Error: Invalid glyph format when performing FontCollection.Install

Prerequisites

• I have written a descriptive issue title
• I have verified that I am running the latest version of Fonts
• I have verified if the problem exist in both DEBUG and RELEASE mode
• I have searched open and closed issues to ensure it has not already been reported

Description

When executing the lines of code below, on my development environment (.net5.0 on macOS with Rider), the below happens.

Exception

InvalidFontFileException: Invalid glyph format, only TTF glyph outlines supported

Callstack

SixLabors.Fonts.FontReader..ctor(Stream stream, TableLoader loader)
SixLabors.Fonts.FontReader..ctor(Stream stream)
SixLabors.Fonts.FontDescription.LoadDescription(string path)
SixLabors.Fonts.FileFontInstance..ctor(string path, long offset)
SixLabors.Fonts.FileFontInstance..ctor(string path)
SixLabors.Fonts.FontCollection.InstallInternal(string path, CultureInfo culture, out FontDescription fontDescription)
SixLabors.Fonts.FontCollection.InstallInternal(string path, CultureInfo culture)
SixLabors.Fonts.FontCollection.Install(string path)

Steps to Reproduce

Code

var fonts = new FontCollection();
var lightFamily = fonts.Install(Path.Combine(_hostingEnvironment.WebRootPath, "fonts/merkury_bold.otf"));

System Configuration

• Fonts version: nuget 1.0.0-beta15
• Other Six Labors packages and versions: SixLabors.ImageSharp==1.0.4, SixLabors.ImageSharp.Drawing==1.0.0-beta13, SixLabors.ImageSharp.Web==1.0.4
• Environment (Operating system, version and so on): macOS Big Sur (11.6)
• .NET Framework version: 5.0
• Additional information: Similar issue reported #29 , but that was with SystemFonts, as was closed as fixed.

[SamVanhoutte]

So, that probably means, you can close this issue, as it is related to my lack of understanding/knowledge on font-specifics. Thanks for your feedback and help!
And appreciating the work you guys deliver ❤️

[tocsoft]

The fact its an *.otf rather than *.ttf is the big give away that its unlikely to be a compatible font. *.ttf is technically a subset of *.otf fonts with a very specific way of storing the glyph outlines.

That font contains CFF outline data (as can be determined by looking at the first 4 bytes of the file spelling OTTO in ascii) which we do not have support for.