Font issue: findfonts should differentiate between thin and regular ttf fonts · Issue #8788 · matplotlib/matplotlib · GitHub

Bug report

Bug summary

The selection criteria for finding fonts using the algorithm in matplotlib.font_manager.findfonts are incomplete. The problem arises with high-quality TTF fonts that have many different styles, for instance "Helvetica Neue", or "Lato". For instance, the "Thin" versions of these fonts are indistinguishable from the "Regular" versions by their font weight (both have e.g. a value of 400) such that the font that is returned by findfonts depends on the ordering of the list matplotlib.font_manager.fontManager.ttflist.

A workaround would be to simply uninstall the unwanted versions of the conflicting fonts from the system. Unfortunately, for the figures that I am trying to create, "Helvetica Neue" is mandatory and it is also an OSX system font, thus cannot be disabled.

I am unsure whether the fonts (for instance) "HelveticaNeue-Thin.ttf" and "HelveticaNeue.ttf" could be distinguished by adding another font metric to the Font class. If not, the proposed solution would be to allow selecting fonts in matplotlib.rcParams by their file name, e.g. setting mathtext.rm : "HelveticaNeue.ttf". This solution would require changing the fontconfig parser in matplotlib.fontconfig_pattern.py to allow filenames.

Code for reproduction

The result of the code below is system-dependent, even when exactly the same font files are installed, because of the ordering of matplotlib.font_manager.fontManager.ttflist.

import matplotlib.font_manager as fm
p = fm.FontProperties(family = 'Helvetica Neue')
fm.findfont(p)

--> 'HelveticaNeue.ttf' or 'HelveticaNeue-Thin.ttf'

The properties of the corresponding Font objects are identical (see matplotlib.font_manager.fontManager.ttflist)

<Font 'Helvetica Neue' (HelveticaNeue.ttf) normal normal 400 normal>
<Font 'Helvetica Neue' (HelveticaNeue-Thin.ttf) normal normal 400 normal>

Actual outcome

See above, system-dependent.

Expected outcome

Findfonts should be deterministic.

Matplotlib version

Operating System: OSX, Windows
Matplotlib Version: 2.0.0
Python Version: 3.6.1

Related to #8551 #8607 #5250 #8550 #7931

This seems to have become a major problem recently.

This has been a recurring issue when adding new fonts to proplot -- I have to manually delete all of the "thin" files. Looks like the issue is in font_manager.ttfFontProperty. Here is where styles and weights are read:

matplotlib/lib/matplotlib/font_manager.py

Lines 358 to 438 in 5fb9709

    
           def ttfFontProperty(font): 
        
               """ 
        
               Extract information from a TrueType font file. 
        
               Parameters 
        
               ---------- 
        
               font : `.FT2Font` 
        
                   The TrueType font file from which information will be extracted. 
        
               Returns 
        
               ------- 
        
               `FontEntry` 
        
                   The extracted font properties. 
        
               """ 
        
               name = font.family_name 
        
               #  Styles are: italic, oblique, and normal (default) 
        
               sfnt = font.get_sfnt() 
        
               # These tables are actually mac_roman-encoded, but mac_roman support may be 
        
               # missing in some alternative Python implementations and we are only going 
        
               # to look for ASCII substrings, where any ASCII-compatible encoding works 
        
               # - or big-endian UTF-16, since important Microsoft fonts use that. 
        
               sfnt2 = (sfnt.get((1, 0,      0, 2), b'').decode('latin-1').lower() or 
        
                        sfnt.get((3, 1, 0x0409, 2), b'').decode('utf_16_be').lower()) 
        
               sfnt4 = (sfnt.get((1, 0,      0, 4), b'').decode('latin-1').lower() or 
        
                        sfnt.get((3, 1, 0x0409, 4), b'').decode('utf_16_be').lower()) 
        
               if sfnt4.find('oblique') >= 0: 
        
                   style = 'oblique' 
        
               elif sfnt4.find('italic') >= 0: 
        
                   style = 'italic' 
        
               elif sfnt2.find('regular') >= 0: 
        
                   style = 'normal' 
        
               elif font.style_flags & ft2font.ITALIC: 
        
                   style = 'italic' 
        
               else: 
        
                   style = 'normal' 
        
               #  Variants are: small-caps and normal (default) 
        
               #  !!!!  Untested 
        
               if name.lower() in ['capitals', 'small-caps']: 
        
                   variant = 'small-caps' 
        
               else: 
        
                   variant = 'normal' 
        
               if font.style_flags & ft2font.BOLD: 
        
                   weight = 700 
        
               else: 
        
                   weight = next((w for w in weight_dict if w in sfnt4), 400) 
        
               #  Stretch can be absolute and relative 
        
               #  Absolute stretches are: ultra-condensed, extra-condensed, condensed, 
        
               #    semi-condensed, normal, semi-expanded, expanded, extra-expanded, 
        
               #    and ultra-expanded. 
        
               #  Relative stretches are: wider, narrower 
        
               #  Child value is: inherit 
        
               if any(word in sfnt4 for word in ['narrow', 'condensed', 'cond']): 
        
                   stretch = 'condensed' 
        
               elif 'demi cond' in sfnt4: 
        
                   stretch = 'semi-condensed' 
        
               elif any(word in sfnt4 for word in ['wide', 'expanded', 'extended']): 
        
                   stretch = 'expanded' 
        
               else: 
        
                   stretch = 'normal' 
        
               #  Sizes can be absolute and relative. 
        
               #  Absolute sizes are: xx-small, x-small, small, medium, large, x-large, 
        
               #    and xx-large. 
        
               #  Relative sizes are: larger, smaller 
        
               #  Length value is an absolute font size, e.g., 12pt 
        
               #  Percentage values are in 'em's.  Most robust specification. 
        
               if not font.scalable: 
        
                   raise NotImplementedError("Non-scalable fonts are not supported") 
        
               size = 'scalable' 
        
               return FontEntry(font.fname, name, style, variant, weight, stretch, size)

What can we do to detect the 'thin' property? Also is 'thin' a style or a weight?

If you're on linux (macos perhaps? if fontconfig is present) you can use https://github.com/anntzer/mplfccache to generate a more accurate font cache (asking fontconfig to list the font properties for you).

I have translated into Python the actual algorithm used by fontconfig to determine font properties at https://github.com/anntzer/freetypybind/blob/master/lib/freetypybind/query_face.py (using my own freetype binding but that shouldn't matter much); someone "just" needs to PR that into Matplotlib...

Mostly closed by #16203.

Font issue: findfonts should differentiate between thin and regular ttf fonts · Issue #8788 · matplotlib/matplotlib · GitHub

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Font issue: findfonts should differentiate between thin and regular ttf fonts #8788

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	def ttfFontProperty(font):
	"""
	Extract information from a TrueType font file.

	Parameters
	----------
	font : `.FT2Font`
	The TrueType font file from which information will be extracted.

	Returns
	-------
	`FontEntry`
	The extracted font properties.

	"""
	name = font.family_name

	# Styles are: italic, oblique, and normal (default)

	sfnt = font.get_sfnt()
	# These tables are actually mac_roman-encoded, but mac_roman support may be
	# missing in some alternative Python implementations and we are only going
	# to look for ASCII substrings, where any ASCII-compatible encoding works
	# - or big-endian UTF-16, since important Microsoft fonts use that.
	sfnt2 = (sfnt.get((1, 0, 0, 2), b'').decode('latin-1').lower() or
	sfnt.get((3, 1, 0x0409, 2), b'').decode('utf_16_be').lower())
	sfnt4 = (sfnt.get((1, 0, 0, 4), b'').decode('latin-1').lower() or
	sfnt.get((3, 1, 0x0409, 4), b'').decode('utf_16_be').lower())

	if sfnt4.find('oblique') >= 0:
	style = 'oblique'
	elif sfnt4.find('italic') >= 0:
	style = 'italic'
	elif sfnt2.find('regular') >= 0:
	style = 'normal'
	elif font.style_flags & ft2font.ITALIC:
	style = 'italic'
	else:
	style = 'normal'

	# Variants are: small-caps and normal (default)

	# !!!! Untested
	if name.lower() in ['capitals', 'small-caps']:
	variant = 'small-caps'
	else:
	variant = 'normal'

	if font.style_flags & ft2font.BOLD:
	weight = 700
	else:
	weight = next((w for w in weight_dict if w in sfnt4), 400)

	# Stretch can be absolute and relative
	# Absolute stretches are: ultra-condensed, extra-condensed, condensed,
	# semi-condensed, normal, semi-expanded, expanded, extra-expanded,
	# and ultra-expanded.
	# Relative stretches are: wider, narrower
	# Child value is: inherit

	if any(word in sfnt4 for word in ['narrow', 'condensed', 'cond']):
	stretch = 'condensed'
	elif 'demi cond' in sfnt4:
	stretch = 'semi-condensed'
	elif any(word in sfnt4 for word in ['wide', 'expanded', 'extended']):
	stretch = 'expanded'
	else:
	stretch = 'normal'

	# Sizes can be absolute and relative.
	# Absolute sizes are: xx-small, x-small, small, medium, large, x-large,
	# and xx-large.
	# Relative sizes are: larger, smaller
	# Length value is an absolute font size, e.g., 12pt
	# Percentage values are in 'em's. Most robust specification.

	if not font.scalable:
	raise NotImplementedError("Non-scalable fonts are not supported")
	size = 'scalable'

	return FontEntry(font.fname, name, style, variant, weight, stretch, size)

Font issue: findfonts should differentiate between thin and regular ttf fonts · Issue #8788 · matplotlib/matplotlib · GitHub

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Font issue: findfonts should differentiate between thin and regular ttf fonts #8788

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tacaswell commented on Jun 22, 2017

lukelbd commented on Dec 18, 2019

anntzer commented on Dec 18, 2019

anntzer commented on May 28, 2020

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