/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/resource.py
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revision 1179 by jonathan, Thu Jun 12 16:12:56 2003 UTC revision 1933 by bh, Tue Nov 11 16:37:53 2003 UTC
# Line 5  Line 5 
5  # This program is free software under the GPL (>=v2)  # This program is free software under the GPL (>=v2)
6  # Read the file COPYING coming with Thuban for details.  # Read the file COPYING coming with Thuban for details.
7    
8    """Handle resources loaded from files such as projections"""
9    
10    __version__ = "$Revision$"
11    # $Source$
12    # $Id$
13    
14    
15  import os  import os
16  import os.path  import os.path
17    import weakref
18    
19  import Thuban  import Thuban
20  from Thuban import _  from Thuban import _
# Line 21  from xml.sax import SAXParseException Line 29  from xml.sax import SAXParseException
29  projdir = \  projdir = \
30          os.path.join(Thuban.__path__[0], os.pardir, "Resources", "Projections")          os.path.join(Thuban.__path__[0], os.pardir, "Resources", "Projections")
31    
 usrdir  = get_application_dir()  
32    
33  PROJ_EXT = ".proj"  PROJ_EXT = ".proj"
34    
35  has_gdal_support = lambda: False  has_gdal_support = lambda: False
36  try:  try:
37        # first try to see if our extension module is there. if it
38        # wasn't even compiled, we obviously don't have gdal support.
39        import gdalwarp
40    
41        # now try to import the python extension. if this doesn't
42        # exist then we can't do anything.
43      import gdal      import gdal
44    
45      """Return True if the gdal library is available."""      """Return True if the gdal library is available."""
46      has_gdal_support = lambda: True      has_gdal_support = lambda: True
47  except ImportError:  except ImportError:
48      pass      pass
49    
50  def read_proj_file(filename):  projfile_cache = weakref.WeakValueDictionary()
51      """Read a single .proj file and return a ProjFile object.  
52        def clear_proj_file_cache():
53      Raises IOError if the file cannot be opened.      """Clear the cache of ProjFile objects maintained by read_proj_file.
54      Raises OSError if the file cannot be read.  
55      Raises SAXParseException if the file is not valid XML.      This function is probably only useful for the test suite.
56      """      """
57        projfile_cache.clear()
58    
59    def read_proj_file(filename):
60        """Read a .proj file and return a ProjFile object and warnings
61    
62      handler = ProjFileReader()      The return value is a tuple with the ProjFile object and a list of
63      handler.read(filename)      strings with warnings messages that might have been generated by the
64      return handler.GetProjFile()      proj file parser.
65    
66        The objects returned cached so that reading the same file
67        (identified by its absolute name) several times yields the same
68        ProjFile object. The cache uses weak references so the objects will
69        be removed from the cache once the last reference an object in the
70        cache is removed.
71    
72        Raises IOError if the file cannot be opened, OSError if the file
73        cannot be read and SAXParseException if the file is not valid XML.
74        """
75        filename = os.path.abspath(filename)
76        if filename in projfile_cache:
77            return projfile_cache[filename], []
78        else:
79            handler = ProjFileReader()
80            handler.read(filename)
81            proj_file = handler.GetProjFile()
82            projfile_cache[filename] = proj_file
83            return proj_file, handler.GetWarnings()
84    
85  def write_proj_file(pf):  def write_proj_file(pf):
86      """Write a single .proj file      """Write a single .proj file
# Line 54  def write_proj_file(pf): Line 91  def write_proj_file(pf):
91      saver = ProjFileSaver(pf)      saver = ProjFileSaver(pf)
92      saver.write(pf.GetFilename())      saver.write(pf.GetFilename())
93    
 def get_proj_files(dir):  
     """Read all .proj files in the given directory and  
     return a list of ProjFile objects.  
     """  
94    
95      list = []  # Constants for the get_system_proj_file function
96      try:  DEFAULT_PROJ_FILE = "defaults.proj"
97          dirlist = os.listdir(dir)  EPSG_PROJ_FILE = "epsg.proj"
98      except OSError:  
99          pass # if we can't get a directory listing just return []  def get_system_proj_file(filename):
100      else:      """Return the projections from the indicated file and a list with warnings
101          for file in filter(lambda s: s.endswith(PROJ_EXT), dirlist):  
102              try:      The filename argument should be the name of a file in the directory
103                  filename = os.path.join(dir, file)      with Thuban's default projection files (Resources/Projections/). If
104                  list.append(read_proj_file(filename))      possible callers should not use hardwired string literal for the
105              except (OSError, IOError, SAXParseException):      name to avoid unnecessary duplication. Instead they should use one
106                  pass # just move onto the next file      of the predefined constants, currently DEFAULT_PROJ_FILE or
107        EPSG_PROJ_FILE.
108      return list  
109        The return value is a tuple with the projections in a ProjFile
110  def get_system_proj_files():      object and a list of strings with warning messages. The warnings
111      """Return a list of ProjFile objects from files that are      list is usually empty but may contain messages about ignored errors.
     supplied by Thuban.  
112    
113      If no files could not be opened return a list with one      If the file could could not be opened return an empty projection
114      empty projection file set to store data in the default file.      file object set to store data in the indicated default file.
115      """      """
116      filename = os.path.join(projdir, "defaults.proj")      fullname = os.path.join(projdir, filename)
117      try:      try:
118          return [read_proj_file(filename)]          return read_proj_file(fullname)
119      except (OSError, IOError, SAXParseException):      except (OSError, IOError, SAXParseException), val:
120          return [ProjFile(filename)]          msg = _('Could not read "%s": %s') % (fullname, str(val))
121            return ProjFile(fullname), [msg]
122  def get_user_proj_files():  
123      """Return a list of ProjFile objects from files that are user-defined.  def get_user_proj_file():
124        """Return the user's projections and a list with warnings
125    
126        The projections read from the user's thuban projection file (usually
127        in ~/.thuban/user.proj). The return value is a tuple with the
128        projections in a ProjFile object and a list of strings with warning
129        messages. The warnings list is usually empty but may contain
130        messages about ignored errors.
131    
132      If no files could not be opened return a list with one      If the file could could not be opened return an empty projection
133      empty projection file set to store data in the default file.      file object set to store data in the default file.
134      """      """
135        usrdir  = get_application_dir()
136      filename = os.path.join(usrdir, "user.proj")      filename = os.path.join(usrdir, "user.proj")
137      try:      try:
138          return [read_proj_file(filename)]          return read_proj_file(filename)
139      except (OSError, IOError, SAXParseException):      except (OSError, IOError, SAXParseException), val:
140          return [ProjFile(filename)]          msg = _('Could not read "%s": %s') % (filename, str(val))
141            return ProjFile(filename), [msg]
142    
143    
144  class ProjFileReader(XMLReader):  class ProjFileReader(XMLReader):
145    
146      def __init__(self):      def __init__(self):
147          XMLReader.__init__(self)          XMLReader.__init__(self)
148          self.__pf = ProjFile("")          self.projfile = ProjFile("")
149            self.warnings = []
150    
151          XMLReader.AddDispatchers(self,          XMLReader.AddDispatchers(self,
152              {'projection': ("start_projection", "end_projection"),              {'projection': ("start_projection", "end_projection"),
153               'parameter':  ("start_parameter", None)})               'parameter':  ("start_parameter", None)})
154                
155      def read(self, file_or_filename):      def read(self, file_or_filename):
156          XMLReader.read(self, file_or_filename)          XMLReader.read(self, file_or_filename)
157    
158          self.__pf.SetFilename(XMLReader.GetFilename(self))          self.projfile.SetFilename(XMLReader.GetFilename(self))
159            
160      def start_projection(self, name, qname, attrs):      def start_projection(self, name, qname, attrs):
161          self.params = []          self.params = []
162          self.name = self.encode(attrs.get((None, 'name'), _("Unknown")))          name = self.encode(attrs.get((None, 'name')))
163            if name is None:
164                name = _("Unknown")
165            self.name = name
166            self.epsg = self.encode(attrs.get((None, 'epsg')))
167    
168      def end_projection(self, name, qname):      def end_projection(self, name, qname):
169          self.__pf.Add(Projection(self.params, self.name))          try:
170                proj = Projection(self.params, self.name, epsg = self.epsg)
171            except IOError, val:
172                self.warnings.append(_('Error in projection "%s": %s')
173                                     % (self.name, str(val)))
174            else:
175                self.projfile.Add(proj)
176    
177      def start_parameter(self, name, qname, attrs):      def start_parameter(self, name, qname, attrs):
178          s = attrs.get((None, 'value'))          s = attrs.get((None, 'value'))
# Line 128  class ProjFileReader(XMLReader): Line 180  class ProjFileReader(XMLReader):
180          self.params.append(s)          self.params.append(s)
181    
182      def GetProjFile(self):      def GetProjFile(self):
183          return self.__pf          return self.projfile
184    
185        def GetWarnings(self):
186            """Return the list of warning messages that may have been produced"""
187            return self.warnings
188    
189    
190  class ProjFileSaver(XMLWriter):  class ProjFileSaver(XMLWriter):
191    
# Line 139  class ProjFileSaver(XMLWriter): Line 196  class ProjFileSaver(XMLWriter):
196      def write(self, file_or_filename):      def write(self, file_or_filename):
197          XMLWriter.write(self, file_or_filename)          XMLWriter.write(self, file_or_filename)
198    
199          self.write_header("projfile", "projfile.dtd")          self.write_header("projectionlist", "projfile.dtd")
200          self.write_projfile(self.__pf)          self.write_projfile(self.__pf)
201          self.close()          self.close()
202    
# Line 148  class ProjFileSaver(XMLWriter): Line 205  class ProjFileSaver(XMLWriter):
205          self.open_element("projectionlist")          self.open_element("projectionlist")
206    
207          for p in pf.GetProjections():          for p in pf.GetProjections():
208              self.open_element("projection", {"name": p.GetName()})              attrs = {"name": p.GetName()}
209                if p.EPSGCode():
210                    attrs["epsg"] = p.EPSGCode()
211                self.open_element("projection", attrs)
212    
213              for param in p.GetAllParameters():              for param in p.GetAllParameters():
214                  self.write_element("parameter", {"value": param})                  self.write_element("parameter", {"value": param})
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