xref: /external/fonttools/Tools/fontTools/ttLib/tables/C_B_D_T_.py

# Copyright 2013 Google, Inc. All Rights Reserved.
#
# Google Author(s): Matt Fontaine


from __future__ import print_function, division, absolute_import
from fontTools.misc.py23 import *
from fontTools.misc import sstruct
from . import E_B_D_T_
from .BitmapGlyphMetrics import BigGlyphMetrics, bigGlyphMetricsFormat, SmallGlyphMetrics, smallGlyphMetricsFormat
from .E_B_D_T_ import BitmapGlyph, BitmapPlusSmallMetricsMixin, BitmapPlusBigMetricsMixin
import struct

class table_C_B_D_T_(E_B_D_T_.table_E_B_D_T_):

	# Change the data locator table being referenced.
	locatorName = 'CBLC'

	# Modify the format class accessor for color bitmap use.
	def getImageFormatClass(self, imageFormat):
		try:
			return E_B_D_T_.table_E_B_D_T_.getImageFormatClass(self, imageFormat)
		except KeyError:
			return cbdt_bitmap_classes[imageFormat]

# Helper method for removing export features not supported by color bitmaps.
# Write data in the parent class will default to raw if an option is unsupported.
def _removeUnsupportedForColor(dataFunctions):
	dataFunctions = dict(dataFunctions)
	del dataFunctions['row']
	return dataFunctions

class ColorBitmapGlyph(BitmapGlyph):

	fileExtension = '.png'
	xmlDataFunctions = _removeUnsupportedForColor(BitmapGlyph.xmlDataFunctions)

class cbdt_bitmap_format_17(BitmapPlusSmallMetricsMixin, ColorBitmapGlyph):

	def decompile(self):
		self.metrics = SmallGlyphMetrics()
		dummy, data = sstruct.unpack2(smallGlyphMetricsFormat, self.data, self.metrics)
		(dataLen,) = struct.unpack(">L", data[:4])
		data = data[4:]

		# For the image data cut it to the size specified by dataLen.
		assert dataLen <= len(data), "Data overun in format 17"
		self.imageData = data[:dataLen]

	def compile(self, ttFont):
		dataList = []
		dataList.append(sstruct.pack(smallGlyphMetricsFormat, self.metrics))
		dataList.append(struct.pack(">L", len(self.imageData)))
		dataList.append(self.imageData)
		return bytesjoin(dataList)

class cbdt_bitmap_format_18(BitmapPlusBigMetricsMixin, ColorBitmapGlyph):

	def decompile(self):
		self.metrics = BigGlyphMetrics()
		dummy, data = sstruct.unpack2(bigGlyphMetricsFormat, self.data, self.metrics)
		(dataLen,) = struct.unpack(">L", data[:4])
		data = data[4:]

		# For the image data cut it to the size specified by dataLen.
		assert dataLen <= len(data), "Data overun in format 18"
		self.imageData = data[:dataLen]

	def compile(self, ttFont):
		dataList = []
		dataList.append(sstruct.pack(bigGlyphMetricsFormat, self.metrics))
		dataList.append(struct.pack(">L", len(self.imageData)))
		dataList.append(self.imageData)
		return bytesjoin(dataList)

class cbdt_bitmap_format_19(ColorBitmapGlyph):

	def decompile(self):
		(dataLen,) = struct.unpack(">L", self.data[:4])
		data = self.data[4:]

		assert dataLen <= len(data), "Data overun in format 19"
		self.imageData = data[:dataLen]

	def compile(self, ttFont):
		return struct.pack(">L", len(self.imageData)) + self.imageData

# Dict for CBDT extended formats.
cbdt_bitmap_classes = {
	17: cbdt_bitmap_format_17,
	18: cbdt_bitmap_format_18,
	19: cbdt_bitmap_format_19,
}