Text
字符布局信息的主要来源是TextLayoutResult
可以通过onTextLayout
参数接收
它的 API 远非完美。getPathForRange
返回Path
这正是您所需要的,但与其他任何东西一样,Path
它不能被修改,例如,您将无法绕过这条路径的拐角,与普通SpanStyle
背景没有太大区别
那里getBoundingBox
只返回一个字符的帧。我玩了一下,得到Rect
了选定范围的 s 列表:
fun TextLayoutResult.getBoundingBoxesForRange(start: Int, end: Int): List<Rect> {
var prevRect: Rect? = null
var firstLineCharRect: Rect? = null
val boundingBoxes = mutableListOf<Rect>()
for (i in start..end) {
val rect = getBoundingBox(i)
val isLastRect = i == end
// single char case
if (isLastRect && firstLineCharRect == null) {
firstLineCharRect = rect
prevRect = rect
}
// `rect.right` is zero for the last space in each line
// looks like an issue to me, reported: https://issuetracker.google.com/issues/197146630
if (!isLastRect && rect.right == 0f) continue
if (firstLineCharRect == null) {
firstLineCharRect = rect
} else if (prevRect != null) {
if (prevRect.bottom != rect.bottom || isLastRect) {
boundingBoxes.add(
firstLineCharRect.copy(right = prevRect.right)
)
firstLineCharRect = rect
}
}
prevRect = rect
}
return boundingBoxes
}
现在您可以在 上绘制这些矩形Canvas
:
Box(Modifier.padding(10.dp)) {
val text =
"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
val selectedParts = listOf(
"consectetur adipiscing",
"officia deserunt",
"dolore magna aliqua. Ut enim ad minim veniam, quis nostrud",
"consequat.",
)
var selectedPartPaths by remember { mutableStateOf(listOf<Path>()) }
Text(
text,
style = MaterialTheme.typography.h6,
onTextLayout = { layoutResult ->
selectedPartPaths = selectedParts.map { part ->
val cornerRadius = CornerRadius(x = 20f, y = 20f)
Path().apply {
val startIndex = text.indexOf(part)
val boundingBoxes = layoutResult
.getBoundingBoxesForRange(
start = startIndex,
end = startIndex + part.count()
)
for (i in boundingBoxes.indices) {
val boundingBox = boundingBoxes[i]
val leftCornerRoundRect =
if (i == 0) cornerRadius else CornerRadius.Zero
val rightCornerRoundRect =
if (i == boundingBoxes.indices.last) cornerRadius else CornerRadius.Zero
addRoundRect(
RoundRect(
boundingBox.inflate(verticalDelta = -2f, horizontalDelta = 7f),
topLeft = leftCornerRoundRect,
topRight = rightCornerRoundRect,
bottomRight = rightCornerRoundRect,
bottomLeft = leftCornerRoundRect,
)
)
}
}
}
},
modifier = Modifier.drawBehind {
selectedPartPaths.forEach { path ->
drawPath(path, style = Fill, color = Color.Blue.copy(alpha = 0.2f))
drawPath(path, style = Stroke(width = 2f), color = Color.Blue)
}
}
)
}
fun Rect.inflate(verticalDelta: Float, horizontalDelta: Float) =
Rect(
left = left - horizontalDelta,
top = top - verticalDelta,
right = right + horizontalDelta,
bottom = bottom + verticalDelta,
)
结果: