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android - Jetpack 撰写 : How to detect what is causing a Composable to recompose

转载 作者:行者123 更新时间:2023-12-04 23:37:13 26 4
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我开始注意到我的应用程序出现了一些卡顿,我相信原因是可组合项在不应该被重新组合时被重新组合。
我检测到一些触发不必要的重新组合的用户交互,但我无法将手指放在导致重新组合的原因上。我在修改状态的每个地方都添加了断点,并且仍然可以找到触发重组的内容。
AS 是否提供了调试这种东西的方法?

最佳答案

AFAIK,还没有 IDE 支持。但是您可以使用下面的自定义修饰符来跟踪重组。
演示

  • https://twitter.com/theapache64/status/1502932832058249220

  • 重组Highlighter.kt

    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

    关于android - Jetpack 撰写 : How to detect what is causing a Composable to recompose,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/68656889/

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