[z_archive/sierpinski.git] / bmp.py

# bmp - bitmap processing
# ref: https://en.wikipedia.org/wiki/BMP_file_format

from struct import unpack

class FormatError(Exception): pass
class MagicError(FileFormatError): pass
class CompressionError(FormatError): pass
class BppError(FormatError): pass

class Bmp(object):
	def __init__(self, fn_or_fo):
		fo = fn_or_fo
		if isinstance(fn_or_fo, basestring):
			fo = open(fn, 'rb')
		self.fo = fo
		self._read()
	def _read(self):
		header = self.fo.read(14)
		magic, filesize, start_address = unpack("<2sI2x2xI", header)
		if magic != "BM": raise MagicError("wrong BMP header magic")
		dib = self.fo.read(40)
		magic, pixelwidth, pixelheight, bpp, compression = unpack("<III2xHI4x4x4x4x4x", dib)
		if magic != 40: raise MagicError("wrong DIB header magic")
		if compression != 0: raise CompressionError("compression not supported")
Commit	Line	Data
596cd671	1	# bmp - bitmap processing
668f4f77	2	# ref: https://en.wikipedia.org/wiki/BMP_file_format
596cd671	3
	4	from struct import unpack
	5
	6	class FormatError(Exception): pass
	7	class MagicError(FileFormatError): pass
	8	class CompressionError(FormatError): pass
	9	class BppError(FormatError): pass
	10
	11	class Bmp(object):
	12	def __init__(self, fn_or_fo):
	13	fo = fn_or_fo
	14	if isinstance(fn_or_fo, basestring):
	15	fo = open(fn, 'rb')
	16	self.fo = fo
	17	self._read()
	18	def _read(self):
	19	header = self.fo.read(14)
	20	magic, filesize, start_address = unpack("<2sI2x2xI", header)
	21	if magic != "BM": raise MagicError("wrong BMP header magic")
	22	dib = self.fo.read(40)
	23	magic, pixelwidth, pixelheight, bpp, compression = unpack("<III2xHI4x4x4x4x4x", dib)
	24	if magic != 40: raise MagicError("wrong DIB header magic")
	25	if compression != 0: raise CompressionError("compression not supported")