Skip to content

Slightly better positioning of subscripts and superscripts of fractions #21850

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
tfpf wants to merge 3 commits into from
Closed

Slightly better positioning of subscripts and superscripts of fractions #21850

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
156b99a
Implement the TeX alignment of subscripts [skip ci]
tfpf Jun 10, 2022
6d2815c
Align both subscript and superscript the way TeX does.
tfpf Jun 11, 2022
584166e
Fix Flake8 errors.
tfpf Jun 11, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
37 changes: 28 additions & 9 deletions lib/matplotlib/_mathtext.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1830,6 +1830,7 @@ def set_names_and_parse_actions():
| p.underset
| p.sqrt
| p.overline
| p.auto_delim
)

p.simple <<= (
Expand Down Expand Up @@ -2206,6 +2207,16 @@ def subsuper(self, s, loc, toks):
result = Hlist([vlist])
return [result]

# Set the minimum shifts for the superscript and subscript (node756).
constants = _get_font_constant_set(state)
if isinstance(nucleus, Char):
shift_up = 0
shift_down = 0
else:
drop_amount = constants.subdrop * xHeight * SHRINK_FACTOR
shift_up = nucleus.height - drop_amount
shift_down = nucleus.depth + drop_amount

# We remove kerning on the last character for consistency (otherwise
# it will compute kerning based on non-shrunk characters and may put
# them too close together when superscripted)
Expand All @@ -2232,7 +2243,6 @@ def subsuper(self, s, loc, toks):
nucleus = Hlist([nucleus])

# Handle regular sub/superscripts
constants = _get_font_constant_set(state)
lc_height = last_char.height
lc_baseline = 0
if self.is_dropsub(last_char):
Expand All @@ -2254,35 +2264,44 @@ def subsuper(self, s, loc, toks):
subkern = 0

if super is None:
# node757
# Align subscript without superscript (node757).
x = Hlist([Kern(subkern), sub])
x.shrink()
if self.is_dropsub(last_char):
shift_down = lc_baseline + constants.subdrop * xHeight
else:
shift_down = constants.sub1 * xHeight
shift_down = max(shift_down, constants.sub1 * xHeight,
x.height - xHeight * 4 / 5)
x.shift_amount = shift_down
else:
# Align superscript (node758).
x = Hlist([Kern(superkern), super])
x.shrink()
if self.is_dropsub(last_char):
shift_up = lc_height - constants.subdrop * xHeight
else:
shift_up = constants.sup1 * xHeight
shift_up = max(shift_up, constants.sup1 * xHeight,
x.depth + xHeight / 4)
if sub is None:
x.shift_amount = -shift_up
else: # Both sub and superscript
else:
# Align subscript with superscript (node759).
y = Hlist([Kern(subkern), sub])
y.shrink()
if self.is_dropsub(last_char):
shift_down = lc_baseline + constants.subdrop * xHeight
else:
shift_down = constants.sub2 * xHeight
# If sub and superscript collide, move super up
clr = (2.0 * rule_thickness -
shift_down = max(shift_down, constants.sub2 * xHeight)
# If the subscript and superscript are too close to each other,
# move the subscript down.
clr = (4 * rule_thickness -
((shift_up - x.depth) - (y.height - shift_down)))
if clr > 0.:
shift_up += clr
shift_down += clr
clr = xHeight * 4 / 5 - shift_up + x.depth
if clr > 0:
shift_up += clr
shift_down -= clr
x = Vlist([
x,
Kern((shift_up - x.depth) - (y.height - shift_down)),
Expand Down