DrawText with multiregion unicode chars

[TomQv]

As discussed here #232 and here #435 Skia can't render text with multiple unicode regions.
At least not 6 years ago, but it seems, this didn't change until now.

For example "Oum Dreyga ⵓⵎ ⴷⵔⵉⴳⴰ أم ادريكة " which is a place in Morocco called Oum Dreyga.
Additionally the name is printed also in local and arabic language.

To print this with SKCanvas.DrawText we would need a Font which has all characters includes, which I didn't find so far.
I only found this http://unifoundry.com/unifont/index.html, but this is a bitmap-font, not so nice.

Second option would be, if DrawText could just ignore characters, which are not in the current typeface, so that these ugly blocks were not rendered:

Is there maybe a setting to ignore unknown chars?

[Gillibald]

https://github.com/toptensoftware/RichTextKit

[taublast]

https://github.com/taublast/DrawnUi.Maui.Demo/blob/main/src/Usual/MainPage.xaml

SkiaMarkDownLabel will auto-split your text into spans with the corresponding fonts to render different unicode chunks, you can use it in a usual MAUI app or grab the source code to integrate in your skiasharp project.

[Gillibald]

Your solution just uses a naive 1:1 character to glyph mapping and does no extra processing. No shaping to bidi analysis. So in the end you just support the Latin writing system. RichTextKit supports all of this.

[taublast]

Thanks for taking a look :) Actually besides drawings glyphs it detects if the chunk needs shaping and draws it as shaped text in that case, what is required for Arabic etc.

[taublast]

There is a nuget for xamarin too, no uwp, android+ios only: https://github.com/taublast/DrawnUi.Xamarin

[Gillibald]

Wasn't clear you are mapping Unicode regions to a code path that shapes the text. Ideally, everything is shaped because you are missing font features that someone might want.

[TomQv]

Thanks, great stuff.
Quick test with Xamarin.Forms works good.
But unfortunate only on UWP.
Android seems to have problems with devicescale. Didn't test iOS yet.

I would prefer a setting in SkiaSharp just to ignore unprintable stuff.