Text component with UTF-8 emoji text draws very slow (takes seconds)

[zoff99]

Describe the bug

i made an emoji popup:

LazyColumn(
    modifier = Modifier.fillMaxSize().padding(start = 1.dp, end = 10.dp),
    verticalArrangement = Arrangement.spacedBy(5.dp),
    state = listState,
) {
    items(items = emojis_cat_0_gropued) {
        Row(modifier = Modifier.fillMaxWidth().height(40.dp)) {
            for (k in 0..(it.size - 1))
            {
                IconButton(modifier = Modifier.width(40.dp).height(40.dp),
                    onClick = { inputText = inputText + it[k] }) {
                    Text(text = it[k], fontSize = 30.sp, maxLines = 1)
                }
            }
        }
    }
}

sadly its unbearably slow to scroll. if i replace the emoji strings with a normal string like "XX" its super fast. what is going on here? its seems just drawing unicode emoji symbols is unbearably slow

Affected platforms Select one of the platforms below:

• Desktop

Versions

• Kotlin version*: 1.9.22
• Compose Multiplatform version*: 1.5.12, 1.5.11, 1.6.0-dev1383
• OS version(s)* (required for Desktop and iOS issues): linux ubuntu 22.04 (but on windows i think also)
• OS architecture (x86 or arm64): x86 64bit
• JDK (for desktop issues): 17 and 21

Screenshots If applicable, add screenshots to help explain your problem.

[zoff99]

emoji popup showing on linux, macos and windows in the lower right corner. when scrolling the box to show more emoji its stuck for 1 second or longer. when replacing all the emoji text with plain "XX" scrolling is super fast like it should be

[mazunin-v-jb]

Hello! I can't compile this code as is. Could you please create a minimal reproducible example?

[zoff99]

fun App()
{
    var al: ArrayList<String> = arrayListOf(
        "😀","😃","😄","😁","😆","😅",
        "🤣","😂","🙂","🙃","🫠","😉",
        "😊","😇","🥰","😍","🤩","😘",
        "😗","☺️","😚","😙","🥲","😋",
        "😛","😜","🤪","😝","🤑","🤗",
        "🤭","🫢","🫣","🤫","🤔","🫡",
        "🤐","🤨","😐","😑","😶","🫥",
        "😶‍🌫️","😏","😒","🙄","😬","😮‍💨",
        "🤥","🫨","😌","😔","😪","🤤",
        "😴","😷","🤒","🤕","🤢","🤮",
        "🤧","🥵","🥶","🥴","😵","😵‍💫",
        "🤯","🤠","🥳","🥸","😎","🤓",
        "🧐","😕","🫤","😟","🙁","☹️",
        "😮","😯","😲","😳","🥺","🥹",
        "😦","😧","😨","😰","😥","😢",
        "😭","😱","😖","😣","😞","😓",
        "😩","😫","🥱","😤","😡","😠",
        "🤬","😈","👿","💀","☠️","💩",
        "🤡","👹","👺","👻","👽","👾",
        "🤖","😺","😸","😹","😻","😼",
        "😽","🙀","😿","😾","🙈","🙉",
        "🙊","💌","💘","💝","💖","💗",
        "💓","💞","💕","💟","❣️","💔",
        "❤️‍🔥","❤️‍🩹","❤️","🩷","🧡","💛",
        "💚","💙","🩵","💜","🤎","🖤",
        "🩶","🤍","💋","💯","💢","💥",
        "💫","💦","💨","🕳️","💬","👁️‍🗨️",
        "🗨️","🗯️","💭","💤","👋","🤚",
        "🖐️","✋","🖖","🫱","🫲","🫳",
        "🫴","🫷","🫸","👌","🤌","🤏",
        "✌️","🤞","🫰","🤟","🤘","🤙",
        "👈","👉","👆","🖕","👇","☝️",
        "🫵","👍","👎","✊","👊","🤛",
        "🤜","👏","🙌","🫶","👐","🤲",
        "🤝","🙏","✍️","💅","🤳","💪",
        "🦾","🦿","🦵","🦶","👂","🦻",
        "👃","🧠","🫀","🫁","🦷","🦴",
        "👀","👁️","👅","👄","🫦","👶",
        "🧒","👦","👧","🧑","👱","👨",
        "🧔","🧔‍♂️","🧔‍♀️","👨‍🦰","👨‍🦱","👨‍🦳",
        "👨‍🦲","👩","👩‍🦰","🧑‍🦰","👩‍🦱","🧑‍🦱",
        "👩‍🦳","🧑‍🦳","👩‍🦲","🧑‍🦲","👱‍♀️","👱‍♂️",
        "🧓","👴","👵","🙍","🙍‍♂️","🙍‍♀️",
        "🙎","🙎‍♂️","🙎‍♀️","🙅","🙅‍♂️","🙅‍♀️",
        "🙆","🙆‍♂️","🙆‍♀️","💁","💁‍♂️","💁‍♀️",
        "🙋","🙋‍♂️","🙋‍♀️","🧏","🧏‍♂️","🧏‍♀️",
        "🙇","🙇‍♂️","🙇‍♀️","🤦","🤦‍♂️","🤦‍♀️",
        "🤷","🤷‍♂️","🤷‍♀️","🧑‍⚕️","👨‍⚕️","👩‍⚕️",
        "🧑‍🎓","👨‍🎓","👩‍🎓","🧑‍🏫","👨‍🏫","👩‍🏫",
        "🧑‍⚖️","👨‍⚖️","👩‍⚖️","🧑‍🌾","👨‍🌾","👩‍🌾",
        "🧑‍🍳","👨‍🍳","👩‍🍳","🧑‍🔧","👨‍🔧","👩‍🔧",
        "🧑‍🏭","👨‍🏭","👩‍🏭","🧑‍💼","👨‍💼","👩‍💼",
        "🧑‍🔬","👨‍🔬","👩‍🔬","🧑‍💻","👨‍💻","👩‍💻",
        "🧑‍🎤","👨‍🎤","👩‍🎤","🧑‍🎨","👨‍🎨","👩‍🎨",
        "🧑‍✈️","👨‍✈️","👩‍✈️","🧑‍🚀","👨‍🚀","👩‍🚀")

    class EmojiStrAndName
    {
        var char: String = ""
        var name: String = ""
    }

    var emojis_cat_all_gropued: java.util.ArrayList<java.util.ArrayList<java.util.ArrayList<EmojiStrAndName>>> = java.util.ArrayList()
    val emojis_cat_gropued: java.util.ArrayList<java.util.ArrayList<EmojiStrAndName>> = java.util.ArrayList()

    val emojis_per_row = 6
    for (i in 0..((al.size - 1) / emojis_per_row))
    {
        val pos = i * emojis_per_row
        val e: java.util.ArrayList<EmojiStrAndName> = java.util.ArrayList()
        for (j in 0..(emojis_per_row - 1))
        {
            val em = EmojiStrAndName()
            try
            {
                em.char = al[pos + j]
                em.name = ""
            }
            catch(_: Exception)
            {
            }
            try
            {
                em.name = "??"
            } catch (_: java.lang.Exception)
            {
            }
            e.add(em)
        }
        emojis_cat_gropued.add(e)
    }
    emojis_cat_all_gropued.add(emojis_cat_gropued)

    Column(Modifier.fillMaxSize().background(Color.White)) {
        val listState = rememberLazyListState()
        Box(Modifier.fillMaxSize()) {
            LazyColumn(
                modifier = Modifier.fillMaxSize().padding(start = 1.dp, end = 10.dp),
                verticalArrangement = Arrangement.spacedBy(5.dp),
                state = listState,
            ) {
                items(items = emojis_cat_all_gropued.get(0)) {
                    Row(modifier = Modifier.fillMaxWidth().height(40.dp)) {
                        println("size="+ it.size)
                        for (k in 0..(it.size - 1))
                        {
                            val emojistr = it[k].char
                            IconButton(modifier = Modifier.width(40.dp).height(40.dp),
                                onClick = {}) {
                                Text(text = emojistr, color = Color.Black, fontSize = 30.sp, maxLines = 1)
                            }
                        }
                    }
                }
            }
            VerticalScrollbar(
                adapter = rememberScrollbarAdapter(listState),
                modifier = Modifier.fillMaxHeight().align(Alignment.CenterEnd).width(10.dp)
            )
        }
    }
}

fun main() = application {
    Window(onCloseRequest = ::exitApplication) {
        App()
    }
}

[zoff99]

@mazunin-v-jb this code shows that when you drag the scrollbar things totally stop and block. you can not scroll smoothly

[zoff99]

with this workaround it is a bit better, but still not great:

                        for (k in 0..(it.size - 1))
                        {
                            val emojistr = it[k].char
                            val placeholder = "?"
                            var curtext by remember { mutableStateOf(placeholder) }
                            val scope = rememberCoroutineScope()
                            IconButton(modifier = Modifier.width(40.dp).height(40.dp),
                                onClick = {}) {
                                Text(text = curtext, color = Color.Black, fontSize = 30.sp, maxLines = 1)
                                scope.launch {
                                    delay(150)
                                    curtext = emojistr
                                }
                            }
                        }

[okushnikov]

Please check the following ticket on YouTrack for follow-ups to this issue. GitHub issues will be closed in the coming weeks.

[zoff99]

why are you closing tickets and referring to another platform?