def getRow(self, row, bitDepth=1, metrics=None, reverseBytes=False):
if metrics is None:
metrics = self.metrics
assert 0 <= row and row < metrics.height, "Illegal row access in bitmap"
# Loop through each byte. This can cover two bytes in the original data or
# a single byte if things happen to be aligned. The very last entry might
# not be aligned so take care to trim the binary data to size and pad with
# zeros in the row data. Bit aligned data is somewhat tricky.
#
# Example of data cut. Data cut represented in x's.
# '|' represents byte boundary.
# data = ...0XX|XXXXXX00|000... => XXXXXXXX
# or
# data = ...0XX|XXXX0000|000... => XXXXXX00
# or
# data = ...000|XXXXXXXX|000... => XXXXXXXX
# or
# data = ...000|00XXXX00|000... => XXXX0000
#
dataList = []
bitRange = self._getBitRange(row, bitDepth, metrics)
stepRange = bitRange + (8, )
for curBit in range(*stepRange):
endBit = min(curBit + 8, bitRange[1])
numBits = endBit - curBit
cutPoint = curBit % 8
firstByteLoc = curBit // 8
secondByteLoc = endBit // 8
if firstByteLoc < secondByteLoc:
numBitsCut = 8 - cutPoint
else:
numBitsCut = endBit - curBit
curByte = _reverseBytes(self.imageData[firstByteLoc])
firstHalf = byteord(curByte) >> cutPoint
firstHalf = ((1 << numBitsCut) - 1) & firstHalf
newByte = firstHalf
if firstByteLoc < secondByteLoc and secondByteLoc < len(
self.imageData):
curByte = _reverseBytes(self.imageData[secondByteLoc])
secondHalf = byteord(curByte) << numBitsCut
newByte = (firstHalf | secondHalf) & ((1 << numBits) - 1)
dataList.append(bytechr(newByte))
# The way the data is kept is opposite the algorithm used.
data = bytesjoin(dataList)
if not reverseBytes:
data = _reverseBytes(data)
return data
def setRows(self, dataRows, bitDepth=1, metrics=None, reverseBytes=False):
if metrics is None:
metrics = self.metrics
if not reverseBytes:
dataRows = list(map(_reverseBytes, dataRows))
# Keep track of a list of ordinal values as they are easier to modify
# than a list of strings. Map to actual strings later.
numBytes = (self._getBitRange(len(dataRows), bitDepth, metrics)[0] +
7) // 8
ordDataList = [0] * numBytes
for row, data in enumerate(dataRows):
bitRange = self._getBitRange(row, bitDepth, metrics)
stepRange = bitRange + (8, )
for curBit, curByte in zip(range(*stepRange), data):
endBit = min(curBit + 8, bitRange[1])
cutPoint = curBit % 8
firstByteLoc = curBit // 8
secondByteLoc = endBit // 8
if firstByteLoc < secondByteLoc:
numBitsCut = 8 - cutPoint
else:
numBitsCut = endBit - curBit
curByte = byteord(curByte)
firstByte = curByte & ((1 << numBitsCut) - 1)
ordDataList[firstByteLoc] |= (firstByte << cutPoint)
if firstByteLoc < secondByteLoc and secondByteLoc < numBytes:
secondByte = (curByte >> numBitsCut) & (
(1 << 8 - numBitsCut) - 1)
ordDataList[secondByteLoc] |= secondByte
# Save the image data with the bits going the correct way.
self.imageData = _reverseBytes(bytesjoin(map(bytechr, ordDataList)))
def hexStr(s): h = string.hexdigits r = '' for c in s: i = byteord(c) r = r + h[(i >> 4) & 0xF] + h[i & 0xF] return r
def _reverseBytes(data):
if len(data) != 1:
return bytesjoin(map(_reverseBytes, data))
byte = byteord(data)
result = 0
for i in range(8):
result = result << 1
result |= byte & 1
byte = byte >> 1
return bytechr(result)
def _data2binary(data, numBits):
binaryList = []
for curByte in data:
value = byteord(curByte)
numBitsCut = min(8, numBits)
for i in range(numBitsCut):
if value & 0x1:
binaryList.append('1')
else:
binaryList.append('0')
value = value >> 1
numBits -= numBitsCut
return strjoin(binaryList)
