Any> {
         val attendance = when (periodSelection) {
             0 -> attendance

app/src/main/java/pl/szczodrzynski/edziennik/ui/base/fragment/ActivityUtil.kt

@@ -42,7 +42,7 @@ internal fun BaseFragment<*, *>.setupCanRefresh() {
                 // keep track of the touch state
                 when (event.action) {
                     MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> isTouched = false
-                    MotionEvent.ACTION_DOWN -> isTouched = true
+                    MotionEvent.ACTION_DOWN, MotionEvent.ACTION_MOVE -> isTouched = true
                 }
                 // disable refresh when scrolled down
                 if (view.canScrollVertically(-1))

app/src/main/java/pl/szczodrzynski/edziennik/ui/base/fragment/PagerFragment.kt

@@ -16,6 +16,8 @@ import com.google.android.material.tabs.TabLayout
 import com.google.android.material.tabs.TabLayoutMediator
 import kotlinx.coroutines.launch
 import pl.szczodrzynski.edziennik.ext.set
+import pl.szczodrzynski.edziennik.ext.setDeclaredField
+import pl.szczodrzynski.edziennik.ui.base.views.RecyclerTabLayout
 
 abstract class PagerFragment<B : ViewBinding, A : AppCompatActivity>(
     inflater: ((inflater: LayoutInflater, parent: ViewGroup?, attachToParent: Boolean) -> B)?,
@@ -76,9 +78,15 @@ abstract class PagerFragment<B : ViewBinding, A : AppCompatActivity>(
             })
         }
 
-        TabLayoutMediator(getTabLayout(), getViewPager()) { tab, position ->
+        when (val tabLayout = getTabLayout()) {
-            tab.text = getPageTitle(position)
+            is TabLayout -> TabLayoutMediator(tabLayout, getViewPager()) { tab, position ->
-        }.attach()
+                tab.text = getPageTitle(position)
+            }.attach()
+
+            is RecyclerTabLayout -> tabLayout.setupWithViewPager(getViewPager()) { tab, position ->
+                tab.setDeclaredField("text", getPageTitle(position))
+            }
+        }
 
         onPageSelected(savedPageSelection)
     }
@@ -103,9 +111,9 @@ abstract class PagerFragment<B : ViewBinding, A : AppCompatActivity>(
     }
 
     /**
-     * Called to retrieve the [TabLayout] view of the pager fragment.
+     * Called to retrieve the [TabLayout] or [RecyclerTabLayout] view of the pager fragment.
      */
-    abstract fun getTabLayout(): TabLayout
+    abstract fun getTabLayout(): ViewGroup
 
     /**
      * Called to retrieve the [ViewPager2] view of the pager fragment.

app/src/main/java/pl/szczodrzynski/edziennik/ui/base/views/RecyclerTabLayout.kt

@@ -0,0 +1,198 @@
+/*
+ * Copyright (c) Kuba Szczodrzyński 2024-7-7.
+ */
+
+package pl.szczodrzynski.edziennik.ui.base.views
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.drawable.Drawable
+import android.util.AttributeSet
+import android.view.View
+import android.view.ViewGroup
+import androidx.core.graphics.drawable.updateBounds
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.viewpager2.widget.ViewPager2
+import com.google.android.material.tabs.TabLayout
+import com.google.android.material.tabs.TabLayoutMediator.TabConfigurationStrategy
+import pl.szczodrzynski.edziennik.ext.getDeclaredField
+import pl.szczodrzynski.edziennik.ext.invokeDeclaredMethod
+import pl.szczodrzynski.edziennik.ext.onClick
+import pl.szczodrzynski.edziennik.ext.setDeclaredField
+import kotlin.math.min
+
+class RecyclerTabLayout @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null,
+    defStyleAttr: Int = 0,
+) : RecyclerView(context, attrs, defStyleAttr) {
+
+    private val tabLayout: TabLayout = TabLayout(context, attrs)
+    private lateinit var linearLayoutManager: LinearLayoutManager
+    private lateinit var viewPager: ViewPager2
+    private lateinit var viewPagerAdapter: RecyclerView.Adapter<ViewHolder>
+    private lateinit var tabAdapter: Adapter
+    private lateinit var tabConfigurationStrategy: TabConfigurationStrategy
+    private lateinit var tab: TabLayout.Tab
+    private lateinit var tabSelectedIndicator: Drawable
+    private var tabIndicatorGravity: Int = 0
+    private var tabIndicatorInterpolator: Any? = null
+
+    private var selectedTab = 0
+
+    fun setupWithViewPager(pager: ViewPager2, strategy: TabConfigurationStrategy) {
+        linearLayoutManager = LinearLayoutManager(context).also {
+            it.orientation = HORIZONTAL
+        }
+        viewPager = pager
+        viewPagerAdapter = pager.adapter!!
+        tabAdapter = Adapter()
+        tabConfigurationStrategy = strategy
+        tab = TabLayout.Tab()
+        tabSelectedIndicator = tabLayout.tabSelectedIndicator
+        tabIndicatorGravity = tabLayout.tabIndicatorGravity
+        tabIndicatorInterpolator = tabLayout.getDeclaredField("tabIndicatorInterpolator")
+
+        this.addOnScrollListener(OnScrollListener())
+        viewPager.registerOnPageChangeCallback(OnPageChangeCallback())
+        viewPagerAdapter.registerAdapterDataObserver(AdapterDataObserver())
+
+        setWillNotDraw(false)
+        setAdapter(tabAdapter)
+        setHasFixedSize(true)
+        layoutManager = linearLayoutManager
+        itemAnimator = null
+        background = tabLayout.background
+    }
+
+    override fun onDraw(canvas: Canvas) {
+        super.onDraw(canvas)
+        // draw the selected tab indicator
+        var indicatorHeight = tabSelectedIndicator.bounds.height()
+        if (indicatorHeight < 0)
+            indicatorHeight = tabSelectedIndicator.intrinsicHeight
+
+        var indicatorTop = 0
+        var indicatorBottom = 0
+        when (tabLayout.tabIndicatorGravity) {
+            TabLayout.INDICATOR_GRAVITY_BOTTOM -> {
+                indicatorTop = height - indicatorHeight
+                indicatorBottom = height
+            }
+
+            TabLayout.INDICATOR_GRAVITY_CENTER -> {
+                indicatorTop = (height - indicatorHeight) / 2
+                indicatorBottom = (height + indicatorHeight) / 2
+            }
+
+            TabLayout.INDICATOR_GRAVITY_TOP -> {
+                indicatorTop = 0
+                indicatorBottom = indicatorHeight
+            }
+
+            TabLayout.INDICATOR_GRAVITY_STRETCH -> {
+                indicatorTop = 0
+                indicatorBottom = height
+            }
+        }
+
+        tabSelectedIndicator.updateBounds(top = indicatorTop, bottom = indicatorBottom)
+        tabSelectedIndicator.draw(canvas)
+    }
+
+    inner class Adapter : RecyclerView.Adapter<Adapter.TabViewHolder>() {
+        override fun getItemCount() =
+            viewPagerAdapter.itemCount
+
+        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
+            TabViewHolder(tabLayout.TabView(context)).also { holder ->
+                holder.tabView.onClick {
+                    viewPager.setCurrentItem(holder.lastPosition, true)
+                }
+            }
+
+        override fun onBindViewHolder(holder: TabViewHolder, position: Int) {
+            val tabView = holder.tabView
+            tabConfigurationStrategy.onConfigureTab(tab, position)
+            tabView.setDeclaredField("tab", tab)
+            tabView.invokeDeclaredMethod("updateTab")
+            tabView.setDeclaredField("tab", null)
+            tabView.isSelected = position == selectedTab
+            tabView.isActivated = position == selectedTab
+            holder.lastPosition = position
+        }
+
+        inner class TabViewHolder(
+            val tabView: TabLayout.TabView,
+            var lastPosition: Int = 0,
+        ) : ViewHolder(tabView)
+    }
+
+    inner class OnScrollListener : RecyclerView.OnScrollListener() {
+        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
+            val left = tabSelectedIndicator.bounds.left
+            val right = tabSelectedIndicator.bounds.right
+            tabSelectedIndicator.updateBounds(left = left - dx, right = right - dx)
+        }
+    }
+
+    inner class OnPageChangeCallback : ViewPager2.OnPageChangeCallback() {
+        override fun onPageScrolled(
+            position: Int,
+            positionOffset: Float,
+            positionOffsetPixels: Int,
+        ) {
+            stopScroll()
+
+            val thisTab = findViewHolderForLayoutPosition(position)?.itemView
+            val nextTab = findViewHolderForLayoutPosition(position + 1)?.itemView
+
+            // scroll to the currently selected tab
+            val thisTabWidth = thisTab?.width ?: 0
+            val nextTabWidth = nextTab?.width ?: 0
+            val tabDistance = (thisTabWidth / 2) + (nextTabWidth / 2)
+            val offset = (width / 2.0f) - (thisTabWidth / 2.0f) - (tabDistance * positionOffset)
+            // 'offset' is the screen position of the tab's left edge
+            linearLayoutManager.scrollToPositionWithOffset(position, offset.toInt())
+
+            // update selection state of the current tab
+            val roundedPosition = Math.round(position + positionOffset)
+            if (selectedTab != roundedPosition) {
+                val previousTab = selectedTab
+                selectedTab = roundedPosition
+                tabAdapter.notifyItemRangeChanged(min(previousTab, selectedTab), 2)
+            }
+
+            // update the width and position of the selected tab indicator
+            tabIndicatorInterpolator?.invokeDeclaredMethod(
+                name = "updateIndicatorForOffset",
+                /* tabLayout = */ TabLayout::class.java to tabLayout,
+                /* startTitle = */ View::class.java to thisTab,
+                /* endTitle = */ View::class.java to nextTab,
+                /* offset = */ Float::class.java to positionOffset,
+                /* indicator = */ Drawable::class.java to tabSelectedIndicator,
+            )
+        }
+    }
+
+    inner class AdapterDataObserver : RecyclerView.AdapterDataObserver() {
+        @SuppressLint("NotifyDataSetChanged")
+        override fun onChanged() =
+            tabAdapter.notifyDataSetChanged()
+
+        override fun onItemRangeChanged(positionStart: Int, itemCount: Int) =
+            tabAdapter.notifyItemRangeChanged(positionStart, itemCount)
+
+        override fun onItemRangeInserted(positionStart: Int, itemCount: Int) =
+            tabAdapter.notifyItemRangeInserted(positionStart, itemCount)
+
+        override fun onItemRangeRemoved(positionStart: Int, itemCount: Int) =
+            tabAdapter.notifyItemRangeRemoved(positionStart, itemCount)
+
+        @SuppressLint("NotifyDataSetChanged")
+        override fun onItemRangeMoved(fromPosition: Int, toPosition: Int, itemCount: Int) =
+            tabAdapter.notifyDataSetChanged()
+    }
+}

app/src/main/java/pl/szczodrzynski/edziennik/ui/timetable/TimetableDayFragment.kt

@@ -101,6 +101,8 @@ class TimetableDayFragment : BaseFragment<TimetableDayFragmentBinding, MainActiv
     }
     private val dayView by dayViewDelegate
 
+    override fun getRefreshScrollingView() = b.scrollView
+
     override suspend fun onViewReady(savedInstanceState: Bundle?) {
         this.inflater = AsyncLayoutInflater(requireContext())
 

app/src/main/java/pl/szczodrzynski/edziennik/utils/ListenerScrollView.kt

@@ -1,46 +0,0 @@
-/*
- * Copyright (c) Kuba Szczodrzyński 2019-11-16.
- */
-
-package pl.szczodrzynski.edziennik.utils
-
-import android.content.Context
-import android.util.AttributeSet
-import android.view.MotionEvent
-import android.widget.ScrollView
-
-class ListenerScrollView(
-        context: Context,
-        attrs: AttributeSet? = null
-) : ScrollView(context, attrs) {
-
-    private var onScrollChangedListener: ((v: ListenerScrollView, scrollX: Int, scrollY: Int, oldScrollX: Int, oldScrollY: Int) -> Unit)? = null
-    private var onRefreshLayoutEnabledListener: ((enabled: Boolean) -> Unit)? = null
-    private var refreshLayoutEnabled = true
-
-    init {
-        setOnTouchListener { _, event ->
-            if (event.action == MotionEvent.ACTION_UP) {
-                refreshLayoutEnabled = scrollY < 10
-                onRefreshLayoutEnabledListener?.invoke(refreshLayoutEnabled)
-            }
-            false
-        }
-    }
-
-    override fun onScrollChanged(l: Int, t: Int, oldl: Int, oldt: Int) {
-        onScrollChangedListener?.invoke(this, l, t, oldl, oldt)
-        if (t > 10 && refreshLayoutEnabled) {
-            refreshLayoutEnabled = false
-            onRefreshLayoutEnabledListener?.invoke(refreshLayoutEnabled)
-        }
-    }
-
-    fun setOnScrollChangedListener(l: ((v: ListenerScrollView, scrollX: Int, scrollY: Int, oldScrollX: Int, oldScrollY: Int) -> Unit)?) {
-        onScrollChangedListener = l
-    }
-
-    fun setOnRefreshLayoutEnabledListener(l: ((enabled: Boolean) -> Unit)?) {
-        onRefreshLayoutEnabledListener = l
-    }
-}

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

@@ -2,32 +2,27 @@
   ~ Copyright (c) Kuba Szczodrzyński 2024-7-3.
   -->
 
-<LinearLayout
+<androidx.coordinatorlayout.widget.CoordinatorLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical">
 
-    <com.google.android.material.tabs.TabLayout
+    <com.google.android.material.appbar.AppBarLayout
-        android:id="@+id/tabLayout"
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
+        android:layout_height="wrap_content">
-        android:background="?colorSurfaceContainerLow"
+
-        app:tabIndicatorColor="?colorPrimary"
+        <com.google.android.material.tabs.TabLayout
-        app:tabMaxWidth="300dp"
+            android:id="@+id/tabLayout"
-        app:tabMinWidth="90dp"
+            android:layout_width="match_parent"
-        app:tabMode="auto"
+            android:layout_height="wrap_content"
-        app:tabPaddingBottom="12dp"
+            app:tabMode="auto" />
-        app:tabPaddingEnd="16dp"
+    </com.google.android.material.appbar.AppBarLayout>
-        app:tabPaddingStart="16dp"
-        app:tabPaddingTop="12dp"
-        app:tabSelectedTextColor="?colorPrimary"
-        app:tabTextColor="?android:textColorPrimary" />
 
     <androidx.viewpager2.widget.ViewPager2
         android:id="@+id/viewPager"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         app:layout_behavior="@string/appbar_scrolling_view_behavior" />
-</LinearLayout>
+</androidx.coordinatorlayout.widget.CoordinatorLayout>

app/src/main/res/layout/fragment_timetable_v2.xml

@@ -10,28 +10,22 @@
         android:id="@+id/timetableLayout"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
+        android:orientation="vertical"
         tools:visibility="gone">
 
         <com.google.android.material.appbar.AppBarLayout
             android:layout_width="match_parent"
-            android:layout_height="wrap_content"
+            android:layout_height="wrap_content">
-            android:background="?colorSurface">
 
-            <com.google.android.material.tabs.TabLayout
+            <pl.szczodrzynski.edziennik.ui.base.views.RecyclerTabLayout
                 android:id="@+id/tabLayout"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
-                android:background="?colorSurfaceContainerLow"
-                app:tabIndicatorColor="?colorPrimary"
-                app:tabMaxWidth="300dp"
-                app:tabMinWidth="90dp"
                 app:tabMode="auto"
-                app:tabPaddingBottom="12dp"
+                app:tabPaddingBottom="16dp"
                 app:tabPaddingEnd="16dp"
                 app:tabPaddingStart="16dp"
-                app:tabPaddingTop="12dp"
+                app:tabPaddingTop="16dp" />
-                app:tabSelectedTextColor="?colorPrimary"
-                app:tabTextColor="?colorOnBackground" />
         </com.google.android.material.appbar.AppBarLayout>
 
         <androidx.viewpager2.widget.ViewPager2

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

@@ -8,18 +8,17 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
-    <pl.szczodrzynski.edziennik.utils.ListenerScrollView
+    <androidx.core.widget.NestedScrollView
         android:id="@+id/scrollView"
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
+        android:layout_height="match_parent"
         android:visibility="gone"
         tools:visibility="visible">
 
         <FrameLayout
             android:id="@+id/dayFrame"
             android:layout_width="match_parent"
-            android:layout_height="wrap_content"
+            android:layout_height="wrap_content">
-            tools:layout_height="match_parent">
 
             <View
                 android:id="@+id/timeIndicatorMarker"
@@ -37,7 +36,7 @@
                 android:background="?colorTertiary"
                 tools:layout_marginTop="100dp" />
         </FrameLayout>
-    </pl.szczodrzynski.edziennik.utils.ListenerScrollView>
+    </androidx.core.widget.NestedScrollView>
 
     <ProgressBar
         android:id="@+id/progressBar"