whats use of `TextUnitType.Em` and how it differs ...

# compose

[Vivek Rajendran]

whats use of TextUnitType.Em and how it differs from Sp?

@kotlin.jvm.JvmInline
value class TextUnitType(internal val type: Long) {
    override fun toString(): String {
        return when (this) {
            Unspecified -> "Unspecified"
            Sp -> "Sp"
            Em -> "Em"
            else -> "Invalid"
        }
    }

    companion object {
        val Unspecified = TextUnitType(UNIT_TYPE_UNSPECIFIED)
        val Sp = TextUnitType(UNIT_TYPE_SP)
        val Em = TextUnitType(UNIT_TYPE_EM)
    }
}

[Stylianos Gakis]

https://developer.android.com/develop/ui/compose/text/style-paragraph#adjust-line-height
This article says:
"You may want to adjust lineHeight using the text unit “em” (relative font size) instead of “sp” (scaled pixels) for improved precision. For more information about selecting an appropriate text unit, see `TextUnit`"
So it looks like it's a scale relative to a baseline. I don't know how 1em is defined though 👀 I know we use them for letterSpacing, and there I guess there is a "baseline" letter spacing and we can increase/decrease that relative to what that baseline is.

[Vivek Rajendran]

Got it. Thanks.

[Zach Klippenstein (he/him) [MOD]]

Sp obeys the accessibility font scale settings