Migrated the Reader screen to jetpack compose.

* Created the `ReaderScreen` for compose UI.
* Created the `ReaderScreenState` to manage the state of UI.

app/src/androidTest/java/org/kiwix/kiwixmobile/page/bookmarks/LibkiwixBookmarkTest.kt

@@ -41,7 +41,7 @@ import org.junit.Rule
 import org.junit.Test
 import org.kiwix.kiwixmobile.BaseActivityTest
 import org.kiwix.kiwixmobile.R
-import org.kiwix.kiwixmobile.core.main.CoreReaderFragment
+import org.kiwix.kiwixmobile.core.main.reader.CoreReaderFragment
 import org.kiwix.kiwixmobile.core.page.bookmark.adapter.LibkiwixBookmarkItem
 import org.kiwix.kiwixmobile.core.utils.LanguageUtils.Companion.handleLocaleChange
 import org.kiwix.kiwixmobile.core.utils.SharedPreferenceUtil

app/src/main/java/org/kiwix/kiwixmobile/nav/destination/library/local/LocalLibraryScreen.kt

@@ -55,6 +55,7 @@ import androidx.compose.ui.unit.dp
 import org.kiwix.kiwixmobile.R.string
 import org.kiwix.kiwixmobile.core.R
 import org.kiwix.kiwixmobile.core.downloader.downloadManager.ZERO
+import org.kiwix.kiwixmobile.core.main.reader.CONTENT_LOADING_PROGRESSBAR_TESTING_TAG
 import org.kiwix.kiwixmobile.core.ui.components.ContentLoadingProgressBar
 import org.kiwix.kiwixmobile.core.ui.components.KiwixAppBar
 import org.kiwix.kiwixmobile.core.ui.components.KiwixButton
@@ -78,7 +79,6 @@ import org.kiwix.kiwixmobile.zimManager.fileselectView.FileSelectListState
 const val NO_FILE_TEXT_TESTING_TAG = "noFileTextTestingTag"
 const val DOWNLOAD_BUTTON_TESTING_TAG = "downloadButtonTestingTag"
 const val BOOK_LIST_TESTING_TAG = "bookListTestingTag"
-const val CONTENT_LOADING_PROGRESSBAR_TESTING_TAG = "contentLoadingProgressBarTestingTag"
 const val SELECT_FILE_BUTTON_TESTING_TAG = "selectFileButtonTestingTag"
 
 @OptIn(ExperimentalMaterial3Api::class)

app/src/main/java/org/kiwix/kiwixmobile/nav/destination/reader/KiwixReaderFragment.kt

@@ -50,11 +50,11 @@ import org.kiwix.kiwixmobile.core.extensions.setImageDrawableCompat
 import org.kiwix.kiwixmobile.core.extensions.snack
 import org.kiwix.kiwixmobile.core.extensions.toast
 import org.kiwix.kiwixmobile.core.main.CoreMainActivity
-import org.kiwix.kiwixmobile.core.main.CoreReaderFragment
+import org.kiwix.kiwixmobile.core.main.reader.CoreReaderFragment
 import org.kiwix.kiwixmobile.core.main.CoreWebViewClient
-import org.kiwix.kiwixmobile.core.main.RestoreOrigin
+import org.kiwix.kiwixmobile.core.main.reader.RestoreOrigin
-import org.kiwix.kiwixmobile.core.main.RestoreOrigin.FromExternalLaunch
+import org.kiwix.kiwixmobile.core.main.reader.RestoreOrigin.FromExternalLaunch
-import org.kiwix.kiwixmobile.core.main.RestoreOrigin.FromSearchScreen
+import org.kiwix.kiwixmobile.core.main.reader.RestoreOrigin.FromSearchScreen
 import org.kiwix.kiwixmobile.core.main.ToolbarScrollingKiwixWebView
 import org.kiwix.kiwixmobile.core.page.history.adapter.WebViewHistoryItem
 import org.kiwix.kiwixmobile.core.reader.ZimReaderSource

core/src/main/java/org/kiwix/kiwixmobile/core/main/reader/CoreReaderFragment.kt

@@ -15,7 +15,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  *
  */
-package org.kiwix.kiwixmobile.core.main
+package org.kiwix.kiwixmobile.core.main.reader
 
 import android.Manifest
 import android.Manifest.permission.POST_NOTIFICATIONS
@@ -131,13 +131,33 @@ import org.kiwix.kiwixmobile.core.extensions.setToolTipWithContentDescription
 import org.kiwix.kiwixmobile.core.extensions.showFullScreenMode
 import org.kiwix.kiwixmobile.core.extensions.snack
 import org.kiwix.kiwixmobile.core.extensions.toast
+import org.kiwix.kiwixmobile.core.main.AddNoteDialog
+import org.kiwix.kiwixmobile.core.main.CompatFindActionModeCallback
+import org.kiwix.kiwixmobile.core.main.CoreMainActivity
+import org.kiwix.kiwixmobile.core.main.CoreSearchWidget
+import org.kiwix.kiwixmobile.core.main.CoreWebViewClient
+import org.kiwix.kiwixmobile.core.main.DarkModeViewPainter
+import org.kiwix.kiwixmobile.core.main.DocumentParser
 import org.kiwix.kiwixmobile.core.main.DocumentParser.SectionsListener
+import org.kiwix.kiwixmobile.core.main.FIND_IN_PAGE_SEARCH_STRING
+import org.kiwix.kiwixmobile.core.main.KiwixTextToSpeech
 import org.kiwix.kiwixmobile.core.main.KiwixTextToSpeech.OnInitSucceedListener
 import org.kiwix.kiwixmobile.core.main.KiwixTextToSpeech.OnSpeakingListener
+import org.kiwix.kiwixmobile.core.main.KiwixWebView
+import org.kiwix.kiwixmobile.core.main.MainMenu
 import org.kiwix.kiwixmobile.core.main.MainMenu.MenuClickListener
-import org.kiwix.kiwixmobile.core.main.RestoreOrigin.FromExternalLaunch
+import org.kiwix.kiwixmobile.core.main.MainRepositoryActions
+import org.kiwix.kiwixmobile.core.main.OnSwipeTouchListener
+import org.kiwix.kiwixmobile.core.main.ServiceWorkerUninitialiser
+import org.kiwix.kiwixmobile.core.main.TableDrawerAdapter
+import org.kiwix.kiwixmobile.core.main.reader.RestoreOrigin.FromExternalLaunch
 import org.kiwix.kiwixmobile.core.main.TableDrawerAdapter.DocumentSection
 import org.kiwix.kiwixmobile.core.main.TableDrawerAdapter.TableClickListener
+import org.kiwix.kiwixmobile.core.main.TabsAdapter
+import org.kiwix.kiwixmobile.core.main.ToolbarScrollingKiwixWebView
+import org.kiwix.kiwixmobile.core.main.UNINITIALISER_ADDRESS
+import org.kiwix.kiwixmobile.core.main.WebViewCallback
+import org.kiwix.kiwixmobile.core.main.WebViewProvider
 import org.kiwix.kiwixmobile.core.navigateToAppSettings
 import org.kiwix.kiwixmobile.core.page.bookmark.adapter.LibkiwixBookmarkItem
 import org.kiwix.kiwixmobile.core.page.history.NavigationHistoryClickListener
@@ -824,9 +844,9 @@ abstract class CoreReaderFragment :
     // the unwanted blank space caused by the toolbar.
     setTopMarginToWebViews(-requireActivity().getToolbarHeight())
     setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED)
-    bottomToolbar?.visibility = View.GONE
+    bottomToolbar?.visibility = GONE
-    contentFrame?.visibility = View.GONE
+    contentFrame?.visibility = GONE
-    progressBar?.visibility = View.GONE
+    progressBar?.visibility = GONE
     backToTopButton?.hide()
     setTabSwitcherVisibility(VISIBLE)
     startAnimation(tabSwitcherRoot, R.anim.slide_down)
@@ -906,10 +926,10 @@ abstract class CoreReaderFragment :
     )
     tabSwitcherRoot?.let {
       if (it.isVisible) {
-        setTabSwitcherVisibility(View.GONE)
+        setTabSwitcherVisibility(GONE)
         startAnimation(it, R.anim.slide_up)
-        progressBar?.visibility = View.VISIBLE
+        progressBar?.visibility = VISIBLE
-        contentFrame?.visibility = View.VISIBLE
+        contentFrame?.visibility = VISIBLE
       }
     }
     progressBar?.hide()
@@ -1058,7 +1078,7 @@ abstract class CoreReaderFragment :
   @Suppress("ReturnCount", "NestedBlockDepth")
   override fun onBackPressed(activity: AppCompatActivity): FragmentActivityExtensions.Super {
     when {
-      tabSwitcherRoot?.visibility == View.VISIBLE -> {
+      tabSwitcherRoot?.visibility == VISIBLE -> {
         selectTab(
           if (currentWebViewIndex < webViewList.size) {
             currentWebViewIndex
@@ -1168,7 +1188,7 @@ abstract class CoreReaderFragment :
             override fun onSpeakingStarted() {
               requireActivity().runOnUiThread {
                 mainMenu?.onTextToSpeechStartedTalking()
-                ttsControls?.visibility = View.VISIBLE
+                ttsControls?.visibility = VISIBLE
                 setActionAndStartTTSService(ACTION_PAUSE_OR_RESUME_TTS, false)
               }
             }
@@ -1176,7 +1196,7 @@ abstract class CoreReaderFragment :
             override fun onSpeakingEnded() {
               requireActivity().runOnUiThread {
                 mainMenu?.onTextToSpeechStoppedTalking()
-                ttsControls?.visibility = View.GONE
+                ttsControls?.visibility = GONE
                 pauseTTSButton?.setText(R.string.tts_pause)
                 setActionAndStartTTSService(ACTION_STOP_TTS)
               }
@@ -1469,15 +1489,15 @@ abstract class CoreReaderFragment :
 
   private fun reopenBook() {
     hideNoBookOpenViews()
-    contentFrame?.visibility = View.VISIBLE
+    contentFrame?.visibility = VISIBLE
     mainMenu?.showBookSpecificMenuItems()
   }
 
   protected fun exitBook(shouldCloseZimBook: Boolean = true) {
     showNoBookOpenViews()
-    bottomToolbar?.visibility = View.GONE
+    bottomToolbar?.visibility = GONE
     actionBar?.title = getString(R.string.reader)
-    contentFrame?.visibility = View.GONE
+    contentFrame?.visibility = GONE
     hideProgressBar()
     mainMenu?.hideBookSpecificMenuItems()
     if (shouldCloseZimBook) {
@@ -1501,7 +1521,7 @@ abstract class CoreReaderFragment :
 
   protected fun hideProgressBar() {
     progressBar?.apply {
-      visibility = View.GONE
+      visibility = GONE
       hide()
     }
   }
@@ -1511,7 +1531,7 @@ abstract class CoreReaderFragment :
       reopenBook()
     }
     tempWebViewForUndo?.let {
-      if (tabSwitcherRoot?.visibility == View.GONE) {
+      if (tabSwitcherRoot?.visibility == GONE) {
         // Remove the top margin from the webView when the tabSwitcher is not visible.
         // We have added this margin in `TabsAdapter` to not show the top margin in tabs.
         // `tempWebViewForUndo` saved with that margin so before showing it to the `contentFrame`
@@ -1610,7 +1630,7 @@ abstract class CoreReaderFragment :
     if (requireActivity().hasNotificationPermission(sharedPreferenceUtil)) {
       ttsControls?.let { ttsControls ->
         when (ttsControls.visibility) {
-          View.GONE -> {
+          GONE -> {
             if (isBackToTopEnabled) {
               backToTopButton?.hide()
             }
@@ -1622,7 +1642,7 @@ abstract class CoreReaderFragment :
             }
           }
 
-          View.VISIBLE -> {
+          VISIBLE -> {
             if (isBackToTopEnabled) {
               backToTopButton?.show()
             }
@@ -1663,14 +1683,14 @@ abstract class CoreReaderFragment :
   }
 
   override fun onHomeMenuClicked() {
-    if (tabSwitcherRoot?.visibility == View.VISIBLE) {
+    if (tabSwitcherRoot?.visibility == VISIBLE) {
       hideTabSwitcher()
     }
     createNewTab()
   }
 
   override fun onTabMenuClicked() {
-    if (tabSwitcherRoot?.visibility == View.VISIBLE) {
+    if (tabSwitcherRoot?.visibility == VISIBLE) {
       hideTabSwitcher()
       selectTab(currentWebViewIndex)
     } else {
@@ -1751,9 +1771,9 @@ abstract class CoreReaderFragment :
   @Suppress("MagicNumber")
   protected open fun openFullScreen() {
     (requireActivity() as CoreMainActivity).disableDrawer(false)
-    toolbarContainer?.visibility = View.GONE
+    toolbarContainer?.visibility = GONE
-    bottomToolbar?.visibility = View.GONE
+    bottomToolbar?.visibility = GONE
-    exitFullscreenButton?.visibility = View.VISIBLE
+    exitFullscreenButton?.visibility = VISIBLE
     exitFullscreenButton?.background?.alpha = 153
     val window = requireActivity().window
     window.decorView.showFullScreenMode(window)
@@ -1769,9 +1789,9 @@ abstract class CoreReaderFragment :
     toolbar?.let(::setUpDrawerToggle)
     setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED)
     sharedPreferenceUtil?.putPrefFullScreen(false)
-    toolbarContainer?.visibility = View.VISIBLE
+    toolbarContainer?.visibility = VISIBLE
     updateBottomToolbarVisibility()
-    exitFullscreenButton?.visibility = View.GONE
+    exitFullscreenButton?.visibility = GONE
     exitFullscreenButton?.background?.alpha = 255
     val window = requireActivity().window
     window.decorView.closeFullScreenMode(window)
@@ -1801,7 +1821,7 @@ abstract class CoreReaderFragment :
         // Show content if there is `Open Library` button showing
         // and we are opening the ZIM file
         hideNoBookOpenViews()
-        contentFrame?.visibility = View.VISIBLE
+        contentFrame?.visibility = VISIBLE
         openAndSetInContainer(zimReaderSource)
         updateTitle()
       } else {
@@ -2014,13 +2034,13 @@ abstract class CoreReaderFragment :
 
   // opens home screen when user closes all tabs
   protected fun showNoBookOpenViews() {
-    noOpenBookButton?.visibility = View.VISIBLE
+    noOpenBookButton?.visibility = VISIBLE
-    noOpenBookText?.visibility = View.VISIBLE
+    noOpenBookText?.visibility = VISIBLE
   }
 
   private fun hideNoBookOpenViews() {
-    noOpenBookButton?.visibility = View.GONE
+    noOpenBookButton?.visibility = GONE
-    noOpenBookText?.visibility = View.GONE
+    noOpenBookText?.visibility = GONE
   }
 
   @Suppress("MagicNumber")
@@ -2101,7 +2121,7 @@ abstract class CoreReaderFragment :
       FrameLayout.LayoutParams.WRAP_CONTENT
     ).apply {
       val rightAndLeftMargin = requireActivity().resources.getDimensionPixelSize(
-        org.kiwix.kiwixmobile.core.R.dimen.activity_horizontal_margin
+        R.dimen.activity_horizontal_margin
       )
       setMargins(
         rightAndLeftMargin,
@@ -2188,11 +2208,11 @@ abstract class CoreReaderFragment :
   private fun updateBottomToolbarVisibility() {
     bottomToolbar?.let {
       if (urlIsValid() &&
-        tabSwitcherRoot?.visibility != View.VISIBLE && !isInFullScreenMode()
+        tabSwitcherRoot?.visibility != VISIBLE && !isInFullScreenMode()
       ) {
-        it.visibility = View.VISIBLE
+        it.visibility = VISIBLE
       } else {
-        it.visibility = View.GONE
+        it.visibility = GONE
       }
     }
   }
@@ -2332,7 +2352,7 @@ abstract class CoreReaderFragment :
   }
 
   private fun contentUrl(articleUrl: String?): String =
-    "${ZimFileReader.CONTENT_PREFIX}$articleUrl".toUri().toString()
+    "${CONTENT_PREFIX}$articleUrl".toUri().toString()
 
   private fun redirectOrOriginal(contentUrl: String): String {
     zimReaderContainer?.let {
@@ -2722,13 +2742,13 @@ abstract class CoreReaderFragment :
         if (it > 200) {
           if (
             (backToTopButton?.isGone == true || backToTopButton?.isInvisible == true) &&
-            ttsControls?.visibility == View.GONE
+            ttsControls?.visibility == GONE
           ) {
             backToTopButton?.show()
           }
         } else {
           backToTopButton?.isVisible
-          if (backToTopButton?.visibility == View.VISIBLE) {
+          if (backToTopButton?.visibility == VISIBLE) {
             backToTopButton?.hide()
           }
         }
@@ -2739,7 +2759,7 @@ abstract class CoreReaderFragment :
   override fun webViewLongClick(url: String) {
     var handleEvent = false
     when {
-      url.startsWith(ZimFileReader.CONTENT_PREFIX) -> {
+      url.startsWith(CONTENT_PREFIX) -> {
         // This is my web site, so do not override; let my WebView load the page
         handleEvent = true
       }

core/src/main/java/org/kiwix/kiwixmobile/core/main/reader/ReaderScreen.kt

@@ -0,0 +1,284 @@
+/*
+ * Kiwix Android
+ * Copyright (c) 2025 Kiwix <android.kiwix.org>
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package org.kiwix.kiwixmobile.core.main.reader
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxScope
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.BottomAppBar
+import androidx.compose.material3.Button
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FloatingActionButton
+import androidx.compose.material3.FloatingActionButtonDefaults
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.alpha
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import org.kiwix.kiwixmobile.core.R
+import org.kiwix.kiwixmobile.core.ui.components.ContentLoadingProgressBar
+import org.kiwix.kiwixmobile.core.ui.components.KiwixAppBar
+import org.kiwix.kiwixmobile.core.ui.components.KiwixButton
+import org.kiwix.kiwixmobile.core.ui.components.KiwixSnackbarHost
+import org.kiwix.kiwixmobile.core.ui.components.ProgressBarStyle
+import org.kiwix.kiwixmobile.core.ui.models.ActionMenuItem
+import org.kiwix.kiwixmobile.core.ui.models.IconItem
+import org.kiwix.kiwixmobile.core.ui.models.IconItem.Drawable
+import org.kiwix.kiwixmobile.core.ui.models.toPainter
+import org.kiwix.kiwixmobile.core.ui.theme.Black
+import org.kiwix.kiwixmobile.core.ui.theme.KiwixDialogTheme
+import org.kiwix.kiwixmobile.core.ui.theme.White
+import org.kiwix.kiwixmobile.core.utils.ComposeDimens.EIGHT_DP
+import org.kiwix.kiwixmobile.core.utils.ComposeDimens.FOUR_DP
+import org.kiwix.kiwixmobile.core.utils.ComposeDimens.READER_BOTTOM_APP_BAR_BUTTON_ICON_SIZE
+import org.kiwix.kiwixmobile.core.utils.ComposeDimens.READER_BOTTOM_APP_BAR_LAYOUT_HEIGHT
+import org.kiwix.kiwixmobile.core.utils.ComposeDimens.TTS_BUTTONS_CONTROL_ALPHA
+
+const val CONTENT_LOADING_PROGRESSBAR_TESTING_TAG = "contentLoadingProgressBarTestingTag"
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Suppress("ComposableLambdaParameterNaming")
+@Composable
+fun ReaderScreen(
+  state: ReaderScreenState,
+  actionMenuItems: List<ActionMenuItem>,
+  navigationIcon: @Composable () -> Unit
+) {
+  KiwixDialogTheme {
+    Scaffold(
+      snackbarHost = { KiwixSnackbarHost(snackbarHostState = state.snackBarHostState) },
+      topBar = { KiwixAppBar(R.string.note, navigationIcon, actionMenuItems) },
+      floatingActionButton = { BackToTopFab(state) }
+    ) { paddingValues ->
+      Box(
+        modifier = Modifier
+          .fillMaxSize()
+          .padding(paddingValues)
+      ) {
+        Column(
+          modifier = Modifier
+            .fillMaxSize(),
+          verticalArrangement = Arrangement.Center,
+          horizontalAlignment = Alignment.CenterHorizontally
+        ) {
+          ShowProgressBarIfZIMFilePageIsLoading(state)
+          if (state.isNoBookOpenInReader) {
+            NoBookOpenView(state.onOpenLibraryButtonClicked)
+          }
+        }
+        TtsControls(state)
+        ShowFullScreenView(state)
+        ShowDonationLayout(state)
+      }
+    }
+  }
+}
+
+@Composable
+private fun ShowFullScreenView(state: ReaderScreenState) {
+  if (state.fullScreenItem.first) {
+    state.fullScreenItem.second
+  }
+}
+
+@Composable
+private fun ShowProgressBarIfZIMFilePageIsLoading(state: ReaderScreenState) {
+  if (state.pageLoadingItem.first) {
+    ContentLoadingProgressBar(
+      modifier = Modifier.testTag(CONTENT_LOADING_PROGRESSBAR_TESTING_TAG),
+      progressBarStyle = ProgressBarStyle.HORIZONTAL,
+      progress = state.pageLoadingItem.second
+    )
+  }
+}
+
+@Composable
+private fun NoBookOpenView(
+  onOpenLibraryButtonClicked: () -> Unit
+) {
+  Column(
+    modifier = Modifier
+      .fillMaxSize()
+      .padding(horizontal = FOUR_DP)
+      .verticalScroll(rememberScrollState()),
+    horizontalAlignment = Alignment.CenterHorizontally,
+    verticalArrangement = Arrangement.Center
+  ) {
+    Text(
+      text = stringResource(R.string.no_open_book),
+      style = MaterialTheme.typography.titleLarge.copy(fontWeight = FontWeight.Medium),
+      textAlign = TextAlign.Center
+    )
+    Spacer(modifier = Modifier.height(EIGHT_DP))
+    KiwixButton(
+      buttonText = stringResource(R.string.open_library),
+      clickListener = onOpenLibraryButtonClicked
+    )
+  }
+}
+
+@Composable
+private fun BoxScope.TtsControls(state: ReaderScreenState) {
+  if (state.showTtsControls) {
+    Row(modifier = Modifier.align(Alignment.TopCenter)) {
+      Button(
+        onClick = state.onPauseTtsClick,
+        modifier = Modifier
+          .weight(1f)
+          .alpha(TTS_BUTTONS_CONTROL_ALPHA)
+      ) {
+        Text(
+          text = stringResource(R.string.tts_pause),
+          fontWeight = FontWeight.Bold
+        )
+      }
+      Spacer(modifier = Modifier.width(FOUR_DP))
+      Button(
+        onClick = state.onStopTtsClick,
+        modifier = Modifier
+          .weight(1f)
+          .alpha(TTS_BUTTONS_CONTROL_ALPHA)
+      ) {
+        Text(
+          text = stringResource(R.string.stop),
+          fontWeight = FontWeight.Bold
+        )
+      }
+    }
+  }
+}
+
+@Composable
+private fun BackToTopFab(state: ReaderScreenState) {
+  if (state.showBackToTopButton) {
+    FloatingActionButton(
+      onClick = state.backToTopButtonClick,
+      modifier = Modifier,
+      containerColor = MaterialTheme.colorScheme.primary,
+      contentColor = MaterialTheme.colorScheme.onPrimary,
+      shape = FloatingActionButtonDefaults.smallShape
+    ) {
+      Icon(
+        painter = Drawable(R.drawable.action_find_previous).toPainter(),
+        contentDescription = stringResource(R.string.pref_back_to_top),
+        tint = White
+      )
+    }
+  }
+}
+
+@Composable
+private fun BottomAppBarOfReaderScreen(
+  onBookmarkClick: () -> Unit,
+  onBackClick: () -> Unit,
+  onHomeClick: () -> Unit,
+  onForwardClick: () -> Unit,
+  onTocClick: () -> Unit
+) {
+  BottomAppBar(
+    containerColor = Black,
+    contentColor = White
+  ) {
+    Row(
+      modifier = Modifier
+        .fillMaxWidth()
+        .height(READER_BOTTOM_APP_BAR_LAYOUT_HEIGHT),
+      verticalAlignment = Alignment.CenterVertically,
+      horizontalArrangement = Arrangement.SpaceEvenly
+    ) {
+      // Bookmark Icon
+      BottomAppBarButtonIcon(
+        onBookmarkClick,
+        Drawable(R.drawable.ic_bookmark_border_24dp),
+        stringResource(R.string.bookmarks)
+      )
+      // Back Icon(for going to previous page)
+      BottomAppBarButtonIcon(
+        onBackClick,
+        Drawable(R.drawable.ic_keyboard_arrow_left_24dp),
+        stringResource(R.string.go_to_previous_page)
+      )
+      // Home Icon(to open the home page of ZIM file)
+      BottomAppBarButtonIcon(
+        onHomeClick,
+        Drawable(R.drawable.action_home),
+        stringResource(R.string.menu_home)
+      )
+      // Forward Icon(for going to next page)
+      BottomAppBarButtonIcon(
+        onForwardClick,
+        Drawable(R.drawable.ic_keyboard_arrow_right_24dp),
+        stringResource(R.string.go_to_next_page)
+      )
+      // Toggle Icon(to open the table of content in right side bar)
+      BottomAppBarButtonIcon(
+        onTocClick,
+        Drawable(R.drawable.ic_toc_24dp),
+        stringResource(R.string.table_of_contents)
+      )
+    }
+  }
+}
+
+@Composable
+private fun BottomAppBarButtonIcon(
+  onClick: () -> Unit,
+  buttonIcon: IconItem,
+  contentDescription: String
+) {
+  IconButton(onClick = onClick) {
+    Icon(
+      buttonIcon.toPainter(),
+      contentDescription,
+      modifier = Modifier.size(READER_BOTTOM_APP_BAR_BUTTON_ICON_SIZE)
+    )
+  }
+}
+
+@Composable
+private fun BoxScope.ShowDonationLayout(state: ReaderScreenState) {
+  if (state.shouldShowDonationPopup) {
+    Box(
+      modifier = Modifier
+        .align(Alignment.BottomCenter)
+        .fillMaxWidth()
+    ) {
+      // TODO create donation popup layout.
+    }
+  }
+}

core/src/main/java/org/kiwix/kiwixmobile/core/main/reader/ReaderScreenState.kt

@@ -0,0 +1,76 @@
+/*
+ * Kiwix Android
+ * Copyright (c) 2025 Kiwix <android.kiwix.org>
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package org.kiwix.kiwixmobile.core.main.reader
+
+import androidx.compose.material3.SnackbarHostState
+import androidx.compose.ui.platform.ComposeView
+
+/**
+ * Represents the UI state for the Reader Screen.
+ *
+ * This data class encapsulates all UI-related states in a single object,
+ * reducing complexity in the Fragment.
+ */
+data class ReaderScreenState(
+  /**
+   * Handles snack bar messages and displays.
+   */
+  val snackBarHostState: SnackbarHostState,
+  /**
+   * Manages the showing of "No open book" message and button.
+   */
+  val isNoBookOpenInReader: Boolean,
+  /**
+   * Handles when open library button clicks.
+   */
+  val onOpenLibraryButtonClicked: () -> Unit,
+  /**
+   * Manages the showing of "ProgressBar" when ZIM file page is loading.
+   *
+   * A [Pair] containing:
+   *  - [Boolean]: Whether page is loading.
+   *  - [Int]: progress of page loading.
+   */
+  val pageLoadingItem: Pair<Boolean, Int>,
+  /**
+   * Manages the showing of "Donation" layout.
+   */
+  val shouldShowDonationPopup: Boolean,
+  /**
+   * Manages the showing of "Full screen view".
+   *
+   * A [Pair] containing:
+   *  - [Boolean]: Whether to show/hide full screen mode.
+   *  - [ComposeView]: full screen view.
+   */
+  val fullScreenItem: Pair<Boolean, ComposeView>,
+  /**
+   * Manages the showing of "BackToTop" fab button.
+   */
+  val showBackToTopButton: Boolean,
+  /**
+   * Handles the click of "BackToTop" fab button.
+   */
+  val backToTopButtonClick: () -> Unit,
+  val showFullscreenButton: Boolean = false,
+  val onExitFullscreenClick: () -> Unit = {},
+  val showTtsControls: Boolean = false,
+  val onPauseTtsClick: () -> Unit = {},
+  val onStopTtsClick: () -> Unit = {},
+)

core/src/main/java/org/kiwix/kiwixmobile/core/search/viewmodel/effects/OpenSearchItem.kt

@@ -25,7 +25,7 @@ import kotlinx.parcelize.Parcelize
 import org.kiwix.kiwixmobile.core.base.SideEffect
 import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions.setNavigationResultOnCurrent
 import org.kiwix.kiwixmobile.core.main.CoreMainActivity
-import org.kiwix.kiwixmobile.core.main.SEARCH_ITEM_TITLE_KEY
+import org.kiwix.kiwixmobile.core.main.reader.SEARCH_ITEM_TITLE_KEY
 import org.kiwix.kiwixmobile.core.reader.addContentPrefix
 import org.kiwix.kiwixmobile.core.search.SearchListItem
 import org.kiwix.kiwixmobile.core.utils.TAG_FILE_SEARCHED

core/src/main/java/org/kiwix/kiwixmobile/core/utils/ComposeDimens.kt

@@ -179,5 +179,9 @@ object ComposeDimens {
   // Settings screen dimes
   val STORAGE_LOADING_PROGRESS_BAR_SIZE = 40.dp
   val CATEGORY_TITLE_TEXT_SIZE = 14.sp
-  val PREFERENCE_TITLE_TEXT_SIZE = 18.sp
+
+  // Reader screen dimes
+  val READER_BOTTOM_APP_BAR_LAYOUT_HEIGHT = 48.dp
+  val READER_BOTTOM_APP_BAR_BUTTON_ICON_SIZE = 30.dp
+  const val TTS_BUTTONS_CONTROL_ALPHA = 0.6f
 }

custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomReaderFragment.kt

@@ -37,9 +37,9 @@ import org.kiwix.kiwixmobile.core.base.BaseActivity
 import org.kiwix.kiwixmobile.core.extensions.browserIntent
 import org.kiwix.kiwixmobile.core.extensions.getResizedDrawable
 import org.kiwix.kiwixmobile.core.extensions.isFileExist
-import org.kiwix.kiwixmobile.core.main.CoreReaderFragment
+import org.kiwix.kiwixmobile.core.main.reader.CoreReaderFragment
 import org.kiwix.kiwixmobile.core.main.MainMenu
-import org.kiwix.kiwixmobile.core.main.RestoreOrigin
+import org.kiwix.kiwixmobile.core.main.reader.RestoreOrigin
 import org.kiwix.kiwixmobile.core.page.history.adapter.WebViewHistoryItem
 import org.kiwix.kiwixmobile.core.reader.ZimReaderSource
 import org.kiwix.kiwixmobile.core.utils.LanguageUtils