android 喷气背包组成:如何检测导致可组合组件重新组合的原因

rdrgkggo  于 2023-02-17  发布在  Android
关注(0)|答案(3)|浏览(128)

我开始注意到我的应用程序中有一些jank,我相信原因是可组合的内容在不应该重新组合的时候被重新组合。
我已经检测到一些用户交互触发了不必要的重组,但我无法指出是什么导致了重组。我已经在每个修改状态的地方添加了断点,但仍然可以找到是什么触发了重组。
AS是否提供了调试此类问题的方法?

zzoitvuj

zzoitvuj1#

答:现在还没有IDE支持。但是你可以使用下面的自定义修改器来跟踪重组。

演示

import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.Stable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.composed
import androidx.compose.ui.draw.drawWithCache
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.geometry.Size
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.SolidColor
import androidx.compose.ui.graphics.drawscope.Fill
import androidx.compose.ui.graphics.drawscope.Stroke
import androidx.compose.ui.graphics.lerp
import androidx.compose.ui.platform.debugInspectorInfo
import androidx.compose.ui.unit.dp
import androidx.compose.ui.util.lerp
import kotlin.math.min
import kotlinx.coroutines.delay

/**
 * A [Modifier] that draws a border around elements that are recomposing. The border increases in
 * size and interpolates from red to green as more recompositions occur before a timeout.
 */
@Stable
fun Modifier.recomposeHighlighter(): Modifier = this.then(recomposeModifier)

// Use a single instance + @Stable to ensure that recompositions can enable skipping optimizations
// Modifier.composed will still remember unique data per call site.
private val recomposeModifier =
    Modifier.composed(inspectorInfo = debugInspectorInfo { name = "recomposeHighlighter" }) {
        // The total number of compositions that have occurred. We're not using a State<> here be
        // able to read/write the value without invalidating (which would cause infinite
        // recomposition).
        val totalCompositions = remember { arrayOf(0L) }
        totalCompositions[0]++

        // The value of totalCompositions at the last timeout.
        val totalCompositionsAtLastTimeout = remember { mutableStateOf(0L) }

        // Start the timeout, and reset everytime there's a recomposition. (Using totalCompositions
        // as the key is really just to cause the timer to restart every composition).
        LaunchedEffect(totalCompositions[0]) {
            delay(3000)
            totalCompositionsAtLastTimeout.value = totalCompositions[0]
        }

        Modifier.drawWithCache {
            onDrawWithContent {
                // Draw actual content.
                drawContent()

                // Below is to draw the highlight, if necessary. A lot of the logic is copied from
                // Modifier.border
                val numCompositionsSinceTimeout =
                    totalCompositions[0] - totalCompositionsAtLastTimeout.value

                val hasValidBorderParams = size.minDimension > 0f
                if (!hasValidBorderParams || numCompositionsSinceTimeout <= 0) {
                    return@onDrawWithContent
                }

                val (color, strokeWidthPx) =
                    when (numCompositionsSinceTimeout) {
                        // We need at least one composition to draw, so draw the smallest border 
                        // color in blue.
                        1L -> Color.Blue to 1f
                        // 2 compositions is _probably_ okay.
                        2L -> Color.Green to 2.dp.toPx()
                        // 3 or more compositions before timeout may indicate an issue. lerp the
                        // color from yellow to red, and continually increase the border size.
                        else -> {
                            lerp(
                                Color.Yellow.copy(alpha = 0.8f),
                                Color.Red.copy(alpha = 0.5f),
                                min(1f, (numCompositionsSinceTimeout - 1).toFloat() / 100f)
                            ) to numCompositionsSinceTimeout.toInt().dp.toPx()
                        }
                    }

                val halfStroke = strokeWidthPx / 2
                val topLeft = Offset(halfStroke, halfStroke)
                val borderSize = Size(size.width - strokeWidthPx, size.height - strokeWidthPx)

                val fillArea = (strokeWidthPx * 2) > size.minDimension
                val rectTopLeft = if (fillArea) Offset.Zero else topLeft
                val size = if (fillArea) size else borderSize
                val style = if (fillArea) Fill else Stroke(strokeWidthPx)

                drawRect(
                    brush = SolidColor(color),
                    topLeft = rectTopLeft,
                    size = size,
                    style = style
                )
            }
        }
    }

来源:https://android-developers.googleblog.com/2022/03/play-time-with-jetpack-compose.html

pgvzfuti

pgvzfuti2#

我不知道有什么方法可以“捕捉”重组触发器,但基本上重组是由一个观察到的状态触发的。换句话说,有一个mutableStatemutableStateList的变化触发了重组。如果你想控制它,你可以看看Side-Effectshttps://developer.android.com/jetpack/compose/side-effects
尤其是这个:https://developer.android.com/jetpack/compose/side-effects#snapshotFlow

jtjikinw

jtjikinw3#

对于调试重组,你需要Android Studio电鳗和重组计数器后.
示例:

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyApplicationTheme {
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colors.background
                ) {
                    Column {
                        A()
                        B()
                    }
                }
            }
        }
    }
}

@Composable
fun A() {
    var count by remember { mutableStateOf(0) }

    // Causes recomposition on click
    Button(onClick = { count++ }, Modifier.wrapContentSize()) {
        Text("Recompose")
    }

    Text("$count")
    count++ // Backwards write, writing to state after it has been read
}

@Composable
fun B() {
    Text("B")
}

在列中,我们有A()和B()合成函数。当用户按下A()中的按钮时,我们有一个向后问题,并无限地重新合成。为了找到问题,我们使用Layout inspector。您可以看到下面的调试屏幕记录。


https://www.veed.io/view/2fda4463-a23d-4567-b853-e7f766e9342a?panel=share

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