matplotlib 未检测到字体

当我使用fontname=与Humor Sans字体我收到此错误：

/usr/lib/python3.5/site-packages/matplotlib/font_manager.py:1288: UserWarning: findfont: Font family ['Humor Sans', 'Comic Sans MS'] not found. Falling back to Bitstream Vera Sans
  (prop.get_family(), self.defaultFamily[fontext]))

我有Humor Sans安装。我使用 archlinux 并且安装了ttf-幽默-sans https://aur.archlinux.org/packages/ttf-humor-sans/包裹。

我已确保字体配置缓存fc-list找到Humor Sans font:

$ fc-list | grep -i Humor
/usr/share/fonts/TTF/Humor-Sans-1.0.ttf: Humor Sans:style=Regular

嗯，仔细一看，这是一种bug。使用以下测试：

import matplotlib.font_manager as fm
import matplotlib.pyplot as plt

font_cache = [i for i in
    fm.findSystemFonts(fontpaths=None, fontext='ttf')
    if 'umor' in i]
for i in font_cache:
    print(i)
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot([1],[1],'o')
ax.set_title('My Title', fontname='Humor Sans')
#ax.set_title('My Title', fontname='Homemade Apple')
fig.savefig('tmp.png')

我比较了Humor Sans反对Homemade Apple（我将其打包到 AUR 包中的免费 google 字体）。问题是matplotlib does matching在指定的字体名称上fontname=，匹配不仅仅使用名称，还使用字体的几个属性。在/home/grochmal/mat3/lib/python3.5/site-packages/matplotlib/font_manager.py你会看到匹配的：

for font in fontlist:
    if (directory is not None and
        os.path.commonprefix([font.fname, directory]) != directory):
        continue
    # Matching family should have highest priority, so it is multiplied
    # by 10.0
    score = \
        self.score_family(prop.get_family(), font.name) * 10.0 + \
        self.score_style(prop.get_style(), font.style) + \
        self.score_variant(prop.get_variant(), font.variant) + \
        self.score_weight(prop.get_weight(), font.weight) + \
        self.score_stretch(prop.get_stretch(), font.stretch) + \
        self.score_size(prop.get_size(), font.size)
    if score < best_score:
         best_score = score
         best_font = font
    if score == 0:
         break

很遗憾Humor Sans永远不会到达匹配阶段，因为并非所有prop.get_...可以填写。本质上它永远不会包含在fontlist. Homemade Apple被包含在内是因为它可以填充所有属性。

字体属性的差异可以看出：

[me@haps aur]# otfinfo --info /usr/share/fonts/TTF/HomemadeApple.ttf
Family:              Homemade Apple
Subfamily:           Regular
Full name:           Homemade Apple
PostScript name:     HomemadeApple
Preferred family:    Homemade Apple
Preferred subfamily: Regular
Mac font menu name:  Homemade Apple
Version:             Version 1.000
Unique ID:           FontDiner,Inc: Homemade Apple: 2010
Description:         Copyright (c) 2010 by Font Diner, Inc. All rights reserved.
Designer:            Font Diner, Inc
Designer URL:        http://www.fontdiner.com
Manufacturer:        Font Diner, Inc
Vendor URL:          http://www.fontdiner.com
Trademark:           Homemade Apple is a trademark of Font Diner, Inc.
Copyright:           Copyright (c) 2010 by Font Diner, Inc. All rights reserved.
License URL:         http://www.apache.org/licenses/LICENSE-2.0
License Description: Licensed under the Apache License, Version 2.0
Vendor ID:           DINR

[me@haps aur]# otfinfo --info /usr/share/fonts/TTF/Humor-Sans-1.0.ttf
Family:              Humor Sans
Subfamily:           Regular
Full name:           Humor Sans
PostScript name:     HumorSans
Version:             Version 2.9 28/3/09
Unique ID:           Fontifier 2.9 (172) www.fontifier.com Humor Sans
Copyright:           Copyright (c) Randall Munroe's biggest fan 2009. Created by www.fontifier.com. usa-1lip-4fvu15
Vendor ID:           Alts

缺少字段Humor Sans不是必需的，公平地说，TTF 中的字体描述方式存在一些不一致的地方（googleitalic vs. oblique例如）因此它不是Humor Sans也有错。您的问题是文件格式不一致以及缺乏处理这些不一致的标准化代码的组合。

我建议找到一种看起来足够相似的不同字体。编辑 TTF 或 matplotlib 代码都非常棘手，并且可能会导致其他问题。