HarfBuzz 4.4.0 breaks character sizing with SDL2_ttf

[a-hurst]

Hi there,

Just reported this to the SDL2_ttf team and they asked that I report it here. Basically, with HarfBuzz 4.4.1, updating the size of a font after opening it seems to update its internal character widths incorrectly such that increasing font size means characters get larger but not much farther apart. See the images in the SDL issue here for an illustration of what's going on: libsdl-org/SDL_ttf#232

If I manually roll back HarfBuzz to 4.3.0 the problem disappears, so it's something that changed between that version and now that's causing problems.

Internally, SDL2_ttf uses FreeType to update the size of an open font and then calls hb_ft_font_changed on the underlying harfbuzz font to update it (see the code for TTF_SetFontSizeDPI here). The calculation of character sizes and spacing happens here. Is this code doing something wrong, or did 4.4.0/4.4.1 introduce an unexpected bug?

Thanks in advance!

Austin

[behdad]

If I manually roll back HarfBuzz to 4.3.0 the problem disappears, so it's something that changed between that version and now that's causing problems.

Things did indeed change. I'm sorry it broke this. I'm looking into it. If you can share your SDL sample app it would help debugging. Thanks.

[behdad]

If you can share your SDL sample app it would help debugging. Thanks.

Nevermind. I can reproduce this now.

[behdad]

Should be fixed.

[a-hurst]

Fantastic, thanks so much!