Add support for CBDT and COLR fonts

[nulano]

Proper fix for #891, partial support for #3346

Changes proposed in this pull request:

• properly detect glyph bitmap mode instead of guessing
• use FT_Convert_Bitmap instead of a custom solution
• add support for Google CBDT (if FreeType is compiled with libpng) and Microsoft COLR fonts

Apple SBIX and W3C SVG fonts are not yet supported by FreeType.

Example:

from PIL import Image, ImageDraw, ImageFont

def test(font, out_name):
    fnt = ImageFont.truetype(font, size=109, layout_engine=ImageFont.LAYOUT_RAQM)
    im = Image.new("RGBA", (600, 600), (100, 100, 100, 100))
    draw = ImageDraw.Draw(im)
    draw.text((0, 32), "a\u263A", fill="#faa2", embedded_color=True, font=fnt)
    draw.text((0, 132), "a\u263A", fill="#faa8", embedded_color=True, font=fnt)
    draw.text((0, 232), "a\u263A", fill="#faa", embedded_color=True, font=fnt)
    draw.text((0, 332), "\U0001F3AC\U0001F44B\U0001F3FB\U0001F44B\U0001F3FF", fill="white", embedded_color=True, font=fnt)
    draw.text((0, 432), "a\u263A", fill="#faa2", font=fnt)
    im.show()
    im.save(f"testemoji_{out_name}.png")

test(r"C:\Users\Nulano\Downloads\NotoColorEmoji.ttf", "cbdt")
test("seguiemj.ttf", "colr")

NotoColorEmoji.ttf (CBDT):

seguiemj.ttf (COLR):

[nulano]

Big-endian s390 is failing, but I'm not sure I can fix it without seeing the output image.

[hugovk]

This increases the size of the sdist by about 20% from 58M to 69M.

Are all these fonts necessary, or can we still be confident in testing with existing fonts (I guess they're not CBDT or COLR), or just one of the smaller additions?

[nulano]

This increases the size of the sdist by about 20% from 58M to 69M.

Are all these fonts necessary, or can we still be confident in testing with existing fonts (I guess they're not CBDT or COLR), or just one of the smaller additions?

DejaVuSans-24-*.ttf (6MB total) can be replaced by a different font or a cut-down version with just a few glyphs for testing.
Edit: replaced by stripped down versions (keeping ASCII range only) with ~60KB each.

The biggest chunk is the 9MB CBDT font NotoColorEmoji.ttf; CBDT fonts are essentially just a collection of bitmaps (uncompressed or PNG), so any font will be large. If the license allows it, stripping out all except the tested bitmaps might be possible.
Edit: FontForge can't open it so I'm not sure how I would strip it down. It might be easier to recompile it from source keeping only the one glyph that is tested.

BungeeColor-Regular_colr_Windows.ttf (COLR font) is just 73.6 KB.

[radarhere]

Big-endian s390 is failing, but I'm not sure I can fix it without seeing the output image.

Here you go - generated with this commit forked from your branch.

[nulano]

Big-endian s390 is failing, but I'm not sure I can fix it without seeing the output image.

Here you go - generated with this commit forked from your branch.

Ah, I had the right idea, but forgot long long is 8 bytes...

Thanks for the help.

[nulano]

This increases the size of the sdist by about 20% from 58M to 69M.

Are all these fonts necessary, or can we still be confident in testing with existing fonts (I guess they're not CBDT or COLR), or just one of the smaller additions?

I've stripped down the DejaVuSans-24-*.ttf fonts to ASCII and used an older version of NotoColorEmoji.ttf (5.1MB). Is this sufficient?
I can't find any other CBDT fonts or a simple way to edit them.

[hugovk]

Looks like we also need the setuptools workaround for 3.8 (like #4958) for Windows/GHA:

RuntimeWarning: The _imaging extension was built for another version of Pillow or PIL:
Core version: None
Pillow version: 8.0.0.dev0
Traceback (most recent call last):
  File "selftest.py", line 6, in <module>
    from PIL import Image, features
  File "<frozen zipimport>", line 259, in load_module
  File "C:\hostedtoolcache\windows\Python\3.8.6\x86\lib\site-packages\pillow-8.0.0.dev0-py3.8-win32.egg\PIL\Image.py", line 97, in <module>
ImportError: The _imaging extension was built for another version of Pillow or PIL:
Core version: None
Pillow version: 8.0.0.dev0
Error: Process completed with exit code 1.

https://github.com/python-pillow/Pillow/pull/4955/checks?check_run_id=1239105264

[nulano]

#4958 already includes 3.8, this branch just needs to be rebased or merge master (I think re-running the checks should suffice)

[hugovk]

There's quite a few Freetype version check and skips, let's put them into a helper, for example:

def skip_unless_freetype(required_version, message):

[nulano]

I went with the following to let the check be reusable for other features:

def skip_unless_feature_version(feature, version_required, reason=None):

[nulano]

Removing test_imagefont_bitmap.test_similar (in favor of the new test test_imagefont.test_bitmap_font) also allows removing 0.9MB DejaVuSans-bitmap.ttf.

[hugovk]

Thank you! Please can you add release notes for this, plus for any of your other PRs since the last release?

[NightMachinery]

Apple font is fine on my system, FYI.

Is there a way to use one font for emojis and another for the normal text?

[nulano]

Apple font is fine on my system, FYI.

Yep, figured that out a few weeks after this PR (#5155).

Is there a way to use one font for emojis and another for the normal text?

Not automatically, see #4808. If you are fine with splitting up the text yourself, you can use the approach outlined here: #3346 (comment).