การจัดแนวบรรทัดใน Jetpack Compose

fun Modifier.firstBaselineToTop(     firstBaselineToTop: Dp, ) = layout { measurable, constraints ->     // Measure the composable     val placeable = measurable.measure(constraints)      // Check the composable has a first baseline     check(placeable[FirstBaseline] != AlignmentLine.Unspecified)     val firstBaseline = placeable[FirstBaseline]      // Height of the composable with padding - first baseline     val placeableY = firstBaselineToTop.roundToPx() - firstBaseline     val height = placeable.height + placeableY     layout(placeable.width, height) {         // Where the composable gets placed         placeable.placeRelative(0, placeableY)     } }  @Preview @Composable private fun TextWithPaddingToBaseline() {     MaterialTheme {         Text("Hi there!", Modifier.firstBaselineToTop(32.dp))     } }
AlignmentLinesSnippets.kt

/**  * AlignmentLine defined by the maximum data value in a [BarChart]  */ private val MaxChartValue = HorizontalAlignmentLine(merger = { old, new ->     min(old, new) })  /**  * AlignmentLine defined by the minimum data value in a [BarChart]  */ private val MinChartValue = HorizontalAlignmentLine(merger = { old, new ->     max(old, new) })
AlignmentLinesSnippets.kt

@Composable private fun BarChart(     dataPoints: List<Int>,     modifier: Modifier = Modifier, ) {     val maxValue: Float = remember(dataPoints) { dataPoints.maxOrNull()!! * 1.2f }      BoxWithConstraints(modifier = modifier) {         val density = LocalDensity.current         with(density) {             // ...             // Calculate baselines             val maxYBaseline = // ...             val minYBaseline = // ...             Layout(                 content = {},                 modifier = Modifier.drawBehind {                     // ...                 }             ) { _, constraints ->                 with(constraints) {                     layout(                         width = if (hasBoundedWidth) maxWidth else minWidth,                         height = if (hasBoundedHeight) maxHeight else minHeight,                         // Custom AlignmentLines are set here. These are propagated                         // to direct and indirect parent composables.                         alignmentLines = mapOf(                             MinChartValue to minYBaseline.roundToInt(),                             MaxChartValue to maxYBaseline.roundToInt()                         )                     ) {}                 }             }         }     } }
AlignmentLinesSnippets.kt

@Composable private fun BarChartMinMax(     dataPoints: List<Int>,     maxText: @Composable () -> Unit,     minText: @Composable () -> Unit,     modifier: Modifier = Modifier, ) {     Layout(         content = {             maxText()             minText()             // Set a fixed size to make the example easier to follow             BarChart(dataPoints, Modifier.size(200.dp))         },         modifier = modifier     ) { measurables, constraints ->         check(measurables.size == 3)         val placeables = measurables.map {             it.measure(constraints.copy(minWidth = 0, minHeight = 0))         }          val maxTextPlaceable = placeables[0]         val minTextPlaceable = placeables[1]         val barChartPlaceable = placeables[2]          // Obtain the alignment lines from BarChart to position the Text         val minValueBaseline = barChartPlaceable[MinChartValue]         val maxValueBaseline = barChartPlaceable[MaxChartValue]         layout(constraints.maxWidth, constraints.maxHeight) {             maxTextPlaceable.placeRelative(                 x = 0,                 y = maxValueBaseline - (maxTextPlaceable.height / 2)             )             minTextPlaceable.placeRelative(                 x = 0,                 y = minValueBaseline - (minTextPlaceable.height / 2)             )             barChartPlaceable.placeRelative(                 x = max(maxTextPlaceable.width, minTextPlaceable.width) + 20,                 y = 0             )         }     } } @Preview @Composable private fun ChartDataPreview() {     MaterialTheme {         BarChartMinMax(             dataPoints = listOf(4, 24, 15),             maxText = { Text("Max") },             minText = { Text("Min") },             modifier = Modifier.padding(24.dp)         )     } }
AlignmentLinesSnippets.kt