Messages

Messages within SWC are referred to as DMs (Darkness Messages). These are the internal messaging system used, and allows players to communicate with each other within the game interface.

Sending Messages

To send a message is simple. At the top of the screen, just under the advertisment banner, there is a row of icons. These are explained in more detail elsewhere, but the one we are interested in is the 3rd from the right - it looks like an envelope. It will have 2 different looks depending on whether you have unread messages or not. These are explained later. Clicking this link will open your Message Inbox.

On the left of this page are three links. [Read Messages], [Send Message] and [Sent Messages]. Simple click the word Send Message and you will open up the compose message part of the page. Alternatively, on the sidebar to the right, near the very bottom, there is a [Send Message] link that will also take you to this page.

You will have 2 text boxes and a radio button option. The first text box is where you input the name of the player you wish to send a message to. The system has an autofill option so if you type the first few letters, it will give you a list of players names that match those letters anywhere in their name. Be aware though that it has a limit to how many names it shows, and it always shows them in alphabetical order. To narrow down the options, simply input more of the name and it will updated as needed. You can also send the same message to more than one person by putting a comma (,) between each name. Be aware though that the autofill only works for the first name.

The radio button option will determine if the reciever will see your name as the sender or not. All Visible messages will have your name and avatar shown when that person reads it. If you choose the Annonymous option, they will not recieve either of those things. However, the administration can find out who sent it, so do not abuse this option. And certainly do not choose it if you ask a question of someone.

The second text box is where you input your message. Simple HTML codes will work, allowing you to imbed pictures, or add bold text etc.

Click the [Send] button and the message will be sent.

Option Options

In addition there are several ways to bypass a lot of these steps. If you are browsing through the forum, each player will have a [Send Message] under the avatar. Clicking this will open the [Send Message] page, with their name already autofilled into the recipient field.

When browsing Profiles, there will be a [Send Message] option there as well, if that players profile is set to visible.

When looking at factions, clicking on a faction leaders name will open a new window with the [Send Message] page open and the leaders name filled in for you.

Checking Messages You Sent

""" pexif is a module which allows you to view and modify meta-data in JPEG/JFIF/EXIF files.

The main way to use this is to create an instance of the JpegFile class. This should be done using one of the static factory methods fromFile, fromString or fromFd.

After manipulating the object you can then write it out using one of the writeFile, writeString or writeFd methods.

The get_exif() method on JpegFile returns the ExifSegment if one exists.

Example:

jpeg = pexif.JpegFile.fromFile("foo.jpg") exif = jpeg.get_exif() .... jpeg.writeFile("new.jpg")

For photos that don't currently have an exef segment you can specify an argument which will create the exef segment if it doesn't exist.

Example:

jpeg = pexif.JpegFile.fromFile("foo.jpg") exif = jpeg.get_exif(create=True) .... jpeg.writeFile("new.jpg")

The JpegFile class handles file that are formatted in something approach the JPEG specification (ISO/IEC 10918-1) Annex B 'Compressed Data Formats', and JFIF and EXIF standard.

In particular, the way a 'jpeg' file is treated by pexif is that a JPEG file is made of a series of segments followed by the image data. In particular it should look something like:

[ SOI | <arbitrary segments> | SOS | image data | EOI ]

So, the library expects a Start-of-Image marker, followed by an arbitrary number of segment (assuming that a segment has the format:

[ <0xFF> <segment-id> <size-byte0> <size-byte1> ]

and that there are no gaps between segments.

The last segment must be the Start-of-Scan header, and the library assumes that following Start-of-Scan comes the image data, finally followed by the End-of-Image marker.

This is probably not sufficient to handle arbitrary files conforming to the JPEG specs, but it should handle files that conform to JFIF or EXIF, as well as files that conform to neither but have both JFIF and EXIF application segment (which is the majority of files in existence!).

When writing out files all segment will be written out in the order in which they were read. Any 'unknown' segment will be written out as is. Note: This may or may not corrupt the data. If the segment format relies on absolute references then this library may still corrupt that segment!

Can have a JpegFile in two modes: Read Only and Read Write.

Read Only mode: trying to access missing elements will result in an AttributeError.

Read Write mode: trying to access missing elements will automatically create them.

E.g:

img.exif.primary.<tagname>

            .geo
            .interop
            .exif.<tagname>
            .exif.makernote.<tagname>
              
       .thumbnail

img.flashpix.<...> img.jfif.<tagname> img.xmp

E.g:

try:

print img.exif.tiff.exif.FocalLength

except AttributeError:

print "No Focal Length data"

"""

import StringIO import sys from struct import unpack, pack

try:

   import decimal

except Import:

   decimal = None

MAX_HEADER_SIZE = 64 * 1024 DELIM = 0xff EOI = 0xd9 SOI_MARKER = chr(DELIM) + '\xd8' EOI_MARKER = chr(DELIM) + '\xd9'

EXIF_OFFSET = 0x8769

TIFF_OFFSET = 6 TIFF_TAG = 0x2a

DEBUG = 0

def debug(*str):

   """Used for print style debugging. Enable by setting the global
   DEBUG to 1."""
   if DEBUG:
       for each in str:
           print each,
       print

class DefaultSegment:

   """DefaultSegment represents a particluar segment of a JPEG file.
   This class is instantiated by JpegFile when parsing Jpeg files
   and is not intended to be used directly by the programmer. This
   base class is used as a default which doesn't know about the internal
   structure of the segment. Other classes subclass this to provide
   extra information about a particular segment.
   """
   
   def __init__(self, marker, fd, data):
       """The constructor for DefaultSegment takes the marker which
       identifies the segments, a file object which is currently positioned
       at the end of the segment. This allows any subclasses to potentially
       extract extra data from the stream. Data contains the contents of the
       segment."""
       self.marker = marker
       self.data = data
       if not self.data is None:
           self.parse_data(data)

   class InvalidSegment(Exception):
       """This exception may be raised by sub-classes in cases when they
       can't correctly identify the segment."""
       pass

   def write(self, fd):
       """This method is called by JpegFile when writing out the file. It
       must write out any data in the segment. This shouldn't in general be
       overloaded by subclasses, they should instead override the get_data()
       method."""
       fd.write('\xff')
       fd.write(pack('B', self.marker))
       data = self.get_data()
       fd.write(pack('>H', len(data) + 2))
       fd.write(data)

   def get_data(self):
       """This method is called by write to generate the data for this segment.
       It should be overloaded by subclasses."""
       return self.data

   def parse_data(self, data):
       """This method is called be init to parse any data for the segment. It
       should be overloaded by subclasses rather than overloading __init__"""
       pass

   def dump(self, fd):
       """This is called by JpegFile.dump() to output a human readable
       representation of the segment. Subclasses should overload this to provide
       extra information."""
       print >> fd, " Section: [%5s] Size: %6d" % \
             (jpeg_markers[self.marker][0], len(self.data))

class StartOfScanSegment(DefaultSegment):

   """The StartOfScan segment needs to be treated specially as the actual
   image data directly follows this segment, and that data is not included
   in the size as reported in the segment header. This instances of this class
   are created by JpegFile and it should not be subclassed.
   """
   def __init__(self, marker, fd, data):
       DefaultSegment.__init__(self, marker, fd, data)

       # For SOS we also pull out the actual data
       img_data = fd.read()
       # -2 accounts for the EOI marker at the end of the file
       self.img_data = img_data[:-2]
       fd.seek(-2, 1)

   def write(self, fd):
       DefaultSegment.write(self, fd)
       fd.write(self.img_data)

   def dump(self, fd):
       print >> fd, " Section: [  SOS] Size: %6d Image data size: %6d" % \
             (len(self.data), len(self.img_data))

def make_syms(dict):

   """A slightly evil function for generating constant symbols without needless
   duplication. For example given a dictionary:
   { 1 : ("foo", ...), 2 : ("bar", ...) }
   This function will create two new globals FOO and BAR with values
   1 and 2 respectively. This avoids a common pattern that was occurring of:
   FOO = 1
   BAR = 2
   names = { FOO : ("foo", ..), BAR : ("bar",...) }

   With two values the gain is not so obvious, but considering a set of 100 it is
   quite useful.
   
   This function takes a dict whose values must be tuples with the first argument
   containing a string. The string value is converted to uppercase and inserted
   into the module global scope.
   """
   
   for key, value in dict.items():
       globals()[value[0].upper()] = key

def make_syms2(dict):

   for key, value in dict.items():
       globals()[value[1]] = key

class ExifType:

   lookup = {}

   def __init__(self, id, name, size):
       self.id = id
       self.name = name
       self.size = size
       ExifType.lookup[id] = self

BYTE = ExifType(1, "byte", 1).id ASCII = ExifType(2, "ascii", 1).id SHORT = ExifType(3, "short", 2).id LONG = ExifType(4, "long", 4).id RATIONAL = ExifType(5, "rational", 8).id UNDEFINED = ExifType(7, "undefined", 1).id SLONG = ExifType(9, "slong", 4).id SRATIONAL = ExifType(10, "srational", 8).id

1. exif_types = {
2. 1: ("byte", 1),
3. 2: ("ascii", 1),
4. 3: ("short", 2),
5. 4: ("long", 4),
6. 5: ("rational", 8),
7. 7: ("undefined", 1),
8. 9: ("slong", 4),
9. 10: ("srational", 8)
10. }
11. make_syms(exif_types)

def exif_type_size(exif_type):

   """Return the size of a type"""
   return ExifType.lookup.get(exif_type).size

class Rational:

   def __init__(self, num, den):
       self.num = num
       self.den = den

   def __repr__(self):
       return "%s / %s" % (self.num, self.den)

   def as_tuple(self):
       return (self.num, self.den)

class IfdData:

   """Base class for IFD"""
   
   name = "Generic Ifd"
   tags = {}
   embedded_tags = {}

   def special_handler(self, tag, data):
       pass

   def ifd_handler(self, data):
       pass

   def extra_ifd_data(self, offset):
       return ""

   def has_key(self, key):
       return self[key] != None

   def __setattr__(self, name, value):
       for key, entry in self.tags.items():
           if entry[1] == name:
               self[key] = value
       self.__dict__[name] = value

   def __getattr__(self, name):
       for key, entry in self.tags.items():
           if entry[1] == name:
               return self[key]
       raise AttributeError

   def __getitem__(self, key):
       if type(key) == type(""):
           return self.__getattr__(key)
       for entry in self.entries:
           if key == entry[0]:
               if entry[1] == ASCII and not entry[2] is None:
                   return entry[2].strip('\0')
               else:
                   return entry[2]
       return None

   def __setitem__(self, key, value):
       if type(key) == type(""):
           return self.__setattr__(key, value)
       found = 0
       if len(self.tags[key]) < 3:
           raise "Error: Tags aren't set up correctly, should have tag type."
       if self.tags[key][2] == ASCII:
           if not value is None and not value.endswith('\0'):
               value = value + '\0'
       for i in range(len(self.entries)):
           if key == self.entries[i][0]:
               found = 1
               entry = list(self.entries[i])
               if value is None:
                   del self.entries[i]
               else:
                   entry[2] = value
                   self.entries[i] = tuple(entry)
               break
       if not found:
           # Find type...
           # Not quite enough yet...
           self.entries.append((key, self.tags[key][2], value))
       return

   def __init__(self, e, offset, exif_file, data = None):
       self.exif_file = exif_file
       self.e = e
       self.entries = []
       if data is None:
           return
       num_entries = unpack(e + 'H', data[offset:offset+2])[0]
       next = unpack(e + "I", data[offset+2+12*num_entries:
                                   offset+2+12*num_entries+4])[0]
       debug("OFFSET %s - %s" % (offset, next))
       
       for i in range(num_entries):
           start = (i * 12) + 2 + offset
           debug("START: ", start)
           entry = unpack(e + "HHII", data[start:start+12])
           tag, exif_type, components, the_data = entry

           debug("%s %s %s %s %s" % (hex(tag), exif_type,
                                     exif_type_size(exif_type), components,
                                     the_data))
           byte_size = exif_type_size(exif_type) * components

           if tag in self.embedded_tags:
               actual_data = self.embedded_tags[tag](e, the_data,
                                                     exif_file, data)
           else:
               if byte_size > 4:
                   debug(" ...offset %s" % the_data)
                   the_data = data[the_data:the_data+byte_size]
               else:
                   the_data = data[start+8:start+8+byte_size]

               if exif_type == BYTE or exif_type == UNDEFINED:
                   actual_data = list(the_data)
               elif exif_type == ASCII:
                   if the_data[-1] != '\0':
                       actual_data = the_data + '\0'
                       #raise JpegFile.InvalidFile("ASCII tag '%s' not 
                       # NULL-terminated: %s [%s]" % (self.tags.get(tag, 
                       # (hex(tag), 0))[0], the_data, map(ord, the_data)))
                       #print "ASCII tag '%s' not NULL-terminated: 
                       # %s [%s]" % (self.tags.get(tag, (hex(tag), 0))[0], 
                       # the_data, map(ord, the_data))
                   actual_data = the_data
               elif exif_type == SHORT:
                   actual_data = list(unpack(e + ("H" * components), the_data))
               elif exif_type == LONG:
                   actual_data = list(unpack(e + ("I" * components), the_data))
               elif exif_type == SLONG:
                   actual_data = list(unpack(e + ("i" * components), the_data))
               elif exif_type == RATIONAL or exif_type == SRATIONAL:
                   if exif_type == RATIONAL: t = "II"
                   else: t = "ii"
                   actual_data = []
                   for i in range(components):
                       actual_data.append(Rational(*unpack(e + t,
                                                           the_data[i*8:
                                                                    i*8+8])))
               else:
                   raise "Can't handle this"

               if (byte_size > 4):
                   debug("%s" % actual_data)

               self.special_handler(tag, actual_data)
           entry = (tag, exif_type, actual_data)
           self.entries.append(entry)

           debug("%-40s %-10s %6d %s" % (self.tags.get(tag, (hex(tag), 0))[0],
                                         ExifType.lookup[exif_type],
                                         components, actual_data))
       self.ifd_handler(data)

   def isifd(self, other):
       """Return true if other is an IFD"""
       return issubclass(other.__class__, IfdData)

   def getdata(self, e, offset, last = 0):
       data_offset = offset+2+len(self.entries)*12+4
       output_data = ""

       out_entries = []

       # Add any specifc data for the particular type
       extra_data = self.extra_ifd_data(data_offset)
       data_offset += len(extra_data)
       output_data += extra_data

       for tag, exif_type, the_data in self.entries:
           magic_type = exif_type
           if (self.isifd(the_data)):
               debug("-> Magic..");
               sub_data, next_offset = the_data.getdata(e, data_offset, 1)
               the_data = [data_offset]
               debug("<- Magic", next_offset, data_offset, len(sub_data),
                     data_offset + len(sub_data))
               data_offset += len(sub_data)
               assert(next_offset == data_offset)
               output_data += sub_data
               magic_type = exif_type
               if exif_type != 4:
                   magic_components = len(sub_data)
               else:
                   magic_components = 1
               exif_type = 4 # LONG
               byte_size = 4
               components = 1
           else:
               magic_components = components = len(the_data)
               byte_size = exif_type_size(exif_type) * components
           
           if exif_type == BYTE or exif_type == UNDEFINED:
               actual_data = "".join(the_data)
           elif exif_type == ASCII:
               actual_data = the_data 
           elif exif_type == SHORT:
               actual_data = pack(e + ("H" * components), *the_data)
           elif exif_type == LONG:
               actual_data = pack(e + ("I" * components), *the_data)
           elif exif_type == SLONG:
               actual_data = pack(e + ("i" * components), *the_data)
           elif exif_type == RATIONAL or exif_type == SRATIONAL:
               if exif_type == RATIONAL: t = "II"
               else: t = "ii"
               actual_data = ""
               for i in range(components):
                   actual_data += pack(e + t, *the_data[i].as_tuple())
           else:
               raise "Can't handle this", exif_type
           if (byte_size) > 4:
               output_data += actual_data
               actual_data = pack(e + "I", data_offset) 
               data_offset += byte_size
           else:
               actual_data = actual_data + '\0' * (4 - len(actual_data))
           out_entries.append((tag, magic_type,
                               magic_components, actual_data))

       data = pack(e + 'H', len(self.entries))
       for entry in out_entries:
           data += pack(self.e + "HHI", *entry[:3])
           data += entry[3]

       next_offset = data_offset
       if last:
           data += pack(self.e + "I", 0)
       else:
           data += pack(self.e + "I", next_offset)
       data += output_data

       assert (next_offset == offset+len(data))

       return data, next_offset

   def dump(self, f, indent = ""):
       """Dump the IFD file"""
       print >> f, indent + "<--- %s start --->" % self.name
       for entry in self.entries:
           tag, exif_type, data = entry
           if exif_type == ASCII:
               data = data.strip('\0')
           if (self.isifd(data)):
               data.dump(f, indent + "    ")
           else:
               if data and len(data) == 1:
                   data = data[0]
               print >> f, indent + "  %-40s %s" % \
                     (self.tags.get(tag, (hex(tag), 0))[0], data)
       print >> f, indent + "<--- %s end --->" % self.name

class IfdInterop(IfdData):

   name = "Interop"
   tags = {
       # Interop stuff
       0x0001: ("Interoperability index", "InteroperabilityIndex"),
       0x0002: ("Interoperability version", "InteroperabilityVersion"),
       0x1000: ("Related image file format", "RelatedImageFileFormat"),
       0x1001: ("Related image file width", "RelatedImageFileWidth"),
       0x1002: ("Related image file length", "RelatedImageFileLength"),
       }

class CanonIFD(IfdData):

   tags = {
       0x0006: ("Image Type", "ImageType"),
       0x0007: ("Firmware Revision", "FirmwareRevision"),
       0x0008: ("Image Number", "ImageNumber"),
       0x0009: ("Owner Name", "OwnerName"),
       0x000c: ("Camera serial number", "SerialNumber"),
       0x000f: ("Customer functions", "CustomerFunctions")
       }
   name = "Canon"

class FujiIFD(IfdData):

   tags = {
       0x0000: ("Note version", "NoteVersion"),
       0x1000: ("Quality", "Quality"),
       0x1001: ("Sharpness", "Sharpness"),
       0x1002: ("White balance", "WhiteBalance"),
       0x1003: ("Color", "Color"),
       0x1004: ("Tone", "Tone"),
       0x1010: ("Flash mode", "FlashMode"),
       0x1011: ("Flash strength", "FlashStrength"),
       0x1020: ("Macro", "Macro"),
       0x1021: ("Focus mode", "FocusMode"),
       0x1030: ("Slow sync", "SlowSync"),
       0x1031: ("Picture mode", "PictureMode"),
       0x1100: ("Motor or bracket", "MotorOrBracket"),
       0x1101: ("Sequence number", "SequenceNumber"),
       0x1210: ("FinePix Color", "FinePixColor"),
       0x1300: ("Blur warning", "BlurWarning"),
       0x1301: ("Focus warning", "FocusWarning"),
       0x1302: ("AE warning", "AEWarning")
       }
   name = "FujiFilm"

   def getdata(self, e, offset, last = 0):
       pre_data = "FUJIFILM"
       pre_data += pack("<I", 12)
       data, next_offset = IfdData.getdata(self, e, 12, last)
       return pre_data + data, next_offset + offset

def IfdMakerNote(e, offset, exif_file, data):

   """Factory function for creating MakeNote entries"""
   if exif_file.make == "Canon":
       # Canon maker note appears to always be in Little-Endian
       return CanonIFD('<', offset, exif_file, data)
   elif exif_file.make == "FUJIFILM":
       # The FujiFILM maker note is special.
       # See http://www.ozhiker.com/electronics/pjmt/jpeg_info/fujifilm_mn.html

       # First it has an extra header
       header = data[offset:offset+8]
       # Which should be FUJIFILM
       if header != "FUJIFILM":
           raise JpegFile.InvalidFile("This is FujiFilm JPEG. " \
                                      "Expecting a makernote header "\
                                      "<FUJIFILM>. Got <%s>." % header)
       # The it has its own offset
       ifd_offset = unpack("<I", data[offset+8:offset+12])[0]
       # and it is always litte-endian
       e = "<"
       # and the data is referenced from the start the Ifd data, not the
       # TIFF file.
       ifd_data = data[offset:]
       return FujiIFD(e, ifd_offset, exif_file, ifd_data)
   else:
       raise JpegFile.InvalidFile("Unknown maker: %s. Can't "\
                                  "currently handle this." % exif_file.make)

class IfdGPS(IfdData):

   name = "GPS"
   tags = {
       0x0: ("GPS tag version", "GPSVersionID", BYTE, 4),
       0x1: ("North or South Latitude", "GPSLatitudeRef", ASCII, 2),
       0x2: ("Latitude", "GPSLatitude", RATIONAL, 3),
       0x3: ("East or West Longitude", "GPSLongitudeRef", ASCII, 2),
       0x4: ("Longitude", "GPSLongitude", RATIONAL, 3),
       0x5: ("Altitude reference", "GPSAltitudeRef", BYTE, 1),
       0x6: ("Altitude", "GPSAltitude", RATIONAL, 1)
       }

make_syms2(IfdGPS.tags)

class IfdExtendedEXIF(IfdData):

   tags = {
       # Exif IFD Attributes
       # A. Tags relating to version
       0x9000: ("Exif Version", "ExifVersion"),
       0xA000: ("Supported Flashpix version", "FlashpixVersion"),
       # B. Tag relating to Image Data Characteristics
       0xA001: ("Color Space Information", "ColorSpace"),
       # C. Tags relating to Image Configuration
       0x9101: ("Meaning of each component", "ComponentConfiguration"),
       0x9102: ("Image compression mode", "CompressedBitsPerPixel"),
       0xA002: ("Valid image width", "PixelXDimension"),
       0xA003: ("Valid image height", "PixelYDimension"),
       # D. Tags relatin to User informatio
       0x927c: ("Manufacturer notes", "MakerNote"),
       0x9286: ("User comments", "UserComment"),
       # E. Tag relating to related file information
       0xA004: ("Related audio file", "RelatedSoundFile"),
       # F. Tags relating to date and time
       0x9003: ("Date of original data generation", "DateTimeOriginal", ASCII),
       0x9004: ("Date of digital data generation", "DateTimeDigitized", ASCII),
       0x9290: ("DateTime subseconds", "SubSecTime"),
       0x9291: ("DateTime original subseconds", "SubSecTimeOriginal"),
       0x9292: ("DateTime digitized subseconds", "SubSecTimeDigitized"),
       # G. Tags relating to Picture taking conditions
       0x829a: ("Exposure Time", "ExposureTime"),
       0x829d: ("F Number", "FNumber"),
       0x8822: ("Exposure Program", "ExposureProgram"),    
       0x8824: ("Spectral Sensitivity", "SpectralSensitivity"),
       0x8827: ("ISO Speed Rating", "ISOSpeedRatings"),
       0x8829: ("Optoelectric conversion factor", "OECF"),
       0x9201: ("Shutter speed", "ShutterSpeedValue"),
       0x9202: ("Aperture", "ApertureValue"),
       0x9203: ("Brightness", "BrightnessValue"),
       0x9204: ("Exposure bias", "ExposureBiasValue"),
       0x9205: ("Maximum lens apeture", "MaxApertureValue"),
       0x9206: ("Subject Distance", "SubjectDistance"),
       0x9207: ("Metering mode", "MeteringMode"),
       0x9208: ("Light mode", "LightSource"),
       0x9209: ("Flash", "Flash"),
       0x920a: ("Lens focal length", "FocalLength"),
       0x9214: ("Subject area", "Subject area"),
       0xa20b: ("Flash energy", "FlashEnergy"),
       0xa20c: ("Spatial frequency results", "SpatialFrquencyResponse"),
       0xa20e: ("Focal plane X resolution", "FocalPlaneXResolution"),
       0xa20f: ("Focal plane Y resolution", "FocalPlaneYResolution"),
       0xa210: ("Focal plane resolution unit", "FocalPlaneResolutionUnit"),
       0xa214: ("Subject location", "SubjectLocation"),
       0xa215: ("Exposure index", "ExposureIndex"),
       0xa217: ("Sensing method", "SensingMethod"),
       0xa300: ("File source", "FileSource"),
       0xa301: ("Scene type", "SceneType"),
       0xa302: ("CFA pattern", "CFAPattern"),
       0xa401: ("Customer image processing", "CustomerRendered"),
       0xa402: ("Exposure mode", "ExposureMode"),
       0xa403: ("White balance", "WhiteBalance"),
       0xa404: ("Digital zoom ratio", "DigitalZoomRation"),
       0xa405: ("Focal length in 35mm film", "FocalLengthIn35mmFilm"),
       0xa406: ("Scene capture type", "SceneCaptureType"),
       0xa407: ("Gain control", "GainControl"),
       0xa40a: ("Sharpness", "Sharpness"),
       0xa40c: ("Subject distance range", "SubjectDistanceRange"),
       
       # H. Other tags
       0xa420: ("Unique image ID", "ImageUniqueID"),
       }
   embedded_tags = {
       0x927c: IfdMakerNote,
       }
   name = "Extended EXIF"

make_syms2(IfdExtendedEXIF.tags)

class IfdTIFF(IfdData):

   """
   """

   tags = {
       # Private Tags
       0x8769: ("Exif IFD Pointer", "ExifOffset", LONG), 
       0xA005: ("Interoparability IFD Pointer", "InteroparabilityIFD", LONG),
       0x8825: ("GPS Info IFD Pointer", "GPSIFD", LONG),
       # TIFF stuff used by EXIF

       # A. Tags relating to image data structure
       0x100: ("Image width", "ImageWidth", LONG),
       0x101: ("Image height", "ImageHeight", LONG),
       0x102: ("Number of bits per component", "BitsPerSample", SHORT),
       0x103: ("Compression Scheme", "Compression", SHORT),
       0x106: ("Pixel Composition", "PhotometricInterpretion", SHORT),
       0x112: ("Orientation of image", "Orientation", SHORT),
       0x115: ("Number of components", "SamplesPerPixel", SHORT),
       0x11c: ("Image data arrangement", "PlanarConfiguration", SHORT),
       0x212: ("Subsampling ration of Y to C", "YCbCrSubsampling", SHORT),
       0x213: ("Y and C positioning", "YCbCrCoefficients", SHORT),
       0x11a: ("X Resolution", "XResolution", RATIONAL),
       0x11b: ("Y Resolution", "YResolution", RATIONAL),
       0x128: ("Unit of X and Y resolution", "ResolutionUnit", SHORT),

       # B. Tags relating to recording offset
       0x111: ("Image data location", "StripOffsets", LONG),
       0x116: ("Number of rows per strip", "RowsPerStrip", LONG),
       0x117: ("Bytes per compressed strip", "StripByteCounts", LONG),
       0x201: ("Offset to JPEG SOI", "JPEGInterchangeFormat", LONG),
       0x202: ("Bytes of JPEG data", "JPEGInterchangeFormatLength", LONG),

       # C. Tags relating to image data characteristics

       # D. Other tags
       0x132: ("File change data and time", "DateTime", ASCII),
       0x10e: ("Image title", "ImageDescription", ASCII),
       0x10f: ("Camera Make", "Make", ASCII),
       0x110: ("Camera Model", "Model", ASCII),
       0x131: ("Camera Software", "Software", ASCII),
       0x13B: ("Artist", "Artist", ASCII),
       0x8298: ("Copyright holder", "Copyright", ASCII),
   }
   
   embedded_tags = {
       0xA005: IfdInterop,
       EXIF_OFFSET: IfdExtendedEXIF,
       0x8825: IfdGPS,
       }

   name = "TIFF Ifd"

   def special_handler(self, tag, data):
       if tag == Make:
           self.exif_file.make = data.strip('\0')

   def new_gps(self):
       if self.has_key(GPSIFD):
           raise ValueError, "Already have a GPS Ifd" 
       gps = IfdGPS(self.e, 0, self.exif_file)
       gps[GPSVersionID] = ['\x02', '\x02', '\x00', '\x00']
       self[GPSIFD] = gps
       return gps

make_syms2(IfdTIFF.tags)

class IfdThumbnail(IfdTIFF):

   name = "Thumbnail"

   def ifd_handler(self, data):
       size = None
       offset = None
       for (tag, exif_type, val) in self.entries:
           if (tag == 0x201):
               offset = val[0]
           if (tag == 0x202):
               size = val[0]
       if size is None or offset is None:
           raise JpegFile.InvalidFile("Thumbnail doesn't have an offset "\
                                      "and/or size")
       self.jpeg_data = data[offset:offset+size]
       if len(self.jpeg_data) != size:
           raise JpegFile.InvalidFile("Not enough data for JPEG thumbnail."\
                                      "Wanted: %d got %d" %
                                      (size, len(self.jpeg_data)))

   def extra_ifd_data(self, offset):
       for i in range(len(self.entries)):
           entry = self.entries[i]
           if entry[0] == 0x201:
               # Print found field and updating
               new_entry = (entry[0], entry[1], [offset])
               self.entries[i] = new_entry
       return self.jpeg_data

class ExifSegment(DefaultSegment):

   """ExifSegment encapsulates the Exif data stored in a JpegFile. An
   ExifSegment contains two Image File Directories (IFDs). One is attribute
   information and the other is a thumbnail. This module doesn't provide
   any useful functions for manipulating the thumbnail, but does provide
   a get_attributes returns an AttributeIfd instances which allows you to
   manipulate the attributes in a Jpeg file."""

   def __init__(self, marker, fd, data):
       self.ifds = []
       self.e = '<'
       self.tiff_endian = 'II'
       DefaultSegment.__init__(self, marker, fd, data)
   
   def parse_data(self, data):
       """Overloads the DefaultSegment method to parse the data of
       this segment. Can raise InvalidFile if we don't get what we expect."""
       exif = unpack("6s", data[:6])[0]
       exif = exif.strip('\0')

       if (exif != "Exif"):
           raise self.InvalidSegment("Bad Exif Marker. Got <%s>, "\
                                      "expecting <Exif>" % exif)

       tiff_data = data[TIFF_OFFSET:]
       data = None # Don't need or want data for now on..
       
       self.tiff_endian = tiff_data[:2]
       if self.tiff_endian == "II":
           self.e = "<"
       elif self.tiff_endian == "MM":
           self.e = ">"
       else:
           raise JpegFile.InvalidFile("Bad TIFF endian header. Got <%s>, "
                                      "expecting <II> or <MM>" % 
                                      self.tiff_endian)

       tiff_tag, tiff_offset = unpack(self.e + 'HI', tiff_data[2:8])

       if (tiff_tag != TIFF_TAG):
           raise JpegFile.InvalidFile("Bad TIFF tag. Got <%x>, expecting "\
                                      "<%x>" % (tiff_tag, TIFF_TAG))

       # Ok, the header parse out OK. Now we parse the IFDs contained in
       # the APP1 header.
       
       # We use this loop, even though we can really only expect and support
       # two IFDs, the Attribute data and the Thumbnail data
       offset = tiff_offset
       count = 0

       while offset:
           count += 1
           num_entries = unpack(self.e + 'H', tiff_data[offset:offset+2])[0]
           start = 2 + offset + (num_entries*12)
           if (count == 1):
               ifd = IfdTIFF(self.e, offset, self, tiff_data)
           elif (count == 2):
               ifd = IfdThumbnail(self.e, offset, self, tiff_data)
           else:
               raise JpegFile.InvalidFile()
           self.ifds.append(ifd)

           # Get next offset
           offset = unpack(self.e + "I", tiff_data[start:start+4])[0]

   def dump(self, fd):
       print >> fd, " Section: [ EXIF] Size: %6d" % \
             (len(self.data))
       for ifd in self.ifds:
           ifd.dump(fd)

   def get_data(self):
       ifds_data = ""
       next_offset = 8
       for ifd in self.ifds:
           debug("OUT IFD")
           new_data, next_offset = ifd.getdata(self.e, next_offset,
                                               ifd == self.ifds[-1])
           ifds_data += new_data
           
       data = ""
       data += "Exif\0\0"
       data += self.tiff_endian
       data += pack(self.e + "HI", 42, 8)
       data += ifds_data
       
       return data

   def get_primary(self, create=False):
       """Return the attributes image file descriptor. If it doesn't
       exit return None, unless create is True in which case a new
       descriptor is created."""
       if len(self.ifds) > 0:
           return self.ifds[0]
       else:
           if create:
               new_ifd = IfdTIFF(self.e, None, self)
               self.ifds.insert(0, new_ifd)
               return new_ifd
           else:
               return None

jpeg_markers = {

   0xc0: ("SOF0", []),
   0xc2: ("SOF2", []),
   0xc4: ("DHT", []),

   0xda: ("SOS", [StartOfScanSegment]),
   0xdb: ("DQT", []),
   0xdd: ("DRI", []),
   
   0xe0: ("APP0", []),
   0xe1: ("APP1", [ExifSegment]),
   0xe2: ("APP2", []),
   0xe3: ("APP3", []),
   0xe4: ("APP4", []),
   0xe5: ("APP5", []),
   0xe6: ("APP6", []),
   0xe7: ("APP7", []),
   0xe8: ("APP8", []),
   0xe9: ("APP9", []),
   0xea: ("APP10", []),
   0xeb: ("APP11", []),
   0xec: ("APP12", []),
   0xed: ("APP13", []),
   0xee: ("APP14", []),
   0xef: ("APP15", []),
   
   0xfe: ("COM", []),
   }

make_syms(jpeg_markers)

class JpegFile:

   """JpegFile object. You should create this using one of the static methods
   fromFile, fromString or fromFd. The JpegFile object allows you to examine and
   modify the contents of the file. To write out the data use one of the methods
   writeFile, writeString or writeFd. To get an ASCII dump of the data in a file
   use the dump method."""
   
   def fromFile(filename, mode="rw"):
       """Return a new JpegFile object from a given filename."""
       return JpegFile(open(filename, "rb"), filename=filename, mode=mode)
   fromFile = staticmethod(fromFile)

   def fromString(str, mode="rw"):
       """Return a new JpegFile object taking data from a string."""
       return JpegFile(StringIO.StringIO(str), "from buffer", mode=mode)
   fromString = staticmethod(fromString)

   def fromFd(fd, mode="rw"):
       """Return a new JpegFile object taking data from a file object."""
       return JpegFile(fd, "fd <%d>" % fd.fileno(), mode=mode)
   fromFd = staticmethod(fromFd)

   class InvalidFile(Exception):
       """This exception is raised if a given file is not able to be parsed."""
       pass

   class NoSection(Exception):
       """This exception is raised if a section is unable to be found."""
       pass
   
   def __init__(self, input, filename=None, mode="rw"):
       """JpegFile Constructor. input is a file object, and filename
       is a string used to name the file. (filename is used only for
       display functions).  You shouldn't use this function directly,
       but rather call one of the static methods fromFile, fromString
       or fromFd."""
       self.filename = filename
       self.mode = mode
       # input is the file descriptor
       soi_marker = input.read(len(SOI_MARKER))

       # The very first thing should be a start of image marker
       if (soi_marker != SOI_MARKER):
           raise self.InvalidFile("Error reading soi_marker. Got <%s> "\
                                  "should be <%s>" % (soi_marker, SOI_MARKER))

       # Now go through and find all the blocks of data
       segments = []
       while 1:
           head = input.read(2)
           delim, mark  =  unpack(">BB", head)
           if (delim != DELIM):
               raise self.InvalidFile("Error, expecting delmiter. "\
                                      "Got <%s> should be <%s>" %
                                      (delim, DELIM))
           if mark == EOI:
               # Hit end of image marker, game-over!
               break
           head2 = input.read(2)
           size = unpack(">H", head2)[0]
           data = input.read(size-2)
           possible_segment_classes = jpeg_markers[mark][1] + [DefaultSegment]
           # Try and find a valid segment class to handle
           # this data
           for segment_class in possible_segment_classes:
               try:
                   # Note: Segment class may modify the input file 
                   # descriptor. This is expected.
                   attempt = segment_class(mark, input, data)
                   segments.append(attempt)
                   break
               except DefaultSegment.InvalidSegment:
                   # It wasn't this one so we try the next type.
                   # DefaultSegment will always work.
                   continue

       self._segments = segments

   def writeString(self):
       """Write the JpegFile out to a string. Returns a string."""
       f = StringIO.StringIO()
       self.writeFd(f)
       return f.getvalue()

   def writeFile(self, filename):
       """Write the JpegFile out to a file named filename."""
       output = open(filename, "wb")
       self.writeFd(output)

   def writeFd(self, output):
       """Write the JpegFile out on the file object output."""
       output.write(SOI_MARKER)
       for segment in self._segments:
           segment.write(output)
       output.write(EOI_MARKER)

   def dump(self, f = sys.stdout):
       """Write out ASCII representation of the file on a given file
       object. Output default to stdout."""
       print >> f, "<Dump of JPEG %s>" % self.filename
       for segment in self._segments:
           segment.dump(f)

   def get_exif(self, create=False):
       """get_exif returns a ExifSegment if one exists for this file.
       If the file does not have an exif segment and the create is
       false, then return None. If create is true, a new exif segment is
       added to the file and returned."""
       for segment in self._segments:
           if segment.__class__ == ExifSegment:
               return segment
       if create:
           return self.add_exif()
       else:
           return None

   def add_exif(self):
       """add_exif adds a new ExifSegment to a file, and returns
       it. When adding an EXIF segment is will add it at the start of
       the list of segments."""
       new_segment = ExifSegment(APP1, None, None)
       self._segments.insert(0, new_segment)
       return new_segment

   def _get_exif(self):
       """Exif Attribute property"""
       if self.mode == "rw":
           return self.get_exif(True)
       else:
           exif = self.get_exif(False)
           if exif is None:
               raise AttributeError
           return exif

   exif = property(_get_exif)

   def get_geo(self):
       """Return a tuple of (latitude, longitude)."""
       if (self.get_exif() is None or self.get_exif().get_primary() is None):
           gps = None
       else:
           gps = self.get_exif().get_primary()[GPSIFD]
       if gps is None:
           raise self.NoSection, "File %s doesn't have a GPS section." % \
               self.filename
       (deg, min, sec) =  gps[GPSLatitude]
       lat = (float(deg.num) / deg.den) +  \
           (1/60.0 * float(min.num) / min.den) + \
           (1/3600.0 * float(sec.num) / sec.den)
       if gps[GPSLatitudeRef] == "S":
           lat = -lat
       
       (deg, min, sec) =  gps[GPSLongitude]
       lng = (float(deg.num) / deg.den) + (1/60.0 *  \
                                           float(min.num) / min.den) + \
             (1/3600.0 * float(sec.num) / sec.den)
       if gps[GPSLongitudeRef] == "W":
           lng = -lng

       return lat, lng

   SEC_DEN = 50000000

   def _parse(val):
       sign = 1
       if val < 0:
           val  = -val
           sign = -1
           
       deg = int(val)
       other = (val - deg) * 60
       minutes = int(other)
       secs = (other - minutes) * 60
       secs = long(secs * JpegFile.SEC_DEN)
       return (sign, deg, minutes, secs)

   _parse = staticmethod(_parse)
       
   def set_geo(self, lat, lng):
       """Set the GeoLocation to a given lat and lng"""
       attr = self.get_exif(create=True).get_primary(create=True)
       gps = attr[GPSIFD]
       if gps is None:
           gps = attr.new_gps()

       sign, deg, min, sec = JpegFile._parse(lat)
       ref = "N"
       if sign < 0:
           ref = "S"

       gps[GPSLatitudeRef] = ref
       gps[GPSLatitude] = [Rational(deg, 1), Rational(min, 1),
                           Rational(sec, JpegFile.SEC_DEN)]
       
       sign, deg, min, sec = JpegFile._parse(lng)
       ref = "E"
       if sign < 0:
           ref = "W"
       gps[GPSLongitudeRef] = ref
       gps[GPSLongitude] = [Rational(deg, 1), Rational(min, 1),
                            Rational(sec, JpegFile.SEC_DEN)]