(libSkShaper) Combined emoji will be drawn as multiple emoji

[Polyisoprene]

Describe the bug
a combined emoji like ✌🏻 will be drawn as two emoji

To Reproduce
Steps to reproduce the behavior:

text = "✌🏻"
surface = skia.Surface(50,50)
paint = skia.Paint(AntiAlias=True, Color=skia.Color(0,0,0,255))
typeface = skia.FontMgr().matchFamilyStyleCharacter( "Noto Sans CJK SC",skia.FontStyle().Normal,["zh", "en"], ord(text))
font = skia.Font(typeface,10)
blob = skia.TextBlob(text, font)
canvas.drawTextBlob(blob, 30,30, paint)

Expected behavior

single emoji appears on the image

Desktop (please complete the following information):

• OS: Ubuntu20.04
• Python: 3.10
• skia-python version: 87.5

Additional context
Add any other context about the problem here.

[HinTak]

This sounds a lot like this upstream issue - google/skia#129

[HinTak]

Changed my mind a bit. I think the correct answer involves a text shaper. Calling a harfbuzz binding of any sort is one answer, but using skshaper is perhaps preferred. Ie. We need to bind
https://api.skia.org/classSkShaper.html

[HinTak]

I tried the emoji modifier with my harfbuzz + freetype + skia code : https://github.com/HinTak/harfbuzz-python-demos/blob/master/hb-view-ot-svg-skia-GL.py and it works as desired, so I think using SkShaper is the correct way to go. My code is fairly harfbuzz and freetype centric, with skia only drawing bitmaps from fonts retrieved via freetype and harfbuzz. On Linux, skia.Font and skia.Fontmgr are essentially Freetype and Fontconfig correspondingly, so the freetype part of my code should be replaceable with indirect calls via skia. harfbuzz corresponds to SkShaper (i.e. SkShaper is implemented via harfbuzz and all SkShaper APIs eventually call harfbuzz on Linux), which isn't hooked up in skia-python yet.

If you are impatient, you can take my code and see what SkShaper calls correspond to those harfbuzz calls, and save me a bit of research time.

[HinTak]

This is fixed in b4331dc as part of #210 .

Mostly you need to do
blob = skia.TextBlob.MakeFromShapedText(text, font) instead of blob = skia.TextBlob(text, font). I thought of overloading the constructor, but it is a bit hard given the constructor and MakeShapedText takes different set of optional arguments, so overloading the two means some arguments get ignored in the other calls. Also the returned result have different bounds, so you need to read the blob.bounds() and adjust offsets. BTW, I found that you made two mistakes in your typeface call (the 2nd and the last arguments are wrong). Anyway, after fixing your mistakes, and make sure a relevant font is picked (check typeface - Noto Color Emoji works, and so does OpenMoji Black), it works.

@kyamagu also as a side-effect, MakeFromShapedText can handle Arabic and most of the middle East and right-to-left languages (Hebrew, Tibetan), and do the right thing for them.

[HinTak]

This is a RFC for the new MakeFromShapedText static method. @Polyisoprene @kyamagu

[HinTak]

You can cut and paste the Persian word for Harfbuzz, use an Arabic font, and have it rendered with MakeFromShapedText, and compare with online images, even if you don't read Arabic.

[Polyisoprene]

This is a RFC for the new MakeFromShapedText static method. @Polyisoprene @kyamagu

Thank you for spending so much time solving this problem, but this method seems to be ineffective。
I installed 'skia_python-120.0b4-cp310 cp310 win_amd64. whl',and i have fixed my incorrect code

import skia

text = "✌🏻"
surface = skia.Surface(350,350)
canvas = surface.getCanvas()
paint = skia.Paint(AntiAlias=True, Color=skia.Color(0,0,0,255))
typeface = skia.FontMgr().makeFromFile("F:\\Python\\test\\NotoColorEmoji.ttf")
font = skia.Font(typeface,30)
blob = skia.TextBlob.MakeFromShapedText(text, font)
canvas.drawTextBlob(blob, 30,30, paint)
img = skia.Image.fromarray(canvas.toarray(colorType=skia.ColorType.kRGBA_8888_ColorType), colorType=skia.ColorType.kRGBA_8888_ColorType)
img.save("1.png")

but I still haven't get the correct image

and after running the code, I get the following output

SkIcuLoader: datafile missing: E:\Python\icudtl.dat.
SkIcuLoader: datafile missing: F:\Envs\normal\lib\site-packages\icudtl.dat.

[HinTak]

@Polyisoprene you wrote you are on Linux:-(. I don't have icudtl in python locations, but I have 3 copies of that file on linux, under chrome/chromium and zoom/cef . The two copies under chrome/chromium are the same. All are over 10MB each. Pretty sure skia-python on Linux doesn't need it, but maybe skia-python on Windows does...

[HinTak]

@Polyisoprene If it wasn't clear, I am suggesting that maybe you copy that file from either Linux chrome or Windows chrome to Windows python where that location is. I think libshaper uses harbuzz on Linux but CoreText on Mac OS. The Window equivalent of Harfbuzz on Windows is uniscribe / usp AFAIK, but I haven't come across uniscribe reference in skia's source code yet, so I have no idea how libshaper works on Windows.

[Polyisoprene]

@Polyisoprene If it wasn't clear, I am suggesting that maybe you copy that file from either Linux chrome or Windows chrome to Windows python where that location is. I think libshaper uses harbuzz on Linux but CoreText on Mac OS. The Window equivalent of Harfbuzz on Windows is uniscribe / usp AFAIK, but I haven't come across uniscribe reference in skia's source code yet, so I have no idea how libshaper works on Windows.

Thanks for your reply. Anyway, at least it works on Linux