Compose从入门到放弃系列-Jetpack Compose 自带Dialog修改背景透明度

修改Jetpack Compose 自带Dialog的透明度

修改

自带的Dialog默认没有背景变暗，用以下方式可以实现。

@Composable
fun DiaAmountLayout(
    content: @Composable DiaAmountWindowScope.() -> Unit
) {
    DiaAmountWindowScopeInstance.content()
}

interface DiaAmountWindowScope {
    @Composable
    fun SetDiaAmount(dimAmount: Float)
}

private object DiaAmountWindowScopeInstance : DiaAmountWindowScope {
    @Composable
    override fun SetDiaAmount(dimAmount: Float) {
        val curView = LocalView.current
        /* 更改dialog window的透明度 */
        LaunchedEffect(curView,dimAmount) {
            try {
                val window = curView.findWindow() ?: return@LaunchedEffect
                val lp = window.attributes
                lp.dimAmount = dimAmount
                window.attributes = lp
            } catch (e: Throwable) {
                e.printStackTrace()
            }
        }
    }

    /**
     * 此代码逻辑来自 ComposeInputMethodManager.kt 下的[androidx.compose.foundation.text2.service.ImmHelper30]
     */
    private tailrec fun Context.findWindow(): Window? = when (this) {
        is Activity -> window
        is ContextWrapper -> baseContext.findWindow()
        else -> null
    }

    private fun View.findWindow(): Window? =
        (parent as? DialogWindowProvider)?.window ?: context.findWindow()

}

测试

@Composable
fun Test(){
    var dimAmount by remember {
        mutableStateOf(1f)
    }

    var show by remember() {
        mutableStateOf(false)
    }


    LaunchedEffect(Unit) {
        while (isActive){
            delay(1000)
            dimAmount-=.2f
            if (dimAmount<0f){
                dimAmount = 1f
            }
        }
    }

    Column(
        Modifier
            .fillMaxSize()
            .background(Color.Red)) {

        Text(
            text = "dimAmount=$dimAmount",
            modifier = Modifier
                .clickable {
                    show = !show
                }
        )

        if (show) {
            Dialog(onDismissRequest = { show = false }) {
                DiaAmountLayout{
                    SetDiaAmount(dimAmount = dimAmount)
                    Box(
                        Modifier
                            .size(200.dp)
                            .background(Color.White), contentAlignment = Alignment.Center) {
                        Column {
                            Text(text = "hello")
                        }
                    }
                }

            }
        }
    }
}

或者

@Composable
fun LaunchDiaAmount(dimAmount: Float) {
    val curView = LocalView.current
    /* 更改dialog window的透明度 */
    LaunchedEffect(curView, dimAmount) {
        try {
            val window = curView.findWindow() ?: return@LaunchedEffect
            val lp = window.attributes
            lp.dimAmount = dimAmount
            window.attributes = lp
        } catch (e: Throwable) {
            e.printStackTrace()
        }
    }
}

/**
 * 此代码逻辑来自 ComposeInputMethodManager.kt 下的[androidx.compose.foundation.text2.service.ImmHelper30]
 */
private tailrec fun Context.findWindow(): Window? = when (this) {
    is Activity -> window
    is ContextWrapper -> baseContext.findWindow()
    else -> null
}

private fun View.findWindow(): Window? =
    (parent as? DialogWindowProvider)?.window ?: context.findWindow()