matrix-messageformat-compose

Kotlin multiplatform library to translate Matrix formatted body from HTML to AnnotatedString for native rendering in Jetpack Compose.

Usage

Minimal working example:

val parseResult = remember(textInput) {
    MatrixHtmlParser().parse(
        input = textInput,
        style = MatrixBodyPreFormatStyle(),
        allowRoomMention = true,
    )
}
MatrixStyledFormattedText(
    parseResult = parseResult,
    inlineContent = parseResult.inlineImages.toInlineContent(
        LocalDensity.current,
        defaultHeight = 20.sp
    ) { info, modifier ->
        // Your inline image rendering logic here
        AsyncImage(
            model = info.uri,
            contentDescription = info.alt ?: info.title,
            modifier = modifier,
        )
    },
)

It is recommended to move MatrixHtmlParser().parse() from above example out of the UI thread into some preprocessing logic, since that's the most expensive part and does not apply any density or theme-specific styling yet.

You can customize rendering by following means:

• MatrixBodyPreFormatStyle: Provides some overrides for the pre-processing step, that are not related to screen density or theme yet.
• MatrixBodyDrawStyle: Holds callbacks to be executed in a DrawScope for drawing behind certain spans, e.g. for background rendering for code blocks and similar.
• MatrixBodyStyledFormatter: abstract class that applies styling to the preprocessed AnnotatedString, that has been deferred from the initial step in order to allow styling from a compose context without the overhead of the full parser running. You can implement this class manually, or start off of DefaultMatrixBodyStyledFormatter to only extend what you want to change from the provided defaults.