new: mark liaison characters

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

@@ -198,7 +198,10 @@ private fun TranscriptionLine(
     TranscriptionText(
         text = text,
         color = contentColor,
-        style = MaterialTheme.typography.bodyLarge.copy(fontSize = 20.sp),
+        style = MaterialTheme.typography.bodyLarge.copy(
+            fontSize = 20.sp,
+            lineHeight = 32.sp,
+        ),
         textAlign = TextAlign.Center,
     )
 }

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

@@ -1,7 +1,12 @@
 package fr.ajaury.gwenedeg.player.ui.components
 
+import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.text.InlineTextContent
 import androidx.compose.foundation.text.appendInlineContent
 import androidx.compose.material3.MaterialTheme
@@ -11,6 +16,7 @@ import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.drawscope.Stroke
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.Placeholder
 import androidx.compose.ui.text.PlaceholderVerticalAlign
@@ -19,25 +25,38 @@ import androidx.compose.ui.text.buildAnnotatedString
 import androidx.compose.ui.text.rememberTextMeasurer
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.em
 import androidx.compose.ui.unit.sp
 import fr.ajaury.gwenedeg.theme.ChomBevTheme
 
 /**
- * Matches a liaison/optional letter written between parentheses in a transcription, e.g. the `n`
- * in `ma(n)`. The captured group is the letter itself, without the surrounding parentheses.
+ * Matches a single letter marked in a transcription, either:
+ *  - between parentheses, e.g. the `n` in `ma(n)` (a muted consonant), captured in group 1, or
+ *  - between square brackets, e.g. the `t` in `[t]din` (a linking consonant), captured in
+ *    group 2.
+ *
+ * The captured group is the bare letter, without its surrounding delimiters.
  */
-private val MUTED_LETTER_REGEX = Regex("""\(([A-Za-z])\)""")
+private val MARKED_LETTER_REGEX = Regex("""\(([A-Za-z])\)|\[([A-Za-z])\]""")
 
-/** Diacritic drawn above an optional letter to mark that it is only sounded on liaison. */
-private const val MUTED_LETTER_MARK = "ø"
+/** Diacritic drawn above a parenthesised letter to mark that it is muted. */
+private const val MUTED_MARK = "ø"
 
 /**
- * Renders a transcription, giving special treatment to letters written between parentheses
- * (liaison consonants such as the `n` in `ma(n)`): the parentheses are dropped, the letter is
- * shown in a muted grey and topped with a small [MUTED_LETTER_MARK].
+ * Zero-width, no-break character placed on both sides of a marked letter so that line wrapping never
+ * separates it from the word it is glued to — breaks still happen at spaces, exactly as for words.
+ */
+private const val WORD_JOINER = "\u2060"
+
+/**
+ * Renders a transcription, giving special treatment to single letters written between delimiters:
+ *  - `(x)` — a liaison consonant: the parentheses are dropped and the letter stays on the line, in
+ *    muted grey, topped with a small [MUTED_MARK].
+ *  - `[x]` — a linking consonant: the brackets are dropped and the letter is raised above the line,
+ *    in muted grey, with a small [LIAISON_MARK] underneath it.
  *
- * Optional letters are emitted as inline content so the line still wraps like normal text.
+ * Marked letters are emitted as inline content so the line still wraps like normal text.
  */
 @Composable
 fun TranscriptionText(
@@ -47,7 +66,7 @@ fun TranscriptionText(
     modifier: Modifier = Modifier,
     textAlign: TextAlign = TextAlign.Center,
 ) {
-    val matches = remember(text) { MUTED_LETTER_REGEX.findAll(text).toList() }
+    val matches = remember(text) { MARKED_LETTER_REGEX.findAll(text).toList() }
 
     if (matches.isEmpty()) {
         Text(
@@ -61,13 +80,16 @@ fun TranscriptionText(
     }
 
     // Muted grey that still follows the surrounding line's dimming (current vs. inactive line).
-    val markColor = color.copy(alpha = color.alpha * 0.6f)
+    val markColor = color.copy(alpha = color.alpha * 0.7f)
 
     val annotatedText = buildAnnotatedString {
         var cursor = 0
         matches.forEachIndexed { index, match ->
             append(text.substring(cursor, match.range.first))
-            appendInlineContent(id = inlineId(index), alternateText = match.groupValues[1])
+            // Glue the marked letter to its neighbouring characters so a line never breaks onto it.
+            append(WORD_JOINER)
+            appendInlineContent(id = inlineId(index), alternateText = match.letter)
+            append(WORD_JOINER)
             cursor = match.range.last + 1
         }
         append(text.substring(cursor))
@@ -78,10 +100,10 @@ fun TranscriptionText(
 
     val inlineContent = matches
         .mapIndexed { index, match ->
-            val letter = match.groupValues[1]
+            val letter = match.letter
             // Reserve exactly the letter's advance width (in em, so it is font-scale independent); the
-            // taller placeholder leaves room for the mark above. Aligning to the text bottom keeps the
-            // letter's baseline in step with the rest of the line.
+            // taller placeholder leaves room for the mark. Aligning to the text bottom keeps the
+            // baseline in step with the rest of the line.
             val letterWidthEm = remember(letter, style) {
                 val letterWidthPx = textMeasurer.measure(text = letter, style = style).size.width
                 val fontSizePx = with(density) { style.fontSize.toPx() }
@@ -95,7 +117,19 @@ fun TranscriptionText(
                     placeholderVerticalAlign = PlaceholderVerticalAlign.TextBottom,
                 ),
             ) {
-                OptionalLetter(letter = letter, color = markColor, style = style)
+                if (match.isBracketed) {
+                    LiaisonLetter(
+                        letter = letter,
+                        color = markColor,
+                        style = style,
+                    )
+                } else {
+                    MutedLetter(
+                        letter = letter,
+                        color = markColor,
+                        style = style,
+                    )
+                }
             }
         }.toMap()
 
@@ -110,33 +144,78 @@ fun TranscriptionText(
 }
 
 @Composable
-private fun OptionalLetter(
+private fun MutedLetter(
     letter: String,
     color: Color,
     style: TextStyle,
 ) {
     Box(modifier = Modifier.fillMaxSize()) {
         Text(
-            text = MUTED_LETTER_MARK,
+            text = MUTED_MARK,
             color = color,
-            style = style.copy(fontSize = style.fontSize * 0.75f, lineHeight = 10.sp),
+            style = style.copy(
+                fontSize = style.fontSize * 0.75f,
+                lineHeight = style.fontSize * 0.75f,
+            ),
             modifier = Modifier.align(Alignment.TopCenter),
         )
         Text(
             text = letter,
             color = color,
-            // Tight line height so the glyph's baseline lands where the surrounding line expects it.
-            style = style.copy(lineHeight = style.fontSize),
+            // Tight line height so a bottom glyph's baseline lands where the surrounding line expects it.
+            style = style.copy(fontSize = style.fontSize, lineHeight = style.fontSize),
             modifier = Modifier.align(Alignment.BottomCenter),
         )
     }
 }
 
-private fun inlineId(index: Int): String = "optional-letter-$index"
+@Composable
+private fun LiaisonLetter(
+    letter: String,
+    color: Color,
+    style: TextStyle,
+) {
+    Column(
+        modifier = Modifier.fillMaxSize().padding(horizontal = 1.dp),
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = letter,
+            color = color,
+            letterSpacing = 1.sp,
+            // Tight line height so a bottom glyph's baseline lands where the surrounding line expects it.
+            style = style.copy(
+                fontSize = style.fontSize * 0.75f,
+                lineHeight = style.fontSize * 0.75f,
+            ),
+        )
+        Canvas(
+            modifier = Modifier
+                .width(100.dp)
+                .height(3.dp),
+        ) {
+            drawArc(
+                color = color,
+                startAngle = 180f,
+                sweepAngle = 180f,
+                useCenter = false,
+                style = Stroke(width = 2f),
+            )
+        }
+    }
+}
+
+private val MatchResult.letter: String
+    get() = groupValues[1].ifEmpty { groupValues[2] }
+
+private val MatchResult.isBracketed: Boolean
+    get() = groupValues[1].isEmpty()
+
+private fun inlineId(index: Int): String = "marked-letter-$index"
 
 @Preview(backgroundColor = 0xFFFFFFFF)
 @Composable
-private fun TranscriptionTextPreview() {
+private fun TranscriptionTextLiaisonPreview() {
     ChomBevTheme {
         TranscriptionText(
             text = "Tomm eo ma(n) divskouarn, penn ma fri",
@@ -148,10 +227,22 @@ private fun TranscriptionTextPreview() {
 
 @Preview(backgroundColor = 0xFFFFFFFF)
 @Composable
-private fun TranscriptionTextNoOptionalLetterPreview() {
+private fun TranscriptionTextBracketPreview() {
     ChomBevTheme {
         TranscriptionText(
-            text = "Demat deoc'h !",
+            text = "Lârit[t] din, mar plij[k] geneoc'h.",
+            color = MaterialTheme.colorScheme.onSurface,
+            style = MaterialTheme.typography.bodyLarge.copy(fontSize = 20.sp),
+        )
+    }
+}
+
+@Preview(backgroundColor = 0xFFFFFFFF)
+@Composable
+private fun LiaisonLetterPreview() {
+    ChomBevTheme {
+        LiaisonLetter(
+            letter = "D",
             color = MaterialTheme.colorScheme.onSurface,
             style = MaterialTheme.typography.bodyLarge.copy(fontSize = 20.sp),
         )