libpng 错误：设置 usetex=True 后使用 matplotlib 时出现读取错误答案

【问题标题】：libpng error: Read Error when using matplotlib after setting usetex=Truelibpng 错误：设置 usetex=True 后使用 matplotlib 时出现读取错误
【发布时间】：2020-04-25 12:24:28
【问题描述】：

在运行 Windows 10 的两台不同机器上，在 matplotlib 中设置选项 usetex=True 后尝试绘图时，我收到错误 libpng error: Read Error 导致 python 崩溃。这在这台机器上之前没有问题，我不确定后来发生了什么变化。

我尝试安装不同的 libpng 版本（1.6.32、1.6.34、1.6.36、1.6.37），但它们都导致相同的结果。

一个最小的例子，直接在使用conda create --name libpngtest python=3 matplotlib libpng 创建一个新环境之后：

>>> import matplotlib.pyplot as plt
>>> from matplotlib import rc
>>> rc('text', usetex=True)
>>> plt.plot(1,2)
[<matplotlib.lines.Line2D object at 0x00000193015A8908>]
>>> plt.show()

此时，python 控制台有时会崩溃而没有任何消息，但我也看到在它崩溃之前打印了libpng error: Read Error。在 jupyter notebook/lab 中，内核将重新启动，libpng error: Read Error 会出现在 jupyter 消息之间运行 jupyter 的终端中。

此时我不确定这是 python 问题还是 TeX 问题（我安装了 MikTeX 2.9，它似乎运行良好），但希望您能提供任何提示。

编辑：设置plt.set_loglevel("debug")后的输出为：

DEBUG:matplotlib.texmanager:serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: serif, font: Computer Modern Roman, info: ('cmr', '')
DEBUG:matplotlib.texmanager:sans-serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:sans-serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: sans-serif, font: Computer Modern Sans Serif, info: ('cmss', '')
DEBUG:matplotlib.texmanager:cursive font is not compatible with usetex.
DEBUG:matplotlib.texmanager:cursive font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: cursive, font: Zapf Chancery, info: ('pzc', '\\usepackage{chancery}')
DEBUG:matplotlib.texmanager:monospace font is not compatible with usetex.
DEBUG:matplotlib.texmanager:monospace font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: monospace, font: Computer Modern Typewriter, info: ('cmtt', '')
DEBUG:matplotlib.texmanager:following keys changed: ['text.latex.preamble', 'text.latex.unicode', 'text.latex.preview', 'font.family', 'font.serif', 'font.sans-serif', 'font.cursive', 'font.monospace']
DEBUG:matplotlib.texmanager:text.latex.preamble : None       ->
DEBUG:matplotlib.texmanager:text.latex.unicode  : None       -> True
DEBUG:matplotlib.texmanager:text.latex.preview  : None       -> False
DEBUG:matplotlib.texmanager:font.family         : None       -> ['sans-serif']
DEBUG:matplotlib.texmanager:font.serif          : None       -> ['DejaVu Serif', 'Bitstream Vera Serif', 'Computer Modern Roman', 'New Century Schoolbook', 'Century Schoolbook L', 'Utopia', 'ITC Bookman', 'Bookman', 'Nimbus Roman No9 L', 'Times New Roman', 'Times', 'Palatino', 'Charter', 'serif']
DEBUG:matplotlib.texmanager:font.sans-serif     : None       -> ['DejaVu Sans', 'Bitstream Vera Sans', 'Computer Modern Sans Serif', 'Lucida Grande', 'Verdana', 'Geneva', 'Lucid', 'Arial', 'Helvetica', 'Avant Garde', 'sans-serif']
DEBUG:matplotlib.texmanager:font.cursive        : None       -> ['Apple Chancery', 'Textile', 'Zapf Chancery', 'Sand', 'Script MT', 'Felipa', 'cursive']
DEBUG:matplotlib.texmanager:font.monospace      : None       -> ['DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Computer Modern Typewriter', 'Andale Mono', 'Nimbus Mono L', 'Courier New', 'Courier', 'Fixed', 'Terminal', 'monospace']
DEBUG:matplotlib.texmanager:RE-INIT
old fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.texmanager:serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: serif, font: Computer Modern Roman, info: ('cmr', '')
DEBUG:matplotlib.texmanager:sans-serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:sans-serif font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: sans-serif, font: Computer Modern Sans Serif, info: ('cmss', '')
DEBUG:matplotlib.texmanager:cursive font is not compatible with usetex.
DEBUG:matplotlib.texmanager:cursive font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: cursive, font: Zapf Chancery, info: ('pzc', '\\usepackage{chancery}')
DEBUG:matplotlib.texmanager:monospace font is not compatible with usetex.
DEBUG:matplotlib.texmanager:monospace font is not compatible with usetex.
DEBUG:matplotlib.texmanager:family: monospace, font: Computer Modern Typewriter, info: ('cmtt', '')
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\1acea6f6c115d0ec7a634ed0529287b9.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.dviread:['kpsewhich', 'cmss10.tfm']
DEBUG:matplotlib.dviread:stdout:
b'C:/Program Files/MiKTeX 2.9/fonts/tfm/public/cm/cmss10.tfm\r\n'
DEBUG:matplotlib.dviread:stderr:
b''
DEBUG:matplotlib.dviread:opening tfm file C:/Program Files/MiKTeX 2.9/fonts/tfm/public/cm/cmss10.tfm
DEBUG:matplotlib.dviread:lh=18, bc=0, ec=127, nw=52, nh=16, nd=11
DEBUG:matplotlib.dviread:['kpsewhich', 'cmss10.vf']
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\d598be7bdc6e0eeebdc83c75321a7705.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.dviread:['kpsewhich', 'cmr10.tfm']
DEBUG:matplotlib.dviread:stdout:
b'C:/Program Files/MiKTeX 2.9/fonts/tfm/public/cm/cmr10.tfm\r\n'
DEBUG:matplotlib.dviread:stderr:
b''
DEBUG:matplotlib.dviread:opening tfm file C:/Program Files/MiKTeX 2.9/fonts/tfm/public/cm/cmr10.tfm
DEBUG:matplotlib.dviread:lh=18, bc=0, ec=127, nw=36, nh=16, nd=10
DEBUG:matplotlib.dviread:['kpsewhich', 'cmr10.vf']
DEBUG:matplotlib.dviread:['kpsewhich', 'cmmi10.tfm']
DEBUG:matplotlib.dviread:stdout:
b'C:/Program Files/MiKTeX 2.9/fonts/tfm/public/cm/cmmi10.tfm\r\n'
DEBUG:matplotlib.dviread:stderr:
b''
DEBUG:matplotlib.dviread:opening tfm file C:/Program Files/MiKTeX 2.9/fonts/tfm/public/cm/cmmi10.tfm
DEBUG:matplotlib.dviread:lh=18, bc=0, ec=127, nw=98, nh=15, nd=9
DEBUG:matplotlib.dviread:['kpsewhich', 'cmmi10.vf']
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\1acea6f6c115d0ec7a634ed0529287b9.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\14cf46b44d83e91d3e4f12cc60007df3.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\1acea6f6c115d0ec7a634ed0529287b9.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\217de38979bbb592496a29d181b7bbc4.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\1acea6f6c115d0ec7a634ed0529287b9.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\3233f296f4d6994ca99a0d418d6458d8.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\1acea6f6c115d0ec7a634ed0529287b9.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.dviread:Dvi: C:\Users\...\.matplotlib\tex.cache\e2c00e1750b187927439ebc0ca3a1a38.dvi
DEBUG:matplotlib.dviread:Dvi._xxx: encountered special: papersize=5203.43999pt,5203.43999pt
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e
DEBUG:matplotlib.texmanager:fontconfig: sans-serifcmrcmsspzccmttd41d8cd98f00b204e9800998ecf8427e

【问题讨论】：

是否生成了 LaTex 日志文件？
@WilliamMiller 这是一个有趣的问题。我运行 python 的目录中没有 LaTeX 日志文件。它会在其他地方生成吗？我查看了我的MiKTeX/2.9/miktex/log 目录，我看到kpsewhich 每次在.vf 文件上运行时都会以退出代码1 结束。这似乎是问题的可能原因......
尽管这在几年前就已经发生了，当时这些命令运行时没有任何问题。
恐怕我不确定在这种情况下它会在哪里生成。这种情况是否持续发生？
是的，每次我用usetex=True生成一个图。

标签： python matplotlib tex libpng

【解决方案1】：

我找到了一种绕过这个问题的方法，尽管我不会称之为解决方案（感谢 matplotlib github repo 上的 anntzer，https://github.com/matplotlib/matplotlib/issues/16163）。从 matplotlib 3.2.0 起，libpng 将不再使用，因此安装 matplotlib 3.2.0-rc 是一种可能的解决方法。

【讨论】：