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anntzeranntzer
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Unify text layout paths.
... i.e. the logic for advancing one character at a time, positioning that character and taking kerning between consecutive characters into account. Such a factoring would also be useful if we ever get to use a text layout engine that supports right-to-left languages (we'd just need to fix `layout` (and the C-version used by agg)).
1 parent 520b5f6 commit 345e667

4 files changed

Lines changed: 61 additions & 74 deletions

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‎lib/matplotlib/_text_layout.py‎

Lines changed: 40 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,40 @@
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"""
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Text layouting utilities.
3+
"""
4+
5+
from .ft2font import KERNING_DEFAULT, LOAD_NO_HINTING
6+
7+
8+
def layout(string, font, *, x0=0, kern_mode=KERNING_DEFAULT):
9+
"""
10+
Render *string* with *font*. For each character in *string*, yield a
11+
(character-index, x-position) pair. When such a pair is yielded, the
12+
font's glyph is set to the corresponding character.
13+
14+
Parameters
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----------
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string : str
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The string to be rendered.
18+
font : FT2Font
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The font.
20+
x0 : float
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The initial x-value
22+
kern_mode : int
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A FreeType kerning mode.
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Yields
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------
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character_index : int
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x_position : float
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"""
30+
x = x0
31+
last_char_idx = None
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for char in string:
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char_idx = font.get_char_index(ord(char))
34+
kern = (font.get_kerning(last_char_idx, char_idx, kern_mode)
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if last_char_idx is not None else 0) / 64
36+
x += kern
37+
glyph = font.load_glyph(char_idx, flags=LOAD_NO_HINTING)
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yield char_idx, x
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x += glyph.linearHoriAdvance / 65536
40+
last_char_idx = char_idx

‎lib/matplotlib/backends/backend_pdf.py‎

Lines changed: 8 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -21,7 +21,7 @@
2121

2222
import numpy as np
2323

24-
from matplotlib import cbook, __version__, rcParams
24+
from matplotlib import _text_layout, cbook, __version__, rcParams
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from matplotlib._pylab_helpers import Gcf
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from matplotlib.backend_bases import (
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_Backend, FigureCanvasBase, FigureManagerBase, GraphicsContextBase,
@@ -2194,12 +2194,11 @@ def draw_text_woven(chunks):
21942194
Op.show)
21952195
oldx = newx
21962196

2197-
lastgind = None
2198-
for c in chunk:
2199-
ccode = ord(c)
2200-
gind = font.get_char_index(ccode)
2197+
for char_idx, newx in _text_layout.layout(
2198+
chunk, font, x0=newx, kern_mode=KERNING_UNFITTED):
2199+
22012200
if mode == 2 and chunk_type == 2:
2202-
glyph_name = font.get_glyph_name(gind)
2201+
glyph_name = font.get_glyph_name(char_idx)
22032202
self.file.output(Op.gsave)
22042203
self.file.output(0.001 * fontsize, 0,
22052204
0, 0.001 * fontsize,
@@ -2208,17 +2207,9 @@ def draw_text_woven(chunks):
22082207
font.fname, glyph_name)
22092208
self.file.output(Name(name), Op.use_xobject)
22102209
self.file.output(Op.grestore)
2211-
2212-
# Move the pointer based on the character width
2213-
# and kerning
2214-
glyph = font.load_char(ccode, flags=LOAD_NO_HINTING)
2215-
if lastgind is not None:
2216-
kern = font.get_kerning(
2217-
lastgind, gind, KERNING_UNFITTED)
2218-
else:
2219-
kern = 0
2220-
lastgind = gind
2221-
newx += kern / 64 + glyph.linearHoriAdvance / 65536
2210+
newx += (
2211+
font.load_glyph(char_idx, flags=LOAD_NO_HINTING)
2212+
.linearHoriAdvance / 65536)
22222213

22232214
if mode == 1:
22242215
self.file.output(Op.end_text)

‎lib/matplotlib/backends/backend_ps.py‎

Lines changed: 5 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -20,13 +20,14 @@
2020
import matplotlib as mpl
2121
from matplotlib import (
2222
cbook, _path, __version__, rcParams, checkdep_ghostscript)
23+
from matplotlib import _text_layout
2324
from matplotlib.backend_bases import (
2425
_Backend, FigureCanvasBase, FigureManagerBase, GraphicsContextBase,
2526
RendererBase)
2627
from matplotlib.cbook import (get_realpath_and_stat, is_writable_file_like,
2728
file_requires_unicode)
2829
from matplotlib.font_manager import is_opentype_cff_font, get_font
29-
from matplotlib.ft2font import KERNING_DEFAULT, LOAD_NO_HINTING
30+
from matplotlib.ft2font import LOAD_NO_HINTING
3031
from matplotlib.ttconv import convert_ttf_to_ps
3132
from matplotlib.mathtext import MathTextParser
3233
from matplotlib._mathtext_data import uni2type1
@@ -623,27 +624,9 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
623624
.encode('ascii', 'replace').decode('ascii'))
624625
self.set_font(ps_name, prop.get_size_in_points())
625626

626-
lastgind = None
627-
lines = []
628-
thisx = 0
629-
thisy = 0
630-
for c in s:
631-
ccode = ord(c)
632-
gind = font.get_char_index(ccode)
633-
name = font.get_glyph_name(gind)
634-
glyph = font.load_char(ccode, flags=LOAD_NO_HINTING)
635-
636-
if lastgind is not None:
637-
kern = font.get_kerning(lastgind, gind, KERNING_DEFAULT)
638-
else:
639-
kern = 0
640-
lastgind = gind
641-
thisx += kern / 64
642-
643-
lines.append('%f %f m /%s glyphshow' % (thisx, thisy, name))
644-
thisx += glyph.linearHoriAdvance / 65536
645-
646-
thetext = '\n'.join(lines)
627+
thetext = '\n'.join(
628+
'%f 0 m /%s glyphshow' % (x, font.get_glyph_name(char_idx))
629+
for char_idx, x in _text_layout.layout(s, font))
647630
self._pswriter.write(f"""\
648631
gsave
649632
{x:f} {y:f} translate

‎lib/matplotlib/textpath.py‎

Lines changed: 8 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -5,10 +5,9 @@
55

66
import numpy as np
77

8-
from matplotlib import cbook, dviread, font_manager, rcParams
8+
from matplotlib import _text_layout, cbook, dviread, font_manager, rcParams
99
from matplotlib.font_manager import FontProperties, get_font
10-
from matplotlib.ft2font import (
11-
KERNING_DEFAULT, LOAD_NO_HINTING, LOAD_TARGET_LIGHT)
10+
from matplotlib.ft2font import LOAD_NO_HINTING, LOAD_TARGET_LIGHT
1211
from matplotlib.mathtext import MathTextParser
1312
from matplotlib.path import Path
1413
from matplotlib.transforms import Affine2D
@@ -162,14 +161,6 @@ def get_glyphs_with_font(self, font, s, glyph_map=None,
162161
Convert string *s* to vertices and codes using the provided ttf font.
163162
"""
164163

165-
# Mostly copied from backend_svg.py.
166-
167-
lastgind = None
168-
169-
currx = 0
170-
xpositions = []
171-
glyph_ids = []
172-
173164
if glyph_map is None:
174165
glyph_map = OrderedDict()
175166

@@ -178,33 +169,15 @@ def get_glyphs_with_font(self, font, s, glyph_map=None,
178169
else:
179170
glyph_map_new = glyph_map
180171

181-
# I'm not sure if I get kernings right. Needs to be verified. -JJL
182-
183-
for c in s:
184-
ccode = ord(c)
185-
gind = font.get_char_index(ccode)
186-
187-
if lastgind is not None:
188-
kern = font.get_kerning(lastgind, gind, KERNING_DEFAULT)
189-
else:
190-
kern = 0
191-
192-
glyph = font.load_char(ccode, flags=LOAD_NO_HINTING)
193-
horiz_advance = glyph.linearHoriAdvance / 65536
194-
195-
char_id = self._get_char_id(font, ccode)
172+
xpositions = []
173+
glyph_ids = []
174+
for char, (_, x) in zip(s, _text_layout.layout(s, font)):
175+
char_id = self._get_char_id(font, ord(char))
176+
glyph_ids.append(char_id)
177+
xpositions.append(x)
196178
if char_id not in glyph_map:
197179
glyph_map_new[char_id] = font.get_path()
198180

199-
currx += kern / 64
200-
201-
xpositions.append(currx)
202-
glyph_ids.append(char_id)
203-
204-
currx += horiz_advance
205-
206-
lastgind = gind
207-
208181
ypositions = [0] * len(xpositions)
209182
sizes = [1.] * len(xpositions)
210183

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