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Wheels: link FreeType against the bundled HarfBuzz #9913

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Wheels: link FreeType against the bundled HarfBuzz #9913

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20 changes: 14 additions & 6 deletions .github/workflows/wheels-dependencies.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,12 @@ function build_brotli {
touch brotli-stamp
}

function build_freetype { # overrides multibuild's function so we can add "$@" args
build_libpng
build_bzip2
build_simple freetype $FREETYPE_VERSION https://download.savannah.gnu.org/releases/freetype tar.gz "$@"
}

function build_harfbuzz {
if [ -e harfbuzz-stamp ]; then return; fi
python3 -m pip install meson ninja
Expand Down Expand Up @@ -304,17 +310,19 @@ function build {

build_brotli

if [[ -n "$IS_MACOS" ]]; then
# Custom freetype build
build_simple freetype $FREETYPE_VERSION https://download.savannah.gnu.org/releases/freetype tar.gz --with-harfbuzz=no
else
build_freetype
fi
# FreeType and HarfBuzz each want the other:
# HarfBuzz reads font data through FreeType, and FreeType's autofitter asks HarfBuzz which glyphs a script covers.
# Break the cycle by building FreeType twice, so that the FreeType we ship is linked against the HarfBuzz we ship.

@radarhere radarhere Aug 29, 2026

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It is unusual that this should be required, right? Have FreeType or Harfbuzz discussed this anywhere?

build_freetype --with-harfbuzz=no

if [[ -z "$IOS_SDK" ]]; then
# On iOS, there's no vendor-provided raqm, and we can't ship it due to
# licensing, so there's no point building harfbuzz.
build_harfbuzz

# Now that HarfBuzz exists, build FreeType again against it.
rm -rf freetype-$FREETYPE_VERSION freetype-stamp
build_freetype --with-harfbuzz=yes
fi
}

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19 changes: 19 additions & 0 deletions docs/releasenotes/13.0.0.rst
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Expand Up @@ -93,6 +93,25 @@ TODO
Other changes
=============

Wheels now use HarfBuzz for hinting
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

FreeType can use HarfBuzz to work out which glyphs a script covers,
so that its autofitter can derive hinting "Blue Zones" for scripts such as Arabic.

Only the Windows wheels were actually built with this support.
The macOS wheels disabled HarfBuzz intreop outright,
and the Linux wheels left it up to FreeType's ``configure``,
which in turn fell back to loading HarfBuzz by its unversioned name at
runtime.

Since the bundled copy of HarfBuzz is renamed when the wheel is audited and repaired
for distribution, that lookup only succeeded if a separate copy happened to be
installed on the system with the expected name (e.g. ``libharfbuzz.so.0``).

All wheels are now linked against the HarfBuzz that Pillow ships,
which may slightly change how text is rendered in scripts that rely on the autofitter.

Python 3.15
^^^^^^^^^^^

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