I wanted to know how to highlight the specific part of the text in jetpack compose. I tried Html.fromHtml()
like this
Text(text = Html.fromHtml(" <font color='red'> Hello </font> World").toString())
But it didn't work. Is there any way I can do this in compose?
With 1.0.0-beta06
you can use the AnnotatedString
to display the text with multiple styles.
Something like:
Text(buildAnnotatedString {
withStyle(style = SpanStyle(color = Color.Red)) {
append("Hello")
}
append(" World ")
})
Check this function below. Here paragraph is your string source and searchQuery is the specific text you want to highlight.
This provides you a dynamic state for text and search highlights.
@Composable
fun getData(): StateFlow<AnnotatedString?> {
val span = SpanStyle(
color = MaterialTheme.colorScheme.onPrimaryContainer,
fontWeight = FontWeight.SemiBold,
background = MaterialTheme.colorScheme.primaryContainer
)
return combine(paragraph, searchQuery) { text, query ->
buildAnnotatedString {
var start = 0
while (text.indexOf(query, start, ignoreCase = true) != -1 && query.isNotBlank()) {
val firstIndex = text.indexOf(query, start, true)
val end = firstIndex + query.length
append(text.substring(start, firstIndex))
withStyle(style = span) {
append(text.substring(firstIndex, end))
}
start = end
}
append(text.substring(start, text.length))
toAnnotatedString()
}
}.stateIn(viewModelScope, SharingStarted.WhileSubscribed(), null)
}
You can use AnnotatedString to append each word/section with it's own style or to add different style at any index which is great if you're using a string resource.
For the hello world example you could construct something like this:
val annotatedString = buildAnnotatedString {
val str = "Hello World" // or stringResource(id = R.string.hello_world)
val boldStr = "Hello" // or stringResource(id = R.string.hello)
val startIndex = str.indexOf(boldStr)
val endIndex = startIndex + boldStr.length
append(str)
addStyle(style = SpanStyle(color = Color.Red), start = startIndex, end = endIndex)
}
Text(
text = annotatedString,
)
Using addStyle
in this way allows us to do some fun things like adding multiple styles to the same text
val annotatedString = buildAnnotatedString {
val str = "Hello Wonderful World" // or stringResource(id = R.string.hello_world)
val boldStr = "Wonderful World" // or stringResource(id = R.string.world)
val startIndex = str.indexOf(boldStr)
val endIndex = startIndex + boldStr.length
append(str)
addStyle(style = SpanStyle(color = Color.Red), start = startIndex, end = endIndex)
val italicsStr = "Wonderful"
val italicsStartIndex = str.indexOf(italicsStr)
val italicsEndIndex = startIndex + italicsStr.length
addStyle(style = SpanStyle(fontStyle = FontStyle.Italic), start = italicsStartIndex, end = italicsEndIndex)
}
Text(
text = annotatedString,
style = TextStyle(fontWeight = FontWeight.Bold),
color = Color.Blue,
)
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