Fix elevation overlay on pre-lolipop (#475)

app/src/main/java/io/github/wulkanowy/ui/modules/attendance/AttendanceFragment.kt

@@ -17,11 +17,13 @@ import io.github.wulkanowy.ui.base.BaseFragment
 import io.github.wulkanowy.ui.modules.attendance.summary.AttendanceSummaryFragment
 import io.github.wulkanowy.ui.modules.main.MainActivity
 import io.github.wulkanowy.ui.modules.main.MainView
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.setOnItemClickListener
 import kotlinx.android.synthetic.main.fragment_attendance.*
 import javax.inject.Inject
 
-class AttendanceFragment : BaseFragment(), AttendanceView, MainView.MainChildView, MainView.TitledView {
+class AttendanceFragment : BaseFragment(), AttendanceView, MainView.MainChildView,
+    MainView.TitledView {
 
     @Inject
     lateinit var presenter: AttendancePresenter
@@ -35,14 +37,11 @@ class AttendanceFragment : BaseFragment(), AttendanceView, MainView.MainChildVie
         fun newInstance() = AttendanceFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.attendance_title
-        get() = R.string.attendance_title
 
-    override val isViewEmpty: Boolean
+    override val isViewEmpty get() = attendanceAdapter.isEmpty
-        get() = attendanceAdapter.isEmpty
 
-    override val currentStackSize: Int?
+    override val currentStackSize get() = (activity as? MainActivity)?.currentStackSize
-        get() = (activity as? MainActivity)?.currentStackSize
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -60,19 +59,21 @@ class AttendanceFragment : BaseFragment(), AttendanceView, MainView.MainChildVie
     }
 
     override fun initView() {
-        attendanceAdapter.setOnItemClickListener { presenter.onAttendanceItemSelected(it) }
+        attendanceAdapter.setOnItemClickListener(presenter::onAttendanceItemSelected)
 
-        attendanceRecycler.run {
+        with(attendanceRecycler) {
             layoutManager = SmoothScrollLinearLayoutManager(context)
             adapter = attendanceAdapter
             addItemDecoration(FlexibleItemDecoration(context)
                 .withDefaultDivider()
-                .withDrawDividerOnLastItem(false)
+                .withDrawDividerOnLastItem(false))
-            )
         }
-        attendanceSwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
+
+        attendanceSwipe.setOnRefreshListener(presenter::onSwipeRefresh)
         attendancePreviousButton.setOnClickListener { presenter.onPreviousDay() }
         attendanceNextButton.setOnClickListener { presenter.onNextDay() }
+
+        attendanceNavContainer.setElevationCompat(requireContext().dpToPx(8f))
     }
 
     override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {

app/src/main/java/io/github/wulkanowy/ui/modules/attendance/summary/AttendanceSummaryFragment.kt

@@ -15,6 +15,7 @@ import eu.davidea.flexibleadapter.items.AbstractFlexibleItem
 import io.github.wulkanowy.R
 import io.github.wulkanowy.ui.base.BaseFragment
 import io.github.wulkanowy.ui.modules.main.MainView
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.setOnItemSelectedListener
 import kotlinx.android.synthetic.main.fragment_attendance_summary.*
 import javax.inject.Inject
@@ -35,11 +36,9 @@ class AttendanceSummaryFragment : BaseFragment(), AttendanceSummaryView, MainVie
         fun newInstance() = AttendanceSummaryFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.attendance_title
-        get() = R.string.attendance_title
 
-    override val isViewEmpty
+    override val isViewEmpty get() = attendanceSummaryAdapter.isEmpty
-        get() = attendanceSummaryAdapter.isEmpty
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
         return inflater.inflate(R.layout.fragment_attendance_summary, container, false)
@@ -52,25 +51,26 @@ class AttendanceSummaryFragment : BaseFragment(), AttendanceSummaryView, MainVie
     }
 
     override fun initView() {
-        attendanceSummaryRecycler.run {
+        with(attendanceSummaryRecycler) {
             layoutManager = SmoothScrollLinearLayoutManager(context)
             adapter = attendanceSummaryAdapter
         }
-        attendanceSummarySwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
 
-        context?.let {
+        attendanceSummarySwipe.setOnRefreshListener(presenter::onSwipeRefresh)
-            subjectsAdapter = ArrayAdapter(it, android.R.layout.simple_spinner_item, ArrayList<String>())
+
+        subjectsAdapter = ArrayAdapter(requireContext(), android.R.layout.simple_spinner_item, mutableListOf())
         subjectsAdapter.setDropDownViewResource(R.layout.item_attendance_summary_subject)
+
+        with(attendanceSummarySubjects) {
+            adapter = subjectsAdapter
+            setOnItemSelectedListener<TextView> { presenter.onSubjectSelected(it?.text?.toString()) }
         }
 
-        attendanceSummarySubjects.run {
+        attendanceSummarySubjectsContainer.setElevationCompat(requireContext().dpToPx(1f))
-            adapter = subjectsAdapter
-            setOnItemSelectedListener { presenter.onSubjectSelected((it as TextView).text.toString()) }
-        }
     }
 
     override fun updateSubjects(data: ArrayList<String>) {
-        subjectsAdapter.run {
+        with(subjectsAdapter) {
             clear()
             addAll(data)
             notifyDataSetChanged()
@@ -78,9 +78,9 @@ class AttendanceSummaryFragment : BaseFragment(), AttendanceSummaryView, MainVie
     }
 
     override fun updateDataSet(data: List<AttendanceSummaryItem>, header: AttendanceSummaryScrollableHeader) {
-        attendanceSummaryAdapter.apply {
+        with(attendanceSummaryAdapter) {
             updateDataSet(data, true)
-            removeAllScrollableHeaders()
+            removeAllScrollableFooters()
             addScrollableHeader(header)
         }
     }

app/src/main/java/io/github/wulkanowy/ui/modules/attendance/summary/AttendanceSummaryPresenter.kt

@@ -46,7 +46,7 @@ class AttendanceSummaryPresenter @Inject constructor(
         loadData(currentSubjectId, true)
     }
 
-    fun onSubjectSelected(name: String) {
+    fun onSubjectSelected(name: String?) {
         Timber.i("Select attendance summary subject $name")
         view?.run {
             showContent(false)

app/src/main/java/io/github/wulkanowy/ui/modules/exam/ExamFragment.kt

@@ -16,6 +16,7 @@ import io.github.wulkanowy.data.db.entities.Exam
 import io.github.wulkanowy.ui.base.BaseFragment
 import io.github.wulkanowy.ui.modules.main.MainActivity
 import io.github.wulkanowy.ui.modules.main.MainView
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.setOnItemClickListener
 import kotlinx.android.synthetic.main.fragment_exam.*
 import javax.inject.Inject
@@ -34,11 +35,9 @@ class ExamFragment : BaseFragment(), ExamView, MainView.MainChildView, MainView.
         fun newInstance() = ExamFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.exam_title
-        get() = R.string.exam_title
 
-    override val isViewEmpty: Boolean
+    override val isViewEmpty get() = examAdapter.isEmpty
-        get() = examAdapter.isEmpty
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
         return inflater.inflate(R.layout.fragment_exam, container, false)
@@ -51,20 +50,21 @@ class ExamFragment : BaseFragment(), ExamView, MainView.MainChildView, MainView.
     }
 
     override fun initView() {
-        examAdapter.run {
+        examAdapter.setOnItemClickListener(presenter::onExamItemSelected)
-            setOnItemClickListener { presenter.onExamItemSelected(it) }
+
-        }
+        with(examRecycler) {
-        examRecycler.run {
             layoutManager = SmoothScrollLinearLayoutManager(context)
             adapter = examAdapter
             addItemDecoration(FlexibleItemDecoration(context)
                 .withDefaultDivider(R.layout.item_exam)
-                .withDrawDividerOnLastItem(false)
+                .withDrawDividerOnLastItem(false))
-            )
         }
-        examSwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
+
+        examSwipe.setOnRefreshListener(presenter::onSwipeRefresh)
         examPreviousButton.setOnClickListener { presenter.onPreviousWeek() }
         examNextButton.setOnClickListener { presenter.onNextWeek() }
+
+        examNavContainer.setElevationCompat(requireContext().dpToPx(8f))
     }
 
     override fun hideRefresh() {

app/src/main/java/io/github/wulkanowy/ui/modules/grade/GradeFragment.kt

@@ -17,6 +17,7 @@ import io.github.wulkanowy.ui.modules.grade.details.GradeDetailsFragment
 import io.github.wulkanowy.ui.modules.grade.statistics.GradeStatisticsFragment
 import io.github.wulkanowy.ui.modules.grade.summary.GradeSummaryFragment
 import io.github.wulkanowy.ui.modules.main.MainView
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.setOnSelectPageListener
 import kotlinx.android.synthetic.main.fragment_grade.*
 import javax.inject.Inject
@@ -37,11 +38,9 @@ class GradeFragment : BaseFragment(), GradeView, MainView.MainChildView, MainVie
         fun newInstance() = GradeFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.grade_title
-        get() = R.string.grade_title
 
-    override val currentPageIndex: Int
+    override val currentPageIndex get() = gradeViewPager.currentItem
-        get() = gradeViewPager.currentItem
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -64,7 +63,7 @@ class GradeFragment : BaseFragment(), GradeView, MainView.MainChildView, MainVie
     }
 
     override fun initView() {
-        pagerAdapter.apply {
+        with(pagerAdapter) {
             containerId = gradeViewPager.id
             addFragmentsWithTitle(mapOf(
                 GradeDetailsFragment.newInstance() to getString(R.string.all_details),
@@ -73,14 +72,18 @@ class GradeFragment : BaseFragment(), GradeView, MainView.MainChildView, MainVie
             ))
         }
 
-        gradeViewPager.run {
+        with(gradeViewPager) {
             adapter = pagerAdapter
             offscreenPageLimit = 3
-            setOnSelectPageListener { presenter.onPageSelected(it) }
+            setOnSelectPageListener(presenter::onPageSelected)
         }
 
-        gradeTabLayout.setupWithViewPager(gradeViewPager)
+        with(gradeTabLayout) {
-        gradeSwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
+            setupWithViewPager(gradeViewPager)
+            setElevationCompat(context.dpToPx(4f))
+        }
+
+        gradeSwipe.setOnRefreshListener(presenter::onSwipeRefresh)
     }
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
@@ -118,11 +121,13 @@ class GradeFragment : BaseFragment(), GradeView, MainView.MainChildView, MainVie
     }
 
     override fun showSemesterDialog(selectedIndex: Int) {
-        arrayOf(getString(R.string.grade_semester, 1),
+        val choices = arrayOf(
-            getString(R.string.grade_semester, 2)).also { array ->
+            getString(R.string.grade_semester, 1),
-            context?.let {
+            getString(R.string.grade_semester, 2)
-                AlertDialog.Builder(it)
+        )
-                    .setSingleChoiceItems(array, selectedIndex) { dialog, which ->
+
+        AlertDialog.Builder(requireContext())
+            .setSingleChoiceItems(choices, selectedIndex) { dialog, which ->
                 presenter.onSemesterSelected(which)
                 dialog.dismiss()
             }
@@ -130,8 +135,6 @@ class GradeFragment : BaseFragment(), GradeView, MainView.MainChildView, MainVie
             .setNegativeButton(android.R.string.cancel) { _, _ -> }
             .show()
     }
-        }
-    }
 
     fun onChildRefresh() {
         presenter.onChildViewRefresh()

app/src/main/java/io/github/wulkanowy/ui/modules/grade/statistics/GradeStatisticsFragment.kt

@@ -19,6 +19,7 @@ import io.github.wulkanowy.data.db.entities.GradeStatistics
 import io.github.wulkanowy.ui.base.BaseFragment
 import io.github.wulkanowy.ui.modules.grade.GradeFragment
 import io.github.wulkanowy.ui.modules.grade.GradeView
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.getThemeAttrColor
 import io.github.wulkanowy.utils.setOnItemSelectedListener
 import kotlinx.android.synthetic.main.fragment_grade_statistics.*
@@ -37,8 +38,7 @@ class GradeStatisticsFragment : BaseFragment(), GradeStatisticsView, GradeView.G
         fun newInstance() = GradeStatisticsFragment()
     }
 
-    override val isViewEmpty
+    override val isViewEmpty get() = gradeStatisticsChart.isEmpty
-        get() = gradeStatisticsChart.isEmpty
 
     private lateinit var gradeColors: List<Pair<Int, Int>>
 
@@ -75,7 +75,7 @@ class GradeStatisticsFragment : BaseFragment(), GradeStatisticsView, GradeView.G
     }
 
     override fun initView() {
-        gradeStatisticsChart.run {
+        with(gradeStatisticsChart) {
             description.isEnabled = false
             setHoleColor(context.getThemeAttrColor(android.R.attr.windowBackground))
             setCenterTextColor(context.getThemeAttrColor(android.R.attr.textColorPrimary))
@@ -84,21 +84,21 @@ class GradeStatisticsFragment : BaseFragment(), GradeStatisticsView, GradeView.G
             legend.textColor = context.getThemeAttrColor(android.R.attr.textColorPrimary)
         }
 
-        context?.let {
+        subjectsAdapter = ArrayAdapter(requireContext(), android.R.layout.simple_spinner_item, mutableListOf())
-            subjectsAdapter = ArrayAdapter(it, android.R.layout.simple_spinner_item, ArrayList<String>())
         subjectsAdapter.setDropDownViewResource(R.layout.item_attendance_summary_subject)
-        }
 
-        gradeStatisticsSubjects.run {
+        with(gradeStatisticsSubjects) {
             adapter = subjectsAdapter
-            setOnItemSelectedListener { presenter.onSubjectSelected((it as TextView).text.toString()) }
+            setOnItemSelectedListener<TextView> { presenter.onSubjectSelected(it?.text?.toString()) }
         }
 
-        gradeStatisticsSwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
+        gradeStatisticsSwipe.setOnRefreshListener(presenter::onSwipeRefresh)
+
+        gradeStatisticsSubjectsContainer.setElevationCompat(requireContext().dpToPx(1f))
     }
 
     override fun updateSubjects(data: ArrayList<String>) {
-        subjectsAdapter.run {
+        with(subjectsAdapter) {
             clear()
             addAll(data)
             notifyDataSetChanged()
@@ -202,7 +202,7 @@ class GradeStatisticsFragment : BaseFragment(), GradeStatisticsView, GradeView.G
 
     override fun onSaveInstanceState(outState: Bundle) {
         super.onSaveInstanceState(outState)
-        outState.putBoolean(GradeStatisticsFragment.SAVED_CHART_TYPE, presenter.currentIsSemester)
+        outState.putBoolean(SAVED_CHART_TYPE, presenter.currentIsSemester)
     }
 
     override fun onDestroyView() {

app/src/main/java/io/github/wulkanowy/ui/modules/grade/statistics/GradeStatisticsPresenter.kt

@@ -62,7 +62,7 @@ class GradeStatisticsPresenter @Inject constructor(
         view?.notifyParentRefresh()
     }
 
-    fun onSubjectSelected(name: String) {
+    fun onSubjectSelected(name: String?) {
         Timber.i("Select grade stats subject $name")
         view?.run {
             showContent(false)
@@ -71,8 +71,8 @@ class GradeStatisticsPresenter @Inject constructor(
             showEmpty(false)
             clearView()
         }
-        (subjects.singleOrNull { it.name == name }?.name).let {
+        (subjects.singleOrNull { it.name == name }?.name)?.let {
-            if (it != currentSubjectName) loadData(currentSemesterId, name, currentIsSemester)
+            if (it != currentSubjectName) loadData(currentSemesterId, it, currentIsSemester)
         }
     }
 

app/src/main/java/io/github/wulkanowy/ui/modules/homework/HomeworkFragment.kt

@@ -13,6 +13,7 @@ import io.github.wulkanowy.data.db.entities.Homework
 import io.github.wulkanowy.ui.base.BaseFragment
 import io.github.wulkanowy.ui.modules.main.MainActivity
 import io.github.wulkanowy.ui.modules.main.MainView
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.setOnItemClickListener
 import kotlinx.android.synthetic.main.fragment_homework.*
 import javax.inject.Inject
@@ -31,8 +32,7 @@ class HomeworkFragment : BaseFragment(), HomeworkView, MainView.TitledView {
         fun newInstance() = HomeworkFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.homework_title
-        get() = R.string.homework_title
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
         return inflater.inflate(R.layout.fragment_homework, container, false)
@@ -45,21 +45,21 @@ class HomeworkFragment : BaseFragment(), HomeworkView, MainView.TitledView {
     }
 
     override fun initView() {
-        homeworkAdapter.run {
+        homeworkAdapter.setOnItemClickListener(presenter::onHomeworkItemSelected)
-            setOnItemClickListener { presenter.onHomeworkItemSelected(it) }
-        }
 
-        homeworkRecycler.run {
+        with(homeworkRecycler) {
             layoutManager = SmoothScrollLinearLayoutManager(context)
             adapter = homeworkAdapter
             addItemDecoration(FlexibleItemDecoration(context)
                 .withDefaultDivider()
-                .withDrawDividerOnLastItem(false)
+                .withDrawDividerOnLastItem(false))
-            )
         }
-        homeworkSwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
+
+        homeworkSwipe.setOnRefreshListener(presenter::onSwipeRefresh)
         homeworkPreviousButton.setOnClickListener { presenter.onPreviousDay() }
         homeworkNextButton.setOnClickListener { presenter.onNextDay() }
+
+        homeworkNavContainer.setElevationCompat(requireContext().dpToPx(8f))
     }
 
     override fun updateData(data: List<HomeworkItem>) {
@@ -110,7 +110,7 @@ class HomeworkFragment : BaseFragment(), HomeworkView, MainView.TitledView {
 
     override fun onSaveInstanceState(outState: Bundle) {
         super.onSaveInstanceState(outState)
-        outState.putLong(HomeworkFragment.SAVED_DATE_KEY, presenter.currentDate.toEpochDay())
+        outState.putLong(SAVED_DATE_KEY, presenter.currentDate.toEpochDay())
     }
 
     override fun onDestroyView() {

app/src/main/java/io/github/wulkanowy/ui/modules/message/MessageFragment.kt

@@ -16,6 +16,7 @@ import io.github.wulkanowy.ui.base.BaseFragmentPagerAdapter
 import io.github.wulkanowy.ui.modules.main.MainView
 import io.github.wulkanowy.ui.modules.message.send.SendMessageActivity
 import io.github.wulkanowy.ui.modules.message.tab.MessageTabFragment
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.setOnSelectPageListener
 import kotlinx.android.synthetic.main.fragment_message.*
 import javax.inject.Inject
@@ -32,11 +33,9 @@ class MessageFragment : BaseFragment(), MessageView, MainView.TitledView {
         fun newInstance() = MessageFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.message_title
-        get() = R.string.message_title
 
-    override val currentPageIndex: Int
+    override val currentPageIndex get() = messageViewPager.currentItem
-        get() = messageViewPager.currentItem
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
         return inflater.inflate(R.layout.fragment_message, container, false)
@@ -48,7 +47,7 @@ class MessageFragment : BaseFragment(), MessageView, MainView.TitledView {
     }
 
     override fun initView() {
-        pagerAdapter.apply {
+        with(pagerAdapter) {
             containerId = messageViewPager.id
             addFragmentsWithTitle(mapOf(
                 MessageTabFragment.newInstance(RECEIVED) to getString(R.string.message_inbox),
@@ -57,12 +56,16 @@ class MessageFragment : BaseFragment(), MessageView, MainView.TitledView {
             ))
         }
 
-        messageViewPager.run {
+        with(messageViewPager) {
             adapter = pagerAdapter
             offscreenPageLimit = 2
-            setOnSelectPageListener { presenter.onPageSelected(it) }
+            setOnSelectPageListener(presenter::onPageSelected)
+        }
+
+        with(messageTabLayout) {
+            setupWithViewPager(messageViewPager)
+            setElevationCompat(context.dpToPx(4f))
         }
-        messageTabLayout.setupWithViewPager(messageViewPager)
 
         openSendMessageButton.setOnClickListener { presenter.onSendMessageButtonClicked() }
     }

app/src/main/java/io/github/wulkanowy/ui/modules/timetable/TimetableFragment.kt

@@ -17,11 +17,13 @@ import io.github.wulkanowy.ui.base.BaseFragment
 import io.github.wulkanowy.ui.modules.main.MainActivity
 import io.github.wulkanowy.ui.modules.main.MainView
 import io.github.wulkanowy.ui.modules.timetable.completed.CompletedLessonsFragment
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.setOnItemClickListener
 import kotlinx.android.synthetic.main.fragment_timetable.*
 import javax.inject.Inject
 
-class TimetableFragment : BaseFragment(), TimetableView, MainView.MainChildView, MainView.TitledView {
+class TimetableFragment : BaseFragment(), TimetableView, MainView.MainChildView,
+    MainView.TitledView {
 
     @Inject
     lateinit var presenter: TimetablePresenter
@@ -35,17 +37,13 @@ class TimetableFragment : BaseFragment(), TimetableView, MainView.MainChildView,
         fun newInstance() = TimetableFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.timetable_title
-        get() = R.string.timetable_title
 
-    override val roomString: String
+    override val roomString get() = getString(R.string.timetable_room)
-        get() = getString(R.string.timetable_room)
 
-    override val isViewEmpty: Boolean
+    override val isViewEmpty get() = timetableAdapter.isEmpty
-        get() = timetableAdapter.isEmpty
 
-    override val currentStackSize: Int?
+    override val currentStackSize get() = (activity as? MainActivity)?.currentStackSize
-        get() = (activity as? MainActivity)?.currentStackSize
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -63,11 +61,9 @@ class TimetableFragment : BaseFragment(), TimetableView, MainView.MainChildView,
     }
 
     override fun initView() {
-        timetableAdapter.run {
+        timetableAdapter.setOnItemClickListener(presenter::onTimetableItemSelected)
-            setOnItemClickListener { presenter.onTimetableItemSelected(it) }
-        }
 
-        timetableRecycler.run {
+        with(timetableRecycler) {
             layoutManager = SmoothScrollLinearLayoutManager(context)
             adapter = timetableAdapter
             addItemDecoration(FlexibleItemDecoration(context)
@@ -75,9 +71,12 @@ class TimetableFragment : BaseFragment(), TimetableView, MainView.MainChildView,
                 .withDrawDividerOnLastItem(false)
             )
         }
-        timetableSwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
+
+        timetableSwipe.setOnRefreshListener(presenter::onSwipeRefresh)
         timetablePreviousButton.setOnClickListener { presenter.onPreviousDay() }
         timetableNextButton.setOnClickListener { presenter.onNextDay() }
+
+        timetableNavContainer.setElevationCompat(requireContext().dpToPx(8f))
     }
 
     override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {

app/src/main/java/io/github/wulkanowy/ui/modules/timetable/completed/CompletedLessonsFragment.kt

@@ -12,6 +12,7 @@ import io.github.wulkanowy.data.db.entities.CompletedLesson
 import io.github.wulkanowy.ui.base.BaseFragment
 import io.github.wulkanowy.ui.modules.main.MainActivity
 import io.github.wulkanowy.ui.modules.main.MainView
+import io.github.wulkanowy.utils.dpToPx
 import io.github.wulkanowy.utils.getCompatDrawable
 import io.github.wulkanowy.utils.setOnItemClickListener
 import kotlinx.android.synthetic.main.fragment_timetable_completed.*
@@ -31,11 +32,9 @@ class CompletedLessonsFragment : BaseFragment(), CompletedLessonsView, MainView.
         fun newInstance() = CompletedLessonsFragment()
     }
 
-    override val titleStringId: Int
+    override val titleStringId get() = R.string.completed_lessons_title
-        get() = R.string.completed_lessons_title
 
-    override val isViewEmpty
+    override val isViewEmpty get() = completedLessonsAdapter.isEmpty
-        get() = completedLessonsAdapter.isEmpty
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
         return inflater.inflate(R.layout.fragment_timetable_completed, container, false)
@@ -48,17 +47,18 @@ class CompletedLessonsFragment : BaseFragment(), CompletedLessonsView, MainView.
     }
 
     override fun initView() {
-        completedLessonsAdapter.run {
+        completedLessonsAdapter.setOnItemClickListener(presenter::onCompletedLessonsItemSelected)
-            setOnItemClickListener { presenter.onCompletedLessonsItemSelected(it) }
-        }
 
-        completedLessonsRecycler.run {
+        with(completedLessonsRecycler) {
             layoutManager = SmoothScrollLinearLayoutManager(context)
             adapter = completedLessonsAdapter
         }
-        completedLessonsSwipe.setOnRefreshListener { presenter.onSwipeRefresh() }
+
+        completedLessonsSwipe.setOnRefreshListener(presenter::onSwipeRefresh)
         completedLessonsPreviousButton.setOnClickListener { presenter.onPreviousDay() }
         completedLessonsNextButton.setOnClickListener { presenter.onNextDay() }
+
+        completedLessonsNavContainer.setElevationCompat(requireContext().dpToPx(8f))
     }
 
     override fun updateData(data: List<CompletedLessonItem>) {
@@ -82,10 +82,8 @@ class CompletedLessonsFragment : BaseFragment(), CompletedLessonsView, MainView.
     }
 
     override fun showFeatureDisabled() {
-        context?.let {
         completedLessonsInfo.text = getString(R.string.error_feature_disabled)
-            completedLessonsInfoImage.setImageDrawable(it.getCompatDrawable(R.drawable.ic_all_close_circle))
+        completedLessonsInfoImage.setImageDrawable(requireContext().getCompatDrawable(R.drawable.ic_all_close_circle))
-        }
     }
 
     override fun showProgress(show: Boolean) {
@@ -114,7 +112,7 @@ class CompletedLessonsFragment : BaseFragment(), CompletedLessonsView, MainView.
 
     override fun onSaveInstanceState(outState: Bundle) {
         super.onSaveInstanceState(outState)
-        outState.putLong(CompletedLessonsFragment.SAVED_DATE_KEY, presenter.currentDate.toEpochDay())
+        outState.putLong(SAVED_DATE_KEY, presenter.currentDate.toEpochDay())
     }
 
     override fun onDestroyView() {

app/src/main/java/io/github/wulkanowy/ui/widgets/FittedScrollableTabLayout.kt

@@ -1,14 +1,13 @@
-package io.github.wulkanowy.ui.modules.grade
+package io.github.wulkanowy.ui.widgets
 
 import android.content.Context
 import android.util.AttributeSet
 import android.view.ViewGroup
-import com.google.android.material.tabs.TabLayout
 
 /**
  * @see <a href="https://stackoverflow.com/a/50382854">Tabs don't fit to screen with tabmode=scrollable, Even with a Custom Tab Layout</a>
  */
-class CustomTabLayout : TabLayout {
+class FittedScrollableTabLayout : MaterialTabLayout {
 
     constructor(context: Context) : super(context)
 

app/src/main/java/io/github/wulkanowy/ui/widgets/MaterialLinearLayout.kt

@@ -1,11 +1,12 @@
 package io.github.wulkanowy.ui.widgets
 
 import android.content.Context
+import android.os.Build.VERSION.SDK_INT
 import android.os.Build.VERSION_CODES.LOLLIPOP
 import android.util.AttributeSet
 import android.widget.LinearLayout
-import androidx.annotation.RequiresApi
 import androidx.core.view.ViewCompat
+import com.google.android.material.elevation.ElevationOverlayProvider
 import com.google.android.material.shape.MaterialShapeDrawable
 
 class MaterialLinearLayout : LinearLayout {
@@ -21,11 +22,18 @@ class MaterialLinearLayout : LinearLayout {
         ViewCompat.setBackground(this, drawable)
     }
 
-    @RequiresApi(LOLLIPOP)
     override fun setElevation(elevation: Float) {
         super.setElevation(elevation)
         if (background is MaterialShapeDrawable) {
             (background as MaterialShapeDrawable).elevation = elevation
         }
     }
+
+    fun setElevationCompat(elevation: Float) {
+        if (SDK_INT >= LOLLIPOP) {
+            setElevation(elevation)
+        } else {
+            setBackgroundColor(ElevationOverlayProvider(context).getSurfaceColorWithOverlayIfNeeded(elevation))
+        }
+    }
 }

app/src/main/java/io/github/wulkanowy/ui/widgets/MaterialTabLayout.kt

@@ -0,0 +1,25 @@
+package io.github.wulkanowy.ui.widgets
+
+import android.content.Context
+import android.os.Build.VERSION.SDK_INT
+import android.os.Build.VERSION_CODES.LOLLIPOP
+import android.util.AttributeSet
+import com.google.android.material.elevation.ElevationOverlayProvider
+import com.google.android.material.tabs.TabLayout
+
+open class MaterialTabLayout : TabLayout {
+
+    constructor(context: Context) : super(context)
+
+    constructor(context: Context, attr: AttributeSet) : super(context, attr)
+
+    constructor(context: Context, attr: AttributeSet, defStyleAttr: Int) : super(context, attr, defStyleAttr)
+
+    fun setElevationCompat(elevation: Float) {
+        if (SDK_INT >= LOLLIPOP) {
+            setElevation(elevation)
+        } else {
+            setBackgroundColor(ElevationOverlayProvider(context).getSurfaceColorWithOverlayIfNeeded(elevation))
+        }
+    }
+}

app/src/main/java/io/github/wulkanowy/utils/SpinnerExtension.kt

@@ -7,14 +7,15 @@ import android.widget.Spinner
 /**
  * @see <a href="https://stackoverflow.com/a/29602298">How to keep onItemSelected from firing off on a newly instantiated Spinner?</a>
  */
-inline fun Spinner.setOnItemSelectedListener(crossinline listener: (view: View?) -> Unit) {
+@Suppress("UNCHECKED_CAST")
+inline fun <T : View> Spinner.setOnItemSelectedListener(crossinline listener: (view: T?) -> Unit) {
     onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
         override fun onNothingSelected(parent: AdapterView<*>?) {}
         override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
             onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
                 override fun onNothingSelected(parent: AdapterView<*>?) {}
                 override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
-                    listener(view)
+                    listener(view as T?)
                 }
             }
         }

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

@@ -60,7 +60,6 @@
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_gravity="bottom"
-        android:elevation="8dp"
         android:orientation="horizontal"
         tools:ignore="UnusedAttribute">
 

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

@@ -15,7 +15,6 @@
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:background="?android:windowBackground"
-            android:elevation="1dp"
             android:padding="5dp"
             android:visibility="invisible"
             tools:ignore="UnusedAttribute"

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

@@ -60,7 +60,6 @@
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_gravity="bottom"
-        android:elevation="8dp"
         android:orientation="horizontal"
         tools:ignore="UnusedAttribute">
 

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

@@ -5,12 +5,11 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
-    <io.github.wulkanowy.ui.modules.grade.CustomTabLayout
+    <io.github.wulkanowy.ui.widgets.FittedScrollableTabLayout
         android:id="@+id/gradeTabLayout"
         android:layout_width="match_parent"
         android:layout_height="48dp"
         android:background="?colorSurface"
-        android:elevation="4dp"
         android:visibility="invisible"
         app:tabMode="scrollable"
         app:tabSelectedTextColor="?colorPrimary"

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

@@ -11,7 +11,6 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:background="?android:windowBackground"
-        android:elevation="1dp"
         android:padding="5dp"
         android:visibility="invisible"
         tools:ignore="UnusedAttribute"

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

@@ -60,7 +60,6 @@
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_gravity="bottom"
-        android:elevation="8dp"
         android:orientation="horizontal"
         tools:ignore="UnusedAttribute">
 

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

@@ -5,12 +5,11 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
-    <com.google.android.material.tabs.TabLayout
+    <io.github.wulkanowy.ui.widgets.MaterialTabLayout
         android:id="@+id/messageTabLayout"
         android:layout_width="match_parent"
         android:layout_height="48dp"
         android:background="?colorSurface"
-        android:elevation="4dp"
         android:visibility="invisible"
         app:tabGravity="fill"
         app:tabIndicatorColor="?colorPrimary"

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

@@ -60,7 +60,6 @@
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_gravity="bottom"
-        android:elevation="8dp"
         android:orientation="horizontal"
         tools:ignore="UnusedAttribute">
 

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

@@ -64,7 +64,6 @@
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_gravity="bottom"
-        android:elevation="8dp"
         android:orientation="horizontal"
         tools:ignore="UnusedAttribute">