photo

John Hurst

Version 1.2.8

20080210:224120

Table of Contents

1. The Main Program

<interpreter definition 1.2>
<banner 1.3>
<basic usage information 1.4>
<todos 1.5>
<imports 1.6>
<initialization 1.7,1.8,1.9,1.10,1.11,3.1,7.1>
<define miscellaneous subroutines 1.12,1.13>
<the addToList routine definition 5.1>
<the makeImage routine definition 6.1>
<the makeSubImages routine definition 7.2>
<the addToIndex routine definition 4.1>
<the visit routine definition 2.1>
<the retrieve routine definition 8.2>
<collect the command line options 1.14>
<perform the top level visit 1.15>
<write list file 1.16> **** Chunk omitted!

1.1 Setup

########################################################################
#                                                                      #
#                           p h o t o . p y                            #
#                                                                      #
########################################################################

#       A program to build photo album web pages.
#
#       John Hurst
#       version 0.10, 06 Mar 2006
#
# This program recursively scans a set of directories (given as
# command line parameters) for images that comprise a photo album to
# be rendered into a set of web pages.  A file 'index.xml' is created
# in each (sub)directory, containing a list of images and
# subdirectories.  This file can be rendered by an XML stylesheet
# 'album.xsl' into HTML pages.

# TODO
#  20060306 flag descriptions that do not have full details (and auto
#           copy this to a 'NOT COMPLETE' line in higher level
#           album.xml data).
# 

import cgi
import EXIF
import getopt
import md5
import os
import os.path
import re
import stat
import sys
import time
import xml.dom
from xml.dom import Node
from xml.dom.minidom import parse
from xml.parsers.expat import ExpatError

lists = {}

Initialize the variable 'lists'. This is a python directory, where the keys are (os) directories paths rooted at the album subdirectory (the cli parameters), and the entries are lists of image file names within that directory. This is used to build a list of images within each (os) directory traversed. The list/directory is initially empty.

descriptions={}
sounds={}

Initialize the variable 'descriptions'. This is a python directory, where the keys are image file names, and the entries are descriptions/captions for the image concerned. It is built from the eponymously named file 'descriptions' in the directory currently being scanned.

ALBUMXSL="file:///home/ajh/lib/xsl/album.xsl"

Define the XSL script used to render all XML files built by this program.

ignorePat=re.compile("(.*(_\d+x\d+).JPG)|(.xvpics)")
medmatch=re.compile(".*_640x480.JPG")
bigmatch=re.compile(".*_1600x1200.JPG")
thumbmatch=re.compile(".*_128x128.JPG")
identifyPat = re.compile(".* (\d+)x(\d+)( |\+).*")
treepat=re.compile('.*/(200[/\d]+)')

maxmissing = 0
maxdir = ''

maxmissing, maxdir are variables that track the directory with the maximum number of missing descriptions. This is purely a convenient device to point the user to where most documenting effort is required!

1.2 Define miscellaneous subroutines

jpgPat=re.compile('(.*)\.(j|J)(p|P)(g|G)$')
def trimJPG(name):
    res=jpgPat.match(name)
    if res:
      name=res.group(1)
    return name

def attrString(el):
  if el.hasAttributes():
    str=''
    nl=el.attributes
    #print "looking at attributes of length %d" % (nl.length)
    for i in range(nl.length):
      attr=nl.item(i)
      str+=' %s="%s"' % (attr.name,attr.value)
    return str
  else:
    return ''
  
def flatString(elem):
  if elem.nodeType==Node.TEXT_NODE:
    return elem.nodeValue
  elif elem.nodeType==Node.ELEMENT_NODE:
    attrs=attrString(elem)
    str=""
    for el in elem.childNodes:
      str+=str+flatString(el)
    return "<%s%s>%s</%s>" % (elem.tagName,attrs,str,elem.tagName)
  else:
    return "[unknown nodeType]"

def flatStringNodes(nodelist):
  str=''
  for node in nodelist:
    str+=flatString(node)
  return str

1.3 Collect the Command Line Options

There are four command line options:

f

Force the generate of the image XML files. This is useful if other relevant components have changed, such as the XSL files, which are not known about here.

l

Do not generate the large subimages.

r

Recursively traverse any subdirectories for further images.

t

Generate only the thumbnail subimages.

(opts,args) = getopt.getopt(sys.argv[1:],'flrt')
forceXmls=recurse=thumbsOnly=False; large=True
for (option,value) in opts:
  if option == '-f':
    forceXmls=True
  elif option == '-r':
    recurse=True
  elif option == '-l':
    large=False
  elif option == '-t':
    thumbsOnly=True

1.4 Perform the Top Level Visit

visitdirs = args

# if there are no directories to visit, include at least current directory
if len(visitdirs)==0:
  visitdirs = ['.']

for dir in visitdirs:
    x = os.path.abspath(dir)
    (h,t) = os.path.split(x)
    (titl,nph,nalb,thm,descr,nmiss)=visit(0,x,lists)
    print "Directory %s has %d images and %d missing descriptions" % (dir,nph,nmiss)
    try:
        highername=x+'/../index.xml'
        higherindex=open(highername)
        higherdom=parse(higherindex)
        higherindex.close()
        #print "parsed %s" % (highername)
        direlements=higherdom.getElementsByTagName('directory')
        for dir in direlements:
            if dir.getAttribute('name')==t:
                #print "found directory %s!" % (t)
                dir.setAttribute('title',titl)
                dir.setAttribute('albums',"%d" % nalb)
                dir.setAttribute('images',"%d" % nph)
                dir.setAttribute('thumb',t+'/'+thm)
                dir.setAttribute('description',descr)
                if nmiss==0:
                  if dir.hasAttribute('missing'):
                    dir.removeAttribute('missing')
                else:
                  dir.setAttribute('missing',"%d" % nmiss)
        newxml=higherdom.toxml()
        #print newxml
        higherindex=open(highername,'w')
        higherindex.write(newxml)
        higherindex.close()
    except IOError:
        print "No higher level index.xml file"
    except ExpatError:
        print "XML error in higher level index.xml file"

1.5 write list file

keys=lists.keys()
for k in keys:
    try:
        listn=k+"/list"
        listf=open(listn,"w")
    except:
        print "Cannot open %s" % (listn)
        continue
    for a in lists[k]:
        listf.write(a+"\n")
    listf.close()

Open the file list in each of the directories visited, and write a list of images found in that directory to the file. This may not be entirely accurate, and needs to be confirmed that it does work correctly. It has not been used recently, and may be superflous to needs. It has now been commented out (v1.2.3).

1.6 Plan for new data structure

In order to develop this program further, it is suggested that a full data structure for each image and album be developed. This data structure would be populated in some way, and would then provide the data for writing the index.xml file. How is it populated?

1. from the current index.xml file
2. from the album.xml file
3. from the image file
4. from the descriptions file
5. from the command line (?)

There would be a list of such data components for each directory visited (hence a local variable to routine visit). This list could be sorted on one or more of its attributes to provide a range of views.

Components of the new data structure:

2. The visit routine

def visit(level,dirname, lists):
    global descriptions, sounds
    <initialize variables for visit routine 2.2>
    <read descriptions file and create dictionary 3.2>
    fnames=os.listdir(".")
    fnames.sort()
    dirs=[];
    <sort fnames into directories and images 2.6>
    <open index.xml and write header 2.3>
    <get information from album XML file 2.4>
    print '  '*level,'Scanning directory "%s" ... (%s)' % (dirname,title)
    <write tree element to index.xml 2.5>
    if not thumb:
        if len(images)>0:
            thumb=images[0]
    if thumb[-4:len(thumb)].lower()=='.jpg':
        thumb=thumb[0:-4]
    <visit all directories 2.7>
    indexout+='  <thumbnail>%s</thumbnail>\n' % (thumb)
    #sys.stdout.write("%d" % (len(images)))
    <scan all images and process them 2.8>
    indexout+='  <summary photos="%d" albums="%d" missing="%d" maxmissing="%d" maxdir="%s"/>\n' % \
              (nphotos,nalbums,missingdescrs,maxmissing,maxdir)
    <wind up index file 2.9>
    <wind up descriptions file 3.3>
    os.chdir(saved)
    return (title,nphotos,nalbums,thumb,description,missingdescrs)

2.1 initialize variables for visit routine

nphotos=nalbums=missingdescrs=gotdescrfile=0
listmissingimages=[]
albumdom=None; title=""; thumb=description=""
maxmissing=0; maxdir=""
saved = os.getcwd()
os.chdir(dirname)
mdescr=-1
images=[]

nphotos

the number of image files found in this subdirectory (album)

nalbums

the number of subalbums (subdirectories containing images) found in this subdirectory

missingdescrs

the number of images for which no description was found in the descriptions file

gotdescrfile

set if the descriptions file was succesfully read

listmissingimages

a list of those images for which a description was found, but no image file

albumdom

the XML-parsed album file

title

the title of this album (subdirectory)

thumb

the thumbnail image used to represent this album

description

the description of this album

maxmissing

maxdir

saved

mdescr

images

2.2 open index.xml and write header

try:
    indexf=open("index.xml","r")
    indexin=indexf.read()
except:
    indexin=''
try:
    albumdom=parse("album.xml")
except:
    print "Cannot parse album.xml in directory %s" % dirname
indexout=''
indexout+='<?xml version="1.0" ?>\n'
indexout+='<?xml-stylesheet type="text/xsl" '
indexout+='href="%s"?>\n' % ALBUMXSL
indexout+='<album>\n'

2.3 get information from album XML file

if albumdom:
    indexout+='  <title>'
    try:
        titles=albumdom.getElementsByTagName('title')
        title=titles[0].firstChild.nodeValue
    except:
        title=""
    indexout+=title
    indexout+='</title>\n'
    thumbs=albumdom.getElementsByTagName('thumbnail')
    fc=thumbs[0].firstChild
    if fc:
        thumb=fc.nodeValue
    else:
        print '  '*level,"There is no thumbnail defined in %s/album.xml" % (dirname)
    albumdescr=albumdom.getElementsByTagName('description')
    if not albumdescr:
        try:
            albumdescr=albumdom.getElementsByTagName('shortdesc')
        except:
            albumdescr=""
    try:
        description=albumdescr[0].firstChild.nodeValue
        description=description.strip()
    except:
        description=""
    indexout+='  <description>'
    indexout+=description
    indexout+='</description>\n'
    commentary=albumdom.getElementsByTagName('commentary')
    if not commentary:
        commentary=albumdom.getElementsByTagName('longdesc')
    if commentary:
        commentary=commentary[0]
        indexout+='  <commentary>'
        indexout+=commentary.toprettyxml()
        indexout+='</commentary>\n'

2.4 write tree element to index.xml

indexout+='  <tree>'
treepath=os.getcwd()
res=treepat.match(treepath)
if res:
    treepath=res.group(1)+'/'
    #print "treepath=%s" % treepath
    indexout+=treepath
indexout+='</tree>\n'

2.5 sort fnames into directories and images

dirIgnores=re.compile("(movies)|(sounds)")
for f in fnames:
    res=ignorePat.match(f)
    if res:
        continue
    if os.path.isdir(f):
      if not dirIgnores.match(f):
        dirs.append(f)
      else:
        print '  '*level,"skipping subdirectory %s" % (f)
      continue
    if os.path.isfile(f):
        (r,e)=os.path.splitext(f)
        if e.lower() in ['.jpg','.avi']:
            if f not in images:
                images.append(f)
                listmissingimages.append(f)
        continue

Sort the list of all files in this directory into directories and images. We detect the first from an os.path.isdir call, and the second by ckecking its extension, which must be either .JPG or .jpg (or capitalisations in between).

2.6 Visit All Directories

for d in dirs:
    missd=0
    if recurse:
        #print "in dir %s, about to visit %s ..." % (dirname,d)
        ad=os.path.abspath(d)
        (dtitle,nimages,ndirs,thumbn,ddescr,missd)=visit(level+1,d,lists)
    else:
        res=retrieve(d)
        if res:
            (dtitle,nimages,ndirs,thumbn,ddescr,missd)=res
        else:
            continue
    nphotos+=nimages;
    nalbums+=ndirs+1
    missingdescrs+=missd
    if missd>maxmissing:
      maxmissing = missd
      maxdir = d
    if not thumb:
        thumb=d+"/"+thumbn
    if thumbn[-4:len(thumbn)].lower()=='.jpg':
        thumbn=thumbn[0:-4]
    indexout+='  <directory title="%s" name="%s"\n' % (dtitle,d)
    indexout+='             albums="%d"\n' % (ndirs)
    indexout+='             images="%d"\n' % (nimages)
    if missd:
        indexout+='             missing="%d"\n' % (missd)
    indexout+='             thumb="%s"\n' % (d+"/"+thumbn)
    indexout+='             description="%s"/>\n' % (ddescr)

2.7 scan all images and process them

inum=0
lastimage=len(images)-1
for i in images:    
    iprev=images[0]; inext=images[lastimage]
    if inum>0:
        iprev=images[inum-1]
    if inum<lastimage:
        inext=images[inum+1]
    descr=makeSubImages(level,lists,i,iprev,inext,mdescr)
    if descr==-1:{Note 2.8.1}
        continue
    if not descr:
        missingdescrs+=1
    addToList(lists,i)
    indexout+=addToIndex(lists,i,descr)
    inum+=1
nphotos+=len(images)

{Note 2.8.1}

dud descriptions file entry, ignore it

2.8 wind up index file

indexout+='</album>\n'
if indexout != indexin:
  indexof = open("index.xml","w")
  indexof.write(indexout)
  indexof.close()
  print '  '*level,"... index.xml"

3. Descriptions

This is a revision of the literate structure to bring all descriptions related material together.

descrpat = re.compile("([^ ]+?)(\.JPG)? (.*?)( # (.*))?$")

descrpat is a pattern to match image names. Note that the first pattern must be non-greedy, or the '.JPG' gets swallowed, and the third pattern likewise, or the ' # ' gets swallowed.

3.1 read descriptions file and create dictionary

try:
    descrf=open("descriptions","r")
    mdescr=os.stat("descriptions")[stat.ST_MTIME]
    gotdescrfile=1
    for l in descrf.readlines():
        res=descrpat.match(l)
        filen=res.group(1)
        ext=res.group(2)
        if not ext: ext=".JPG"
        imgtitle=res.group(3)
        comment=res.group(4)
        soundname=res.group(5)
        #print filen,ext,trail,comment,soundname
        if res:
            descriptions[filen]=imgtitle
            # this is silly. We removed the '.JPG' in descrpat,
            # but now reattach it, because we want these to be
            # proper filenames.  Needs more thought.
            if comment:
              sounds[filen]=soundname
              print '  '*level,"Got a sound file:%s" % (soundname)
            images.append(filen+ext)
        else:
            images.append(l.rstrip())
except IOError:
    print "cannot open descriptions file in directory %s" % dirname
    descriptions={}
    sounds={}

Build the python dictionary of descriptions. We attempt to open a file in the current directory called descriptions, and use that to initialize the dictionary. The file has the format of one entry per line for each photo, with the name of the photo at the start of the line (with or without the .JPG extension), followed by at least one blank, followed by the descritive text, terminated by the end of line.

3.2 wind up descriptions file

if not gotdescrfile:
    if os.path.exists('descriptions'):
        print "OOPS!! attempt to overwrite existing descriptions file"
    else:
        descr=open('descriptions','w')
        for i in images:
            descr.write(trimJPG(i)+' \n')
        descr.close()
elif listmissingimages:
    print "There are images not mentioned in the descriptions file:"
    print "appending them to the descriptions file."
    descr=open('descriptions','a')
    for i in listmissingimages:
        descr.write(trimJPG(i)+' \n')
    descr.close()

We finalise the descriptions file. Two scenarios are relevant: either a) the descriptions file does not exist, in which case we build a new one, with just the image names of those images found in the directory scan, or b) the descriptions file exists, but there are images found not mentioned in it. In this latter case, we append image names to the file. No attempt is made to insert them in their 'correct' position.

If there are no changes required, the descriptions file is untouched. The existence of the descriptions file is determined by whether the flag gotdescrfile is set.

4. the addToIndex routine definition

def addToIndex(lists,imagename,descr):
    (r,e)=os.path.splitext(imagename)
    # this was inserted to try an control the length of captions.  It
    # is dangerous, however, as it can munge the well-formedness of
    # any contained XML.
    #if len(descr)>200:
    #    descr=descr[0:200] + ' ...'
    return '  <image name="%s">%s</image>\n' % (r,descr) # was cgi.escape(descr)

I've changed my mind a couple of times about escaping the description string. Currently the string is not escaped, meaning that any special XML characters (ampersand, less than, etc.) must be entered in escaped form. But this model does allow URLs and the like to appear in the description captions.

5. the addToList routine definition

# 'addToList' is called to add an image name to the list of images.
# See above for the format of the data structure 'list'.  It is
# assumed that the image name is a full path from the album root ((one
# of) the CLI parameter(s)).  The directory part is removed and used
# to match against the keys of 'lists'.  A new entry is created if
# this path has not previously been seen.  The image name is then
# added to this list, if it is not already there.
def addToList(lists,imagefile):
    (base,tail)=os.path.split(os.path.abspath(imagefile))
    (name,ext)=os.path.splitext(tail)
    if lists.has_key(base):
        a = lists[base]
    else:
        a = []
        lists[base] = a
    if not name in a:
        a.append(name)

6. the makeImage routine

def makeImage(level,orgwd,orght,newwd,newht,newname,orgname,orgmod):
    # orgwd: original image width
    # orght: original image height
    # newwd: new image width
    # newht: new image height
    # newname: new image file name
    # orgname: original image file name
    # orgmod: original image modification date/time
    #
    #print "makeImage(%d,%d,%d,%d,%s,%s,%s)" % \
    #      (orgwd,orght,newwd,newht,newname,orgname,orgmod)
    if orght>orgwd: # portrait mode, swap height and width
        t=newht
        newht=newwd
        newwd=t
    if orght>newht: # check that resolution is large enough
        newmod=0
        if os.path.isfile(newname):
            newmod=os.stat(newname)[stat.ST_MTIME]
        if orgmod>newmod:
            print '  '*level,"Writing %s at %dx%d ..." % (newname,newht,newwd)
            size=" -size %dx%d " % (newht,newwd)
            resize=" -resize %dx%d " % (newht,newwd)
            #print size+orgname+resize+newname
            os.system("/sw/bin/convert"+size+orgname+resize+newname)
        pass
    return

7. the makeSubImages routine

This routine is responsible for building all the smaller images from the master image.

7.1 New SubImage generalized size definitions

We define here data structures to handle generalized sub-image size definitions. Not yet active.

imageSizeDefs=[(128,128,"thumb"),(384,288,"small"),\
               (640,480,"medium"),(1200,900,"large"),(0,0,"original")]
imageSizes=[]; derivedImageMatch=[]
for (wd,ht,sizeName) in imageSizeDefs:
  imageSizes.append("%dx%d" % (wd,ht))
  derivedImageMatch.append(re.compile(".*_%dx%d.JPG" % (wd,ht)))

Initialize the image size parameters. imageSizeDefs is normative, and defines all required image sizes. The first entry is deemed to be the thumbnail size, and an entry of (0,0) refers to the original size. imageSizes is an equivalent list of strings in the form %dx%d, and derivedImageMatch is an equivalent list of patterns to match image names of those sizes. (Except the last, which fix!)

def makeSubImages(level,lists,imagename,iprev,inext,mdescr):
    global descriptions,forceXmls
    (r,e)=os.path.splitext(imagename)
    thumbn=r+"_128x128"+e
    smalln=r+"_384x288"+e
    medn=r+"_640x480"+e
    bign=r+"_1200x900"+e
    viewn=r+".xml"
    <return on missing image file 7.3>
    <get all modification times 7.4>
    <makeSubImages: make any sub images required 7.5>
    # check if there is a new description
    olddescr=descr=""
    try:
      oldxmldom=parse(viewn)
      olddescr=oldxmldom.getElementsByTagName('description')
      olddescr=flatStringNodes(olddescr[0].childNodes)
      olddescr=olddescr.strip()
    except:
      print "Could not get old description for %s" % viewn
      pass
    if descriptions.has_key(r):
        descr=descriptions[r].strip()
    # create the new IMAGE.xml if the descriptions file exists
    # (mdescr>0) and is more recent than IMAGE.xml, or the IMAGE.JPG
    # is more recent  than IMAGE.xml, and there is a new description
    #print "mdescr=%d, mview=%d, mfile=%d" % (mdescr,mview,mfile)
    if forceXmls or \
       (mview==0) or \
       (  (olddescr!=descr) and \
          (  (mdescr>0 and mdescr>mview) or \
             (mfile>mview)\
          )\
       ):
        <makeSubImages: write image xml file 7.6>
    return descr

if not os.path.isfile(imagename):
    if descriptions.has_key(r):
        descr=descriptions[r].strip()
        return descr
    else:
        print "descriptions entry '%s' : image not found" % (imagename)
        return -1

Check that the image file exists. If it doesn't, then there are two possible reasons. Firstly, the image file has been removed for space reasons, in which case there will be an entry in the descriptions database, and we return that without attempting to make any sub images.

Alternatively, no such descriptions entry means the image is genuinely missing, and therefore we should print a warning message, and return a missing image flag.

mfile=os.stat(imagename)[stat.ST_MTIME]
mthumb=msmall=mmed=mbig=mfile-1
mview=0
if os.path.isfile(thumbn):
  mthumb=os.stat(thumbn)[stat.ST_MTIME]
if os.path.isfile(smalln):
  msmall=os.stat(smalln)[stat.ST_MTIME]
if os.path.isfile(medn):
  mmed=os.stat(medn)[stat.ST_MTIME]
if os.path.isfile(bign):
  mbig=os.stat(bign)[stat.ST_MTIME]
if os.path.isfile(viewn):
  mview=os.stat(viewn)[stat.ST_MTIME]
#print "%d > (%d,%d,%d)" % (mfile,mthumb,mmed,mbig)

Get all the modification times. The default modification times are that mview is the oldest, mfile is the youngest, and all the others are in between.

if mfile>min(mthumb,msmall,mmed,mbig):
  (cmd_stdin,cmd_stdout)=os.popen4("/sw/bin/identify "+imagename)
  cmd_out=""
  for line in cmd_stdout.readline():
    cmd_out=cmd_out+line
  names=[thumbn,medn,bign,imagename]
  (b,t)=os.path.split(imagename)
  #print "base=%s, tail=%s" % (b,t)
  #print "Making images for %s" % (imagename)
  #print "checking %s ... (%s)" % (imagename,cmd_out)
  res=identifyPat.match(cmd_out)
  if res:
    ht=int(res.group(1))
    wd=int(res.group(2))
    makeImage(level,wd,ht,128,128,thumbn,imagename,mfile)
    if not thumbsOnly:
      makeImage(level,wd,ht,384,288,smalln,imagename,mfile)
      makeImage(level,wd,ht,640,480,medn,imagename,mfile)
      if large:
        makeImage(level,wd,ht,1200,900,bign,imagename,mfile)
    count=1

print '  '*level,"Writing %s ..." % (viewn)
imagef=open(imagename,'rb')
exiftags={}
try:
    exiftags=EXIF.process_file(imagef)
except ValueError:
    print "cannot extract exif data from %s" % imagename
#for tag in exiftags.keys():
    #print "%s = %s" % (tag,exiftags[tag])
imagexmlf = open(viewn,"w")
imagexmlf.write('<?xml version="1.0" ?>\n')
imagexmlf.write('<?xml-stylesheet type="text/xsl" ')
imagexmlf.write('href="%s"?>\n' % ALBUMXSL)
imagexmlf.write('<album>\n')
(rp,ep)=os.path.splitext(iprev)
(rn,en)=os.path.splitext(inext)
treepath=os.getcwd()+'/'
res=treepat.match(treepath)
if res:
  imagexmlf.write('  <tree>%s</tree>\n' % (res.group(1)))
imagexmlf.write('  <view name="%s" \n' % (r))
imagexmlf.write('        prev="%s" next="%s"\n' % (rp,rn))
if sounds.has_key(r):
  snd=sounds[r]
  print "  Adding sound: %s" % (snd)
  imagexmlf.write('        audio="sounds/SND_%s.WAV">\n' % (snd))
else:
  imagexmlf.write('>\n')
imagexmlf.write('    <description>\n')
imagexmlf.write('      %s\n' % descr) # was cgi.escape(descr)
imagexmlf.write('    </description>\n')
if exiftags.has_key('EXIF DateTimeOriginal'):
    datetime=exiftags['EXIF DateTimeOriginal']
    imagexmlf.write('    <datetime>%s</datetime>\n' % datetime)
if exiftags.has_key('EXIF ExposureTime'):
    shutter=exiftags['EXIF ExposureTime']
    imagexmlf.write('    <shutter>%s</shutter>\n' % shutter)
if exiftags.has_key('EXIF FNumber'):
    aperture=exiftags['EXIF FNumber']
    try:
        aperture=str(eval(str(aperture)+'.0'))
    except:
        pass
    imagexmlf.write('    <aperture>%s</aperture>\n' % aperture)
imagexmlf.write('  </view>\n')
imagexmlf.write('</album>\n')
imagexmlf.close()

See comment under <the addToIndex routine definition 4.1> regarding escaping the description string.

8. the retrieve support routines definition

def getNodeValue(dom,field,missing):
    try:
        val = dom.getElementsByTagName(field).item(0).firstChild.nodeValue
    except:
        val=missing
    return val

def retrieveField(field):
    try:
        val = index.getElementsByTagName(field).item(0).firstChild.nodeValue
    except:
        val="[could not retrieve %s]" % (field)
    return val

These two support routines for retrieve encapsulate data extraction from the DOM model. They perform the same basic operation, differeing only in the default parameters required.

def retrieve(d):
    <the retrieve support routines definition 8.1>
    missing=0
    try:
        index = parse(d+'/index.xml')
    except:
        (etype,eval,etrace)=sys.exc_info()
        print "Cannot open index.xml in directory %s because %s" % (d,etype)
        return None
    #print "Successfully parsed index.xml in directory %s" % (d)
    try:
        album = parse(d+'/album.xml')
    except:
        (etype,eval,etrace)=sys.exc_info()
        print "Cannot open album.xml in directory %s because %s" % (d,etype)
        album=None
    title = retrieveField('title')
    description = retrieveField('description')
    imageElems=index.getElementsByTagName('image')
    summary=index.getElementsByTagName('summary').item(0)
    photos=int(summary.getAttribute('photos'))
    albums=int(summary.getAttribute('albums'))
    missing=int(summary.getAttribute('missing'))

    # sort out the vexed problem of the thumbnail
    if album:
        albumThumbs=album.getElementsByTagName('thumbnail')
    else:
        albumThumbs=''
    thumbDefault=getNodeValue(index,'thumbnail','')
    thumb=thumbDefault
    if not thumbDefault:
        thumbDefault=getNodeValue(album,'thumbnail','')
    #print "    albumThumb: %s" % (thumbDefault)
    if not thumbDefault:
        thumb=thumbDefault

    miss=index.getElementsByTagName('missingdescriptions')
    if miss:
        missing=int(miss.item(0).firstChild.nodeValue)
    if 0:
        print "retrieved:"
        print "    title: %s" % (title)
        print "    photos: %d" % (photos)
        print "    albums: %d" % (albums)
        print "    thumb: %s" % (thumb)
        print "    description: %s" % (description)
    return (title,photos,albums,thumb,description,missing)

retrieve is called when we do not wish to recursively visit a subdirectory. Instead, relevant details from the subdirectory are extracted ('retrieved') from an index.xml file, which has been constructed when the relevant subdirectory was visited.

There is a slight problem with identifying a thumbnail for this album, since the definite source is that in the album.xml file. However, this may be blank, in which has we need to promote the first thumbnail within the directory (or subdirectories where the directory has no images of its own).

9. Indices

Document History

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