blup/blup/frame.py

"""
This module is part of the 'blup' package and contains the definition of a
basic Frame class.

"""

class FrameDimension(object):
	""" This class serves as container for the dimensions of a frame. """

	def __init__(self, width=18, height=8, depth=2, channels=1):
		self.width = width
		self.height = height
		self.depth = depth
		self.channels = channels
	
	def size(self):
		return (self.width, self.height)
	
	def depth(self):
		return self.depth
	
	def channels(self):
		return self.channels
	
	def __eq__(self, other):
		if ( self.width == other.width and self.height == other.height and
		     self.depth == other.depth and self.channels == other.channels ):
		   return True
		else:
			return False
	
	def __ne__(self, other):
		return not self.__eq__(other)
	
	def __str__(self):
		return "(%d, %d, %d, %d)" % (self.width, self.height, self.depth,
		                             self.channels)

class Frame(object):
	""" This class describes a single frame. """

	def __init__(self, dimension):
		"""
		Initialize the frame with the given dimensions. The 'depth' parameter
		describes, how many different values a single pixel can have.

		"""
		self.__dimension = dimension
		width = dimension.width
		height = dimension.height
		if dimension.channels == 1:
			self.__pixels = [ [ 0 ] * width for i in range(height) ]
		else:
			self.__pixels = [ [ tuple([0]*dimension.channels) ] * width for i in range(height) ]

	@property
	def dimension(self):
		return self.__dimension

	@property
	def size(self):
		return (self.__dimension.width, self.__dimension.height)
	@property
	def depth(self):
		return self.__dimension.depth
	@property
	def channels(self):
		return self.__dimension.channels

	@property
	def pixels(self):
		return self.__pixels

	@pixels.setter
	def pixels(self, pixels):
		if len(pixels) != self.__dimension.height:
			raise ValueError('not enough rows given')
		widths = set(map(lambda r: len(r), pixels))
		if len(widths) != 1:
			raise ValueError('rows are not of the same length')
		if widths.pop() != self.__dimension.width:
			raise ValueError('rows are too short')

		# TODO check depth
		# TODO check number of channels

		self.__pixels = pixels

	def transform(self, depth):
		""" Transform the frame to a frame with a different depth. """
		oldmaxval = self.__dimension.depth - 1
		newmaxval = depth - 1
		factor = (newmaxval*1.0) / (oldmaxval*1.0)
		newdim = FrameDimension(self.__dimension.width,
		                        self.__dimension.height,
		                        depth,
								self.__dimension.channels)
		newframe = Frame(newdim)

		transformfkt = lambda p: int(round(p * factor))
		for y in range(self.__dimension.height):
			if self.__dimension.channels == 1:
				newframe.__pixels[y] = map(transformfkt, self.__pixels[y])
			else:
				for x in range(self.__dimension.width):
					newframe.__pixels[y][x] = tuple(map(transformfkt, p))

		return newframe

	def getPixel(self, x, y):
		""" Return the pixel value at (x, y). """
		return self.__pixels[y][x]

	def setPixel(self, x, y, value):
		""" Set the pixel value at (x, y). """
		if self.__dimension.channels == 1:
			if value < 0 or value >= self.__dimension.depth:
				raise ValueError('pixel value not in depth range')
		else:
			if len(value) != self.__dimension.channels:
				raise ValueError('channel count does not match')
			for v in value:
				if v < 0 or v >= self.__dimension.depth:
					raise ValueError('pixel value not in depth range')
		if x < 0 or x >= self.dimension.width:
		    raise ValueError('invalid x coordinate')
		if y < 0 or y >= self.dimension.height:
		    raise ValueError('invalid y coordinate')
		self.__pixels[y][x] = value


	def getPixelsAsBytes(self):
		""" Return the frame as a byte string. """
		if self.__dimension.channels != 1:
			raise Exception('cannot convert a multi-channel frame')

		bytes = ''
		for y in range(self.__dimension.width):
			for x in range(self.__dimension.height):
				bytes += chr(self.__pixels[x][y])
		return bytes

	def invert(self):
		""" Ivert the frame. """
		for y in range(self.__dimension.height):
			for x in range(self.__dimension.width):
				if self.__dimension.channels == 1:
					self.__pixels[x][y] = ((self.__dimension.depth - 1) -
					                       self.__pixels[x][y])
				else:
					self.__pixels[y][x] = tuple(map(
					                      lambda x: ((self.depth - 1) - x),
					                      self.__pixels[y][x]))