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Convert SVG text to paths via fontTools; drop embedded font

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This commit is contained in:
Adrian A. Baumann
2026-07-12 14:41:11 +02:00
parent 6b1523539f
commit 6e9cd9109c
3 changed files with 67 additions and 36 deletions
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web/app.py
+65 -35
View File
@@ -1,37 +1,35 @@
import base64
import pathlib
from flask import Flask, render_template, request, Response
from html import escape
from fontTools.ttLib import TTFont
from fontTools.pens.svgPathPen import SVGPathPen
app = Flask(__name__)
VERSION = "0.6"
_LOGO_PATH = pathlib.Path(__file__).parent / 'static' / 'logo.png'
_LOGO_B64 = base64.b64encode(_LOGO_PATH.read_bytes()).decode()
_FONT_PATH = pathlib.Path('/usr/local/share/fonts/г/ГОСТ_тип_А.ttf')
_FONT_B64 = base64.b64encode(_FONT_PATH.read_bytes()).decode()
_FONT_FACE = (
'<defs><style>'
'@font-face {'
'font-family:"ГОСТ тип А";'
f'src:url("data:font/truetype;base64,{_FONT_B64}") format("truetype");'
'}'
'</style></defs>'
)
_FONT_OBJ = TTFont(str(_FONT_PATH))
_GLYPH_SET = _FONT_OBJ.getGlyphSet()
_CMAP = _FONT_OBJ.getBestCmap()
_HMTX = _FONT_OBJ['hmtx'].metrics
_UPM = _FONT_OBJ['head'].unitsPerEm
# SVG absolute coordinate constants (1 user unit = 1 mm)
ZERO_X = 60.844130 # x of the zero/left tick
MAX_X = 180.251230 # x of the full-scale/right tick
BAR_Y = 107.54670 # y at the top of the scale bar (tick baseline)
SCALE_LEN = MAX_X - ZERO_X # 119.4071 mm
ZERO_X = 60.844130
MAX_X = 180.251230
BAR_Y = 107.54670
SCALE_LEN = MAX_X - ZERO_X # 119.4071 mm
BIG_H = 5.0895 # major tick height
SMALL_H = 2.6683 # minor tick height
BIG_H = 5.0895
SMALL_H = 2.6683
_UNIT_AREA_WIDTH = 18.445 # canvas mm available for the unit label
_UNIT_SCALE_X = 0.96486402
_UNIT_CHAR_EM = 0.65 # approximate advance-width ratio for GOST typ A
_UNIT_AREA_WIDTH = 18.445
_UNIT_SCALE_X = 0.96486402
_UNIT_CHAR_EM = 0.65
def _unit_font_size(unit: str) -> float:
@@ -45,6 +43,38 @@ def _fmt(v: float) -> str:
return f"{v:.4g}"
def _text_to_paths(text, x, y, font_size, anchor='start', fill='#1a1a1a', wrap_transform=None):
"""Convert a text string to SVG <path> elements using glyph outlines."""
s = font_size / _UPM
# Compute total advance width for centering
if anchor == 'middle':
total_w = sum(
_HMTX.get(_CMAP.get(ord(ch)), (0, 0))[0] * s
for ch in text if _CMAP.get(ord(ch))
)
x -= total_w / 2
parts = []
cx = x
for ch in text:
gn = _CMAP.get(ord(ch))
if gn is None:
continue
pen = SVGPathPen(_GLYPH_SET)
_GLYPH_SET[gn].draw(pen)
d = pen.getCommands()
if d:
t = f'translate({cx:.5f},{y:.5f}) scale({s:.8f},{-s:.8f})'
parts.append(f'<path style="fill:{fill}" transform="{t}" d="{d}"/>')
cx += _HMTX.get(gn, (0, 0))[0] * s
inner = '\n'.join(parts)
if wrap_transform:
return f'<g transform="{wrap_transform}">{inner}</g>'
return inner
def generate_svg(unit, min_val, max_val, range_label, big_ticks, small_ticks, label_count):
big_interval = SCALE_LEN / big_ticks
big_xs = [ZERO_X + i * big_interval for i in range(big_ticks + 1)]
@@ -57,7 +87,6 @@ def generate_svg(unit, min_val, max_val, range_label, big_ticks, small_ticks, la
'<svg width="157.18373mm" height="26.683672mm"'
' viewBox="0 0 157.18373 26.683672" version="1.1"'
' xmlns="http://www.w3.org/2000/svg">',
_FONT_FACE,
' <g transform="translate(-37.352226,-90.454928)">',
# Background rect with scale-bar cutout
@@ -66,14 +95,14 @@ def generate_svg(unit, min_val, max_val, range_label, big_ticks, small_ticks, la
' d="M 37.444226,90.546928 V 117.0466 H 194.44395 V 90.546928 Z'
' M 58.443978,107.54692 H 183.64409 v 6.19963 H 58.443978 Z" />',
# Unit label (large letter in left panel)
f' <text style="font-size:{_unit_font_size(unit):.4f}px;font-family:\'ГОСТ тип А\',monospace;fill:#1a1a1a"'
f' x="41.455711" y="109.03796"'
f' transform="scale(0.96486402,1.0364155)">{escape(unit)}</text>',
# Unit label — paths in local coordinate space, wrapped in the same scale transform
' ' + _text_to_paths(
unit, 41.455711, 109.03796, _unit_font_size(unit),
wrap_transform=f'scale({_UNIT_SCALE_X},1.0364155)'
),
# Range label inside the strip on the right
f' <text style="font-size:3.60539px;font-family:\'ГОСТ тип А\',monospace;fill:#1a1a1a"'
f' x="184.79707" y="113.6755">{escape(range_label)}</text>',
' ' + _text_to_paths(range_label, 184.79707, 113.6755, 3.60539),
]
# Major ticks
@@ -94,13 +123,14 @@ def generate_svg(unit, min_val, max_val, range_label, big_ticks, small_ticks, la
f' style="stroke:#1a1a1a;stroke-width:0.302;stroke-linecap:butt" />'
)
# Numeric labels (centered on their tick, above the tick area)
# Numeric labels centered on their tick
for idx in label_indices:
x = big_xs[idx]
val = min_val + (max_val - min_val) * idx / big_ticks
parts.append(
f' <text style="font-size:8.89194px;font-family:\'ГОСТ тип А\',monospace;fill:#1a1a1a"'
f' text-anchor="middle" x="{x:.5f}" y="101.49598">{escape(_fmt(val))}</text>'
' ' + _text_to_paths(
_fmt(val), x, 101.49598, 8.89194, anchor='middle'
)
)
parts += [' </g>', '</svg>']
@@ -109,16 +139,16 @@ def generate_svg(unit, min_val, max_val, range_label, big_ticks, small_ticks, la
@app.route('/')
def index():
return render_template('index.html', logo_b64=_LOGO_B64)
return render_template('index.html', logo_b64=_LOGO_B64, version=VERSION)
@app.route('/generate', methods=['POST'])
def generate():
unit = request.form.get('unit', '%')
min_val = float(request.form.get('min', 0))
max_val = float(request.form.get('max', 100))
unit = request.form.get('unit', '%')
min_val = float(request.form.get('min', 0))
max_val = float(request.form.get('max', 100))
range_label = request.form.get('range_label', '5mA')
big_ticks = max(1, min(50, int(request.form.get('big_ticks', 10))))
big_ticks = max(1, min(50, int(request.form.get('big_ticks', 10))))
small_ticks = max(0, min(20, int(request.form.get('small_ticks', 4))))
label_count = max(2, int(request.form.get('label_count', 6)))
web/requirements.txt
+1
View File
@@ -1,2 +1,3 @@
flask
gunicorn
fonttools