Show the title on short week and day blocks (#289)

The pinch clamped its lower bound to `ceil(fillPx)`. Rounding a fill height up
by the fraction of a pixel that 24 hours don't divide the viewport into makes
the timeline up to one pixel per hour taller than the viewport those hours are
supposed to fill — roughly 24px of leftover scroll, enough to bounce off
Android's overscroll stretch. `FitDay` resolves to the unrounded height and sits
still, so the two ways of reaching "the whole day on one screen" disagreed.
That inconsistency is what #290 is about.

Clamps to `fillPx` itself. The whole-pixel rounding exists so the hour gutter's
24 stacked boxes share a grid with the lines and blocks drawn at the fractional
height, and it still applies everywhere the pinch is free to move. The floor is
the one height where matching `FitDay` matters more — and because it is the
clamp *result* rather than a bound the gesture is merely held against, the pinch
lands on it exactly, so the next frame reads it back unchanged and the focal
anchor gets no correction to apply.

Week and Day both measure their viewport inside a `BoxWithConstraints` below the
all-day strip, so the strip appearing only changes the height both paths agree
on — that half of the report needed no change.

Tests: the two cases that encoded the old rounding are updated (the dead-space
invariant still holds, now exactly rather than by a pixel), plus one for the
reported symptom and one asserting the pinch floor equals what `FitDay`
resolves to at the same viewport.

Closes #290

Co-authored-by: Jean-Luc Makiola <business@jeanlucmakiola.de>
Reviewed-on: https://codeberg.org/jlmakiola/calendula/pulls/315

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

@@ -17,6 +17,7 @@ import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.rememberTextMeasurer
+import androidx.compose.ui.text.style.LineHeightStyle
 import androidx.compose.ui.text.style.TextDecoration
 import androidx.compose.ui.unit.Constraints
 import androidx.compose.ui.unit.Dp
@@ -32,6 +33,93 @@ val BLOCK_TEXT_PADDING = 4.dp
 /** The same, above and below — what a block's height has to pay before any text. */
 val BLOCK_TEXT_INSET = 2.dp
 
+/**
+ * Block text with Material's outer leading trimmed off. The label roles wrap a
+ * 12sp glyph in a 16sp line box, and on a block short enough to be at risk that
+ * leading is the difference between a title and a bare colour chip (#289).
+ * Outer edges only, so a wrapped title keeps its interior line spacing.
+ */
+private val BlockLineHeight = 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] as a timed block draws it — see [BlockLineHeight]. */
+fun TextStyle.asBlockText(): TextStyle = copy(lineHeightStyle = BlockLineHeight)
+
+/** What one trimmed line of [style] actually draws in. */
+@Composable
+fun rememberBlockLineHeight(style: TextStyle): Dp {
+    val measurer = rememberTextMeasurer()
+    val density = LocalDensity.current
+    return remember(style, density, measurer) {
+        with(density) { measurer.measure(LINE_SAMPLE, style.asBlockText()).size.height.toDp() }
+    }
+}
+
+/**
+ * What a timed block of a given height has to spend on text, and what each line
+ * of it costs.
+ */
+@Immutable
+data class BlockTextMetrics(
+    /** Padding above and below the text — see [rememberBlockTextMetrics]. */
+    val inset: Dp,
+    /** Height left for text once [inset] is paid at both edges. */
+    val available: Dp,
+    /** What the first line of a title draws in. */
+    val titleLine: Dp,
+    /** What every title line after the first adds: a whole line box, the trim
+     *  reaching only the outer edges. */
+    val titleLeading: Dp,
+    /** What the time label's one line draws in. */
+    val timeLine: Dp,
+) {
+    /** Whether the block can draw a title at all. */
+    val fitsTitle: Boolean get() = available >= titleLine
+
+    /** Height a title of [lines] lines occupies. */
+    fun titleHeight(lines: Int): Dp =
+        if (lines <= 0) 0.dp else titleLine + titleLeading * (lines - 1)
+
+    /** Title lines that fit [within], which may be none. */
+    fun titleBudget(within: Dp): Int =
+        if (within < titleLine) 0 else 1 + ((within - titleLine) / titleLeading).toInt()
+}
+
+/**
+ * The vertical padding a block [height] tall can afford around a title line of
+ * [titleLine].
+ *
+ * The inset is what the block gives up first: breathing room is worth having
+ * where there is room to breathe, but on a block down to its last few pixels a
+ * bare colour chip where a label would have fit reads as a rendering fault. It
+ * tapers rather than snapping, so a pinch closes the gap gradually instead of
+ * dropping it in one frame (#289).
+ */
+internal fun blockTextInset(height: Dp, titleLine: Dp): Dp =
+    minOf(BLOCK_TEXT_INSET, (height - titleLine) / 2).coerceAtLeast(0.dp)
+
+/** Text metrics for a timed block [height] tall. */
+@Composable
+fun rememberBlockTextMetrics(height: Dp): BlockTextMetrics {
+    val titleStyle = MaterialTheme.typography.labelMedium
+    val titleLine = rememberBlockLineHeight(titleStyle)
+    val titleLeading = with(LocalDensity.current) { titleStyle.lineHeight.toDp() }
+    val timeLine = rememberBlockLineHeight(MaterialTheme.typography.labelSmall.asEventTime())
+    val inset = blockTextInset(height, titleLine)
+    return BlockTextMetrics(
+        inset = inset,
+        available = height - inset * 2,
+        titleLine = titleLine,
+        titleLeading = titleLeading,
+        timeLine = timeLine,
+    )
+}
+
 /** Most lines a time label may wrap over before it is worth more than a title line. */
 const val MAX_TIME_LINES = 2
 
@@ -70,9 +158,9 @@ fun blockTextLines(text: String, style: TextStyle, textWidth: Dp, max: Int): Int
  */
 @Composable
 fun blockTimeLines(label: String, textWidth: Dp, spare: Dp): Int {
-    val timeLineHeight = with(LocalDensity.current) {
-        MaterialTheme.typography.labelSmall.lineHeight.toDp()
-    }
+    val timeLineHeight = rememberBlockLineHeight(
+        MaterialTheme.typography.labelSmall.asEventTime(),
+    )
     return if (spare >= timeLineHeight) {
         blockTextLines(
             text = label,
@@ -109,7 +197,8 @@ fun BlockTitle(
         text = title,
         modifier = modifier,
         style = MaterialTheme.typography.labelMedium
-            .let { if (fontWeight == null) it else it.copy(fontWeight = fontWeight) },
+            .let { if (fontWeight == null) it else it.copy(fontWeight = fontWeight) }
+            .asBlockText(),
         maxLines = maxLines,
         overflow = overflow.overflow,
         softWrap = overflow.softWrap,
@@ -150,7 +239,7 @@ fun BlockTimeLabel(
         Text(
             text = text,
             // Regular weight against the title's medium above it (#219).
-            style = MaterialTheme.typography.labelSmall.asEventTime(),
+            style = MaterialTheme.typography.labelSmall.asEventTime().asBlockText(),
             maxLines = maxLines,
             overflow = overflow.overflow,
             softWrap = overflow.softWrap,

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

@@ -790,20 +790,15 @@ private fun DragCopy(
     val width = with(density) { sizePx.width.toDp() }
     val height = with(density) { sizePx.height.toDp() }
     val textWidth = width - (BLOCK_OUTER_INSET + BLOCK_TEXT_PADDING) * 2
-    val titleLineHeight = with(density) {
-        MaterialTheme.typography.labelMedium.lineHeight.toDp()
-    }
-    val timeLineHeight = with(density) {
-        MaterialTheme.typography.labelSmall.lineHeight.toDp()
-    }
     // The block's size, spent the block's way — text sits at the top as it does
-    // on the block, so the copy hands back to the grid without shifting (#267).
+    // on the block, so the copy hands back to the grid without shifting (#267),
+    // and it squeezes its inset on the same terms so a short block's title does
+    // not vanish the moment it is lifted (#289).
     // The title is served in full first and the range lives off what is left:
     // the hour gutter down the side still says where the copy sits, so the
     // range is the half that can afford to go.
-    val available = height - BLOCK_TEXT_INSET * 2
-    val titleBudget = (available / titleLineHeight).toInt().coerceAtLeast(0)
-    val allowed = titleLines.coerceAtMost(titleBudget)
+    val metrics = rememberBlockTextMetrics(height)
+    val allowed = titleLines.coerceAtMost(metrics.titleBudget(metrics.available))
     // Re-measured at the copy's own width rather than spent on the source's
     // count: a block sharing its column with another is a lane wide where the
     // copy is a whole column, so the source's second line is one the copy never
@@ -818,10 +813,10 @@ private fun DragCopy(
             max = allowed,
         )
     }
-    val left = available - titleLineHeight * lines
-    val showTime = label != null && left >= timeLineHeight
+    val left = metrics.available - metrics.titleHeight(lines)
+    val showTime = label != null && left >= metrics.timeLine
     val timeMaxLines = if (showTime) {
-        blockTimeLines(label!!, textWidth, left - timeLineHeight)
+        blockTimeLines(label!!, textWidth, left - metrics.timeLine)
     } else {
         1
     }
@@ -857,7 +852,7 @@ private fun DragCopy(
                 clip = false
             }
             .eventSurface(paint, shape, cuts)
-            .padding(horizontal = BLOCK_TEXT_PADDING, vertical = BLOCK_TEXT_INSET),
+            .padding(horizontal = BLOCK_TEXT_PADDING, vertical = metrics.inset),
     ) {
         Column {
             if (lines > 0) {

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

@@ -19,7 +19,6 @@ import androidx.compose.ui.input.pointer.PointerEventPass
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.unit.Dp
 import kotlin.math.abs
-import kotlin.math.ceil
 import kotlin.math.floor
 import kotlin.math.roundToInt
 
@@ -197,18 +196,26 @@ fun rememberTimelinePinchZoom(
  * names, jumping the whole column as a pinch drifts across each half pixel.
  * Pinning the hour to whole pixels keeps every part of the timeline on one grid.
  *
- * The bounds themselves are pulled onto that grid too, each in the direction
- * that keeps its own promise — up for the fill floor, so no dead space opens
- * under midnight, down for the ceiling. A fractional bound would be a height the
- * pinch can be held against but never actually land on, and the difference feeds
- * the focal anchor a scroll correction on every frame the fingers sit still.
+ * The ceiling is pulled onto that grid too, downwards, so it stays a height the
+ * pinch can actually land on.
+ *
+ * [fillPx] is deliberately *not* rounded (#290). It is the one height the whole
+ * day exactly fills the viewport at, and it is the same value
+ * [TimelineScale.FitDay] resolves to — rounding it up by the fraction of a pixel
+ * that 24 hours don't divide the viewport into leaves the timeline a pixel per
+ * hour taller than its own viewport, so a pinched-all-the-way-out day still
+ * scrolls a hair and bounces off Android's overscroll stretch, while the
+ * identical FitDay preset sits still. Being the clamp result rather than a bound
+ * the gesture is merely held against, it is a height the pinch does land on: the
+ * next frame reads it back unchanged and the focal anchor is handed nothing to
+ * correct.
  */
 internal fun pinchedHourHeightPx(target: Float, fillPx: Float, maxPx: Float): Float =
     // Filling the viewport wins over the ceiling: on a screen tall enough for
     // the two to disagree, dead space is the worse of the two failures.
     target.roundToInt().toFloat()
         .coerceAtMost(floor(maxPx))
-        .coerceAtLeast(ceil(fillPx))
+        .coerceAtLeast(fillPx)
 
 /**
  * The scroll offset that keeps the moment under [centroidY] under it after the

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

@@ -83,9 +83,9 @@ import de.jeanlucmakiola.calendula.ui.common.CalendarView
 import de.jeanlucmakiola.calendula.ui.common.IMPLEMENTED_VIEWS
 import de.jeanlucmakiola.calendula.ui.common.BLOCK_OUTER_INSET
 import de.jeanlucmakiola.calendula.ui.common.BLOCK_TEXT_PADDING
-import de.jeanlucmakiola.calendula.ui.common.BLOCK_TEXT_INSET
 import de.jeanlucmakiola.calendula.ui.common.BlockTimeLabel
 import de.jeanlucmakiola.calendula.ui.common.BlockTitle
+import de.jeanlucmakiola.calendula.ui.common.rememberBlockTextMetrics
 import de.jeanlucmakiola.calendula.ui.common.blockTimeLines
 import de.jeanlucmakiola.calendula.ui.common.animatedBlockPlacement
 import de.jeanlucmakiola.calendula.ui.common.ghostAlpha
@@ -763,30 +763,24 @@ private fun EventBlock(
     val timeLabel = "${minToHm(block.startMin, use24Hour, locale)}–" +
         minToHm(block.endMin, use24Hour, locale)
     val density = LocalDensity.current
-    val titleLineHeight = with(density) {
-        MaterialTheme.typography.labelMedium.lineHeight.toDp()
-    }
-    val timeLineHeight = with(density) {
-        MaterialTheme.typography.labelSmall.lineHeight.toDp()
-    }
+    val metrics = rememberBlockTextMetrics(height)
     // A block that cannot afford both lines spends its space on the title, and
     // one too short even for that drops the title rather than serving a sliced one.
     // Height alone decides: a duration threshold would keep hiding the time on a
     // half-hour block the user has pinched open to three times the room it needs.
-    val available = height - BLOCK_TEXT_INSET * 2
-    val showTime = available >= titleLineHeight + timeLineHeight
-    val showTitle = available >= titleLineHeight
+    val showTime = metrics.available >= metrics.titleLine + metrics.timeLine
+    val showTitle = metrics.fitsTitle
     val textWidth = width - (BLOCK_OUTER_INSET + BLOCK_TEXT_PADDING) * 2
     // Only lines the block can actually draw: a block too short for the time is
     // too short for a second title line too, and asking for one served a sliced
     // one — as well as handing the drag copy a count it couldn't honour, so the
     // title re-wrapped the moment the block was lifted (#267).
-    val titleBudget = (available / titleLineHeight).toInt().coerceAtLeast(1)
+    val titleBudget = metrics.titleBudget(metrics.available).coerceAtLeast(1)
     val titleMaxLines = if (showTime) 1 else titleBudget.coerceAtMost(2)
     // On a day column — wide enough for "09:30–11:00" several times over — the
     // range never needs the second line, until lanes cut the column down.
-    val spare = available - titleLineHeight * titleMaxLines -
-        if (showTime) timeLineHeight else 0.dp
+    val spare = metrics.available - metrics.titleHeight(titleMaxLines) -
+        if (showTime) metrics.timeLine else 0.dp
     val timeMaxLines = if (showTime) blockTimeLines(timeLabel, textWidth, spare) else 1
     val paint = eventPaint(block.event, dark)
     val zone = remember { TimeZone.currentSystemDefault() }
@@ -827,7 +821,7 @@ private fun EventBlock(
             // After clickable, so it is the inner node and wins the main pass;
             // the tap still works, since a drag consumes the up.
             .then(dragModifier)
-            .padding(horizontal = BLOCK_TEXT_PADDING, vertical = BLOCK_TEXT_INSET)
+            .padding(horizontal = BLOCK_TEXT_PADDING, vertical = metrics.inset)
             .semantics {
                 contentDescription = "$title, $timeLabel"
                 if (moveAction != null) customActions = listOf(moveAction)

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

@@ -91,11 +91,11 @@ import de.jeanlucmakiola.calendula.ui.common.IMPLEMENTED_VIEWS
 import de.jeanlucmakiola.calendula.ui.common.EventDimAlpha
 import de.jeanlucmakiola.calendula.ui.common.BLOCK_OUTER_INSET
 import de.jeanlucmakiola.calendula.ui.common.BLOCK_TEXT_PADDING
-import de.jeanlucmakiola.calendula.ui.common.BLOCK_TEXT_INSET
 import de.jeanlucmakiola.calendula.ui.common.BlockTimeLabel
 import de.jeanlucmakiola.calendula.ui.common.BlockTitle
 import de.jeanlucmakiola.calendula.ui.common.blockTextLines
 import de.jeanlucmakiola.calendula.ui.common.blockTimeLines
+import de.jeanlucmakiola.calendula.ui.common.rememberBlockTextMetrics
 import de.jeanlucmakiola.calendula.ui.common.animatedBlockPlacement
 import de.jeanlucmakiola.calendula.ui.common.ghostAlpha
 import de.jeanlucmakiola.calendula.ui.common.LocalEventMove
@@ -909,13 +909,7 @@ private fun EventBlock(
     val timeLabel = "${minToHm(block.startMin, use24Hour, locale)}–" +
         minToHm(block.endMin, use24Hour, locale)
     val density = LocalDensity.current
-    val titleLineHeight = with(density) {
-        MaterialTheme.typography.labelMedium.lineHeight.toDp()
-    }
-    val timeLineHeight = with(density) {
-        MaterialTheme.typography.labelSmall.lineHeight.toDp()
-    }
-    val available = height - BLOCK_TEXT_INSET * 2
+    val metrics = rememberBlockTextMetrics(height)
     // Only full-width (non-overlapping) blocks that are tall enough show the
     // time. On narrow overlapping columns we drop it so the title can wrap to
     // fill the whole block, mirroring Google Calendar — and a block that cannot
@@ -923,19 +917,19 @@ private fun EventBlock(
     // its own: a duration threshold would keep hiding the time on a half-hour
     // block the user has pinched open to three times the room it needs.
     val showTime = block.laneCount == 1 &&
-        available >= titleLineHeight + timeLineHeight
+        metrics.available >= metrics.titleLine + metrics.timeLine
     val textWidth = width - (BLOCK_OUTER_INSET + BLOCK_TEXT_PADDING) * 2
     // A short block drops the title rather than serving a horizontally sliced
     // one: half a letter reads as a rendering fault, while a bare colour chip
     // reads as what it is — an event too brief to label. Tap still opens it, and
     // the semantics description carries the full title either way.
-    val showTitle = available >= titleLineHeight
+    val showTitle = metrics.fitsTitle
     // The title is served first, out of everything the block has left once the
     // time is down to one line — but only takes the lines it will actually use,
     // and only wraps at all once a line is wide enough to hold more than a
     // syllable. Below that the extra lines just stack fragments of the word.
-    val contentHeight = available - if (showTime) timeLineHeight else 0.dp
-    val titleBudget = (contentHeight / titleLineHeight).toInt().coerceAtLeast(1)
+    val contentHeight = metrics.available - if (showTime) metrics.timeLine else 0.dp
+    val titleBudget = metrics.titleBudget(contentHeight).coerceAtLeast(1)
     val paint = eventPaint(block.event, dark)
     // Every line the height affords, however narrow the lane: two events side by
     // side leave columns well under a word wide, and cutting the title to one
@@ -948,8 +942,8 @@ private fun EventBlock(
         textWidth = textWidth,
         max = titleBudget,
     )
-    val spare = available - titleLineHeight * titleMaxLines -
-        if (showTime) timeLineHeight else 0.dp
+    val spare = metrics.available - metrics.titleHeight(titleMaxLines) -
+        if (showTime) metrics.timeLine else 0.dp
     val timeMaxLines = if (showTime) blockTimeLines(timeLabel, textWidth, spare) else 1
     val dimCutoff = LocalDimCutoff.current
     val dimmed = dimCutoff != null && block.event.hasEnded(dimCutoff)
@@ -991,7 +985,7 @@ private fun EventBlock(
             // After clickable, so it is the inner node and wins the main pass;
             // the tap still works, since a drag consumes the up.
             .then(dragModifier)
-            .padding(horizontal = BLOCK_TEXT_PADDING, vertical = BLOCK_TEXT_INSET)
+            .padding(horizontal = BLOCK_TEXT_PADDING, vertical = metrics.inset)
             .semantics {
                 contentDescription = "$title, $timeLabel"
                 if (moveAction != null) customActions = listOf(moveAction)

app/src/test/java/de/jeanlucmakiola/calendula/ui/common/BlockTextMetricsTest.kt

@@ -0,0 +1,88 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import com.google.common.truth.Truth.assertThat
+import org.junit.jupiter.api.Test
+
+class BlockTextMetricsTest {
+
+    /** One trimmed labelMedium line at font scale 1: a 12sp glyph, leading off. */
+    private val titleLine = 14.dp
+
+    /** A block with room to spare, for the line arithmetic. */
+    private fun metrics(height: Dp = 100.dp) = BlockTextMetrics(
+        inset = blockTextInset(height, titleLine),
+        available = height - blockTextInset(height, titleLine) * 2,
+        titleLine = titleLine,
+        titleLeading = 16.dp,
+        timeLine = 13.dp,
+    )
+
+    @Test
+    fun `a block with room keeps the full inset`() {
+        assertThat(blockTextInset(height = 60.dp, titleLine = titleLine))
+            .isEqualTo(BLOCK_TEXT_INSET)
+    }
+
+    @Test
+    fun `the inset tapers instead of snapping as the block shrinks`() {
+        // Half the inset left over is half the inset kept, so a pinch closes the
+        // gap frame by frame rather than dropping it in one.
+        assertThat(blockTextInset(height = titleLine + 2.dp, titleLine = titleLine))
+            .isEqualTo(1.dp)
+    }
+
+    @Test
+    fun `a block exactly one title tall spends nothing on padding`() {
+        assertThat(blockTextInset(height = titleLine, titleLine = titleLine)).isEqualTo(0.dp)
+    }
+
+    @Test
+    fun `a block shorter than a line never insets negatively`() {
+        assertThat(blockTextInset(height = 4.dp, titleLine = titleLine)).isEqualTo(0.dp)
+    }
+
+    @Test
+    fun `the title survives a block that used to be too short for it`() {
+        // 18dp is under the old floor — a title line plus 2dp of inset at each
+        // edge — and over the new one, which is the line on its own (#289).
+        val m = metrics(height = 18.dp)
+        assertThat(m.fitsTitle).isTrue()
+    }
+
+    @Test
+    fun `a block under one line still drops the title`() {
+        assertThat(metrics(height = 10.dp).fitsTitle).isFalse()
+    }
+
+    @Test
+    fun `every title line after the first costs a whole line box`() {
+        // The trim reaches the outer edges only, so the leading between two
+        // lines is still there to pay for.
+        val m = metrics()
+        assertThat(m.titleHeight(1)).isEqualTo(14.dp)
+        assertThat(m.titleHeight(2)).isEqualTo(30.dp)
+        assertThat(m.titleHeight(3)).isEqualTo(46.dp)
+        assertThat(m.titleHeight(0)).isEqualTo(0.dp)
+    }
+
+    @Test
+    fun `the budget is what the block can actually draw, not what divides into it`() {
+        val m = metrics()
+        // Two lines cost 30dp: 29 buys one, 30 buys the second.
+        assertThat(m.titleBudget(29.dp)).isEqualTo(1)
+        assertThat(m.titleBudget(30.dp)).isEqualTo(2)
+        assertThat(m.titleBudget(13.dp)).isEqualTo(0)
+    }
+
+    @Test
+    fun `a budget line is always one the block can pay for`() {
+        val m = metrics()
+        (0..80).forEach { dp ->
+            val within = dp.dp
+            val budget = m.titleBudget(within)
+            assertThat(m.titleHeight(budget)).isAtMost(within)
+        }
+    }
+}

app/src/test/java/de/jeanlucmakiola/calendula/ui/common/TimelineZoomTest.kt

@@ -1,5 +1,6 @@
 package de.jeanlucmakiola.calendula.ui.common
 
+import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.dp
 import com.google.common.truth.Truth.assertThat
 import org.junit.jupiter.api.Test
@@ -75,17 +76,16 @@ class TimelineZoomTest {
     }
 
     @Test
-    fun `a pinch held against a fractional bound stays put`() {
-        // A bound that is not a whole pixel is a height the pinch can be pushed
-        // against but never land on, so every frame of a held gesture would look
-        // like a scale change and hand the focal anchor a scroll correction.
+    fun `a pinch held against either bound stays put`() {
         val fillPx = 62.083f
         val maxPx = 616.5f
 
         val floor = pinchedHourHeightPx(target = 1f, fillPx, maxPx)
         val ceiling = pinchedHourHeightPx(target = 9_000f, fillPx, maxPx)
 
-        assertThat(floor).isEqualTo(63f)
+        // The ceiling is pulled onto the pixel grid so it stays landable; the
+        // fill floor is landable as it is, being the clamp result itself.
+        assertThat(floor).isEqualTo(fillPx)
         assertThat(ceiling).isEqualTo(616f)
         // Landing there and being pushed further must not move them again.
         assertThat(pinchedHourHeightPx(floor * 0.9f, fillPx, maxPx)).isEqualTo(floor)
@@ -100,6 +100,35 @@ class TimelineZoomTest {
         assertThat(floor * 24).isAtLeast(viewport)
     }
 
+    @Test
+    fun `pinching all the way out leaves nothing to scroll`() {
+        // #290: rounding the fill floor up to a whole pixel made the day one
+        // pixel per hour taller than the viewport it was supposed to fill, so a
+        // fully zoomed-out timeline still scrolled a hair and bounced off
+        // Android's overscroll stretch -- while FitDay, at the same zoom, sat
+        // still. 1490 is deliberately not divisible by 24.
+        val viewport = 1490f
+        val floor = pinchedHourHeightPx(target = 1f, fillPx = viewport / 24f, maxPx = 616f)
+        assertThat(floor * 24).isWithin(0.01f).of(viewport)
+    }
+
+    @Test
+    fun `the pinch floor is the height FitDay resolves to`() {
+        // The inconsistency the issue is about: the two ways to reach "the whole
+        // day on one screen" have to arrive at the same height.
+        val density = Density(2.5f)
+        val viewport = 596.dp
+        with(density) {
+            val fitDay = TimelineScale.FitDay.hourHeight(viewport).toPx()
+            val pinched = pinchedHourHeightPx(
+                target = 1f,
+                fillPx = fillHourHeight(viewport).toPx(),
+                maxPx = MAX_PINCH_HOUR_HEIGHT.toPx(),
+            )
+            assertThat(pinched).isWithin(0.01f).of(fitDay)
+        }
+    }
+
     @Test
     fun `a settled pinch is what gets persisted`() {
         var persisted: TimelineScale? = null