提问人:JJ123 提问时间:3/20/2021 更新时间:11/18/2023 访问量:4052
子组合布局何时支持内部布局(如果有的话)?
When will Subcompose Layout support Intrinsic layout, if ever?
问:
我在 in 的源代码中看到了这个函数。androidx.compose.ui.layout.SubcomposeLayout.kt
androidx.compose.ui:ui:1.0.0-beta02
private fun createMeasurePolicy(
block: SubcomposeMeasureScope.(Constraints) -> MeasureResult
): MeasurePolicy = object : LayoutNode.NoIntrinsicsMeasurePolicy(
error = "Intrinsic measurements are not currently supported by SubcomposeLayout"
) {
...
}
当可组合项将在子可组合项中呈现时,我似乎不能使用内在测量。
作为参考,我正在尝试在 ModalBottomSheet 中使用这样的视图。目的是在工作表中有一个可滚动的视图,粘性视图始终位于底部(如按钮)。我希望可滚动内容只占用所需的空间,并且在工作表展开状态下并不总是全屏显示,确实如此。weight(1f)
Column(
modifier = Modifier
.height(IntrinsicSize.Min)
.wrapContentHeight(Alignment.Bottom),
verticalArrangement = Arrangement.Bottom
) {
Column(
content = sheetContent,
modifier = Modifier
.weight(1f)
.wrapContentHeight(Alignment.Bottom)
)
Box {
bottomStickyContent?.let { it() }
}
}
答:
3赞
JJ123
3/20/2021
#1
听起来答案是否定的,不会很快获得内在支持,如果有的话。SubcomposeLayout
我通过代码更新以使用约束布局解决了这个问题。
ConstraintLayout {
val (sticky, column) = createRefs()
Column(
content = sheetContent,
modifier = Modifier
.constrainAs(column) {
top.linkTo(parent.top)
bottom.linkTo(sticky.top)
height = Dimension.preferredWrapContent
}
.wrapContentHeight(Alignment.Bottom)
)
Box(
modifier = Modifier
.constrainAs(sticky) {
bottom.linkTo(parent.bottom)
}
) {
bottomStickyContent?.let { it() }
}
}
0赞
AndroidEngineX
11/18/2023
#2
对我来说,在布局中提供支持是没有意义的。Intrinsic
Subcompose
如果您认为,在正常的容器(非)布局中,该预测量(与实际测量相比,预测量很便宜,并遵循一些启发性)所有项目并找到子项可以采用的最大或最小尺寸,然后容器将该尺寸强制执行给每个子项Subcompose
Intrisic
在布局的情况下,某些组件的测量是预先完成的,但不是全部(以防止测量潜在的非常大的集合)。它无法知道所有孩子的最大或最小尺寸应该是多少。Subcompose
即使是最新的组合也会出现以下错误
java.lang.IllegalStateException: Asking for intrinsic measurements of SubcomposeLayout layouts is not supported. This includes components that are built on top of SubcomposeLayout, such as lazy lists, BoxWithConstraints, TabRow, etc. To mitigate this:
- if intrinsic measurements are used to achieve 'match parent' sizing,, consider replacing the parent of the component with a custom layout which controls the order in which children are measured, making intrinsic measurement not needed
- adding a size modifier to the component, in order to fast return the queried intrinsic measurement
我从 MAD compose 系列视频中推断出这一点
评论