_h_m_t_x.py revision 035bc7da2318f0dcacecba2e1e24c0a4bf3cf80c 
1import sys
2import DefaultTable
3import array
4from fontTools import ttLib
5from fontTools.misc.textTools import safeEval
6import warnings
7
8
9class table__h_m_t_x(DefaultTable.DefaultTable):
10
11	headerTag = 'hhea'
12	advanceName = 'width'
13	sideBearingName = 'lsb'
14	numberOfMetricsName = 'numberOfHMetrics'
15
16	def decompile(self, data, ttFont):
17		numGlyphs = ttFont['maxp'].numGlyphs
18		numberOfMetrics = int(getattr(ttFont[self.headerTag], self.numberOfMetricsName))
19		if numberOfMetrics > numGlyphs:
20			numberOfMetrics = numGlyphs # We warn later.
21		# Note: advanceWidth is unsigned, but we read/write as signed.
22		metrics = array.array("h", data[:4 * numberOfMetrics])
23		if sys.byteorder <> "big":
24			metrics.byteswap()
25		data = data[4 * numberOfMetrics:]
26		numberOfSideBearings = numGlyphs - numberOfMetrics
27		sideBearings = array.array("h", data[:2 * numberOfSideBearings])
28		data = data[2 * numberOfSideBearings:]
29
30		if sys.byteorder <> "big":
31			sideBearings.byteswap()
32		if data:
33			sys.stderr.write("too much data for hmtx/vmtx table\n")
34		self.metrics = {}
35		for i in range(numberOfMetrics):
36			glyphName = ttFont.getGlyphName(i)
37			self.metrics[glyphName] = list(metrics[i*2:i*2+2])
38		lastAdvance = metrics[-2]
39		for i in range(numberOfSideBearings):
40			glyphName = ttFont.getGlyphName(i + numberOfMetrics)
41			self.metrics[glyphName] = [lastAdvance, sideBearings[i]]
42
43	def compile(self, ttFont):
44		metrics = []
45		for glyphName in ttFont.getGlyphOrder():
46			metrics.append(self.metrics[glyphName])
47		lastAdvance = metrics[-1][0]
48		lastIndex = len(metrics)
49		while metrics[lastIndex-2][0] == lastAdvance:
50			lastIndex -= 1
51			if lastIndex <= 1:
52				# all advances are equal
53				lastIndex = 1
54				break
55		additionalMetrics = metrics[lastIndex:]
56		additionalMetrics = [sb for advance, sb in additionalMetrics]
57		metrics = metrics[:lastIndex]
58		setattr(ttFont[self.headerTag], self.numberOfMetricsName, len(metrics))
59
60		metrics = sum(metrics,[])
61		metrics = array.array("h", metrics)
62		if sys.byteorder <> "big":
63			metrics.byteswap()
64		data = metrics.tostring()
65
66		additionalMetrics = array.array("h", additionalMetrics)
67		if sys.byteorder <> "big":
68			additionalMetrics.byteswap()
69		data = data + additionalMetrics.tostring()
70		return data
71
72	def toXML(self, writer, ttFont):
73		names = self.metrics.keys()
74		names.sort()
75		for glyphName in names:
76			advance, sb = self.metrics[glyphName]
77			writer.simpletag("mtx", [
78					("name", glyphName),
79					(self.advanceName, advance),
80					(self.sideBearingName, sb),
81					])
82			writer.newline()
83
84	def fromXML(self, (name, attrs, content), ttFont):
85		if not hasattr(self, "metrics"):
86			self.metrics = {}
87		if name == "mtx":
88			self.metrics[attrs["name"]] = [safeEval(attrs[self.advanceName]),
89					safeEval(attrs[self.sideBearingName])]
90
91	def __getitem__(self, glyphName):
92		return self.metrics[glyphName]
93
94	def __setitem__(self, glyphName, (advance, sb)):
95		self.metrics[glyphName] = advance, sb
96
97