Custom Font Not Applied During SVG Rendering

[martin-barre]

Hello everyone

I have a problem with the SkiaSharp library when I try to generate a PNG image from an SVG containing text with a custom font.

input.svg

<svg xmlns="http://www.w3.org/2000/svg" version="1.1" width="720" height="480">
  <rect width="100%" height="100%" fill="#365d9c" />
  <text x="360" y="240" font-family="CustomFont" font-size="96" text-anchor="middle">Hello world!</text>
</svg>

Program.cs

string projectDirectory = AppDomain.CurrentDomain.BaseDirectory;

var fileStream = File.OpenRead($"{projectDirectory}/input.svg");
var svg = new SKSvg();
svg.Settings.TypefaceProviders = [new CustomTypefaceProvider()];
svg.Load(fileStream);

var picture = svg.Picture;
var imageInfo = new SKImageInfo((int)picture.CullRect.Width, (int)picture.CullRect.Height);
var surface = SKSurface.Create(imageInfo);
    
var canvas = surface.Canvas;
canvas.Clear(SKColors.Transparent);
canvas.DrawPicture(picture);
canvas.Flush();

var image = surface.Snapshot();
var data = image.Encode(SKEncodedImageFormat.Png, 100);

File.WriteAllBytes($"{projectDirectory}/output.png", data.ToArray());

CustomTypefaceProvider.cs

public class CustomTypefaceProvider : ITypefaceProvider
{
    private readonly Dictionary<string, SKTypeface> _typefaces = new() {
        { "CustomFont", SKFontManager.Default.CreateTypeface(Path.Combine(AppContext.BaseDirectory, "CustomFont.ttf")) }
    };

    public SKTypeface? FromFamilyName(string fontFamily, SKFontStyleWeight fontWeight, SKFontStyleWidth fontWidth, SKFontStyleSlant fontStyle)
    {
        return _typefaces.GetValueOrDefault(fontFamily);
    }
}

As you can see, I have an SVG that includes a tag with a specific font-family, and I render it as a PNG using SkiaSharp.

The issue is that the custom font is not applied during rendering, despite using a CustomTypefaceProvider.

However, if I override my custom font with a standard font like Arial, the custom font work perfectly.

input.svg

<text x="360" y="240" font-family="Arial" font-size="96" text-anchor="middle">Hello world!</text>

CustomTypefaceProvider.cs

{ "Arial", SKFontManager.Default.CreateTypeface(Path.Combine(AppContext.BaseDirectory, "CustomFont.ttf")) }

I don’t understand why the custom font only work when I replace another font.

Has anyone encountered this issue before? Any ideas on how to ensure that the custom font is properly loaded and usable by SkiaSharp during image generation without replacing an existing font?

Any help or suggestions would be greatly appreciated. Thanks in advance!