path: root/awlsim/gui/fup/fup_grid.py

# -*- coding: utf-8 -*-
#
# AWL simulator - FUP - Grid classes
#
# Copyright 2016-2018 Michael Buesch <m@bues.ch>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#

from __future__ import division, absolute_import, print_function, unicode_literals
#from awlsim.common.cython_support cimport * #@cy
from awlsim.common.compat import *

from awlsim.common.xmlfactory import *

from awlsim.awloptimizer.awloptimizer import *

from awlsim.gui.geo2d import *
from awlsim.gui.fup.fup_base import *
from awlsim.gui.fup.fup_wire import *
from awlsim.gui.fup.fup_elem import *
from awlsim.gui.fup.fup_elembool import *
from awlsim.gui.fup.fup_elemoperand import *
from awlsim.gui.fup.fup_elemmove import *


class FupGrid_factory(XmlFactory):
	def parser_open(self, tag=None):
		self.__haveGridTag = False
		if tag:
			self.__parseGridTag(tag)
		XmlFactory.parser_open(self, tag)

	def __parseGridTag(self, tag):
		self.grid.clear()
		width = tag.getAttrInt("width")
		height = tag.getAttrInt("height")
		uuid = tag.getAttr("uuid", None)
		self.grid.resize(width, height)
		self.grid.uuid = uuid
		self.__haveGridTag = True

	def parser_beginTag(self, tag):
		if tag.name == "grid" and not self.__haveGridTag:
			self.__parseGridTag(tag)
			return
		if tag.name == "wires":
			self.parser_switchTo(FupWire.factory(grid=self.grid))
			return
		if tag.name == "elements":
			self.parser_switchTo(FupElem.factory(grid=self.grid))
			return
		if tag.name == "optimizers":
			optType = tag.getAttr("type")
			if optType == "awl":
				optSettingsCont = self.grid.optSettingsCont
				self.parser_switchTo(optSettingsCont.factory(
					settingsContainer=optSettingsCont))
				return
		XmlFactory.parser_beginTag(self, tag)

	def parser_endTag(self, tag):
		if tag.name == "grid":
			self.grid.removeOrphanWires()
			self.parser_finish()
			return
		XmlFactory.parser_endTag(self, tag)

	# Composer filters:
	composer_withOptSettings	= lambda self: True
	composer_withWireRenum		= lambda self: True
	composer_wireFilter		= lambda self, wire: True
	composer_elemFilter		= lambda self, wire: True

	def composer_getTags(self):
		grid = self.grid
		childTags = []

		if self.composer_withOptSettings():
			optSettingsCont = grid.optSettingsCont
			childTags.extend(
				optSettingsCont.factory(
					settingsContainer=optSettingsCont).composer_getTags())

		if self.composer_withWireRenum():
			grid.renumberWires()
		wireTags = []
		for wire in sorted(grid.wires, key=lambda w: w.idNum):
			if self.composer_wireFilter(wire):
				wireTags.extend(wire.factory(wire=wire).composer_getTags())
		childTags.append(self.Tag(name="wires",
					  tags=wireTags))

		elemTags = []
		for elem in grid.elems:
			if self.composer_elemFilter(elem):
				elemTags.extend(elem.factory(elem=elem).composer_getTags())
		childTags.append(self.Tag(name="elements",
					  tags=elemTags))

		return [
			self.Tag(name="grid",
				tags=childTags,
				attrs={
					"width" : str(grid.width),
					"height" : str(grid.height),
					"uuid" : str(grid.uuid),
				}),
		]

class FupGrid(FupBaseClass):
	"""FUP/FBD element grid.
	"""

	factory = FupGrid_factory

	# Resize event callback.
	# If this is a callable, it it called with (width, height) on resize events.
	resizeEvent = None

	# Infinite width/height
	INFINITE = -1

	def __init__(self, drawWidget, width, height, uuid=None):
		"""drawWidget => FupDrawWidget() instance.
		width => The grid width.
		height => The grid height.
		"""
		FupBaseClass.__init__(self, uuid=uuid)

		self.__drawWidget = drawWidget
		self.width = width
		self.height = height

		self.elems = []			# The FupElem_xxx()s in this grid
		self.__elemsByUUID = {}
		self.wires = set()		# The FupConnIn/Out()s in this grid

		self.selectedCells = set()	# Set of tuples (gridX, gridY) of selected cells
		self.selectedElems = set()	# Set of selected elements in this grid
		self.expandedElems = set()	# Set of expanded elements in this grid
		self.clickedElem = None		# The recently clicked element in this grid
		self.clickedConn = None		# The recently clicked connection in this grid
		self.clickedArea = None		# The recently clicked area in this grid

		self.optSettingsCont = AwlOptimizerSettingsContainer()

		self.wireGrid = FupWireGrid(self)

	def getFont(self, size=8, bold=False):
		if self.__drawWidget:
			return self.__drawWidget.getFont(size=size, bold=bold)
		return QFont()

	@property
	def zoom(self):
		if self.__drawWidget:
			return self.__drawWidget.zoom
		return 1.0

	def clear(self):
		for wire in set(self.wires):
			wire.disconnectAll()
		self.wires.clear()
		self.elems = []
		self.__elemsByUUID = {}
		self.selectedCells.clear()
		self.selectedElems.clear()
		self.wireGrid.clear()

	def resize(self, width, height):
		"""Resize the grid.
		Returns True, if the resize was successfull.
		"""
		if width == self.width and height == self.height:
			return True
		if self.elems:
			minWidth = max(e.x + e.width for e in self.elems)
			minHeight = max(e.y + e.height for e in self.elems)
		else:
			minWidth = minHeight = 0
		if (width < minWidth and width != self.INFINITE) or\
		   (height < minHeight and height != self.INFINITE):
			return False
		self.width = width
		self.height = height
		if callable(self.resizeEvent):
			self.resizeEvent(width, height)
		return True

	@property
	def interfDef(self):
		"""Get the block interface definition (AwlInterfDef() instance).
		"""
		if self.__drawWidget:
			return self.__drawWidget.interfDef
		return None

	def getUnusedWireIdNum(self):
		"""Get an unused wire idNum.
		"""
		if self.wires:
			return max(w.idNum for w in self.wires) + 1
		return 0

	def addWire(self, wire):
		"""Add a wire to the grid.
		Does nothing, if the wire does exist already.
		"""
		self.wires.add(wire)

	def removeWire(self, wire):
		"""Remove a wire to the grid.
		Does nothing, if the wire does not exist.
		"""
		with contextlib.suppress(KeyError):
			self.wires.remove(wire)
		self.wireGrid.clear()

	def getWireById(self, wireIdNum):
		"""Get a wire by its idNum.
		"""
		if wireIdNum >= 0:
			for wire in self.wires:
				if wire.idNum == wireIdNum:
					return wire
		return None

	def removeOrphanWires(self, dangling=True):
		"""Remove all unconnected wires.
		If 'dangling' is True, wires that only have a single connection
		are also removed.
		"""
		connLimit = 1 if dangling else 0
		newWiresSet = set()
		while self.wires:
			wire = self.wires.pop()
			if len(wire.connections) > connLimit:
				# Keep this wire.
				newWiresSet.add(wire)
			else:
				# Drop this wire and remove all
				# connections from it.
				for conn in set(wire.connections):
					wire.disconnect(conn)
		self.wires = newWiresSet

	def renumberWires(self, idNumOffset=0):
		"""Re-assign all wire idNums.
		"""
		for i, wire in enumerate(sorted(self.wires,
						key=lambda w: w.idNum)):
			wire.idNum = i + idNumOffset

	def checkWireLine(self, painter, excludeWires, lineSeg):
		#TODO remove me
		"""Checks if a wire line would be drawable and does not collide
		with another wire line.
		excludeWires => Iterable if FupWire()s to exclude from the check.
		lineSeg => The LineSeg2D() that should be drawn.
		Returns a set of colliding self.CollLines() instances.
		"""
		collisions = set()
		for line in self.__collCacheLines:
			if line.wire in excludeWires:
				continue
			for otherLineSeg in line.lineSegments:
				inter = lineSeg.intersection(otherLineSeg)
				if inter:
					# We have a collision.
					collisions.add(line.dup())
		return collisions

	def drawWireLine(self, painter, wire, lineSeg):
		#TODO remove me
		"""Draw a wire line on 'painter'.
		wire => The FupWire() this line segment belongs to.
		lineSeg => The LineSeg2D() that describes the line to draw.
		"""
		if not lineSeg:
			return # Zero length line
		painter.drawLine(lineSeg.pointA.xInt, lineSeg.pointA.yInt,
				 lineSeg.pointB.xInt, lineSeg.pointB.yInt)
		self.collisionCacheAdd(self.CollLines((lineSeg,), wire=wire))

	def checkWireCollisions(self):
		"""Mark all wires as must-check-collisions.
		The collision check will be done at the next wire re-draw.
		"""
		for wire in self.wires:
			wire.checkCollisions()

	@property
	def cellPixWidth(self):
		if self.__drawWidget:
			return self.__drawWidget.cellPixWidth
		return 0

	@property
	def cellPixHeight(self):
		if self.__drawWidget:
			return self.__drawWidget.cellPixHeight
		return 0

	def __haveCollision(self, x, y, height, width, excludeElems=set()):
		if (self.width != self.INFINITE) and\
		   (x < 0 or x >= self.width):
			return True # Position is not on grid.
		if (self.height != self.INFINITE) and\
		   (y < 0 or y >= self.height):
			return True # Position is not on grid.
		for xx in range(x, x + width):
			for yy in range(y, y + height):
				elem = self.getElemAt(xx, yy)
				if elem in excludeElems:
					continue # Element is ignored.
				if elem:
					return True # Collision with other element.
		return False

	def canPlaceElem(self, elem, offsetX=0, offsetY=0):
		"""Check it we could place the element,
		but do not actually insert it into the grid.
		"""
		return not self.__haveCollision(elem.x + offsetX,
						elem.y + offsetY,
						elem.height,
						elem.width)

	def placeElem(self, elem):
		"""Insert an element into the grid.
		Returns False, if it was not possible to place the element.
		"""
		# Check if we already have this UUID.
		# A bug in old Awlsim versions generated duplicate UUIDs.
		if self.getElemByUUID(elem.uuid):
			printWarning("FUP element %s duplicate UUID. "
				"Generating new UUID." % elem)
			elem.regenAllUUIDs()
		# Check if we have a collision.
		if not self.canPlaceElem(elem):
			return False
		# Add the element.
		self.elems.append(elem)
		self.__elemsByUUID[elem.uuid] = elem
		# Reparent the element and all connected wires.
		elem.grid = self
		for conn in elem.connections:
			if conn.wire:
				conn.wire.grid = self
		return True

	def removeElem(self, elem):
		with contextlib.suppress(ValueError):
			self.elems.remove(elem)
		self.__elemsByUUID.pop(elem.uuid, None)
		elem.breakConnections()
		with contextlib.suppress(ValueError):
			self.selectedElems.remove(elem)
		self.wireGrid.clear()

	def moveElemTo(self, elem, toX, toY,
		       relativeCoords=False,
		       checkOnly=False,
		       excludeCheckElems=set()):
		"""Move elem to position (toX, toY).
		If relativeCoords=True, the (toX, toY) coodinates are relative
		to the current position.
		If checkOnly=True, the actual move is not performed.
		All elements included in excludeCheckElems are excluded from
		the collision check.
		"""
		if relativeCoords:
			toX, toY = elem.x + toX, elem.y + toY
		if toX == elem.x and toY == elem.y:
			return True # No move needed
		# Check collision
		excludeElems = excludeCheckElems.copy()
		excludeElems.add(elem) # Can't collide with ourselves.
		if self.__haveCollision(toX, toY,
					elem.height, elem.width,
					excludeElems=excludeElems):
			return False # Collision. Cannot move.
		# Move the element.
		if not checkOnly:
			elem.x = toX
			elem.y = toY
			elem.checkWireCollisions()
		return True

	def getElemByUUID(self, uuid):
		"""Get an element by UUID string.
		Returns None, if no such element was found.
		"""
		return self.__elemsByUUID.get(uuid, None)

	def getElemAt(self, x, y):
		for elem in self.elems:
			ex, ey = elem.x, elem.y
			ew, eh = elem.width, elem.height
			if x >= ex and x < ex + ew and\
			   y >= ey and y < ey + eh:
				return elem
		return None

	def haveElemAt(self, x, y):
		return self.getElemAt(x, y) is not None

	def getElemsInRect(self, x0, y0, x1, y1):
		"""Get all elements placed within the given grid rectangle.
		"""
		return (elem for elem in self.elems
			if elem.isInGridRect(x0, y0, x1, y1))

	def selectElem(self, elem):
		if elem:
			self.selectedElems.add(elem)

	def selectElemAt(self, x, y):
		elem = self.getElemAt(x, y)
		if elem:
			self.selectElem(elem)
		else:
			self.deselectAllElems()

	def selectElemsInRect(self, x0, y0, x1, y1, clear=False):
		"""Select all elements within the given grid rectangle.
		"""
		if clear:
			self.deselectAllElems()
		for elem in self.getElemsInRect(x0, y0, x1, y1):
			self.selectElem(elem)

	def deselectElem(self, elem):
		with contextlib.suppress(KeyError):
			self.selectedElems.remove(elem)

	def deselectElemAt(self, x, y):
		elem = self.getElemAt(x, y)
		if elem:
			self.deselectElem(elem)

	def deselectAllElems(self):
		self.selectedElems.clear()

	def expandElem(self, elem, expand=True, area=None):
		ok = False
		if elem and expand and not elem in self.expandedElems:
			ok = elem.expand(expand, area)
			if ok:
				self.expandedElems.add(elem)
		if elem and not expand and elem in self.expandedElems:
			ok = elem.expand(expand, area)
			if ok:
				self.expandedElems.remove(elem)
		return ok

	def unexpandAllElems(self):
		if self.expandedElems:
			for elem in self.expandedElems.copy():
				self.expandElem(elem, False)
			return True
		return False

	def selectCell(self, x, y):
		"""Select the cell at grid coordinate X/Y.
		This does not affect element selection.
		"""
		self.selectedCells.add((x, y))

	def deselectCell(self, x, y):
		"""Deselect the cell at grid coordinate X/Y.
		This does not affect element selection.
		"""
		self.selectedCells.remove((x, y))

	def deselectAllCells(self):
		"""Deselect all cells.
		This does not affect element selection.
		"""
		self.selectedCells.clear()

	def cellIsSelected(self, x, y):
		"""Check if a cell is selected.
		"""
		return (x, y) in self.selectedCells

	def merge(self, otherGrid,
		  offsetX=0, offsetY=0,
		  selectInsertedElems=True):
		"""Merge another grid 'otherGrid' into this grid.
		'offsetX' and 'offsetY' are the positions in 'self'
		by which 'otherGrid' shall be shifted.
		If 'selectInsertedElems' is True, all inserted elements
		will be selected and other elements will be deselected.
		Returns True, if the merge was successful without collisions.
		Returns False and does nothing, if there are collisions.
		"""

		oldWidth, oldHeight = self.width, self.height

		def fail():
			self.resize(oldWidth, oldHeight)
			return False

		# Resize the grid, if it is too small to old all
		# elements from otherGrid.
		maxXElem = sorted((e for e in otherGrid.elems),
				  key=lambda e: e.x,
				  reverse=True)[0]
		maxYElem = sorted((e for e in otherGrid.elems),
				  key=lambda e: e.y,
				  reverse=True)[0]
		newWidth = max(offsetX + maxXElem.x + maxXElem.width,
			       oldWidth)
		newHeight = max(offsetY + maxYElem.y + maxYElem.height,
				oldHeight)
		if not self.resize(newWidth, newHeight):
			return fail()

		# Check if we can place all elements.
		for elem in otherGrid.elems:
			if not self.canPlaceElem(elem, offsetX, offsetY):
				return fail()

		# Actually place all elements.
		for elem in otherGrid.elems:
			elem.x += offsetX
			elem.y += offsetY
			self.placeElem(elem)

		# Merge the wires with this grid.
		# Renumber all wires to ensure we don't have duplications.
		self.renumberWires()
		freeIdNum = len(self.wires)
		otherGrid.renumberWires(idNumOffset=freeIdNum)
		self.wires |= otherGrid.wires

		# Update selections.
		self.deselectAllCells()
		if selectInsertedElems:
			self.deselectAllElems()
			for elem in otherGrid.elems:
				self.selectElem(elem)
		return True

	def regenAllUUIDs(self):
		"""Re-generate all UUIDs that belong to this grid,
		all its elements, connections and all wires.
		"""
		self.uuid = None # regenerate
		for elem in self.elems:
			elem.regenAllUUIDs()
		for wire in self.wires:
			wire.uuid = None # regenerate

class FupWireGrid(object):
	"""Wire-subgrid.
	"""

	__slots__ = (
		"fupGrid",
		"__wireGrid",
	)

	# Width and height factors of the wire sub-grid.
	WIREGRID_FACTORS = (5, 1)

	def __init__(self, fupGrid):
		self.fupGrid = fupGrid	# The main parent FUP grid
		self.clear()

	@property
	def width(self):
		"""Number of wire-sub-grid cells, in X direction.
		"""
		return self.fupGrid.width * self.WIREGRID_FACTORS[0]

	@property
	def height(self):
		"""Number of wire-sub-grid cells, in Y direction.
		"""
		return self.fupGrid.height * self.WIREGRID_FACTORS[1]

	@property
	def cellPixWidth(self):
		return self.fupGrid.cellPixWidth // self.WIREGRID_FACTORS[0]

	@property
	def cellPixHeight(self):
		return self.fupGrid.cellPixHeight // self.WIREGRID_FACTORS[1]

	def clear(self):
		"""Clear the wire grid.
		"""
		# The wire grid dict is a dict of FupWireGridCell objects
		# with a tuple (x, y) as key, which holds the wire grid coordinates.
		self.__wireGrid = {}

	def pixToWireGridCoords(self, pixCoordX, pixCoordY):
		"""Convert pixel coordinates to wire grid coordinates.
		"""
		return (pixCoordX // self.cellPixWidth,
			pixCoordY // self.cellPixHeight)

	def hasCell(self, x, y):
		"""Check if a given cell at wire grid coordinates (x, y) exists.
		"""
		return (x, y) in self.__wireGrid

	def getCell(self, x, y, create=False):
		"""Get a FupWireGridCell object at wire grid coordinates (x, y).
		"""
		try:
			cell = self.__wireGrid[(x, y)]
		except KeyError as e:
			if not create:
				return None
			cell = FupWireGridCell(x=x, y=y, wireGrid=self)
			self.__wireGrid[(x, y)] = cell
		return cell

	def __fillBlockers(self, fupGridX, fupGridY):
		xStart = fupGridX * self.WIREGRID_FACTORS[0]
		yStart = fupGridY * self.WIREGRID_FACTORS[1]

		for wireGridX in range(xStart, xStart + self.WIREGRID_FACTORS[0]):
			for wireGridY in range(yStart, yStart + self.WIREGRID_FACTORS[1]):
				cell = self.getCell(wireGridX, wireGridY, create=True)
				cell.wire = FupWireGridCell.PSEUDO_WIRE

	def __doBuildPath(self):
		pass#TODO
		return True

	def __buildPath(self, wire, fromX, fromY, toX, toY):
		collection = FupWireGridCellCollection()

		if fromX > toX:
			return False

		# Get the first cell and add a junction towards the output connection.
		cell = self.getCell(fromX, fromY, create=True)
		cell.addJunctionWest()
		collection.add(cell)

		yInc = 1 if toY > fromY else (-1 if toY < fromY else 0)
		x, y = fromX, fromY

		if fromX == toX:
			#TODO: The wire will overlap with the target elem. That is Ok.

			if fromY != toY:
				cell.setHAlign(cell.HALIGN_WEST)
				cell.addJunctionVertical(yInc)

				y += yInc
				while True:
					cell = self.getCell(x, y, create=True)
					#TODO check coll

					cell.setHAlign(cell.HALIGN_WEST)
					cell.addJunctionVertical(-yInc)
					pass#TODO
					if y == toY:
						break
					cell.addJunctionVertical(yInc)
					y += yInc
		else:
			startX = x
			while True:
				collection.pushSnapshot()
				ok = self.__doBuildPath()
				if ok:
					break
				collection.popSnapshot()
				if startX == toX:
					return False
				startX += 1

#		if fromY != toY:
#			cell.addJunctionVertical(yInc)
#
#			# Search for an x position where we can do the vertical line.
#			while True:
#				cell = self.getCell(x, y, create=True)
#				cell.addJunctionWest()
#				collection.add(cell)
#
#				nextCell = self.getCell(x, y + yInc, create=True)
#				if not nextCell.wire or nextCell.wire == wire:
#					break
#				cell.addJunctionEast()
#				x += 1
#				if x > toX:
#					# We're too far.
#					collection.popAllSnapshots()
#					return False
#			x, y = nextCell.x, nextCell.y
#
#			# Actually do the vertical line.
#			while True:
#				cell = self.getCell(x, y, create=True)
#				if cell.wire and cell.wire != wire:
#					# Collision
#					collection.popAllSnapshots()
#					return False
#				cell.addJunctionVertical(-yInc)
#				collection.add(cell)
#				if y == toY:
#					break
#				cell.addJunctionVertical(yInc)
#				y += yInc
#
#		# Do the horizontal line.
#		first = True
#		while True:
#			cell = self.getCell(x, y, create=True)
#			if cell.wire and cell.wire != wire:
#				# Collision
#				collection.popAllSnapshots()
#				return False
#			if not first:
#				cell.addJunctionWest()
#			cell.addJunctionEast()
#			collection.add(cell)
#			if x == toX:
#				break
#			x += 1
#			first = False

		collection.clearAllSnapshots()
		return True

	def build(self):
		"""Build the wire grid.
		"""
		# Fill the wire grid with blocker cells where elements are.
		for elem in self.fupGrid.elems:
			for fupGridX in range(elem.x, elem.x + elem.width):
				for fupGridY in range(elem.y, elem.y + elem.height):
					self.__fillBlockers(fupGridX, fupGridY)

		# Build the wire grid from all wires.
		for wire in sorted(self.fupGrid.wires, key=lambda w: w.idNum):
			outConnPixX, outConnPixY = wire.outConn.pixCoords
			outConnX, outConnY = self.pixToWireGridCoords(outConnPixX, outConnPixY)

			for inConn in wire.connections:
				if inConn is wire.outConn:
					continue
				assert(inConn.IN)

				# Draw the wire from out to in.

				inConnPixX, inConnPixY = inConn.pixCoords
				inConnX, inConnY = self.pixToWireGridCoords(inConnPixX, inConnPixY)

				ok = self.__buildPath(wire,
						      outConnX + 1, outConnY,
						      inConnX, inConnY)
				if not ok:
					pass#TODO

	def draw(self, painter):
		"""Draw all wires.
		"""
		for cell in dictValues(self.__wireGrid):
			cell.draw(painter)

class FupWireGridCell(object):
	"""Wire-grid cell.
	"""

	__slots__ = (
		"x",
		"y",
		"wireGrid",
		"wire",
		"junctions",
		"hAlign",
		"vAlign",
		"snapshots",
	)

	EnumGen.start
	JUNCTION_NORTH_BIT	= EnumGen.item
	JUNCTION_EAST_BIT	= EnumGen.item
	JUNCTION_SOUTH_BIT	= EnumGen.item
	JUNCTION_WEST_BIT	= EnumGen.item
	EnumGen.end

	JUNCTION_NORTH		= 1 << JUNCTION_NORTH_BIT
	JUNCTION_EAST		= 1 << JUNCTION_EAST_BIT
	JUNCTION_SOUTH		= 1 << JUNCTION_SOUTH_BIT
	JUNCTION_WEST		= 1 << JUNCTION_WEST_BIT

	EnumGen.start
	HALIGN_WEST		= EnumGen.item
	HALIGN_CENTER		= EnumGen.item
	HALIGN_EAST		= EnumGen.item
	EnumGen.end

	EnumGen.start
	VALIGN_NORTH		= EnumGen.item
	VALIGN_CENTER		= EnumGen.item
	VALIGN_SOUTH		= EnumGen.item
	EnumGen.end

	BRANCH_DIA		= 4

	PSEUDO_WIRE		= FupWire(grid=None)

	def __init__(self,
		     x=0,
		     y=0,
		     wireGrid=None,
		     wire=None,
		     junctions=0,
		     hAlign=HALIGN_CENTER,
		     vAlign=VALIGN_CENTER):
		self.x = x
		self.y = y
		self.wireGrid = wireGrid
		self.wire = wire
		self.junctions = junctions
		self.hAlign = hAlign
		self.vAlign = vAlign
		self.snapshots = deque()

	def pushSnapshot(self):
		self.snapshots.append(copy(self))

	def popSnapshot(self):
		try:
			otherCell = self.snapshots.pop()
		except IndexError as e:
			return
		self.assign(otherCell)

	def popAllSnapshots(self):
		try:
			otherCell = self.snapshots.popleft()
		except IndexError as e:
			return
		self.assign(otherCell)
		self.clearSnapshots()

	def clearSnapshots(self):
		self.snapshots.clear()

	def assign(self, other):
		self.x = other.x
		self.y = other.y
		self.wireGrid = other.wireGrid
		self.wire = other.wire
		self.junctions = other.junctions
		self.hAlign = other.hAlign
		self.vAlign = other.vAlign

	def __copy__(self):
		newCell = self.__class__()
		newCell.assign(self)
		return newCell

	def __deepcopy__(self, memo):
		raise NotImplementedError

	def addJunctionNorth(self):
		self.junctions |= self.JUNCTION_NORTH

	def addJunctionEast(self):
		self.junctions |= self.JUNCTION_EAST

	def addJunctionVertical(self, direction):
		if direction > 0:
			self.addJunctionSouth()
		elif direction < 0:
			self.addJunctionNorth()

	def addJunctionSouth(self):
		self.junctions |= self.JUNCTION_SOUTH

	def addJunctionWest(self):
		self.junctions |= self.JUNCTION_WEST

	def addJunctionHorizontal(self, direction):
		if direction > 0:
			self.addJunctionEast()
		elif direction < 0:
			self.addJunctionWest()

	def setHAlign(self, hAlign):
		self.hAlign = hAlign

	def setVAlign(self, vAlign):
		self.vAlign = vAlign

	@property
	def nrJunctions(self):
		return (((self.junctions >> self.JUNCTION_NORTH_BIT) & 1) +
			((self.junctions >> self.JUNCTION_EAST_BIT) & 1) +
			((self.junctions >> self.JUNCTION_SOUTH_BIT) & 1) +
			((self.junctions >> self.JUNCTION_WEST_BIT) & 1))

	def draw(self, painter):
		wireGrid = self.wireGrid
		if not wireGrid:
			return

		cellPixWidth = wireGrid.cellPixWidth
		cellPixHeight = wireGrid.cellPixHeight
		xPix = cellPixWidth * self.x
		yPix = cellPixHeight * self.y

		wirePen = QPen(QColor("#000000"))
		wirePen.setWidth(2)
		painter.setPen(wirePen)

		# Draw horizontal wire segments.
		if self.junctions & (self.JUNCTION_WEST | self.JUNCTION_EAST):
			#TODO also check hAlign here
			if self.junctions & self.JUNCTION_WEST:
				xStart = xPix
			else:
				if self.hAlign != self.HALIGN_EAST:
					xStart = xPix + cellPixWidth // 2
				else:
					xStart = xPix + cellPixWidth
			if self.junctions & self.JUNCTION_EAST:
				xEnd = xPix + cellPixWidth
			else:
				if self.hAlign != self.HALIGN_WEST:
					xEnd = xPix + cellPixWidth // 2
				else:
					xEnd = xPix

			if self.vAlign == self.VALIGN_NORTH:
				y = yPix
			elif self.vAlign == self.VALIGN_CENTER:
				y = yPix + cellPixHeight // 2
			else: # VALIGN_SOUTH
				y = yPix + cellPixHeight

			painter.drawLine(xStart, y, xEnd, y)

		# Draw vertical wire segments.
		if self.junctions & (self.JUNCTION_NORTH | self.JUNCTION_SOUTH):
			if self.junctions & self.JUNCTION_NORTH:
				yStart = yPix
			else:
				yStart = yPix + cellPixHeight // 2
			if self.junctions & self.JUNCTION_SOUTH:
				yEnd = yPix + cellPixHeight
			else:
				yEnd = yPix + cellPixHeight // 2

			if self.hAlign == self.HALIGN_WEST:
				x = xPix
			elif self.hAlign == self.HALIGN_CENTER:
				x = xPix + cellPixWidth // 2
			else: # HALIGN_EAST
				x = xPix + cellPixWidth

			painter.drawLine(x, yStart, x, yEnd)

		# Draw the branch circle, if required.
		if self.nrJunctions > 2:
			wireBranchPen = QPen(QColor("#000000"))
			wireBranchPen.setWidth(1)
			wireBranchBrush = QBrush(QColor("#000000"))
			painter.setPen(wireBranchPen)
			painter.setBrush(wireBranchBrush)
			branchR, branchD = self.BRANCH_DIA // 2, self.BRANCH_DIA
			#TODO alignment
			painter.drawEllipse(x - branchR, y - branchR,
					    branchD, branchD)

class FupWireGridCellCollection(object):
	def __init__(self):
		self.cells = set()

	def add(self, cell):
		self.cells.add(cell)

	def pushSnapshot(self):
		for cell in self.cells:
			cell.pushSnapshot()

	def popSnapshot(self):
		for cell in self.cells:
			cell.popSnapshot()

	def popAllSnapshots(self):
		for cell in self.cells:
			cell.popAllSnapshots()

	def clearAllSnapshots(self):
		for cell in self.cells:
			cell.clearSnapshots()