First of all thanks for the great tool. Very handy. I am just asking/suggesting a

No problem. The <a href="https://fonttools.readthedocs.io/en/latest/ttLib/ttFont.html

<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/us

Report data modification and writing back to fontfile! about font-line HOT 6 CLOSED

source-foundry commented on June 24, 2024 1

Report data modification and writing back to fontfile!

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Comments (6)

chrissimpkins commented on June 24, 2024 1

Thanks for the note! To clarify your request here, you would like the report command output to be available in a table in the binary? Where / how would it be ideal to access it?

My initial concern about this is that a tool could change the metrics data in the font and not update the information that is recorded by font-line in the binary. How should we approach that?

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chrissimpkins commented on June 24, 2024 1

Ah, I see. Are you familiar with Python? This should be reasonably straightforward using the fonttools library and your config file format of choice.

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chrissimpkins commented on June 24, 2024 1

No problem. The fontTools.ttLib.TTFont documentation will be a good place to start. TTFont is a font object that is instantiated from a binary file path. It provides access to all of the OpenType tables that you will need to edit and is the data structure that is used in font-line for read/write access to the metrics data.

Have a look at

font-line/lib/fontline/metrics.py

Lines 17 to 63 in fad1442

 # Vertical metrics values as integers 

 self.os2_typo_ascender = tt["OS/2"].sTypoAscender 

 self.os2_typo_descender = tt["OS/2"].sTypoDescender 

 self.os2_win_ascent = tt["OS/2"].usWinAscent 

 self.os2_win_descent = tt["OS/2"].usWinDescent 

 self.os2_typo_linegap = tt["OS/2"].sTypoLineGap 

 try: 

 self.os2_x_height = tt["OS/2"].sxHeight 

 except AttributeError: 

 self.os2_x_height = "---- (OS/2 table does not contain sxHeight record)" 

 try: 

 self.os2_cap_height = tt["OS/2"].sCapHeight 

 except AttributeError: 

 self.os2_cap_height = "---- (OS/2 table does not contain sCapHeight record)" 

 self.hhea_ascent = tt["hhea"].ascent 

 self.hhea_descent = tt["hhea"].descent 

 self.hhea_linegap = tt["hhea"].lineGap 

 self.ymax = tt["head"].yMax 

 self.ymin = tt["head"].yMin 

 self.units_per_em = tt["head"].unitsPerEm 

 # Bit flag checks 

 self.fsselection_bit7_mask = 1 << 7 

 self.fsselection_bit7_set = ( 

 tt["OS/2"].fsSelection & self.fsselection_bit7_mask 

 ) != 0 

 # Calculated values 

 self.os2_typo_total_height = self.os2_typo_ascender + abs(self.os2_typo_descender) 

 self.os2_win_total_height = self.os2_win_ascent + self.os2_win_descent 

 self.hhea_total_height = self.hhea_ascent + abs(self.hhea_descent) 

 self.hhea_btb_distance = self.hhea_total_height + self.hhea_linegap 

 self.typo_btb_distance = self.os2_typo_total_height + self.os2_typo_linegap 

 self.win_external_leading = self.hhea_linegap - ( 

 (self.os2_win_ascent + self.os2_win_descent) 

 - (self.hhea_ascent - self.hhea_descent) 

 ) 

 if self.win_external_leading < 0: 

 self.win_external_leading = 0 

 self.win_btb_distance = ( 

 self.os2_win_ascent + self.os2_win_descent + self.win_external_leading 

 ) 

 self.typo_to_upm = 1.0 * self.typo_btb_distance / self.units_per_em 

 self.winascdesc_to_upm = 1.0 * self.win_btb_distance / self.units_per_em 

 self.hheaascdesc_to_upm = 1.0 * self.hhea_btb_distance / self.units_per_em

for details on how to get at the metrics data in each of the relevant OT tables. In that block of font-line source, tt is the TTFont object. What you will want to do is edit those data with the desired values and then save the font to disk. save takes a file path and allows you to either save in place or on a different path. I think that the only missing piece will be to decide how you want to configure the data. JSON is supported in the Python stdlib. There are 3rd party packages on PyPI for toml, yaml, etc. Those should be the pieces to get to where you want to go!

Let me know if you run into any issues and if you come up with something that others can use!

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charityrolfson433 commented on June 24, 2024 1

Thanks for taking all this time to help me. I will try to get something out of it. Thank you again.

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charityrolfson433 commented on June 24, 2024

@chrissimpkins i am not very familiar in this field, also not very techy to with all the terminology. so you have to pardon me for my limited knowledge.

I want to change the Metrics table values which are generated in the text file (ie, [head] yMax:, [head] yMin:, [OS/2] TypoAscender:... and other values) to gain the line-gap according to my personal taste, where I know the default way to change is to use the percentage command.

I also not that good or able to tell you how can we achieve that. My thoughts are this: We generate the Metrics table in a text file and will it be possible to write back the modified values to the font anyhow? something like font-line font-report.txt > font.ttf may be?

i can do it with any font-editor app/software (fontforge or anything of such sort) but as command line utilities are always faster in working with, also if I ever in need of editing in bulk amount it would be a perfect choice.

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charityrolfson433 commented on June 24, 2024

Thank you very much for the information.
Yes I am a little familiar with Python and fonttools. I sometimes use fonttool's TTX but not very advanced user. Can you link me to some tutorial or article from where people like me (with limited knowledge) can learn about what I am trying to achieve here?

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Report data modification and writing back to fontfile! about font-line HOT 6 CLOSED

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	# Vertical metrics values as integers
	self.os2_typo_ascender = tt["OS/2"].sTypoAscender
	self.os2_typo_descender = tt["OS/2"].sTypoDescender
	self.os2_win_ascent = tt["OS/2"].usWinAscent
	self.os2_win_descent = tt["OS/2"].usWinDescent
	self.os2_typo_linegap = tt["OS/2"].sTypoLineGap
	try:
	self.os2_x_height = tt["OS/2"].sxHeight
	except AttributeError:
	self.os2_x_height = "---- (OS/2 table does not contain sxHeight record)"
	try:
	self.os2_cap_height = tt["OS/2"].sCapHeight
	except AttributeError:
	self.os2_cap_height = "---- (OS/2 table does not contain sCapHeight record)"
	self.hhea_ascent = tt["hhea"].ascent
	self.hhea_descent = tt["hhea"].descent
	self.hhea_linegap = tt["hhea"].lineGap
	self.ymax = tt["head"].yMax
	self.ymin = tt["head"].yMin
	self.units_per_em = tt["head"].unitsPerEm

	# Bit flag checks
	self.fsselection_bit7_mask = 1 << 7
	self.fsselection_bit7_set = (
	tt["OS/2"].fsSelection & self.fsselection_bit7_mask
	) != 0

	# Calculated values
	self.os2_typo_total_height = self.os2_typo_ascender + abs(self.os2_typo_descender)
	self.os2_win_total_height = self.os2_win_ascent + self.os2_win_descent
	self.hhea_total_height = self.hhea_ascent + abs(self.hhea_descent)

	self.hhea_btb_distance = self.hhea_total_height + self.hhea_linegap
	self.typo_btb_distance = self.os2_typo_total_height + self.os2_typo_linegap
	self.win_external_leading = self.hhea_linegap - (
	(self.os2_win_ascent + self.os2_win_descent)
	- (self.hhea_ascent - self.hhea_descent)
	)
	if self.win_external_leading < 0:
	self.win_external_leading = 0
	self.win_btb_distance = (
	self.os2_win_ascent + self.os2_win_descent + self.win_external_leading
	)

	self.typo_to_upm = 1.0 * self.typo_btb_distance / self.units_per_em
	self.winascdesc_to_upm = 1.0 * self.win_btb_distance / self.units_per_em
	self.hheaascdesc_to_upm = 1.0 * self.hhea_btb_distance / self.units_per_em