BringIntoViewResponder

A parent that can respond to bringChildIntoView requests from its children, and scroll so that the item is visible on screen. To apply a responder to an element, pass it to the bringIntoViewResponder modifier.

When a component calls BringIntoViewRequester.bringIntoView, the nearest BringIntoViewResponder is found, which is responsible for, in order:

1. Calculating a rectangle that its parent responder should bring into view by returning it from calculateRectForParent.

2. Performing any scroll or other layout adjustments needed to ensure the requested rectangle is brought into view in bringChildIntoView.

Here is a sample where a composable is brought into view:

import androidx.compose.foundation.horizontalScroll
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.relocation.BringIntoViewRequester
import androidx.compose.foundation.relocation.bringIntoViewRequester
import androidx.compose.foundation.rememberScrollState
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.ui.Modifier
import androidx.compose.ui.focus.focusTarget
import androidx.compose.ui.focus.onFocusChanged

Row(Modifier.horizontalScroll(rememberScrollState())) {
    repeat(100) {
        val bringIntoViewRequester = remember { BringIntoViewRequester() }
        val coroutineScope = rememberCoroutineScope()
        Box(
            Modifier
                // This associates the RelocationRequester with a Composable that wants to be
                // brought into view.
                .bringIntoViewRequester(bringIntoViewRequester)
                .onFocusChanged {
                    if (it.isFocused) {
                        coroutineScope.launch {
                            // This sends a request to all parents that asks them to scroll so
                            // that this item is brought into view.
                            bringIntoViewRequester.bringIntoView()
                        }
                    }
                }
                .focusTarget()
        )
    }
}

Here is a sample where a part of a composable is brought into view:

import androidx.compose.foundation.Canvas
import androidx.compose.foundation.border
import androidx.compose.foundation.horizontalScroll
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.relocation.BringIntoViewRequester
import androidx.compose.foundation.relocation.bringIntoViewRequester
import androidx.compose.foundation.rememberScrollState
import androidx.compose.material.Button
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.geometry.Rect
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.unit.dp

with(LocalDensity.current) {
    val bringIntoViewRequester = remember { BringIntoViewRequester() }
    val coroutineScope = rememberCoroutineScope()
    Column {
        Box(
            Modifier.border(2.dp, Color.Black)
                .size(500f.toDp())
                .horizontalScroll(rememberScrollState())
        ) {
            Canvas(
                Modifier.size(1500f.toDp(), 500f.toDp())
                    // This associates the RelocationRequester with a Composable that wants
                    // to be brought into view.
                    .bringIntoViewRequester(bringIntoViewRequester)
            ) {
                drawCircle(color = Color.Red, radius = 250f, center = Offset(750f, 250f))
            }
        }
        Button(
            onClick = {
                val circleCoordinates = Rect(500f, 0f, 1000f, 500f)
                coroutineScope.launch {
                    // This sends a request to all parents that asks them to scroll so that
                    // the circle is brought into view.
                    bringIntoViewRequester.bringIntoView(circleCoordinates)
                }
            }
        ) {
            Text("Bring circle into View")
        }
    }
}

Summary

suspend fun bringChildIntoView(localRect: () -> Rect): Unit

fun calculateRectForParent(localRect: Rect): Rect