[ft-devel] Weird behaviour in FT_Glyph_StrokeBorder

[Foaly]

Hello there!

This is Foaly and I am contributor to the SFML library. We want to change our implementation of outlines from using FT_Glyph_Stroke to FT_Glyph_StrokeBorder, which according to the documentation allows to get an outline only outside the glyph.

I have played around with the different parameters and different fonts, but none of them return the behaviour of drawing an outside border as I understand it from https://www.freetype.org/freetype2/docs/reference/ft2-glyph_stroker.html#FT_Glyph_StrokeBorder

The attached image is a rendering using the the current master (c6a965b4d3) on MacOS 10.11.6 with Clang 7.3.0 using the system Arial.ttf.

Both states of the inside parameter seem to return different results than documented.

Can you confirm that this behaviour is as intended or is this a bug? Because to me it does not look like what I would expect from reading the documentation.

Thank, Foaly

P.S.: FYI here you can find the SFML ticket on the topic: https://github.com/SFML/SFML/issues/1313

As well as the relavant code point in SFML: https://github.com/SFML/SFML/blob/master/src/SFML/Graphics/Font.cpp#L561

stoke_comp.png
Description: PNG image