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Move PostScript Type3 subsetting to pure python. #18370

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Merged
merged 1 commit into from
Oct 3, 2020
Merged

Move PostScript Type3 subsetting to pure python. #18370

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132 changes: 107 additions & 25 deletions lib/matplotlib/backends/backend_ps.py
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Original file line number Diff line number Diff line change
Expand Up @@ -25,8 +25,8 @@
_Backend, _check_savefig_extra_args, FigureCanvasBase, FigureManagerBase,
GraphicsContextBase, RendererBase)
from matplotlib.cbook import is_writable_file_like, file_requires_unicode
from matplotlib.font_manager import is_opentype_cff_font, get_font
from matplotlib.ft2font import LOAD_NO_HINTING
from matplotlib.font_manager import get_font
from matplotlib.ft2font import LOAD_NO_HINTING, LOAD_NO_SCALE
from matplotlib._ttconv import convert_ttf_to_ps
from matplotlib.mathtext import MathTextParser
from matplotlib._mathtext_data import uni2type1
Expand Down Expand Up @@ -134,6 +134,86 @@ def _move_path_to_path_or_stream(src, dst):
shutil.move(src, dst, copy_function=shutil.copyfile)


def _font_to_ps_type3(font_path, glyph_ids):
"""
Subset *glyph_ids* from the font at *font_path* into a Type 3 font.

Parameters
----------
font_path : path-like
Path to the font to be subsetted.
glyph_ids : list of int
The glyph indices to include in the subsetted font.

Returns
-------
str
The string representation of a Type 3 font, which can be included
verbatim into a PostScript file.
"""
font = get_font(font_path, hinting_factor=1)

preamble = """\
%!PS-Adobe-3.0 Resource-Font
%%Creator: Converted from TrueType to Type 3 by Matplotlib.
10 dict begin
/FontName /{font_name} def
/PaintType 0 def
/FontMatrix [{inv_units_per_em} 0 0 {inv_units_per_em} 0 0] def
/FontBBox [{bbox}] def
/FontType 3 def
/Encoding [{encoding}] def
/CharStrings {num_glyphs} dict dup begin
/.notdef 0 def
""".format(font_name=font.postscript_name,
inv_units_per_em=1 / font.units_per_EM,
bbox=" ".join(map(str, font.bbox)),
encoding=" ".join("/{}".format(font.get_glyph_name(glyph_id))
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Is this safe, or do you need to escape any Postscript special values?

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this should be safe per https://github.com/adobe-type-tools/agl-specification#6-assigning-glyph-names-in-new-fonts. We can always revisit if someone finds a font with a bad glyph name...

for glyph_id in glyph_ids),
num_glyphs=len(glyph_ids) + 1)
postamble = """
end readonly def

/BuildGlyph {
exch begin
CharStrings exch
2 copy known not {pop /.notdef} if
true 3 1 roll get exec
end
} d

/BuildChar {
1 index /Encoding get exch get
1 index /BuildGlyph get exec
} d

FontName currentdict end definefont pop
"""

entries = []
for glyph_id in glyph_ids:
g = font.load_glyph(glyph_id, LOAD_NO_SCALE)
v, c = font.get_path()
entries.append(
"/%(name)s{%(bbox)s sc\n" % {
"name": font.get_glyph_name(glyph_id),
"bbox": " ".join(map(str, [g.horiAdvance, 0, *g.bbox])),
}
+ _path.convert_to_string(
# Convert back to TrueType's internal units (1/64's).
# (Other dimensions are already in these units.)
Path(v * 64, c), None, None, False, None, 0,
# No code for quad Beziers triggers auto-conversion to cubics.
# Drop intermediate closepolys (relying on the outline
# decomposer always explicitly moving to the closing point
# first).
[b"m", b"l", b"", b"c", b""], True).decode("ascii")
+ "ce} d"
)

return preamble + "\n".join(entries) + postamble


class RendererPS(_backend_pdf_ps.RendererPDFPSBase):
"""
The renderer handles all the drawing primitives using a graphics
Expand Down Expand Up @@ -922,22 +1002,18 @@ def print_figure_impl(fh):
# Can't use more than 255 chars from a single Type 3 font.
if len(glyph_ids) > 255:
fonttype = 42
# The ttf to ps (subsetting) support doesn't work for
# OpenType fonts that are Postscript inside (like the STIX
# fonts). This will simply turn that off to avoid errors.
if is_opentype_cff_font(font_path):
raise RuntimeError(
"OpenType CFF fonts can not be saved using "
"the internal Postscript backend at this "
"time; consider using the Cairo backend")
fh.flush()
try:
convert_ttf_to_ps(os.fsencode(font_path),
fh, fonttype, glyph_ids)
except RuntimeError:
_log.warning("The PostScript backend does not "
"currently support the selected font.")
raise
if fonttype == 3:
fh.write(_font_to_ps_type3(font_path, glyph_ids))
else:
try:
convert_ttf_to_ps(os.fsencode(font_path),
fh, fonttype, glyph_ids)
except RuntimeError:
_log.warning(
"The PostScript backend does not currently "
"support the selected font.")
raise
print("end", file=fh)
print("%%EndProlog", file=fh)

Expand Down Expand Up @@ -1312,30 +1388,36 @@ def pstoeps(tmpfile, bbox=None, rotated=False):
# The usage comments use the notation of the operator summary
# in the PostScript Language reference manual.
psDefs = [
# name proc *d* -
"/d { bind def } bind def",
# x y *m* -
"/m { moveto } bind def",
"/m { moveto } d",
# x y *l* -
"/l { lineto } bind def",
"/l { lineto } d",
# x y *r* -
"/r { rlineto } bind def",
"/r { rlineto } d",
# x1 y1 x2 y2 x y *c* -
"/c { curveto } bind def",
# *closepath* -
"/cl { closepath } bind def",
"/c { curveto } d",
# *cl* -
"/cl { closepath } d",
# *ce* -
"/ce { closepath eofill } d",
# w h x y *box* -
"""/box {
m
1 index 0 r
0 exch r
neg 0 r
cl
} bind def""",
} d""",
# w h x y *clipbox* -
"""/clipbox {
box
clip
newpath
} bind def""",
} d""",
# wx wy llx lly urx ury *setcachedevice* -
"/sc { setcachedevice } d",
]


Expand Down
112 changes: 112 additions & 0 deletions lib/matplotlib/tests/baseline_images/test_backend_ps/type3.eps
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Original file line number Diff line number Diff line change
@@ -0,0 +1,112 @@
%!PS-Adobe-3.0 EPSF-3.0
%%Orientation: portrait
%%BoundingBox: 18.0 180.0 594.0 612.0
%%EndComments
%%BeginProlog
/mpldict 11 dict def
mpldict begin
/d { bind def } bind def
/m { moveto } d
/l { lineto } d
/r { rlineto } d
/c { curveto } d
/cl { closepath } d
/ce { closepath eofill } d
/box {
m
1 index 0 r
0 exch r
neg 0 r
cl
} d
/clipbox {
box
clip
newpath
} d
/sc { setcachedevice } d
%!PS-Adobe-3.0 Resource-Font
%%Creator: Converted from TrueType to Type 3 by Matplotlib.
10 dict begin
/FontName /DejaVuSans def
/PaintType 0 def
/FontMatrix [0.00048828125 0 0 0.00048828125 0 0] def
/FontBBox [-2090 -948 3673 2524] def
/FontType 3 def
/Encoding [/I /J /slash] def
/CharStrings 4 dict dup begin
/.notdef 0 def
/I{604 0 201 0 403 1493 sc
201 1493 m
403 1493 l
403 0 l
201 0 l
201 1493 l

ce} d
/J{604 0 -106 -410 403 1493 sc
201 1493 m
403 1493 l
403 104 l
403 -76 369 -207 300 -288 c
232 -369 122 -410 -29 -410 c
-106 -410 l
-106 -240 l
-43 -240 l
46 -240 109 -215 146 -165 c
183 -115 201 -25 201 104 c
201 1493 l

ce} d
/slash{690 0 0 -190 690 1493 sc
520 1493 m
690 1493 l
170 -190 l
0 -190 l
520 1493 l

ce} d
end readonly def

/BuildGlyph {
exch begin
CharStrings exch
2 copy known not {pop /.notdef} if
true 3 1 roll get exec
end
} d

/BuildChar {
1 index /Encoding get exch get
1 index /BuildGlyph get exec
} d

FontName currentdict end definefont pop
end
%%EndProlog
mpldict begin
18 180 translate
576 432 0 0 clipbox
gsave
0 0 m
576 0 l
576 432 l
0 432 l
cl
1.000 setgray
fill
grestore
0.000 setgray
/DejaVuSans findfont
12.000 scalefont
setfont
gsave
288.000000 216.000000 translate
0.000000 rotate
0.000000 0 m /I glyphshow
3.539062 0 m /slash glyphshow
7.582031 0 m /J glyphshow
grestore

end
showpage
5 changes: 5 additions & 0 deletions lib/matplotlib/tests/test_backend_ps.py
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Original file line number Diff line number Diff line change
Expand Up @@ -157,3 +157,8 @@ def test_useafm():
ax.set_axis_off()
ax.axhline(.5)
ax.text(.5, .5, "qk")


@image_comparison(["type3.eps"])
def test_type3_font():
plt.figtext(.5, .5, "I/J")
7 changes: 2 additions & 5 deletions lib/matplotlib/tests/test_font_manager.py
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Original file line number Diff line number Diff line change
Expand Up @@ -120,11 +120,8 @@ def test_find_ttc():

fig, ax = plt.subplots()
ax.text(.5, .5, "\N{KANGXI RADICAL DRAGON}", fontproperties=fp)
fig.savefig(BytesIO(), format="raw")
fig.savefig(BytesIO(), format="svg")
fig.savefig(BytesIO(), format="pdf")
with pytest.raises(RuntimeError):
fig.savefig(BytesIO(), format="ps")
for fmt in ["raw", "svg", "pdf", "ps"]:
fig.savefig(BytesIO(), format=fmt)


def test_find_invalid(tmpdir):
Expand Down