Question

我的自定义布局中有一个可拖动的修饰符。问题是我所有的可放置物都作为一个块移动，而我希望它们单独移动。循环遍历它们以确保一次只选择一个放置的正确方法是什么？或者有没有更好的方法来解决它？这是我的自定义布局：

    @Composable
fun CustomLayout(
    modifier: Modifier = Modifier,
    content: @Composable() () -> Unit
) {
    val coroutineScope = rememberCoroutineScope()
    val offsetX = remember { Animatable(0f) }
    val offsetY = remember { Animatable(0f) }

    Layout(
        modifier = modifier
            .offset {
                IntOffset(
                    offsetX.value.roundToInt(),
                    offsetY.value.roundToInt()
                )
            }
            .draggable(
                state = rememberDraggableState { delta ->
                    coroutineScope.launch {
                        offsetX.snapTo(offsetX.value + delta)
                    }
                },
                orientation = Orientation.Horizontal,
                onDragStarted = {},
                onDragStopped = {

                    coroutineScope.launch {

                        offsetX.animateTo(
                            targetValue = 0f,
                            animationSpec = tween(
                                durationMillis = 1000,
                                delayMillis = 0
                            )
                        )
                    }
                }
            ),
        content = content
    ) { measurables, constraints ->
        val tileSize = constraints.maxWidth / 7
        val childConstraints = constraints.copy(
            minWidth = minOf(constraints.minWidth, tileSize),
            maxWidth = tileSize
        )
        val placeables = measurables.map { measurable ->
            measurable.measure(childConstraints)
        }

        layout(constraints.maxWidth, constraints.maxHeight) {
            var yPosition = 0
            val xPosition = 0
            placeables.forEachIndexed { index, placeable ->
                if (index <= 6) {
                    placeable.placeRelative(x = xPosition, y = yPosition)
                } else {
                    placeable.placeRelative(
                        constraints.maxWidth - tileSize,
                        yPosition - placeable.height * 7
                    )
                }
                yPosition += placeable.height
            }
        }
    }
}

这里我想一次只移动一个图块：

Answer 1

您的解决方案不起作用，因为您将偏移应用于整个布局，但您需要将其应用于单个项目。

Layout 仅用于布局项目：在 MeasureScope 中，我们只能访问项目大小/位置，我们不能向它们添加修饰符，因为它们会修改状态和它'会导致递归。

我的建议是将项目计数和项目生成器传递给您的 Composable，以便我们可以为每个项目添加偏移和可拖动修饰符：

@Composable
fun DraggableLayout(
    modifier: Modifier = Modifier,
    count: Int,
    item: @Composable (Int, Modifier) -> Unit
) {
    val coroutineScope = rememberCoroutineScope()
    val offsetsX = remember { mutableStateMapOf<Int, Animatable<Float, AnimationVector1D>>() }
    CustomLayout(
        modifier = modifier,
        content = {
            for (i in 0 until count) {
                item(
                    i,
                    Modifier
                        .offset {
                            IntOffset(
                                offsetsX[i]?.value?.roundToInt() ?: 0,
                                0
                            )
                        }
                        .draggable(
                            state = rememberDraggableState { delta ->
                                coroutineScope.launch {
                                    val offsetX = offsetsX[i] ?: Animatable(0f)
                                    offsetX.snapTo(offsetX.value + delta)
                                    offsetsX[i] = offsetX
                                }
                            },
                            orientation = Orientation.Horizontal,
                            onDragStarted = {},
                            onDragStopped = {
                                coroutineScope.launch {
                                    offsetsX[i]!!.animateTo(
                                        targetValue = 0f,
                                        animationSpec = tween(
                                            durationMillis = 1000,
                                            delayMillis = 0
                                        )
                                    )
                                }
                            }
                        ),
                )
            }
        }
    )
}

@Composable
fun CustomLayout(
    modifier: Modifier = Modifier,
    content: @Composable () -> Unit
) {
    Layout(
        modifier = modifier,
        content = content,
    ) { measurables, constraints ->
        val tileSize = constraints.maxWidth / 7
        val childConstraints = constraints.copy(
            minWidth = minOf(constraints.minWidth, tileSize),
            maxWidth = tileSize
        )
        val placeables = measurables.map { measurable ->
            measurable.measure(childConstraints)
        }

        layout(constraints.maxWidth, constraints.maxHeight) {
            var yPosition = 0
            val xPosition = 0
            placeables.forEachIndexed { index, placeable ->
                if (index <= 6) {
                    placeable.placeRelative(x = xPosition, y = yPosition)
                } else {
                    placeable.placeRelative(
                        constraints.maxWidth - tileSize,
                        yPosition - placeable.height * 7
                    )
                }
                yPosition += placeable.height
            }
        }
    }
}

像这样使用它：

CustomLayout(
    count = 10,
    item = { i, modifier ->
        Text(
            "Test $i",
            modifier = Modifier
                .size(50.dp)
                .then(modifier)
        )
    }
)

结果：

如何将布局修改器单独应用于 Jetpack Compose 中的每个可放置项？

1 个答案: