/[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 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
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()
     try:  
         handler = ProjFileReader(filename)  
51    
52          load_xmlfile(filename, handler)  def clear_proj_file_cache():
53          pf = handler.GetProjFile()      """Clear the cache of ProjFile objects maintained by read_proj_file.
     except OSError:  
         pass  
54    
55      return pf      This function is probably only useful for the test suite.
56        """
57        projfile_cache.clear()
58    
59  def WriteProjFile(pf):  def read_proj_file(filename):
60      saver = ProjFileSaver(pf)      """Read a .proj file and return a ProjFile object and warnings
61      saver.write(pf.GetFileName())  
62        The return value is a tuple with the ProjFile object and a list of
63        strings with warnings messages that might have been generated by the
64        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  def GetProjections(dir):      Raises IOError if the file cannot be opened, OSError if the file
73      """Read all .proj files in the given directory and      cannot be read and SAXParseException if the file is not valid XML.
     return a list of ProjFile objects.  
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):
86        """Write a single .proj file
87    
88        Raises IOError if the file cannot be written.
89        """
90    
91        saver = ProjFileSaver(pf)
92        saver.write(pf.GetFilename())
93    
94      list = []  
95    # Constants for the get_system_proj_file function
96    DEFAULT_PROJ_FILE = "defaults.proj"
97    EPSG_PROJ_FILE = "epsg.proj"
98    
99    def get_system_proj_file(filename):
100        """Return the projections from the indicated file and a list with warnings
101    
102        The filename argument should be the name of a file in the directory
103        with Thuban's default projection files (Resources/Projections/). If
104        possible callers should not use hardwired string literal for the
105        name to avoid unnecessary duplication. Instead they should use one
106        of the predefined constants, currently DEFAULT_PROJ_FILE or
107        EPSG_PROJ_FILE.
108    
109        The return value is a tuple with the projections in a ProjFile
110        object and a list of strings with warning messages. The warnings
111        list is usually empty but may contain messages about ignored errors.
112    
113        If the file could could not be opened return an empty projection
114        file object set to store data in the indicated default file.
115        """
116        fullname = os.path.join(projdir, filename)
117      try:      try:
118          for file in filter(lambda s: s.endswith(PROJ_EXT), os.listdir(dir)):          return read_proj_file(fullname)
119              filename = os.path.join(dir, file)      except (OSError, IOError, SAXParseException), val:
120              list.extend(ReadProjFile(filename))          msg = _('Could not read "%s": %s') % (fullname, str(val))
121      except OSError:          return ProjFile(fullname), [msg]
122          pass  
123    def get_user_proj_file():
124      return list      """Return the user's projections and a list with warnings
125    
126  def GetSuppliedProjections():      The projections read from the user's thuban projection file (usually
127      """Return a list of ProjFile objects from files that are      in ~/.thuban/user.proj). The return value is a tuple with the
128      supplied by Thuban.      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 the file could could not be opened return an empty projection
133        file object set to store data in the default file.
134      """      """
135      return GetProjections(projdir)      usrdir  = get_application_dir()
136        filename = os.path.join(usrdir, "user.proj")
137        try:
138            return read_proj_file(filename)
139        except (OSError, IOError, SAXParseException), val:
140            msg = _('Could not read "%s": %s') % (filename, str(val))
141            return ProjFile(filename), [msg]
142    
143    
144    class ProjFileReader(XMLReader):
145    
146        def __init__(self):
147            XMLReader.__init__(self)
148            self.projfile = ProjFile("")
149            self.warnings = []
150    
151            XMLReader.AddDispatchers(self,
152                {'projection': ("start_projection", "end_projection"),
153                 'parameter':  ("start_parameter", None)})
154    
155        def read(self, file_or_filename):
156            XMLReader.read(self, file_or_filename)
157    
158            self.projfile.SetFilename(XMLReader.GetFilename(self))
159    
 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)  
           
160      def start_projection(self, name, qname, attrs):      def start_projection(self, name, qname, attrs):
161          self.params = []          self.params = []
162          self.name = attrs.get((None, 'name'), "Unknown")          name = self.encode(attrs.get((None, 'name')))
163      XMLProcessor.start_dispatcher['projection'] = "start_projection"          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      XMLProcessor.end_dispatcher['projection'] = "end_projection"              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'))
179          s = str(s) # we can't handle unicode in proj          s = str(s) # we can't handle unicode in proj
180          self.params.append(s)          self.params.append(s)
     XMLProcessor.start_dispatcher['parameter'] = "start_parameter"  
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(XMLSaver):  class ProjFileSaver(XMLWriter):
191    
192      def __init__(self, pf):      def __init__(self, pf):
193          XMLSaver.__init__(self)          XMLWriter.__init__(self)
194          self.pf = pf          self.__pf = pf
195    
196      def write(self, file_or_filename):      def write(self, file_or_filename):
197          XMLSaver.write(self, file_or_filename)          XMLWriter.write(self, file_or_filename)
198    
199          self.write_header("projfile", "thuban.dtd")          self.write_header("projectionlist", "projfile.dtd")
200          self.write_projfile(self.pf)          self.write_projfile(self.__pf)
201          self.close()          self.close()
202    
203      def write_projfile(self, pf):      def write_projfile(self, pf):
# Line 105  class ProjFileSaver(XMLSaver): Line 205  class ProjFileSaver(XMLSaver):
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.GetParameters():              for param in p.GetAllParameters():
214                  self.write_element("parameter", {"value": param})                  self.write_element("parameter", {"value": param})
215    
216              self.close_element("projection")              self.close_element("projection")
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