timer UI improvements + bug fixes

- add page indicator
- add default timer based on saved prefs when the database is created
- post scolling to the first timer when a new timer is added

app/src/main/kotlin/com/simplemobiletools/clock/databases/AppDatabase.kt

@@ -5,9 +5,12 @@ import androidx.room.Database
 import androidx.room.Room
 import androidx.room.RoomDatabase
 import androidx.room.TypeConverters
+import androidx.sqlite.db.SupportSQLiteDatabase
+import com.simplemobiletools.clock.extensions.config
 import com.simplemobiletools.clock.helpers.Converters
 import com.simplemobiletools.clock.interfaces.TimerDao
 import com.simplemobiletools.clock.models.Timer
+import java.util.concurrent.Executors
 
 @Database(entities = [Timer::class], version = 1)
 @TypeConverters(Converters::class)
@@ -23,6 +26,12 @@ abstract class AppDatabase : RoomDatabase() {
                 synchronized(AppDatabase::class) {
                     if (db == null) {
                         db = Room.databaseBuilder(context.applicationContext, AppDatabase::class.java, "app.db")
+                            .addCallback(object : Callback() {
+                                override fun onCreate(db: SupportSQLiteDatabase) {
+                                    super.onCreate(db)
+                                    insertDefaultTimer(context)
+                                }
+                            })
                             .build()
                         db!!.openHelper.setWriteAheadLoggingEnabled(true)
                     }
@@ -31,6 +40,25 @@ abstract class AppDatabase : RoomDatabase() {
             return db!!
         }
 
+        private fun insertDefaultTimer(context: Context) {
+            Executors.newSingleThreadScheduledExecutor().execute {
+                val config = context.config
+                db!!.TimerDao().insertOrUpdateTimer(
+                    Timer(
+                        id = null,
+                        seconds = config.timerSeconds,
+                        state = config.timerState,
+                        vibrate = config.timerVibrate,
+                        soundUri = config.timerSoundUri,
+                        soundTitle = config.timerSoundTitle,
+                        label = config.timerLabel ?: "",
+                        createdAt = System.currentTimeMillis(),
+                        channelId = config.timerChannelId,
+                    )
+                )
+            }
+        }
+
         fun destroyInstance() {
             db = null
         }

app/src/main/kotlin/com/simplemobiletools/clock/fragments/TimerFragment.kt

@@ -53,10 +53,20 @@ class TimerFragment : Fragment() {
             timer_view_pager.setPageTransformer { _, _ -> }
             timer_view_pager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
                 override fun onPageSelected(position: Int) {
+                    Log.i(TAG, "onPageSelected: $position")
                     updateViews(position)
+                    indicator_view.setCurrentPosition(0)
                 }
             })
 
+            activity?.let {
+                val textColor = it.config.textColor
+                indicator_view.setSelectedDotColor(textColor)
+                indicator_view.setDotColor(textColor.adjustAlpha(0.5f))
+                indicator_view.attachToPager(timer_view_pager)
+            }
+
+
             timer_add.setOnClickListener {
                 activity?.hideKeyboard(it)
                 activity?.timerHelper?.insertNewTimer {
@@ -101,14 +111,12 @@ class TimerFragment : Fragment() {
 
     private fun updateViews(position: Int) {
         activity?.runOnUiThread {
-            if (timerAdapter.itemCount > 0) {
+            if (timerAdapter.itemCount > position) {
                 val timer = timerAdapter.getItemAt(position)
                 updateViewStates(timer.state)
                 view.timer_play_pause.beVisible()
             } else {
-                view.timer_delete.beGone()
-                view.timer_play_pause.beGone()
-                view.timer_reset.beGone()
+                Log.e(TAG, "updateViews: position $position is greater than adapter itemCount ${timerAdapter.itemCount}")
             }
         }
     }
@@ -117,15 +125,18 @@ class TimerFragment : Fragment() {
         activity?.timerHelper?.getTimers { timers ->
             Log.d(TAG, "refreshTimers: $timers")
             timerAdapter.submitList(timers) {
-                Log.e(TAG, "submitted list: timerPositionToScrollTo=$timerPositionToScrollTo")
-                if (timerPositionToScrollTo != INVALID_POSITION && timerAdapter.itemCount > timerPositionToScrollTo) {
-                    Log.e(TAG, "scrolling to position=$timerPositionToScrollTo")
-                    view.timer_view_pager.setCurrentItem(timerPositionToScrollTo, false)
-                    timerPositionToScrollTo = INVALID_POSITION
-                } else if (scrollToLatest) {
-                    view.timer_view_pager.setCurrentItem(0, false)
+                view.timer_view_pager.post {
+                    Log.e(TAG, "submitted list: timerPositionToScrollTo=$timerPositionToScrollTo")
+                    if (timerPositionToScrollTo != INVALID_POSITION && timerAdapter.itemCount > timerPositionToScrollTo) {
+                        Log.e(TAG, "scrolling to position=$timerPositionToScrollTo")
+                        view.timer_view_pager.setCurrentItem(timerPositionToScrollTo, false)
+                        timerPositionToScrollTo = INVALID_POSITION
+                    } else if (scrollToLatest) {
+                        Log.e(TAG, "scrolling to latest")
+                        view.timer_view_pager.setCurrentItem(0, false)
+                    }
+                    updateViews(timer_view_pager.currentItem)
                 }
-                updateViews(timer_view_pager.currentItem)
             }
         }
     }

app/src/main/kotlin/com/simplemobiletools/clock/helpers/TimerHelper.kt

@@ -1,13 +1,10 @@
 package com.simplemobiletools.clock.helpers
 
 import android.content.Context
-import android.media.RingtoneManager
 import android.util.Log
+import com.simplemobiletools.clock.extensions.config
 import com.simplemobiletools.clock.extensions.timerDb
 import com.simplemobiletools.clock.models.Timer
-import com.simplemobiletools.clock.models.TimerState
-import com.simplemobiletools.commons.extensions.getDefaultAlarmSound
-import com.simplemobiletools.commons.extensions.getDefaultAlarmTitle
 import com.simplemobiletools.commons.helpers.ensureBackgroundThread
 
 class TimerHelper(val context: Context) {
@@ -42,17 +39,18 @@ class TimerHelper(val context: Context) {
 
     fun insertNewTimer(callback: () -> Unit = {}) {
         ensureBackgroundThread {
+            val config = context.config
             timerDao.insertOrUpdateTimer(
                 Timer(
                     id = null,
-//                    seconds = DEFAULT_TIME,
-                    seconds = 5,
-                    TimerState.Idle,
-                    false,
-                    context.getDefaultAlarmSound(RingtoneManager.TYPE_ALARM).uri,
-                    context.getDefaultAlarmTitle(RingtoneManager.TYPE_ALARM),
-                    "",
-                    System.currentTimeMillis(),
+                    seconds = config.timerSeconds,
+                    state = config.timerState,
+                    vibrate = config.timerVibrate,
+                    soundUri = config.timerSoundUri,
+                    soundTitle = config.timerSoundTitle,
+                    label = config.timerLabel ?: "",
+                    createdAt = System.currentTimeMillis(),
+                    channelId = config.timerChannelId,
                 )
             )
 

app/src/main/kotlin/com/simplemobiletools/clock/views/pageindicator/PagerIndicator.kt

@@ -0,0 +1,577 @@
+package com.simplemobiletools.clock.views.pageindicator
+
+import android.animation.ArgbEvaluator
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.Paint
+import android.util.AttributeSet
+import android.util.SparseArray
+import android.view.View
+import android.widget.LinearLayout
+import androidx.annotation.ColorInt
+import androidx.annotation.IntDef
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.viewpager2.widget.ViewPager2
+import com.simplemobiletools.clock.R
+
+/**
+ * Page indicator that scrolls to selected item based on
+ * [PagerIndicator](https://github.com/TinkoffCreditSystems/PagerIndicator)
+ * */
+class PagerIndicator @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null,
+    defStyleAttr: Int = R.attr.scrollingPagerIndicatorStyle
+) : View(context, attrs, defStyleAttr) {
+    @IntDef(RecyclerView.HORIZONTAL, RecyclerView.VERTICAL)
+    annotation class Orientation
+
+    private var infiniteDotCount = 0
+    private val dotMinimumSize: Int
+    private val dotNormalSize: Int
+    private val dotSelectedSize: Int
+    private val spaceBetweenDotCenters: Int
+    private var visibleDotCount = 0
+    private var visibleDotThreshold: Int
+    private var orientation: Int
+    private var visibleFramePosition = 0f
+    private var visibleFrameWidth = 0f
+    private var firstDotOffset = 0f
+    private var dotScale: SparseArray<Float>? = null
+    private var itemCount = 0
+    private val paint: Paint
+    private val colorEvaluator = ArgbEvaluator()
+
+    @ColorInt
+    private var dotColor: Int
+
+    @ColorInt
+    private var selectedDotColor: Int
+    private var looped: Boolean
+    private var attachRunnable: Runnable? = null
+    private var currentAttacher: PagerAttacher<*>? = null
+    private var dotCountInitialized = false
+
+    /**
+     * Sets dot count
+     *
+     * @param count new dot count
+     */
+    var dotCount: Int
+        get() = if (looped && itemCount > visibleDotCount) {
+            infiniteDotCount
+        } else {
+            itemCount
+        }
+        set(count) {
+            initDots(count)
+        }
+
+    init {
+        val attributes = context.obtainStyledAttributes(
+            attrs,
+            R.styleable.PagerIndicator,
+            defStyleAttr,
+            R.style.PagerIndicator)
+        dotColor = attributes.getColor(R.styleable.PagerIndicator_spi_dotColor, 0)
+        selectedDotColor =
+            attributes.getColor(R.styleable.PagerIndicator_spi_dotSelectedColor, dotColor)
+        dotNormalSize =
+            attributes.getDimensionPixelSize(R.styleable.PagerIndicator_spi_dotSize, 0)
+        dotSelectedSize =
+            attributes.getDimensionPixelSize(R.styleable.PagerIndicator_spi_dotSelectedSize,
+                0)
+        val dotMinimumSize =
+            attributes.getDimensionPixelSize(R.styleable.PagerIndicator_spi_dotMinimumSize,
+                -1)
+        this.dotMinimumSize = if (dotMinimumSize <= dotNormalSize) dotMinimumSize else -1
+        spaceBetweenDotCenters =
+            attributes.getDimensionPixelSize(R.styleable.PagerIndicator_spi_dotSpacing,
+                0) + dotNormalSize
+        looped = attributes.getBoolean(R.styleable.PagerIndicator_spi_looped, false)
+        val visibleDotCount =
+            attributes.getInt(R.styleable.PagerIndicator_spi_visibleDotCount, 5)
+        setVisibleDotCount(visibleDotCount)
+        visibleDotThreshold =
+            attributes.getInt(R.styleable.PagerIndicator_spi_visibleDotThreshold, 2)
+        orientation = attributes.getInt(R.styleable.PagerIndicator_spi_orientation,
+            RecyclerView.HORIZONTAL)
+        attributes.recycle()
+        paint = Paint()
+        paint.isAntiAlias = true
+        if (isInEditMode) {
+            dotCount = visibleDotCount
+            onPageScrolled(visibleDotCount / 2, 0f)
+        }
+    }
+
+    /**
+     * You should make indicator looped in your PagerAttacher implementation if your custom pager is looped too
+     * If pager has less items than visible_dot_count, indicator will work as usual;
+     * otherwise it will always be in infinite state.
+     *
+     * @param looped true if pager is looped
+     */
+    fun setLooped(looped: Boolean) {
+        this.looped = looped
+        reattach()
+        invalidate()
+    }
+
+    /**
+     * @return not selected dot color
+     */
+    @ColorInt
+    fun getDotColor(): Int {
+        return dotColor
+    }
+
+    /**
+     * Sets dot color
+     *
+     * @param color dot color
+     */
+    fun setDotColor(@ColorInt color: Int) {
+        dotColor = color
+        invalidate()
+    }
+
+    /**
+     * @return the selected dot color
+     */
+    @ColorInt
+    fun getSelectedDotColor(): Int {
+        return selectedDotColor
+    }
+
+    /**
+     * Sets selected dot color
+     *
+     * @param color selected dot color
+     */
+    fun setSelectedDotColor(@ColorInt color: Int) {
+        selectedDotColor = color
+        invalidate()
+    }
+
+    /**
+     * Maximum number of dots which will be visible at the same time.
+     * If pager has more pages than visible_dot_count, indicator will scroll to show extra dots.
+     * Must be odd number.
+     *
+     * @return visible dot count
+     */
+    fun getVisibleDotCount(): Int {
+        return visibleDotCount
+    }
+
+    /**
+     * Sets visible dot count. Maximum number of dots which will be visible at the same time.
+     * If pager has more pages than visible_dot_count, indicator will scroll to show extra dots.
+     * Must be odd number.
+     *
+     * @param visibleDotCount visible dot count
+     * @throws IllegalStateException when pager is already attached
+     */
+    fun setVisibleDotCount(visibleDotCount: Int) {
+        require(visibleDotCount % 2 != 0) { "visibleDotCount must be odd" }
+        this.visibleDotCount = visibleDotCount
+        infiniteDotCount = visibleDotCount + 2
+        if (attachRunnable != null) {
+            reattach()
+        } else {
+            requestLayout()
+        }
+    }
+
+    /**
+     * The minimum number of dots which should be visible.
+     * If pager has less pages than visibleDotThreshold, no dots will be shown.
+     *
+     * @return visible dot threshold.
+     */
+    fun getVisibleDotThreshold(): Int {
+        return visibleDotThreshold
+    }
+
+    /**
+     * Sets the minimum number of dots which should be visible.
+     * If pager has less pages than visibleDotThreshold, no dots will be shown.
+     *
+     * @param visibleDotThreshold visible dot threshold.
+     */
+    fun setVisibleDotThreshold(visibleDotThreshold: Int) {
+        this.visibleDotThreshold = visibleDotThreshold
+        if (attachRunnable != null) {
+            reattach()
+        } else {
+            requestLayout()
+        }
+    }
+
+    /**
+     * The visible orientation of the dots
+     *
+     * @return dot orientation (RecyclerView.HORIZONTAL, RecyclerView.VERTICAL)
+     */
+    @Orientation
+    fun getOrientation(): Int {
+        return orientation
+    }
+
+    /**
+     * Set the dot orientation
+     *
+     * @param orientation dot orientation (RecyclerView.HORIZONTAL, RecyclerView.VERTICAL)
+     */
+    fun setOrientation(@Orientation orientation: Int) {
+        this.orientation = orientation
+        if (attachRunnable != null) {
+            reattach()
+        } else {
+            requestLayout()
+        }
+    }
+
+    /**
+     * Attaches indicator to ViewPager2
+     *
+     * @param pager pager to attach
+     */
+    fun attachToPager(pager: ViewPager2) {
+        attachToPager<ViewPager2>(pager, ViewPager2Attacher())
+    }
+
+    /**
+     * Attaches to any custom pager
+     *
+     * @param pager    pager to attach
+     * @param attacher helper which should setup this indicator to work with custom pager
+     */
+    fun <T> attachToPager(pager: T, attacher: PagerAttacher<T>) {
+        detachFromPager()
+        attacher.attachToPager(this, pager)
+        currentAttacher = attacher
+        attachRunnable = Runnable {
+            itemCount = -1
+            attachToPager(pager, attacher)
+        }
+    }
+
+    /**
+     * Detaches indicator from pager.
+     */
+    fun detachFromPager() {
+        if (currentAttacher != null) {
+            currentAttacher!!.detachFromPager()
+            currentAttacher = null
+            attachRunnable = null
+        }
+        dotCountInitialized = false
+    }
+
+    /**
+     * Detaches indicator from pager and attaches it again.
+     * It may be useful for refreshing after adapter count change.
+     */
+    fun reattach() {
+        if (attachRunnable != null) {
+            attachRunnable!!.run()
+            invalidate()
+        }
+    }
+
+    /**
+     * This method must be called from ViewPager.OnPageChangeListener.onPageScrolled or from some
+     * similar callback if you use custom PagerAttacher.
+     *
+     * @param page   index of the first page currently being displayed
+     * Page position+1 will be visible if offset is nonzero
+     * @param offset Value from [0, 1) indicating the offset from the page at position
+     */
+    fun onPageScrolled(page: Int, offset: Float) {
+        require(!(offset < 0 || offset > 1)) { "Offset must be [0, 1]" }
+        if (page < 0 || page != 0 && page >= itemCount) {
+            throw IndexOutOfBoundsException("page must be [0, adapter.getItemCount())")
+        }
+        if (!looped || itemCount <= visibleDotCount && itemCount > 1) {
+            dotScale!!.clear()
+            if (orientation == LinearLayout.HORIZONTAL) {
+                scaleDotByOffset(page, offset)
+                if (page < itemCount - 1) {
+                    scaleDotByOffset(page + 1, 1 - offset)
+                } else if (itemCount > 1) {
+                    scaleDotByOffset(0, 1 - offset)
+                }
+            } else { // Vertical orientation
+                scaleDotByOffset(page, offset)
+            }
+            invalidate()
+        }
+        if (orientation == LinearLayout.HORIZONTAL) {
+            adjustFramePosition(offset, page)
+        } else {
+            adjustFramePosition(offset, page - 1)
+        }
+        invalidate()
+    }
+
+    /**
+     * Sets currently selected position (according to your pager's adapter)
+     *
+     * @param position new current position
+     */
+    fun setCurrentPosition(position: Int) {
+        if (position != 0 && (position < 0 || position >= itemCount)) {
+            throw IndexOutOfBoundsException("Position must be [0, adapter.getItemCount()]")
+        }
+        if (itemCount == 0) {
+            return
+        }
+        adjustFramePosition(0f, position)
+        updateScaleInIdleState(position)
+    }
+
+    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
+        // Width
+        val measuredWidth: Int
+        // Height
+        val measuredHeight: Int
+        if (orientation == LinearLayoutManager.HORIZONTAL) {
+            // We ignore widthMeasureSpec because width is based on visibleDotCount
+            measuredWidth = if (isInEditMode) {
+                // Maximum width with all dots visible
+                (visibleDotCount - 1) * spaceBetweenDotCenters + dotSelectedSize
+            } else {
+                if (itemCount >= visibleDotCount) visibleFrameWidth.toInt() else (itemCount - 1) * spaceBetweenDotCenters + dotSelectedSize
+            }
+            val heightMode = MeasureSpec.getMode(heightMeasureSpec)
+            val heightSize = MeasureSpec.getSize(heightMeasureSpec)
+
+            // Height
+            val desiredHeight = dotSelectedSize
+            measuredHeight = when (heightMode) {
+                MeasureSpec.EXACTLY -> heightSize
+                MeasureSpec.AT_MOST -> desiredHeight.coerceAtMost(heightSize)
+                MeasureSpec.UNSPECIFIED -> desiredHeight
+                else -> desiredHeight
+            }
+        } else {
+            measuredHeight = if (isInEditMode) {
+                (visibleDotCount - 1) * spaceBetweenDotCenters + dotSelectedSize
+            } else {
+                if (itemCount >= visibleDotCount) visibleFrameWidth.toInt() else (itemCount) * spaceBetweenDotCenters + dotSelectedSize
+            }
+            val widthMode = MeasureSpec.getMode(widthMeasureSpec)
+            val widthSize = MeasureSpec.getSize(widthMeasureSpec)
+
+            // Width
+            val desiredWidth = dotSelectedSize
+            measuredWidth = when (widthMode) {
+                MeasureSpec.EXACTLY -> widthSize
+                MeasureSpec.AT_MOST -> desiredWidth.coerceAtMost(widthSize)
+                MeasureSpec.UNSPECIFIED -> desiredWidth
+                else -> desiredWidth
+            }
+        }
+        setMeasuredDimension(measuredWidth, measuredHeight)
+    }
+
+    override fun onDraw(canvas: Canvas) {
+        val dotCount = dotCount
+        if (dotCount < visibleDotThreshold) {
+            return
+        }
+
+        // Some empirical coefficients
+        val scaleDistance = (spaceBetweenDotCenters + (dotSelectedSize - dotNormalSize) / 2) * 0.7f
+        val smallScaleDistance = (dotSelectedSize / 2).toFloat()
+        val centerScaleDistance = 6f / 7f * spaceBetweenDotCenters
+        val firstVisibleDotPos =
+            (visibleFramePosition - firstDotOffset).toInt() / spaceBetweenDotCenters
+        var lastVisibleDotPos = (firstVisibleDotPos
+            + (visibleFramePosition + visibleFrameWidth - getDotOffsetAt(firstVisibleDotPos)).toInt()
+            / spaceBetweenDotCenters)
+
+        // If real dots count is less than we can draw inside visible frame, we move lastVisibleDotPos
+        // to the last item
+        if (firstVisibleDotPos == 0 && lastVisibleDotPos + 1 > dotCount) {
+            lastVisibleDotPos = dotCount - 1
+        }
+        for (i in firstVisibleDotPos..lastVisibleDotPos) {
+            val dot = getDotOffsetAt(i)
+            if (dot >= visibleFramePosition && dot < visibleFramePosition + visibleFrameWidth) {
+                var diameter: Float
+                var scale: Float
+
+                // Calculate scale according to current page position
+                scale = if (looped && itemCount > visibleDotCount) {
+                    val frameCenter = visibleFramePosition + visibleFrameWidth / 2
+                    if (dot >= frameCenter - centerScaleDistance
+                        && dot <= frameCenter
+                    ) {
+                        (dot - frameCenter + centerScaleDistance) / centerScaleDistance
+                    } else if (dot > frameCenter
+                        && dot < frameCenter + centerScaleDistance
+                    ) {
+                        1 - (dot - frameCenter) / centerScaleDistance
+                    } else {
+                        0f
+                    }
+                } else {
+                    getDotScaleAt(i)
+                }
+                diameter = dotNormalSize + (dotSelectedSize - dotNormalSize) * scale
+
+                // Additional scale for dots at corners
+                if (itemCount > visibleDotCount) {
+                    val currentScaleDistance = if (!looped && (i == 0 || i == dotCount - 1)) {
+                        smallScaleDistance
+                    } else {
+                        scaleDistance
+                    }
+                    var size = width
+                    if (orientation == LinearLayoutManager.VERTICAL) {
+                        size = height
+                    }
+                    if (dot - visibleFramePosition < currentScaleDistance) {
+                        val calculatedDiameter =
+                            diameter * (dot - visibleFramePosition) / currentScaleDistance
+                        if (calculatedDiameter <= dotMinimumSize) {
+                            diameter = dotMinimumSize.toFloat()
+                        } else if (calculatedDiameter < diameter) {
+                            diameter = calculatedDiameter
+                        }
+                    } else if (dot - visibleFramePosition > size - currentScaleDistance) {
+                        val calculatedDiameter =
+                            diameter * (-dot + visibleFramePosition + size) / currentScaleDistance
+                        if (calculatedDiameter <= dotMinimumSize) {
+                            diameter = dotMinimumSize.toFloat()
+                        } else if (calculatedDiameter < diameter) {
+                            diameter = calculatedDiameter
+                        }
+                    }
+                }
+                paint.color = calculateDotColor(scale)
+                if (orientation == LinearLayoutManager.HORIZONTAL) {
+                    canvas.drawCircle(dot - visibleFramePosition, (
+                        measuredHeight / 2).toFloat(),
+                        diameter / 2,
+                        paint)
+                } else {
+                    canvas.drawCircle((measuredWidth / 2).toFloat(),
+                        dot - visibleFramePosition,
+                        diameter / 2,
+                        paint)
+                }
+            }
+        }
+    }
+
+    @ColorInt
+    private fun calculateDotColor(dotScale: Float): Int {
+        return colorEvaluator.evaluate(dotScale, dotColor, selectedDotColor) as Int
+    }
+
+    private fun updateScaleInIdleState(currentPos: Int) {
+        if (!looped || itemCount < visibleDotCount) {
+            dotScale!!.clear()
+            dotScale!!.put(currentPos, 1f)
+            invalidate()
+        }
+    }
+
+    private fun initDots(itemCount: Int) {
+        if (this.itemCount == itemCount && dotCountInitialized) {
+            return
+        }
+        this.itemCount = itemCount
+        dotCountInitialized = true
+        dotScale = SparseArray()
+        if (itemCount < visibleDotThreshold) {
+            requestLayout()
+            invalidate()
+            return
+        }
+        firstDotOffset =
+            if (looped && this.itemCount > visibleDotCount) 0f else dotSelectedSize / 2.toFloat()
+        visibleFrameWidth =
+            ((visibleDotCount - 1) * spaceBetweenDotCenters + dotSelectedSize).toFloat()
+        requestLayout()
+        invalidate()
+    }
+
+    private fun adjustFramePosition(offset: Float, pos: Int) {
+        if (itemCount <= visibleDotCount) {
+            // Without scroll
+            visibleFramePosition = 0f
+        } else if (!looped && itemCount > visibleDotCount) {
+            // Not looped with scroll
+            val center = getDotOffsetAt(pos) + spaceBetweenDotCenters * offset
+            visibleFramePosition = center - visibleFrameWidth / 2
+
+            // Block frame offset near start and end
+            val firstCenteredDotIndex = visibleDotCount / 2
+            val lastCenteredDot = getDotOffsetAt(dotCount - 1 - firstCenteredDotIndex)
+            if (visibleFramePosition + visibleFrameWidth / 2 < getDotOffsetAt(firstCenteredDotIndex)) {
+                visibleFramePosition = getDotOffsetAt(firstCenteredDotIndex) - visibleFrameWidth / 2
+            } else if (visibleFramePosition + visibleFrameWidth / 2 > lastCenteredDot) {
+                visibleFramePosition = lastCenteredDot - visibleFrameWidth / 2
+            }
+        } else {
+            // Looped with scroll
+            val center = getDotOffsetAt(infiniteDotCount / 2) + spaceBetweenDotCenters * offset
+            visibleFramePosition = center - visibleFrameWidth / 2
+        }
+    }
+
+    private fun scaleDotByOffset(position: Int, offset: Float) {
+        if (dotScale == null || dotCount == 0) {
+            return
+        }
+        setDotScaleAt(position, 1 - Math.abs(offset))
+    }
+
+    private fun getDotOffsetAt(index: Int): Float {
+        return firstDotOffset + index * spaceBetweenDotCenters
+    }
+
+    private fun getDotScaleAt(index: Int): Float {
+        val scale = dotScale!![index]
+        return scale ?: 0f
+    }
+
+    private fun setDotScaleAt(index: Int, scale: Float) {
+        if (scale == 0f) {
+            dotScale!!.remove(index)
+        } else {
+            dotScale!!.put(index, scale)
+        }
+    }
+
+    /**
+     * Interface for attaching to custom pagers.
+     *
+     * @param <T> custom pager's class
+    </T> */
+    interface PagerAttacher<T> {
+        /**
+         * Here you should add all needed callbacks to track pager's item count, position and offset
+         * You must call:
+         * [PagerIndicator.setDotCount] - initially and after page selection,
+         * [PagerIndicator.setCurrentPosition] - initially and after page selection,
+         * [PagerIndicator.onPageScrolled] - in your pager callback to track scroll offset,
+         * [PagerIndicator.reattach] - each time your adapter items change.
+         *
+         * @param indicator indicator
+         * @param pager     pager to attach
+         */
+        fun attachToPager(indicator: PagerIndicator, pager: T)
+
+        /**
+         * Here you should unregister all callbacks previously added to pager and adapter
+         */
+        fun detachFromPager()
+    }
+}

app/src/main/kotlin/com/simplemobiletools/clock/views/pageindicator/ViewPager2Attacher.kt

@@ -0,0 +1,80 @@
+package com.simplemobiletools.clock.views.pageindicator
+
+import androidx.recyclerview.widget.RecyclerView
+import androidx.recyclerview.widget.RecyclerView.AdapterDataObserver
+import androidx.viewpager2.widget.ViewPager2
+import androidx.viewpager2.widget.ViewPager2.OnPageChangeCallback
+
+/**
+ * ViewPager2 Attacher for [PagerIndicator]
+) */
+class ViewPager2Attacher : PagerIndicator.PagerAttacher<ViewPager2> {
+    private var dataSetObserver: AdapterDataObserver? = null
+    private var attachedAdapter: RecyclerView.Adapter<*>? = null
+    private var onPageChangeListener: OnPageChangeCallback? = null
+    private var pager: ViewPager2? = null
+
+    override fun attachToPager(indicator: PagerIndicator, pager: ViewPager2) {
+        attachedAdapter = pager.adapter
+        checkNotNull(attachedAdapter) { "Set adapter before call attachToPager() method" }
+        this.pager = pager
+        updateIndicatorDotsAndPosition(indicator)
+        dataSetObserver = object : AdapterDataObserver() {
+            override fun onChanged() {
+                indicator.reattach()
+            }
+        }
+        attachedAdapter!!.registerAdapterDataObserver(dataSetObserver!!)
+        onPageChangeListener = object : OnPageChangeCallback() {
+            var idleState = true
+            override fun onPageScrolled(
+                position: Int,
+                positionOffset: Float,
+                positionOffsetPixel: Int
+            ) {
+                updateIndicatorOnPagerScrolled(indicator, position, positionOffset)
+            }
+
+            override fun onPageSelected(position: Int) {
+                if (idleState) {
+                    updateIndicatorDotsAndPosition(indicator)
+                }
+            }
+
+            override fun onPageScrollStateChanged(state: Int) {
+                idleState = state == ViewPager2.SCROLL_STATE_IDLE
+            }
+        }
+        pager.registerOnPageChangeCallback(onPageChangeListener!!)
+    }
+
+    override fun detachFromPager() {
+        attachedAdapter!!.unregisterAdapterDataObserver(dataSetObserver!!)
+        pager!!.unregisterOnPageChangeCallback(onPageChangeListener!!)
+    }
+
+    private fun updateIndicatorDotsAndPosition(indicator: PagerIndicator) {
+        indicator.dotCount = attachedAdapter!!.itemCount
+        indicator.setCurrentPosition(pager!!.currentItem)
+    }
+
+    private fun updateIndicatorOnPagerScrolled(
+        indicator: PagerIndicator,
+        position: Int,
+        positionOffset: Float
+    ) {
+        // ViewPager may emit negative positionOffset for very fast scrolling
+        val offset: Float = when {
+            positionOffset < 0 -> {
+                0f
+            }
+            positionOffset > 1 -> {
+                1f
+            }
+            else -> {
+                positionOffset
+            }
+        }
+        indicator.onPageScrolled(position, offset)
+    }
+}

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

@@ -8,15 +8,27 @@
 
     <androidx.viewpager2.widget.ViewPager2
         android:id="@+id/timer_view_pager"
-        android:layout_width="match_parent"
+        android:layout_width="0dp"
         android:layout_height="0dp"
+        android:layout_marginEnd="@dimen/medium_margin"
         android:layout_marginBottom="@dimen/medium_margin"
         android:orientation="vertical"
         app:layout_constraintBottom_toTopOf="@id/timer_play_pause"
-        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintEnd_toStartOf="@id/indicator_view"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <com.simplemobiletools.clock.views.pageindicator.PagerIndicator
+        android:id="@+id/indicator_view"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginEnd="@dimen/medium_margin"
+        app:layout_constraintBottom_toTopOf="@id/timer_play_pause"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintVertical_bias="0.05"
+        app:spi_orientation="vertical" />
+
     <ImageView
         android:id="@+id/timer_reset"
         android:layout_width="@dimen/stopwatch_button_small_size"

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

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <attr name="scrollingPagerIndicatorStyle"/>
+
+    <declare-styleable name="PagerIndicator">
+        <attr name="spi_dotColor" format="color" />
+        <attr name="spi_dotSelectedColor" format="color" />
+        <attr name="spi_dotSize" format="dimension" />
+        <attr name="spi_dotSelectedSize" format="dimension" />
+        <attr name="spi_dotMinimumSize" format="dimension" />
+        <attr name="spi_dotSpacing" format="dimension" />
+        <attr name="spi_visibleDotCount" format="integer" />
+        <attr name="spi_visibleDotThreshold" format="integer" />
+        <attr name="spi_looped" format="boolean" />
+        <attr name="spi_orientation" format="enum">
+            <enum name="horizontal" value="0" />
+            <enum name="vertical" value="1" />
+        </attr>
+    </declare-styleable>
+</resources>

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

@@ -2,4 +2,14 @@
 
     <style name="AppTheme" parent="AppTheme.Base"/>
 
+    <style name="PagerIndicator">
+        <item name="spi_dotColor">@android:color/darker_gray</item>
+        <item name="spi_dotSelectedColor">@android:color/darker_gray</item>
+        <item name="spi_dotSize">6dp</item>
+        <item name="spi_dotSelectedSize">10dp</item>
+        <item name="spi_dotSpacing">8dp</item>
+        <item name="spi_visibleDotCount">5</item>
+        <item name="spi_visibleDotThreshold">2</item>
+        <item name="spi_looped">false</item>
+    </style>
 </resources>