Fix #4848 Content Description Generation for Content and SelectionInt…

…eractionContent ViewModels (#5704)

<!-- READ ME FIRST: Please fill in the explanation section below and
check off every point from the Essential Checklist! -->
## Explanation
<!--
- Explain what your PR does. If this PR fixes an existing bug, please
include
- "Fixes #bugnum:" in the explanation so that GitHub can auto-close the
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  - when this PR is merged.
  -->
Fix #4848 
This PR addresses post-PR review issues from #5614 by refining content
description generation. The key updates include:

- The `getContentDescription` function is now utilized in
`ContentViewModel` and `SelectionInteractionContentViewModel`, ensuring
accurate content descriptions with the necessary `customTagHandlers`
1. `ContentViewModel`: Handles `CUSTOM_LIST_LI_TAG`,
`CUSTOM_LIST_OL_TAG`, `CUSTOM_LIST_UL_TAG`, `CUSTOM_IMG_TAG`,
`CUSTOM_CONCEPT_CARD_TAG`, and `CUSTOM_MATH_TAG`
   2. `SelectionInteractionContentViewModel`: Handles `CUSTOM_IMG_TAG`  

- Improved handling of tags where content resides in attributes, such as
anchor tags: `<a href="https://example.com">Click here</a>`, ensuring
proper extraction of meaningful descriptions

- Handled edge cases in `CustomHtmlContentHandler` to improve
`getContentDescription` logic, addressing inconsistencies and included
comments for better understanding.

## Essential Checklist
<!-- Please tick the relevant boxes by putting an "x" in them. -->
- [x] The PR title and explanation each start with "Fix #bugnum: " (If
this PR fixes part of an issue, prefix the title with "Fix part of
#bugnum: ...".)
- [x] Any changes to
[scripts/assets](https://github.com/oppia/oppia-android/tree/develop/scripts/assets)
files have their rationale included in the PR explanation.
- [x] The PR follows the [style
guide](https://github.com/oppia/oppia-android/wiki/Coding-style-guide).
- [x] The PR does not contain any unnecessary code changes from Android
Studio
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#undo-unnecessary-changes)).
- [x] The PR is made from a branch that's **not** called "develop" and
is up-to-date with "develop".
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app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt

@@ -1,5 +1,6 @@
 package org.oppia.android.app.player.state
 
+import android.app.Application
 import android.content.Context
 import android.view.LayoutInflater
 import android.view.View
@@ -91,7 +92,18 @@ import org.oppia.android.databinding.SubmittedHtmlAnswerItemBinding
 import org.oppia.android.databinding.TextInputInteractionItemBinding
 import org.oppia.android.domain.translation.TranslationController
 import org.oppia.android.util.accessibility.AccessibilityService
+import org.oppia.android.util.logging.ConsoleLogger
+import org.oppia.android.util.parser.html.CUSTOM_CONCEPT_CARD_TAG
+import org.oppia.android.util.parser.html.CUSTOM_IMG_TAG
+import org.oppia.android.util.parser.html.CUSTOM_LIST_LI_TAG
+import org.oppia.android.util.parser.html.CUSTOM_LIST_OL_TAG
+import org.oppia.android.util.parser.html.CUSTOM_LIST_UL_TAG
+import org.oppia.android.util.parser.html.CUSTOM_MATH_TAG
+import org.oppia.android.util.parser.html.ConceptCardTagHandler
 import org.oppia.android.util.parser.html.HtmlParser
+import org.oppia.android.util.parser.html.ImageTagHandler
+import org.oppia.android.util.parser.html.LiTagHandler
+import org.oppia.android.util.parser.html.MathTagHandler
 import org.oppia.android.util.threading.BackgroundDispatcher
 import javax.inject.Inject
 
@@ -145,7 +157,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
   private val hasConversationView: Boolean,
   private val resourceHandler: AppLanguageResourceHandler,
   private val translationController: TranslationController,
-  private var userAnswerState: UserAnswerState
+  private var userAnswerState: UserAnswerState,
+  private val consoleLogger: ConsoleLogger,
+  private val conceptCardTagHandlerFactory: ConceptCardTagHandler.Factory,
 ) : HtmlParser.CustomOppiaTagActionListener {
   /**
    * A list of view models corresponding to past view models that are hidden by default. These are
@@ -180,6 +194,25 @@ class StatePlayerRecyclerViewAssembler private constructor(
     }
   }
 
+  private val displayLocale = resourceHandler.getDisplayLocale()
+  private val customTagHandlers = mapOf(
+    CUSTOM_LIST_LI_TAG to LiTagHandler(context, displayLocale),
+    CUSTOM_LIST_UL_TAG to LiTagHandler(context, displayLocale),
+    CUSTOM_LIST_OL_TAG to LiTagHandler(context, displayLocale),
+    CUSTOM_IMG_TAG to ImageTagHandler(consoleLogger),
+    CUSTOM_CONCEPT_CARD_TAG to ConceptCardTagHandler(
+      conceptCardTagHandlerFactory.createConceptCardLinkClickListener(),
+      consoleLogger
+    ),
+    // Pick an arbitrary line height since rendering doesn't actually happen.
+    CUSTOM_MATH_TAG to MathTagHandler(
+      consoleLogger,
+      context.assets,
+      10.0f,
+      false,
+      context.applicationContext as Application,
+    )
+  )
   private val isSplitView = ObservableField<Boolean>(false)
 
   override fun onConceptCardLinkClicked(view: View, skillId: String) {
@@ -350,7 +383,8 @@ class StatePlayerRecyclerViewAssembler private constructor(
         gcsEntityId,
         hasConversationView,
         isSplitView.get()!!,
-        playerFeatureSet.conceptCardSupport
+        playerFeatureSet.conceptCardSupport,
+        customTagHandlers
       )
     }
   }
@@ -913,7 +947,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
     private val translationController: TranslationController,
     private val multiTypeBuilderFactory: BindableAdapter.MultiTypeBuilder.Factory,
     private val singleTypeBuilderFactory: BindableAdapter.SingleTypeBuilder.Factory,
-    private val userAnswerState: UserAnswerState
+    private val userAnswerState: UserAnswerState,
+    private val consoleLogger: ConsoleLogger,
+    private val conceptCardTagHandlerFactory: ConceptCardTagHandler.Factory,
   ) {
 
     private val adapterBuilder: BindableAdapter.MultiTypeBuilder<StateItemViewModel,
@@ -1400,7 +1436,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
         hasConversationView,
         resourceHandler,
         translationController,
-        userAnswerState
+        userAnswerState,
+        consoleLogger,
+        conceptCardTagHandlerFactory
       )
       if (playerFeatureSet.conceptCardSupport) {
         customTagListener.proxyListener = assembler
@@ -1420,7 +1458,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
       private val resourceHandler: AppLanguageResourceHandler,
       private val translationController: TranslationController,
       private val multiAdapterBuilderFactory: BindableAdapter.MultiTypeBuilder.Factory,
-      private val singleAdapterFactory: BindableAdapter.SingleTypeBuilder.Factory
+      private val singleAdapterFactory: BindableAdapter.SingleTypeBuilder.Factory,
+      private val consoleLogger: ConsoleLogger,
+      private val conceptCardTagHandlerFactory: ConceptCardTagHandler.Factory,
     ) {
       /**
        * Returns a new [Builder] for the specified GCS resource bucket information for loading
@@ -1446,7 +1486,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
           translationController,
           multiAdapterBuilderFactory,
           singleAdapterFactory,
-          userAnswerState
+          userAnswerState,
+          consoleLogger,
+          conceptCardTagHandlerFactory
         )
       }
     }

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/ContentViewModel.kt

@@ -1,38 +1,35 @@
 package org.oppia.android.app.player.state.itemviewmodel
 
-import android.text.Spannable
-import android.text.SpannableStringBuilder
+import org.oppia.android.util.parser.html.CustomHtmlContentHandler
 
 /** [StateItemViewModel] for content-card state. */
 class ContentViewModel(
   val htmlContent: CharSequence,
   val gcsEntityId: String,
   val hasConversationView: Boolean,
   val isSplitView: Boolean,
-  val supportsConceptCards: Boolean
+  val supportsConceptCards: Boolean,
+  val customTagHandlers: Map<String, CustomHtmlContentHandler.CustomTagHandler>
 ) : StateItemViewModel(ViewType.CONTENT) {
 
   private val underscoreRegex = Regex("(?<=\\s|[,.;?!])_{3,}(?=\\s|[,.;?!])")
   private val replacementText = "Blank"
 
+  /** Returns content description by extracting text from [htmlContent]. */
+  fun getContentDescription(): String {
+    val contentDescription = CustomHtmlContentHandler.getContentDescription(
+      htmlContent.toString(),
+      imageRetriever = null,
+      customTagHandlers = customTagHandlers
+    )
+    return replaceRegexWithBlank(contentDescription)
+  }
+
   /**
    * Replaces "2+ underscores, with space/punctuation on both sides" in the input text with a
    * replacement string "blank", returning a Spannable.
    * Adjusts offsets to handle text length changes during replacements.
    */
-  fun replaceRegexWithBlank(inputText: CharSequence): Spannable {
-    val spannableStringBuilder = SpannableStringBuilder(inputText)
-    val matches = underscoreRegex.findAll(inputText)
-    var lengthOffset = 0
-
-    for (match in matches) {
-      val matchStart = match.range.first + lengthOffset
-      val matchEnd = match.range.last + 1 + lengthOffset
-      spannableStringBuilder.replace(matchStart, matchEnd, replacementText)
-
-      // Adjust offset due to change in length (difference between old and new text length)
-      lengthOffset += replacementText.length - (matchEnd - matchStart)
-    }
-    return spannableStringBuilder
-  }
+  private fun replaceRegexWithBlank(inputText: CharSequence): String =
+    underscoreRegex.replace(inputText, replacementText)
 }

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/SelectionInteractionContentViewModel.kt

@@ -2,18 +2,38 @@ package org.oppia.android.app.player.state.itemviewmodel
 
 import androidx.databinding.ObservableBoolean
 import org.oppia.android.app.model.SubtitledHtml
+import org.oppia.android.app.model.WrittenTranslationContext
 import org.oppia.android.app.viewmodel.ObservableViewModel
+import org.oppia.android.domain.translation.TranslationController
+import org.oppia.android.util.parser.html.CustomHtmlContentHandler
 
 /** [ObservableViewModel] for MultipleChoiceInput values or ItemSelectionInput values. */
 class SelectionInteractionContentViewModel(
   val htmlContent: SubtitledHtml,
   val hasConversationView: Boolean,
   private val itemIndex: Int,
   private val selectionInteractionViewModel: SelectionInteractionViewModel,
-  val isEnabled: ObservableBoolean
+  val isEnabled: ObservableBoolean,
+  val customTagHandlers: Map<String, CustomHtmlContentHandler.CustomTagHandler>,
+  private val writtenTranslationContext: WrittenTranslationContext,
+  private val translationController: TranslationController,
 ) : ObservableViewModel() {
   var isAnswerSelected = ObservableBoolean()
 
+  /** Returns content description by extracting text from [htmlContent]. */
+  fun getContentDescription(): String {
+    val contentSubtitledHtml =
+      translationController.extractString(
+        htmlContent, writtenTranslationContext
+      )
+    return CustomHtmlContentHandler.getContentDescription(
+      contentSubtitledHtml,
+      imageRetriever = null,
+      customTagHandlers = customTagHandlers
+    )
+  }
+
+  /** Handles item click by updating the selection state based on user interaction. */
   fun handleItemClicked() {
     val isCurrentlySelected = isAnswerSelected.get()
     val shouldNowBeSelected =

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/SelectionInteractionViewModel.kt

@@ -22,6 +22,10 @@ import org.oppia.android.app.player.state.answerhandling.InteractionAnswerReceiv
 import org.oppia.android.app.translation.AppLanguageResourceHandler
 import org.oppia.android.app.viewmodel.ObservableArrayList
 import org.oppia.android.domain.translation.TranslationController
+import org.oppia.android.util.logging.ConsoleLogger
+import org.oppia.android.util.parser.html.CUSTOM_IMG_TAG
+import org.oppia.android.util.parser.html.CustomHtmlContentHandler
+import org.oppia.android.util.parser.html.ImageTagHandler
 import javax.inject.Inject
 
 /** Corresponds to the type of input that should be used for an item selection interaction view. */
@@ -52,7 +56,8 @@ class SelectionInteractionViewModel private constructor(
   val writtenTranslationContext: WrittenTranslationContext,
   private val translationController: TranslationController,
   private val resourceHandler: AppLanguageResourceHandler,
-  userAnswerState: UserAnswerState
+  userAnswerState: UserAnswerState,
+  consoleLogger: ConsoleLogger
 ) : StateItemViewModel(ViewType.SELECTION_INTERACTION), InteractionAnswerHandler {
   private val interactionId: String = interaction.id
 
@@ -81,9 +86,20 @@ class SelectionInteractionViewModel private constructor(
       ObservableBoolean(true)
     }
   }
-  val choiceItems: ObservableList<SelectionInteractionContentViewModel> =
-    computeChoiceItems(choiceSubtitledHtmls, hasConversationView, this, enabledItemsList)
+  private val customTagHandlers = mapOf<String, CustomHtmlContentHandler.CustomTagHandler>(
+    CUSTOM_IMG_TAG to ImageTagHandler(consoleLogger)
+  )
 
+  val choiceItems: ObservableList<SelectionInteractionContentViewModel> =
+    computeChoiceItems(
+      choiceSubtitledHtmls,
+      hasConversationView,
+      this,
+      enabledItemsList,
+      this@SelectionInteractionViewModel.writtenTranslationContext,
+      translationController,
+      customTagHandlers
+    )
   private var pendingAnswerError: String? = null
   private val isAnswerAvailable = ObservableField(false)
   val errorMessage = ObservableField<String>("")
@@ -287,7 +303,8 @@ class SelectionInteractionViewModel private constructor(
   /** Implementation of [StateItemViewModel.InteractionItemFactory] for this view model. */
   class FactoryImpl @Inject constructor(
     private val translationController: TranslationController,
-    private val resourceHandler: AppLanguageResourceHandler
+    private val resourceHandler: AppLanguageResourceHandler,
+    private val consoleLogger: ConsoleLogger
   ) : InteractionItemFactory {
     override fun create(
       entityId: String,
@@ -310,7 +327,8 @@ class SelectionInteractionViewModel private constructor(
         writtenTranslationContext,
         translationController,
         resourceHandler,
-        userAnswerState
+        userAnswerState,
+        consoleLogger
       )
     }
   }
@@ -320,7 +338,10 @@ class SelectionInteractionViewModel private constructor(
       choiceSubtitledHtmls: List<SubtitledHtml>,
       hasConversationView: Boolean,
       selectionInteractionViewModel: SelectionInteractionViewModel,
-      enabledItemsList: List<ObservableBoolean>
+      enabledItemsList: List<ObservableBoolean>,
+      writtenTranslationContext: WrittenTranslationContext,
+      translationController: TranslationController,
+      customTagHandlers: Map<String, CustomHtmlContentHandler.CustomTagHandler>
     ): ObservableArrayList<SelectionInteractionContentViewModel> {
       val observableList = ObservableArrayList<SelectionInteractionContentViewModel>()
       observableList += choiceSubtitledHtmls.mapIndexed { index, subtitledHtml ->
@@ -329,7 +350,10 @@ class SelectionInteractionViewModel private constructor(
           hasConversationView = hasConversationView,
           itemIndex = index,
           selectionInteractionViewModel = selectionInteractionViewModel,
-          isEnabled = enabledItemsList[index]
+          isEnabled = enabledItemsList[index],
+          customTagHandlers,
+          writtenTranslationContext,
+          translationController
         )
       }
       return observableList

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

@@ -50,7 +50,7 @@
       android:minWidth="48dp"
       android:minHeight="48dp"
       android:text="@{htmlContent}"
-      android:contentDescription="@{viewModel.replaceRegexWithBlank(htmlContent)}"
+      android:contentDescription="@{viewModel.getContentDescription()}"
       android:textColor="@color/component_color_shared_primary_text_color"
       android:textColorLink="@color/component_color_shared_link_text_color"
       android:textSize="16sp"

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

@@ -43,6 +43,7 @@
       android:layout_toEndOf="@+id/item_selection_checkbox"
       android:fontFamily="sans-serif"
       android:text="@{htmlContent}"
+      android:contentDescription="@{viewModel.getContentDescription()}"
       android:textColor="@{viewModel.isEnabled ? @color/component_color_shared_item_selection_interaction_enabled_color : @color/component_color_shared_item_selection_interaction_disabled_color}"
       android:textSize="16sp" />
   </RelativeLayout>

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

@@ -43,6 +43,7 @@
       android:layout_toEndOf="@+id/multiple_choice_radio_button"
       android:fontFamily="sans-serif"
       android:text="@{htmlContent}"
+      android:contentDescription="@{viewModel.getContentDescription()}"
       android:textColor="@{viewModel.isAnswerSelected() ? @color/component_color_shared_selection_interaction_selected_text_color : @color/component_color_shared_selection_interaction_unselected_text_color}"
       android:textSize="16sp" />
   </RelativeLayout>