[Bug]: Saving as an SVG and PDF produce different outputs with Latex characters, with wrong character sizing #29791
Comments
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We don;'t provide the styles |
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I am almost certain that this is the same issue as the glyph sizing issue reported in #12928 (which that PR didn't fix). Probably need to revive #14159... Repro: rcParams["text.latex.preamble"] = r"\usepackage{siunitx}"; figtext(.5, .5, r"\si{\um}", usetex=True); savefig("/tmp/test.svg")
# or, without siunitx
figtext(.5, .5, r"ff\textwon", usetex=True); savefig("/tmp/test.svg") |
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Figured this out (after 6 years...). The following patch fixes the issue (it is derived from #27654 (comment) but not loading the incompatible type1cm anymore, which may have been the cause of the test failures reported in the linked comment) diff --git i/lib/matplotlib/mpl-data/matplotlibrc w/lib/matplotlib/mpl-data/matplotlibrc
index ab412302f3..3dc0a4e2e3 100644
--- i/lib/matplotlib/mpl-data/matplotlibrc
+++ w/lib/matplotlib/mpl-data/matplotlibrc
@@ -334,7 +334,7 @@
# become quite long.
# The following packages are always loaded with usetex,
# so beware of package collisions:
- # geometry, inputenc, type1cm.
+ # color, fix-cm, geometry, graphicx, textcomp.
# PostScript (PSNFSS) font packages may also be
# loaded, depending on your font settings.
diff --git i/lib/matplotlib/mpl-data/stylelib/classic.mplstyle w/lib/matplotlib/mpl-data/stylelib/classic.mplstyle
index 6cba66076a..ca9b04a2cb 100644
--- i/lib/matplotlib/mpl-data/stylelib/classic.mplstyle
+++ w/lib/matplotlib/mpl-data/stylelib/classic.mplstyle
@@ -122,8 +122,8 @@ text.latex.preamble : # IMPROPER USE OF THIS FEATURE WILL LEAD TO LATEX FAILURE
# Note that it has to be put on a single line, which may
# become quite long.
# The following packages are always loaded with usetex, so
- # beware of package collisions: color, geometry, graphicx,
- # type1cm, textcomp.
+ # beware of package collisions:
+ # color, fix-cm, geometry, graphicx, textcomp.
# Adobe Postscript (PSSNFS) font packages may also be
# loaded, depending on your font settings.
diff --git i/lib/matplotlib/texmanager.py w/lib/matplotlib/texmanager.py
index 94fc94e9e8..c10f90a796 100644
--- i/lib/matplotlib/texmanager.py
+++ w/lib/matplotlib/texmanager.py
@@ -67,6 +67,13 @@ class TexManager:
_grey_arrayd = {}
_font_families = ('serif', 'sans-serif', 'cursive', 'monospace')
+ # Check for the cm-super package (which registers unicode computer modern
+ # support just by being installed) without actually loading any package
+ # (because we already load the incompatible fix-cm).
+ _check_cmsuper_installed = (
+ r'\IfFileExists{type1ec.sty}{}{\PackageError{matplotlib-support}{'
+ r'Missing cm-super package, required by Matplotlib}{}}'
+ )
_font_preambles = {
'new century schoolbook': r'\renewcommand{\rmdefault}{pnc}',
'bookman': r'\renewcommand{\rmdefault}{pbk}',
@@ -83,10 +90,10 @@ class TexManager:
# Loading the type1ec package ensures that cm-super is installed, which
# is necessary for Unicode computer modern. (It also allows the use of
# computer modern at arbitrary sizes, but that's just a side effect.)
- 'monospace': r'\usepackage{type1ec}',
- 'computer modern roman': r'\usepackage{type1ec}',
- 'computer modern sans serif': r'\usepackage{type1ec}',
- 'computer modern typewriter': r'\usepackage{type1ec}',
+ 'monospace': _check_cmsuper_installed,
+ 'computer modern roman': _check_cmsuper_installed,
+ 'computer modern sans serif': _check_cmsuper_installed,
+ 'computer modern typewriter': _check_cmsuper_installed,
}
_font_types = {
'new century schoolbook': 'serif',
@@ -200,6 +207,7 @@ class TexManager:
font_preamble, fontcmd = cls._get_font_preamble_and_command()
baselineskip = 1.25 * fontsize
return "\n".join([
+ r"\RequirePackage{fix-cm}",
r"\documentclass{article}",
r"% Pass-through \mathdefault, which is used in non-usetex mode",
r"% to use the default text font but was historically suppressed",It also supersedes #14159 which turns out to not have been the right approach after all. This would also close #27654 and #28675. The fundamental underlying issue is the following: for glyph to path conversion (used by svg), textpath renders the text at fontsize FONT_SCALE = 100, and scales it appropriately after. But type1ec, despite its name, doesn't actually allow rendering glyphs such as the micro-sign or the won sign at that size; manually compiling the tex file generated by texmanager.py shows the warning i.e. the micro sign is actually rendered ~3x smaller than the rest of the text (and then the ratio is kept when scaling down the text). Why greater sizes are now allowed remains a bit a mystery to me, as there's clearly an entry for bigger sizes in https://mirrors.ircam.fr/pub/CTAN/fonts/ps-type1/cm-super/type1ec.sty ( More links:
A side question that remains is whether textpath should really generate the glyphs at fontsize 100 and scale them (usually down) later. Indeed, size 100 computer modern is not the same as size 5 computer modern scaled up 20 times (see e.g. https://tex.stackexchange.com/questions/18721/). FWIW I don't see why textpath couldn't just do the rendering at the "real" requested size indicated in fontproperties... |
Bug summary
When saving certain outputs using Latex rendering as an SVG, it produces wrong outputs. Using plt.show() it renders correctly, and it works for saving as a PDF, but saving the output as a SVG math environment characters can render in the wrong size (see attached screenshots.)
Code for reproduction
Actual outcome
Expected outcome
ion_ranges_plot.pdf
Additional information
No response
Operating system
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Matplotlib Version
3.10.1
Matplotlib Backend
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Python version
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Jupyter version
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Installation
None
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