PixMapWrapper.py

"""PixMapWrapper - defines the PixMapWrapper class, which wraps an opaque
QuickDraw PixMap data structure in a handy Python class.  Also provides 
methods to convert to/from pixel data (from, e.g., the img module) or a
Python Imaging Library Image object.

J. Strout <joe@strout.net>  February 1999"""

from Carbon import Qd
from Carbon import QuickDraw
import struct
import MacOS
import img
import imgformat

# PixMap data structure element format (as used with struct)
_pmElemFormat = {
	'baseAddr':'l',		# address of pixel data
	'rowBytes':'H',		# bytes per row, plus 0x8000
	'bounds':'hhhh',	# coordinates imposed over pixel data
		'top':'h',
		'left':'h',
		'bottom':'h',
		'right':'h',
	'pmVersion':'h',	# flags for Color QuickDraw
	'packType':'h',		# format of compression algorithm
	'packSize':'l',		# size after compression
	'hRes':'l',			# horizontal pixels per inch
	'vRes':'l',			# vertical pixels per inch
	'pixelType':'h',	# pixel format
	'pixelSize':'h',	# bits per pixel
	'cmpCount':'h',		# color components per pixel
	'cmpSize':'h',		# bits per component
	'planeBytes':'l',	# offset in bytes to next plane
	'pmTable':'l',		# handle to color table
	'pmReserved':'l'	# reserved for future use
}

# PixMap data structure element offset
_pmElemOffset = {
	'baseAddr':0,
	'rowBytes':4,
	'bounds':6,
		'top':6,
		'left':8,
		'bottom':10,
		'right':12,
	'pmVersion':14,
	'packType':16,
	'packSize':18,
	'hRes':22,
	'vRes':26,
	'pixelType':30,
	'pixelSize':32,
	'cmpCount':34,
	'cmpSize':36,
	'planeBytes':38,
	'pmTable':42,
	'pmReserved':46
}

class PixMapWrapper:
	"""PixMapWrapper -- wraps the QD PixMap object in a Python class,
	with methods to easily get/set various pixmap fields.  Note: Use the
	PixMap() method when passing to QD calls."""

	def __init__(self):
		self.__dict__['data'] = ''
		self._header = struct.pack("lhhhhhhhlllhhhhlll",
			id(self.data)+MacOS.string_id_to_buffer,
			0,						# rowBytes
			0, 0, 0, 0,				# bounds
			0,						# pmVersion
			0, 0,					# packType, packSize
			72<<16, 72<<16,			# hRes, vRes
			QuickDraw.RGBDirect,	# pixelType
			16,						# pixelSize
			2, 5,					# cmpCount, cmpSize,
			0, 0, 0)				# planeBytes, pmTable, pmReserved
		self.__dict__['_pm'] = Qd.RawBitMap(self._header)
	
	def _stuff(self, element, bytes):
		offset = _pmElemOffset[element]
		fmt = _pmElemFormat[element]
		self._header = self._header[:offset] \
			+ struct.pack(fmt, bytes) \
			+ self._header[offset + struct.calcsize(fmt):]
		self.__dict__['_pm'] = None
	
	def _unstuff(self, element):
		offset = _pmElemOffset[element]
		fmt = _pmElemFormat[element]
		return struct.unpack(fmt, self._header[offset:offset+struct.calcsize(fmt)])[0]

	def __setattr__(self, attr, val):
		if attr == 'baseAddr':
			raise 'UseErr', "don't assign to .baseAddr -- assign to .data instead"
		elif attr == 'data':
			self.__dict__['data'] = val
			self._stuff('baseAddr', id(self.data) + MacOS.string_id_to_buffer)
		elif attr == 'rowBytes':
			# high bit is always set for some odd reason
			self._stuff('rowBytes', val | 0x8000)
		elif attr == 'bounds':
			# assume val is in official Left, Top, Right, Bottom order!
			self._stuff('left',val[0])
			self._stuff('top',val[1])
			self._stuff('right',val[2])
			self._stuff('bottom',val[3])
		elif attr == 'hRes' or attr == 'vRes':
			# 16.16 fixed format, so just shift 16 bits
			self._stuff(attr, int(val) << 16)
		elif attr in _pmElemFormat.keys():
			# any other pm attribute -- just stuff
			self._stuff(attr, val)
		else:
			self.__dict__[attr] = val	

	def __getattr__(self, attr):
		if attr == 'rowBytes':
			# high bit is always set for some odd reason
			return self._unstuff('rowBytes') & 0x7FFF
		elif attr == 'bounds':
			# return bounds in official Left, Top, Right, Bottom order!
			return ( \
				self._unstuff('left'),
				self._unstuff('top'),
				self._unstuff('right'),
				self._unstuff('bottom') )
		elif attr == 'hRes' or attr == 'vRes':
			# 16.16 fixed format, so just shift 16 bits
			return self._unstuff(attr) >> 16
		elif attr in _pmElemFormat.keys():
			# any other pm attribute -- just unstuff
			return self._unstuff(attr)
		else:
			return self.__dict__[attr]	

		
	def PixMap(self):
		"Return a QuickDraw PixMap corresponding to this data."
		if not self.__dict__['_pm']:
			self.__dict__['_pm'] = Qd.RawBitMap(self._header)
		return self.__dict__['_pm']

	def blit(self, x1=0,y1=0,x2=None,y2=None, port=None):
		"""Draw this pixmap into the given (default current) grafport.""" 
		src = self.bounds
		dest = [x1,y1,x2,y2]
		if x2 == None:
			dest[2] = x1 + src[2]-src[0]
		if y2 == None:
			dest[3] = y1 + src[3]-src[1]
		if not port: port = Qd.GetPort()
		Qd.CopyBits(self.PixMap(), port.portBits, src, tuple(dest),
				QuickDraw.srcCopy, None)
	
	def fromstring(self,s,width,height,format=imgformat.macrgb):
		"""Stuff this pixmap with raw pixel data from a string.
		Supply width, height, and one of the imgformat specifiers."""
		# we only support 16- and 32-bit mac rgb...
		# so convert if necessary
		if format != imgformat.macrgb and format != imgformat.macrgb16:
			# (LATER!)
			raise "NotImplementedError", "conversion to macrgb or macrgb16"
		self.data = s
		self.bounds = (0,0,width,height)
		self.cmpCount = 3
		self.pixelType = QuickDraw.RGBDirect
		if format == imgformat.macrgb:
			self.pixelSize = 32
			self.cmpSize = 8
		else:
			self.pixelSize = 16
			self.cmpSize = 5
		self.rowBytes = width*self.pixelSize/8

	def tostring(self, format=imgformat.macrgb):
		"""Return raw data as a string in the specified format."""
		# is the native format requested?  if so, just return data
		if (format == imgformat.macrgb and self.pixelSize == 32) or \
		   (format == imgformat.macrgb16 and self.pixelsize == 16):
			return self.data
		# otherwise, convert to the requested format
		# (LATER!)
			raise "NotImplementedError", "data format conversion"

	def fromImage(self,im):
		"""Initialize this PixMap from a PIL Image object."""
		# We need data in ARGB format; PIL can't currently do that,
		# but it can do RGBA, which we can use by inserting one null
		# up frontpm = 
		if im.mode != 'RGBA': im = im.convert('RGBA')
		data = chr(0) + im.tostring()
		self.fromstring(data, im.size[0], im.size[1])

	def toImage(self):
		"""Return the contents of this PixMap as a PIL Image object."""
		import Image
		# our tostring() method returns data in ARGB format,
		# whereas Image uses RGBA; a bit of slicing fixes this...
		data = self.tostring()[1:] + chr(0)
		bounds = self.bounds
		return Image.fromstring('RGBA',(bounds[2]-bounds[0],bounds[3]-bounds[1]),data)

def test():
	import MacOS
	import macfs
	import Image
	fsspec, ok = macfs.PromptGetFile("Image File:")
	if not ok: return
	path = fsspec.as_pathname()
	pm = PixMapWrapper()
	pm.fromImage( Image.open(path) )
	pm.blit(20,20)
	return pm