new: add adjustable subtitle text size in player and preferences UI

shared/src/commonMain/kotlin/fr/ajaury/gwenedeg/player/ui/PlayerScreen.kt

@@ -72,6 +72,8 @@ fun PlayerScreen(
         onNextSentenceClicked = viewModel::goToNextSentence,
         onShowTranscriptionChange = viewModel::setShowTranscription,
         onShowTranslationChange = viewModel::setShowTranslation,
+        onTextSizeDecrease = viewModel::decreaseSubtitleTextSize,
+        onTextSizeIncrease = viewModel::increaseSubtitleTextSize,
         onSpeedChange = viewModel::setPlaybackSpeed,
         onBackClicked = onBackClicked,
     )
@@ -88,6 +90,8 @@ fun PlayerScreen(
     onNextSentenceClicked: () -> Unit = {},
     onShowTranscriptionChange: (Boolean) -> Unit = {},
     onShowTranslationChange: (Boolean) -> Unit = {},
+    onTextSizeDecrease: () -> Unit = {},
+    onTextSizeIncrease: () -> Unit = {},
     onSpeedChange: (Float) -> Unit = {},
     onBackClicked: () -> Unit = {},
 ) {
@@ -184,6 +188,8 @@ fun PlayerScreen(
                 subtitlePreferences = uiState.subtitlePreferences,
                 onShowTranscriptionChange = onShowTranscriptionChange,
                 onShowTranslationChange = onShowTranslationChange,
+                onTextSizeDecrease = onTextSizeDecrease,
+                onTextSizeIncrease = onTextSizeIncrease,
                 onDismiss = { showPreferences = false },
             )
         }

shared/src/commonMain/kotlin/fr/ajaury/gwenedeg/player/ui/SubtitleList.kt

@@ -17,6 +17,7 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
@@ -27,9 +28,11 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.font.FontStyle
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import fr.ajaury.gwenedeg.core.model.Phrase
@@ -90,23 +93,34 @@ fun SubtitleList(
         }
     }
 
+    val density = LocalDensity.current
     BoxWithConstraints(modifier = modifier) {
-        LazyColumn(
-            state = listState,
-            modifier = Modifier.fillMaxSize(),
-            horizontalAlignment = Alignment.CenterHorizontally,
-            verticalArrangement = Arrangement.spacedBy(4.dp),
-            // Half-height padding so the first and last lines can reach the vertical center.
-            contentPadding = PaddingValues(vertical = maxHeight / 2),
+        // Half-height padding so the first and last lines can reach the vertical center. Captured here
+        // because `maxHeight` (BoxWithConstraintsScope) is not in scope inside the provider lambda.
+        val verticalPadding = maxHeight / 2
+        // Scale only the subtitle fonts by overriding the density's fontScale (dp layout is untouched).
+        CompositionLocalProvider(
+            LocalDensity provides Density(
+                density = density.density,
+                fontScale = density.fontScale * subtitlePreferences.textScale,
+            ),
         ) {
-            itemsIndexed(lines) { index, line ->
-                val isCurrent = index == centeredIndex
-                Subtitle(
-                    line = line,
-                    isCurrent = isCurrent,
-                    subtitlePreferences = subtitlePreferences,
-                    onClick = { onSeek(index) },
-                )
+            LazyColumn(
+                state = listState,
+                modifier = Modifier.fillMaxSize(),
+                horizontalAlignment = Alignment.CenterHorizontally,
+                verticalArrangement = Arrangement.spacedBy(4.dp),
+                contentPadding = PaddingValues(vertical = verticalPadding),
+            ) {
+                itemsIndexed(lines) { index, line ->
+                    val isCurrent = index == centeredIndex
+                    Subtitle(
+                        line = line,
+                        isCurrent = isCurrent,
+                        subtitlePreferences = subtitlePreferences,
+                        onClick = { onSeek(index) },
+                    )
+                }
             }
         }
     }

shared/src/commonMain/kotlin/fr/ajaury/gwenedeg/player/ui/viewmodel/PlayerViewModel.kt

@@ -9,6 +9,7 @@ import fr.ajaury.gwenedeg.player.domain.PlaybackRepository
 import fr.ajaury.gwenedeg.player.model.PlaybackState
 import fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository
 import fr.ajaury.gwenedeg.preferences.model.PlaybackPreferences
+import fr.ajaury.gwenedeg.preferences.model.SubtitlePreferences
 import fr.ajaury.gwenedeg.records.domain.RecordRepository
 import fr.ajaury.gwenedeg.records.model.Record
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -125,6 +126,22 @@ class PlayerViewModel(
         }
     }
 
+    fun increaseSubtitleTextSize() {
+        val current = uiState.value.subtitlePreferences.textScale
+        setSubtitleTextScale(SubtitlePreferences.nextTextScale(current))
+    }
+
+    fun decreaseSubtitleTextSize() {
+        val current = uiState.value.subtitlePreferences.textScale
+        setSubtitleTextScale(SubtitlePreferences.previousTextScale(current))
+    }
+
+    private fun setSubtitleTextScale(scale: Float) {
+        viewModelScope.launch {
+            preferencesRepository.setSubtitleTextScale(scale)
+        }
+    }
+
     fun stop() {
         playbackRepository.stop()
     }

shared/src/commonMain/kotlin/fr/ajaury/gwenedeg/preferences/ui/SubtitlePreferencesBottomSheet.kt

@@ -2,27 +2,38 @@ package fr.ajaury.gwenedeg.preferences.ui
 
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Add
+import androidx.compose.material.icons.filled.Remove
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.ModalBottomSheet
 import androidx.compose.material3.SheetState
 import androidx.compose.material3.Text
 import androidx.compose.material3.rememberModalBottomSheetState
 import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import fr.ajaury.gwenedeg.preferences.model.SubtitlePreferences
 import fr.ajaury.gwenedeg.resources.generated.resources.Res
 import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_preferences_title
+import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_text_size_decrease
+import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_text_size_increase
+import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_text_size_label
 import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_transcription_description
 import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_transcription_label
 import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_translation_description
 import fr.ajaury.gwenedeg.resources.generated.resources.subtitle_translation_label
 import fr.ajaury.gwenedeg.theme.ChomBevTheme
 import org.jetbrains.compose.resources.stringResource
+import kotlin.math.roundToInt
 
 /**
  * Bottom sheet letting the user toggle the display of the Breton transcription (BZH) and the
@@ -34,6 +45,8 @@ fun SubtitlePreferencesBottomSheet(
     subtitlePreferences: SubtitlePreferences,
     onShowTranscriptionChange: (Boolean) -> Unit = {},
     onShowTranslationChange: (Boolean) -> Unit = {},
+    onTextSizeDecrease: () -> Unit = {},
+    onTextSizeIncrease: () -> Unit = {},
     onDismiss: () -> Unit = {},
     sheetState: SheetState = rememberModalBottomSheetState(),
 ) {
@@ -45,6 +58,8 @@ fun SubtitlePreferencesBottomSheet(
             subtitlePreferences = subtitlePreferences,
             onShowTranscriptionChange = onShowTranscriptionChange,
             onShowTranslationChange = onShowTranslationChange,
+            onTextSizeDecrease = onTextSizeDecrease,
+            onTextSizeIncrease = onTextSizeIncrease,
         )
     }
 }
@@ -54,6 +69,8 @@ private fun SubtitlePreferencesContent(
     subtitlePreferences: SubtitlePreferences,
     onShowTranscriptionChange: (Boolean) -> Unit = {},
     onShowTranslationChange: (Boolean) -> Unit = {},
+    onTextSizeDecrease: () -> Unit = {},
+    onTextSizeIncrease: () -> Unit = {},
 ) {
     Column(
         modifier = Modifier
@@ -78,9 +95,63 @@ private fun SubtitlePreferencesContent(
             checked = subtitlePreferences.showTranslation,
             onCheckedChange = onShowTranslationChange,
         )
+        SubtitleTextSizeControl(
+            textScale = subtitlePreferences.textScale,
+            onDecrease = onTextSizeDecrease,
+            onIncrease = onTextSizeIncrease,
+        )
     }
 }
 
+@Composable
+private fun SubtitleTextSizeControl(
+    textScale: Float,
+    onDecrease: () -> Unit = {},
+    onIncrease: () -> Unit = {},
+) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(vertical = 8.dp),
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Text(
+            text = stringResource(Res.string.subtitle_text_size_label),
+            style = MaterialTheme.typography.bodyLarge,
+            modifier = Modifier.weight(1f),
+        )
+        IconButton(
+            onClick = onDecrease,
+            enabled = textScale > SubtitlePreferences.TEXT_SCALE_STEPS.first(),
+        ) {
+            Icon(
+                imageVector = Icons.Default.Remove,
+                contentDescription = stringResource(Res.string.subtitle_text_size_decrease),
+            )
+        }
+        Text(
+            text = formatTextScale(textScale),
+            style = MaterialTheme.typography.titleMedium,
+        )
+        IconButton(
+            onClick = onIncrease,
+            enabled = textScale < SubtitlePreferences.TEXT_SCALE_STEPS.last(),
+        ) {
+            Icon(
+                imageVector = Icons.Default.Add,
+                contentDescription = stringResource(Res.string.subtitle_text_size_increase),
+            )
+        }
+    }
+}
+
+/** Formats a text-scale multiplier as a short label, e.g. 1.0 -> "x1", 1.2 -> "x1.2". */
+private fun formatTextScale(scale: Float): String {
+    val tenths = (scale * 10).roundToInt()
+    return if (tenths % 10 == 0) "x${tenths / 10}" else "x${tenths / 10}.${tenths % 10}"
+}
+
 @Preview
 @Composable
 private fun SubtitlePreferencesContentPreview() {