A question for <@U015TKX93PD>. I am trying to find...

# compose-desktop

[Kirill Grouchnikov]

A question for @Igor Demin. I am trying to find the right place in Skiko / Compose-JB that converts Compose's font definition (the relevant parts of TextStyle such as fontFamily, fontStyle, fontWeight, fontSize) to Skiko's Typeface or Font. Is there any public function or class that provides that bridge? There's some code in here for example that looks interesting, but it's all either internal or works with local font resources.

[Igor Demin]

There is no public API that allows to convert from Compose FontFamily to Skia Typeface. If you need to know how it is converted internally, you are looking at the right place (the code in there is not trivial though)

[Kirill Grouchnikov]

Ah, that's a bummer. Any plans to make such a bridge that may be needed since Compose's Canvas doesn't have any APIs to draw text directly?

[Igor Demin]

Any plans to make such a bridge

There are no specific plans.

convert from Compose FontFamily to Skia Typeface

There is a way to convert Font to SkTypeface though:

val loader = LocalFontLoader.current
val typeface = remember { loader.load(Font("NotoSans-Italic.ttf")) }

Converting FontFamily is more difficult, because the are some `FontFamily`'s that are not converting to SkTypeface (GenericFontFamily, for example), they just passed as a String to SkiaParagraph.

draw text directly?

You can draw Paragraph on Canvas:

val loader = LocalFontLoader.current
val density = LocalDensity.current
val par = remember {
    Paragraph("text", TextStyle.Default, width = 200f, density = density, resourceLoader = loader)
}
Canvas(Modifier.fillMaxSize()) {
    drawIntoCanvas {
        par.paint(it, Color.Black)
    }
}

[Kirill Grouchnikov]

I'm working on the desktop equivalent of Android's Canvas.drawTextOnPath. Eventually it goes down to Skia's Canvas.drawTextBlob where the blob is created by TextBlobBuilder configured with appendRunRSXform . Every glyph along the Path has its own RSXform to properly position and rotate it to follow the path's curvature. This is where I'd like to have the option to convert Compose's TextStyle to Skia's Font to pass it to TextBlobBuilder.appendRunRSXform, and even before that to call Font.getStringGlyphs and other similar methods. Using higher level APIs like Paragraph is not good here, as it doesn't provide the lower-level glyph-based metrics that are needed.

[Kirill Grouchnikov]

Here's how the target visuals look like: