dxfReader.py

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"""This module provides a function for reading dxf files and parsing them into a useful tree of objects and data.

        The convert function is called by the readDXF fuction to convert dxf strings into the correct data based
        on their type code.  readDXF expects a (full path) file name as input.
"""

# --------------------------------------------------------------------------
# DXF Reader v0.9 by Ed Blake (AKA Kitsu)
#  2008.05.08 modif.def convert() by Remigiusz Fiedler (AKA migius)
# --------------------------------------------------------------------------
# ***** BEGIN GPL LICENSE BLOCK *****
#
# 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
# ***** END GPL LICENCE BLOCK *****
# --------------------------------------------------------------------------


from dxfImportObjects import *

class Object:
        """Empty container class for dxf objects"""

        def __init__(self, _type='', block=False):
                """_type expects a string value."""
                self.type = _type
                self.name = ''
                self.data = []

        def __str__(self):
                if self.name:
                        return self.name
                else:
                        return self.type

        def __repr__(self):
                return str(self.data)

        def get_type(self, kind=''):
                """Despite the name, this method actually returns all objects of type 'kind' from self.data."""
                if type:
                        objects = []
                        for item in self.data:
                                if type(item) != list and item.type == kind:
                                        # we want this type of object
                                        objects.append(item)
                                elif type(item) == list and item[0] == kind:
                                        # we want this type of data
                                        objects.append(item[1])
                        return objects


class InitializationError(Exception): pass

class StateMachine:
        """(finite) State Machine from the great David Mertz's great Charming Python article."""

        def __init__(self):
                self.handlers = []
                self.startState = None
                self.endStates = []

        def add_state(self, handler, end_state=0):
                """All states and handlers are functions which return
                a state and a cargo."""
                self.handlers.append(handler)
                if end_state:
                        self.endStates.append(handler)
        def set_start(self, handler):
                """Sets the starting handler function."""
                self.startState = handler


        def run(self, cargo=None):
                if not self.startState:
                        raise InitializationError,\
                                  "must call .set_start() before .run()"
                if not self.endStates:
                        raise InitializationError, \
                                  "at least one state must be an end_state"
                handler = self.startState
                while 1:
                        (newState, cargo) = handler(cargo)
                        #print cargo
                        if newState in self.endStates:
                                return newState(cargo)
                                #break
                        elif newState not in self.handlers:
                                raise RuntimeError, "Invalid target %s" % newState
                        else:
                                handler = newState

def get_name(data):
        """Get the name of an object from its object data.

        Returns a pair of (data_item, name) where data_item is the list entry where the name was found
        (the data_item can be used to remove the entry from the object data).  Be sure to check
        name not None before using the returned values!
        """
        value = None
        for item in data:
                if item[0] == 2:
                        value = item[1]
                        break
        return item, value

def get_layer(data):
        """Expects object data as input.

        Returns (entry, layer_name) where entry is the data item that provided the layer name.
        """
        value = None
        for item in data:
                if item[0] == 8:
                        value = item[1]
                        break
        return item, value


def convert(code, value):
        """Convert a string to the correct Python type based on its dxf code.
        code types:
                ints = 60-79, 170-179, 270-289, 370-389, 400-409, 1060-1070
                longs = 90-99, 420-429, 440-459, 1071
                floats = 10-39, 40-59, 110-139, 140-149, 210-239, 460-469, 1010-1059
                hex = 105, 310-379, 390-399
                strings = 0-9, 100, 102, 300-309, 410-419, 430-439, 470-479, 999, 1000-1009
        """
        if 59 < code < 80 or 169 < code < 180 or 269 < code < 290 or 369 < code < 390 or 399 < code < 410 or 1059 < code < 1071:
                value = int(float(value))
        elif 89 < code < 100 or 419 < code < 430 or 439 < code < 460 or code == 1071:
                value = long(float(value))
        elif 9 < code < 60 or 109 < code < 150 or 209 < code < 240 or 459 < code < 470 or 1009 < code < 1060:
                value = float(value)
        elif code == 105 or 309 < code < 380 or 389 < code < 400:
                value = int(value, 16) # should be left as string?
        else: # it's already a string so do nothing
                pass
        return value


def findObject(infile, kind=''):
        """Finds the next occurance of an object."""
        obj = False
        while 1:
                line = infile.readline()
                if not line: # readline returns '' at eof
                        return False
                if not obj: # We're still looking for our object code
                        if line.lower().strip() == '0':
                                obj = True # found it
                else: # we are in an object definition
                        if kind: # if we're looking for a particular kind
                                if line.lower().strip() == kind:
                                        obj = Object(line.lower().strip())
                                        break
                        else: # otherwise take anything non-numeric
                                if line.lower().strip() not in string.digits:
                                        obj = Object(line.lower().strip())
                                        break
                        obj = False # whether we found one or not it's time to start over
        return obj

def handleObject(infile):
        """Add data to an object until end of object is found."""
        line = infile.readline()
        if line.lower().strip() == 'section':
                return 'section' # this would be a problem
        elif line.lower().strip() == 'endsec':
                return 'endsec' # this means we are done with a section
        else: # add data to the object until we find a new object
                obj = Object(line.lower().strip())
                obj.name = obj.type
                done = False
                data = []
                while not done:
                        line = infile.readline()
                        if not data:
                                if line.lower().strip() == '0':
                                        #we've found an object, time to return
                                        return obj
                                else:
                                        # first part is always an int
                                        data.append(int(line.lower().strip()))
                        else:
                                data.append(convert(data[0], line.strip()))
                                obj.data.append(data)
                                data = []

def handleTable(table, infile):
        """Special handler for dealing with nested table objects."""
        item, name = get_name(table.data)
        if name: # We should always find a name
                table.data.remove(item)
                table.name = name.lower()
        # This next bit is from handleObject
        # handleObject should be generalized to work with any section like object
        while 1:
                obj = handleObject(infile)
                if obj.type == 'table':
                        print "Warning: previous table not closed!"
                        return table
                elif obj.type == 'endtab':
                        return table # this means we are done with the table
                else: # add objects to the table until one of the above is found
                        table.data.append(obj)




def handleBlock(block, infile):
        """Special handler for dealing with nested table objects."""
        item, name = get_name(block.data)
        if name: # We should always find a name
                # block.data.remove(item)
                block.name = name
        # This next bit is from handleObject
        # handleObject should be generalized to work with any section like object
        while 1:
                obj = handleObject(infile)
                if obj.type == 'block':
                        print "Warning: previous block not closed!"
                        return block
                elif obj.type == 'endblk':
                        return block # this means we are done with the table
                else: # add objects to the table until one of the above is found
                        block.data.append(obj)




"""These are the states/functions used in the State Machine.
states:
 start - find first section
 start_section - add data, find first object
   object - add obj-data, watch for next obj (called directly by start_section)
 end_section - look for next section or eof
 end - return results
"""

def start(cargo):
        """Expects the infile as cargo, initializes the cargo."""
        #print "Entering start state!"
        infile = cargo
        drawing = Object('drawing')
        section = findObject(infile, 'section')
        if section:
                return start_section, (infile, drawing, section)
        else:
                return error, (infile, "Failed to find any sections!")

def start_section(cargo):
        """Expects [infile, drawing, section] as cargo, builds a nested section object."""
        #print "Entering start_section state!"
        infile = cargo[0]
        drawing = cargo[1]
        section = cargo[2]
        # read each line, if it is an object declaration go to object mode
        # otherwise create a [index, data] pair and add it to the sections data.
        done = False
        data = []
        while not done:
                line = infile.readline()

                if not data: # if we haven't found a dxf code yet
                        if line.lower().strip() == '0':
                                # we've found an object
                                while 1: # no way out unless we find an end section or a new section
                                        obj = handleObject(infile)
                                        if obj == 'section': # shouldn't happen
                                                print "Warning: failed to close previous section!"
                                                return end_section, (infile, drawing)
                                        elif obj == 'endsec': # This section is over, look for the next
                                                drawing.data.append(section)
                                                return end_section, (infile, drawing)
                                        elif obj.type == 'table': # tables are collections of data
                                                obj = handleTable(obj, infile) # we need to find all there contents
                                                section.data.append(obj) # before moving on
                                        elif obj.type == 'block': # the same is true of blocks
                                                obj = handleBlock(obj, infile) # we need to find all there contents
                                                section.data.append(obj) # before moving on
                                        else: # found another sub-object
                                                section.data.append(obj)
                        else:
                                data.append(int(line.lower().strip()))
                else: # we have our code, now we just need to convert the data and add it to our list.
                        data.append(convert(data[0], line.strip()))
                        section.data.append(data)
                        data = []
def end_section(cargo):
        """Expects (infile, drawing) as cargo, searches for next section."""
        #print "Entering end_section state!"
        infile = cargo[0]
        drawing = cargo[1]
        section = findObject(infile, 'section')
        if section:
                return start_section, (infile, drawing, section)
        else:
                return end, (infile, drawing)

def end(cargo):
        """Expects (infile, drawing) as cargo, called when eof has been reached."""
        #print "Entering end state!"
        infile = cargo[0]
        drawing = cargo[1]
        #infile.close()
        return drawing

def error(cargo):
        """Expects a (infile, string) as cargo, called when there is an error during processing."""
        #print "Entering error state!"
        infile = cargo[0]
        err = cargo[1]
        infile.close()
        print "There has been an error:"
        print err
        return False

def readDXF(filename):
        """Given a file name try to read it as a dxf file.

        Output is an object with the following structure
        drawing
                header
                        header data
                classes
                        class data
                tables
                        table data
                blocks
                        block data
                entities
                        entity data
                objects
                        object data
        where foo data is a list of sub-objects.  True object data
        is of the form [code, data].
"""
        infile = open(filename)

        sm = StateMachine()
        sm.add_state(error, True)
        sm.add_state(end, True)
        sm.add_state(start_section)
        sm.add_state(end_section)
        sm.add_state(start)
        sm.set_start(start)
        try:
                drawing = sm.run(infile)
                if drawing:
                        drawing.name = filename
                        for obj in drawing.data:
                                item, name = get_name(obj.data)
                                if name:
                                        obj.data.remove(item)
                                        obj.name = name.lower()
                                        setattr(drawing, name.lower(), obj)
                                        # Call the objectify function to cast
                                        # raw objects into the right types of object
                                        obj.data = objectify(obj.data)
                                #print obj.name
        finally:
                infile.close()
        return drawing
if __name__ == "__main__":
        filename = r".\examples\block-test.dxf"
        drawing = readDXF(filename)
        for item in drawing.entities.data:
                print item