69913fd3fc
third_party subdir is for forks/clones of external projects. The svg code isn't a modification to that project, but an addition to the font-building code in noto/color_emoji. This also fixes a slight bug in the html generation, which set the default large glyph image but forgot to set the hex version of the text below it.
108 lines
4.3 KiB
Python
Executable File
108 lines
4.3 KiB
Python
Executable File
# Copyright 2015 Google, Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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# Google Author(s): Doug Felt
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import svg_cleaner
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class SvgBuilder(object):
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"""Modifies a font to add SVG glyphs from a document or string. Once built you
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can call add_from_filename or add_from_doc multiple times to add SVG
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documents, which should contain a single root svg element representing the glyph.
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This element must have width and height attributes (in px), these are used to
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determine how to scale the glyph. The svg should be designed to fit inside
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this bounds and have its origin at the top left. Adding the svg generates a
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transform to scale and position the glyph, so the svg element should not have
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a transform attribute since it will be overwritten. Any id attribute on the
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glyph is also overwritten.
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Adding a glyph can generate additional default glyphs for components of a
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ligature that are not already present.
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It is possible to add SVG images to a font that already has corresponding
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glyphs. If a glyph exists already, then its hmtx advance is assumed valid.
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Otherwise we will generate an advance based on the image's width and scale
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factor. Callers should ensure that glyphs for components of ligatures are
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added before the ligatures themselves, otherwise glyphs generated for missing
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ligature components will be assigned zero metrics metrics that will not be
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overridden later."""
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def __init__(self, font_builder):
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font_builder.init_svg()
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self.font_builder = font_builder
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self.cleaner = svg_cleaner.SvgCleaner()
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font = font_builder.font
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self.font_ascent = font['hhea'].ascent
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self.font_height = self.font_ascent - font['hhea'].descent
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self.font_upem = font['head'].unitsPerEm
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def add_from_filename(self, ustr, filename):
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with open(filename, "r") as fp:
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return self.add_from_doc(ustr, fp.read())
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def _get_int_px(self, val):
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if not val.lower().endswith('px'):
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raise "expected width or height ending in 'px' but got: %s" % val
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return int(val[:-2])
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def add_from_doc(self, ustr, svgdoc):
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"""Cleans the svg doc, tweaks the root svg element's
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attributes, then updates the font. ustr is the character or ligature
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string, svgdoc is the svg document xml. The doc must have a single
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svg root element."""
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# The svg element must have an id attribute of the form 'glyphNNN' where NNN
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# is the glyph id. We capture the index of the glyph we're adding and write
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# it into the svg.
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#
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# We generate a transform that places the origin at the top left of the
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# ascent and uniformly scales it to fit both the font height (ascent -
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# descent) and glyph advance if it is already present. The width and height
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# attributes are not used by rendering, so they are removed from the element
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# once we're done with them.
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cleaner = self.cleaner
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fbuilder = self.font_builder
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tree = cleaner.tree_from_text(svgdoc)
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cleaner.clean_tree(tree)
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name, index, exists = fbuilder.add_components_and_ligature(ustr)
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tree.attrs['id'] = 'glyph%s' % index
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image_width = self._get_int_px(tree.attrs.pop('width'))
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image_height = self._get_int_px(tree.attrs.pop('height'))
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scale = float(self.font_height) / image_height;
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if exists:
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width = fbuilder.hmtx[name][0]
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# Special case for preexisting zero advance, we scale to height.
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if width > 0:
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hscale = float(width) / image_width;
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if hscale < scale:
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scale = hscale
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transform = 'translate(0, -%s) scale(%s)' % (self.font_ascent, scale)
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tree.attrs['transform'] = transform
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svgdoc = cleaner.tree_to_text(tree)
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hmetrics = None
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if not exists:
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# horiz advance and lsb
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hmetrics = [int(round(image_width * scale)), 0]
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fbuilder.add_svg(svgdoc, hmetrics, name, index)
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