/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/resource.py
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revision 696 by jonathan, Wed Apr 16 16:39:49 2003 UTC revision 1940 by bh, Tue Nov 11 18:27:39 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
17    import weakref
18    
19  import Thuban  import Thuban
20  from Thuban.Model.load import XMLProcessor, load_xmlfile  from Thuban import _
21  from Thuban.Model.save import XMLSaver  
22    from Thuban.Lib.fileutil import get_application_dir
23    
24    from Thuban.Model.xmlreader import XMLReader
25    from Thuban.Model.xmlwriter import XMLWriter
26  from Thuban.Model.proj import Projection, ProjFile  from Thuban.Model.proj import Projection, ProjFile
27    from xml.sax import SAXParseException
28    
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  = os.path.expanduser("~/.thuban")  
32    
33  PROJ_EXT = ".proj"  PROJ_EXT = ".proj"
34    
35  def ReadProjFile(filename):  has_gdal_support = lambda: False
36      """Read a single .proj file and return a ProjFile object."""  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
44    
45        """Return True if the gdal library is available."""
46        has_gdal_support = lambda: True
47    except ImportError:
48        pass
49    
50      projs = []  projfile_cache = weakref.WeakValueDictionary()
51      try:  
52          handler = ProjFileReader(filename)  def clear_proj_file_cache():
53        """Clear the cache of ProjFile objects maintained by read_proj_file.
54    
55          load_xmlfile(filename, handler)      This function is probably only useful for the test suite.
56          pf = handler.GetProjFile()      """
57      except OSError:      projfile_cache.clear()
         pass  
58    
59      return pf  def read_proj_file(filename):
60        """Read a .proj file and return a ProjFile object and warnings
61    
62  def WriteProjFile(pf):      The return value is a tuple with the ProjFile object and a list of
63      saver = ProjFileSaver(pf)      strings with warnings messages that might have been generated by the
64      saver.write(pf.GetFileName())      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 GetProjections(dir):  def write_proj_file(pf):
86      """Read all .proj files in the given directory and      """Write a single .proj file
87      return a list of ProjFile objects.  
88        Raises IOError if the file cannot be written.
89      """      """
90    
91      list = []      saver = ProjFileSaver(pf)
92        saver.write(pf.GetFilename())
93    
94    #
95    # Constants for the get_system_proj_file function
96    #
97    
98    # The default projection file with a few predefined projections
99    DEFAULT_PROJ_FILE = "defaults.proj"
100    
101    # The epsg projections.
102    EPSG_PROJ_FILE = "epsg.proj"
103    
104    # Deprecated EPSG projections.
105    EPSG_DEPRECATED_PROJ_FILE = "epsg-deprecated.proj"
106    
107    def get_system_proj_file(filename):
108        """Return the projections from the indicated file and a list with warnings
109    
110        The filename argument should be the name of a file in the directory
111        with Thuban's default projection files (Resources/Projections/). If
112        possible callers should not use hardwired string literal for the
113        name to avoid unnecessary duplication. Instead they should use one
114        of the predefined constants, currently DEFAULT_PROJ_FILE,
115        EPSG_PROJ_FILE or EPSG_DEPRECATED_PROJ_FILE.
116    
117        The return value is a tuple with the projections in a ProjFile
118        object and a list of strings with warning messages. The warnings
119        list is usually empty but may contain messages about ignored errors.
120    
121        If the file could could not be opened return an empty projection
122        file object set to store data in the indicated default file.
123        """
124        fullname = os.path.join(projdir, filename)
125      try:      try:
126          for file in filter(lambda s: s.endswith(PROJ_EXT), os.listdir(dir)):          return read_proj_file(fullname)
127              filename = os.path.join(dir, file)      except (OSError, IOError, SAXParseException), val:
128              list.extend(ReadProjFile(filename))          msg = _('Could not read "%s": %s') % (fullname, str(val))
129      except OSError:          return ProjFile(fullname), [msg]
130          pass  
131    def get_user_proj_file():
132      return list      """Return the user's projections and a list with warnings
133    
134  def GetSuppliedProjections():      The projections read from the user's thuban projection file (usually
135      """Return a list of ProjFile objects from files that are      in ~/.thuban/user.proj). The return value is a tuple with the
136      supplied by Thuban.      projections in a ProjFile object and a list of strings with warning
137        messages. The warnings list is usually empty but may contain
138        messages about ignored errors.
139    
140        If the file could could not be opened return an empty projection
141        file object set to store data in the default file.
142      """      """
143      return GetProjections(projdir)      usrdir  = get_application_dir()
144        filename = os.path.join(usrdir, "user.proj")
145        try:
146            return read_proj_file(filename)
147        except (OSError, IOError, SAXParseException), val:
148            msg = _('Could not read "%s": %s') % (filename, str(val))
149            return ProjFile(filename), [msg]
150    
151    
152    class ProjFileReader(XMLReader):
153    
154        def __init__(self):
155            XMLReader.__init__(self)
156            self.projfile = ProjFile("")
157            self.warnings = []
158    
159            XMLReader.AddDispatchers(self,
160                {'projection': ("start_projection", "end_projection"),
161                 'parameter':  ("start_parameter", None)})
162    
163        def read(self, file_or_filename):
164            XMLReader.read(self, file_or_filename)
165    
166            self.projfile.SetFilename(XMLReader.GetFilename(self))
167    
 def GetUserProjections():  
     """Return a list of ProjFile objects from files that are user-defined."""  
     return GetProjections(usrdir)  
   
 class ProjFileReader(XMLProcessor):  
   
     def __init__(self, filename):  
         XMLProcessor.__init__(self, os.path.dirname(filename))  
           
         self.pf = ProjFile(filename)  
           
168      def start_projection(self, name, qname, attrs):      def start_projection(self, name, qname, attrs):
169          self.params = []          self.params = []
170          self.name = attrs.get((None, 'name'), "Unknown")          name = self.encode(attrs.get((None, 'name')))
171      XMLProcessor.start_dispatcher['projection'] = "start_projection"          if name is None:
172                name = _("Unknown")
173            self.name = name
174            self.epsg = self.encode(attrs.get((None, 'epsg')))
175    
176      def end_projection(self, name, qname):      def end_projection(self, name, qname):
177          self.pf.Add(Projection(self.params, self.name))          try:
178      XMLProcessor.end_dispatcher['projection'] = "end_projection"              proj = Projection(self.params, self.name, epsg = self.epsg)
179            except IOError, val:
180                self.warnings.append(_('Error in projection "%s": %s')
181                                     % (self.name, str(val)))
182            else:
183                self.projfile.Add(proj)
184    
185      def start_parameter(self, name, qname, attrs):      def start_parameter(self, name, qname, attrs):
186          s = attrs.get((None, 'value'))          s = attrs.get((None, 'value'))
187          s = str(s) # we can't handle unicode in proj          s = str(s) # we can't handle unicode in proj
188          self.params.append(s)          self.params.append(s)
     XMLProcessor.start_dispatcher['parameter'] = "start_parameter"  
189    
190      def GetProjFile(self):      def GetProjFile(self):
191          return self.pf          return self.projfile
192    
193        def GetWarnings(self):
194            """Return the list of warning messages that may have been produced"""
195            return self.warnings
196    
197    
198  class ProjFileSaver(XMLSaver):  class ProjFileSaver(XMLWriter):
199    
200      def __init__(self, pf):      def __init__(self, pf):
201          XMLSaver.__init__(self)          XMLWriter.__init__(self)
202          self.pf = pf          self.__pf = pf
203    
204      def write(self, file_or_filename):      def write(self, file_or_filename):
205          XMLSaver.write(self, file_or_filename)          XMLWriter.write(self, file_or_filename)
206    
207          self.write_header("projfile", "thuban.dtd")          self.write_header("projectionlist", "projfile.dtd")
208          self.write_projfile(self.pf)          self.write_projfile(self.__pf)
209          self.close()          self.close()
210    
211      def write_projfile(self, pf):      def write_projfile(self, pf):
# Line 105  class ProjFileSaver(XMLSaver): Line 213  class ProjFileSaver(XMLSaver):
213          self.open_element("projectionlist")          self.open_element("projectionlist")
214    
215          for p in pf.GetProjections():          for p in pf.GetProjections():
216              self.open_element("projection", {"name": p.GetName()})              attrs = {"name": p.GetName()}
217                if p.EPSGCode():
218                    attrs["epsg"] = p.EPSGCode()
219                self.open_element("projection", attrs)
220    
221              for param in p.GetParameters():              for param in p.GetAllParameters():
222                  self.write_element("parameter", {"value": param})                  self.write_element("parameter", {"value": param})
223    
224              self.close_element("projection")              self.close_element("projection")
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