Pack wrapped lines onto the font's own extent (#190)

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/CalendarText.kt

@@ -0,0 +1,57 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.rememberTextMeasurer
+import androidx.compose.ui.text.style.LineHeightStyle
+import androidx.compose.ui.unit.Dp
+
+/**
+ * The calendar surfaces' line-height treatment. Material wraps an 11sp glyph in
+ * a 16sp line box — room a label wants when it stands on its own, and close to
+ * a fifth of an event row when it doesn't. The outer edges only, so a wrapped
+ * title keeps its interior line spacing (#190).
+ *
+ * Trimmed rather than set to a smaller line height: the font picker can load a
+ * serif, a monospace or a file of the user's own, and a line height under a
+ * face's own ascent and descent overlaps its lines. There is nothing to trim
+ * below that, so this is safe whatever font is chosen.
+ */
+private val TrimmedLines = LineHeightStyle(
+    alignment = LineHeightStyle.Alignment.Center,
+    trim = LineHeightStyle.Trim.Both,
+)
+
+/** Ascenders and descenders both, so a line is measured at its full extent. */
+private const val LINE_SAMPLE = "Ag"
+
+/** [this] with Material's outer leading trimmed — see [TrimmedLines]. */
+fun TextStyle.trimmedLines(): TextStyle = copy(lineHeightStyle = TrimmedLines)
+
+/**
+ * [style] with its wrapped lines packed onto the face's own extent instead of
+ * Material's line box.
+ *
+ * [trimmedLines] takes the leading off the outer edges of a run of text; this
+ * takes it from between the lines as well, which is the half a wrapped event
+ * title pays for twice over. The line height is *measured* from the font rather
+ * than picked, so it lands exactly on the face's ascent-plus-descent and can
+ * never be short enough to overlap — whatever the font picker has loaded (#190).
+ */
+@Composable
+fun rememberPackedLines(style: TextStyle): TextStyle {
+    val line = rememberTrimmedLineHeight(style)
+    return with(LocalDensity.current) { style.trimmedLines().copy(lineHeight = line.toSp()) }
+}
+
+/** What one trimmed line of [style] actually draws in. */
+@Composable
+fun rememberTrimmedLineHeight(style: TextStyle): Dp {
+    val measurer = rememberTextMeasurer()
+    val density = LocalDensity.current
+    return remember(style, density, measurer) {
+        with(density) { measurer.measure(LINE_SAMPLE, style.trimmedLines()).size.height.toDp() }
+    }
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/CalendarTransitions.kt

@@ -83,10 +83,8 @@ fun calendarSlideTransition(
         initialContentExit =
             slideOutHorizontally(spec) { w -> -dir * w / SLIDE_TRAVEL_DIVISOR } + fadeOut(fadeSpec),
         // AnimatedContent clips to the animating container by default, which
-        // shears the pages against the viewport edge as they pass. Left off even
-        // where the two pages differ in height — the split grid stands as many
-        // rows as its month spans (#162) — since a page sliding out over the row
-        // below it reads as travel, and the shear reads as a fault.
+        // shears the pages against the viewport edge as they pass. There is no
+        // size change here to contain — both pages are the same grid.
         sizeTransform = SizeTransform(clip = false),
     )
 }

app/src/main/java/de/jeanlucmakiola/calendula/ui/day/DayScreen.kt

@@ -115,6 +115,7 @@ import de.jeanlucmakiola.calendula.ui.common.rememberCalendarPageSwipe
 import de.jeanlucmakiola.floret.identity.rememberReduceMotion
 import de.jeanlucmakiola.calendula.ui.common.next
 import de.jeanlucmakiola.calendula.ui.common.EventChipShape
+import de.jeanlucmakiola.calendula.ui.common.trimmedLines
 import de.jeanlucmakiola.calendula.ui.common.rememberCalendarSlideSpec
 import de.jeanlucmakiola.floret.locale.currentLocale
 import de.jeanlucmakiola.calendula.ui.common.LocalUse24HourFormat
@@ -140,7 +141,8 @@ import kotlin.time.Clock
 import java.util.Locale
 import kotlin.math.roundToInt
 
-private val ALL_DAY_ROW_HEIGHT = 24.dp
+/** One lane of the all-day strip, sized to a trimmed bar line (#190). */
+private val ALL_DAY_ROW_HEIGHT = 20.dp
 private val ALL_DAY_VERTICAL_PADDING = 6.dp
 
 /** Total all-day strip height for the day (0 when there are no all-day events). */
@@ -529,7 +531,7 @@ private fun AllDayBar(
         val titleOverflow = eventTitleOverflow()
         Text(
             text = title,
-            style = MaterialTheme.typography.labelSmall,
+            style = MaterialTheme.typography.labelSmall.trimmedLines(),
             maxLines = 1,
             overflow = titleOverflow.overflow,
             softWrap = titleOverflow.softWrap,

app/src/main/java/de/jeanlucmakiola/calendula/ui/month/MonthScreen.kt

@@ -153,6 +153,7 @@ import de.jeanlucmakiola.calendula.ui.common.LocalUse24HourFormat
 import de.jeanlucmakiola.calendula.ui.common.inlineTimeLabel
 import de.jeanlucmakiola.calendula.ui.common.eventAccent
 import de.jeanlucmakiola.calendula.ui.common.EventChipShape
+import de.jeanlucmakiola.calendula.ui.common.trimmedLines
 import de.jeanlucmakiola.calendula.ui.common.monthBarShape
 import de.jeanlucmakiola.calendula.ui.common.rememberCurrentMinute
 import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
@@ -1141,10 +1142,10 @@ private val MONTH_EXPAND_THRESHOLD = 48.dp
  * lists whatever day is selected — and a downward drag trades the pane away for
  * the full paged grid, an upward one brings it back (#53).
  *
- * The grid slides between months like the paged style, and stands only as many
- * rows tall as its own month spans (#162). A swipe between a five-row month and
- * a six-row one therefore moves the pane by a row as well as swapping the grid;
- * the row it hands back is worth more to the pane than a still edge is.
+ * The grid slides between months like the paged style, which it can only do
+ * because it always reserves [SPLIT_GRID_ROWS] rows. Sized to its own month it
+ * stood 4–6 rows tall, so every swipe shunted the pane up or down by a row on
+ * top of swapping the grid — the pane now holds still and only the grid moves.
  *
  * Expansion is deliberately **not** a stored preference. It is a way to look at
  * the month you are on, not a fourth style; persisted, someone would expand it
@@ -1441,6 +1442,13 @@ private val SPLIT_DOT_SIZE = 5.dp
 // the paged grid's lanes, so the two caps have to be the same number or a dot
 // would have no bar to become (#53).
 
+/**
+ * Rows the split grid always reserves — the most any month needs. A month that
+ * fits in fewer pads the remainder with blank rows rather than shrinking, which
+ * is what lets the pane below hold still from month to month.
+ */
+private const val SPLIT_GRID_ROWS = 6
+
 /**
  * The expand handle: M3's drag-handle pill (32×4dp), in a row tall enough to be a
  * comfortable tap target on its own.
@@ -1453,11 +1461,6 @@ private val SPLIT_HANDLE_ROW_HEIGHT = 24.dp
  * The split style's grid (#53): the month compressed to day numbers and event
  * dots, with the selected day listed underneath by [SplitDayPane].
  *
- * Only the rows the month actually spans. It used to pad every month out to six
- * so the pane below held still from page to page, but a row is a sixth of the
- * grid and a third of what the pane gets to show — too much to leave blank on
- * the months that don't need it (#162).
- *
  * Tapping selects rather than drilling into the Day view — the pane is the
  * answer to "what's on this day", so opening a whole screen for it would defeat
  * the layout. The full Day view stays one tap away on the pane's date header.
@@ -1516,6 +1519,12 @@ internal fun SplitMonthGrid(
                 }
             }
         }
+        // Hold the grid at a constant height whatever shape the month is, so the
+        // pane beneath it doesn't move as you page and one month can slide over
+        // another without a height change under it.
+        repeat(SPLIT_GRID_ROWS - state.weeks.size) {
+            Spacer(Modifier.fillMaxWidth().height(SPLIT_ROW_HEIGHT))
+        }
     }
 }
 
@@ -2536,7 +2545,7 @@ private fun MonthBar(
         val titleOverflow = eventTitleOverflow()
         Text(
             text = label,
-            style = MaterialTheme.typography.labelSmall,
+            style = MaterialTheme.typography.labelSmall.trimmedLines(),
             maxLines = 1,
             overflow = titleOverflow.overflow,
             softWrap = titleOverflow.softWrap,

app/src/main/java/de/jeanlucmakiola/calendula/ui/theme/Type.kt

@@ -1,10 +1,24 @@
 package de.jeanlucmakiola.calendula.ui.theme
 
 import androidx.compose.material3.Typography
+import androidx.compose.ui.unit.sp
 
 /**
- * Default Material 3 Expressive typography. Custom font + tuned scale will
- * land in a later UI-design iteration; the defaults are intentional for V1
- * scaffolding to keep the foundation lean.
+ * Tracking the two label roles the calendar grids are set in. Material gives
+ * both 0.5sp, tuned for isolated UI labels with room around them; a month chip
+ * is a text box some 37dp wide, where 0.5sp on an 11sp glyph spends most of a
+ * character on spacing alone. 0.1sp is what Material itself sets labelLarge to,
+ * so the label family stays coherent (#190).
  */
-val CalendulaTypography = Typography()
+private val LabelTracking = 0.1.sp
+
+/**
+ * Material 3 Expressive typography with the label roles' tracking tightened.
+ * Everything else is the default scale.
+ */
+val CalendulaTypography: Typography = Typography().let { base ->
+    base.copy(
+        labelMedium = base.labelMedium.copy(letterSpacing = LabelTracking),
+        labelSmall = base.labelSmall.copy(letterSpacing = LabelTracking),
+    )
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/week/WeekScreen.kt

@@ -118,6 +118,7 @@ import de.jeanlucmakiola.calendula.ui.common.rememberTimelineDragController
 import de.jeanlucmakiola.calendula.ui.common.startInstant
 import de.jeanlucmakiola.calendula.ui.common.LocalDimCutoff
 import de.jeanlucmakiola.calendula.ui.common.EventChipShape
+import de.jeanlucmakiola.calendula.ui.common.trimmedLines
 import de.jeanlucmakiola.calendula.ui.common.NowLine
 import de.jeanlucmakiola.calendula.ui.common.rememberCurrentMinute
 import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
@@ -155,7 +156,8 @@ import kotlin.time.Clock
 import java.time.format.TextStyle as JavaTextStyle
 import java.util.Locale
 
-private val ALL_DAY_ROW_HEIGHT = 24.dp
+/** One lane of the all-day strip, sized to a trimmed bar line (#190). */
+private val ALL_DAY_ROW_HEIGHT = 20.dp
 private val ALL_DAY_VERTICAL_PADDING = 6.dp
 /** Gap between day columns; part of the column pitch a drag maps positions through. */
 private val COLUMN_GAP = 2.dp
@@ -664,7 +666,7 @@ private fun AllDayBar(
         val titleOverflow = eventTitleOverflow()
         Text(
             text = title,
-            style = MaterialTheme.typography.labelSmall,
+            style = MaterialTheme.typography.labelSmall.trimmedLines(),
             maxLines = 1,
             overflow = titleOverflow.overflow,
             softWrap = titleOverflow.softWrap,

app/src/test/java/de/jeanlucmakiola/calendula/ui/theme/FontsTest.kt

@@ -1,5 +1,6 @@
 package de.jeanlucmakiola.calendula.ui.theme
 
+import androidx.compose.ui.unit.sp
 import com.google.common.truth.Truth.assertThat
 import org.junit.jupiter.api.Test
 
@@ -48,6 +49,19 @@ class FontsTest {
         assertThat(typography.labelSmall.fontFamily).isEqualTo(plain)
     }
 
+    @Test
+    fun `picking a font keeps the tightened label tracking`() {
+        // The font picker only swaps the family; the tracking the grids are laid
+        // out against has to survive it (#190).
+        val typography = calendulaTypography(
+            brand = BundledFont.Lora.family,
+            plain = BundledFont.AtkinsonHyperlegible.family,
+        )
+
+        assertThat(typography.labelSmall.letterSpacing).isEqualTo(0.1.sp)
+        assertThat(typography.labelMedium.letterSpacing).isEqualTo(0.1.sp)
+    }
+
     @Test
     fun `a null role keeps that role's default family while the other is applied`() {
         val plain = BundledFont.Lora.family