/[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 1830 by bh, Thu Oct 16 16:36:00 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
     saver.write(pf.GetFileName())  
61    
62  def GetProjections(dir):      The return value is a tuple with the ProjFile object and a list of
63      """Read all .proj files in the given directory and      strings with warnings messages that might have been generated by the
64      return a list of ProjFile objects.      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):
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    
95    def get_system_proj_file():
96        """Return the standard projections and a list with warnings
97    
98        The projections read from the default thuban projection file
99        (usually in Resources/Projections/defaults.proj). The return value
100        is a tuple with the projections in a ProjFile object and a list of
101        strings with warning messages. The warnings list is usually empty
102        but may contain messages about ignored errors.
103    
104      list = []      If the file could could not be opened return an empty projection
105        file object set to store data in the default file.
106        """
107        filename = os.path.join(projdir, "defaults.proj")
108      try:      try:
109          for file in filter(lambda s: s.endswith(PROJ_EXT), os.listdir(dir)):          return read_proj_file(filename)
110              filename = os.path.join(dir, file)      except (OSError, IOError, SAXParseException), val:
111              list.extend(ReadProjFile(filename))          msg = _('Could not read "%s": %s') % (filename, str(val))
112      except OSError:          return ProjFile(filename), [msg]
113          pass  
114    def get_user_proj_file():
115      return list      """Return the user's projections and a list with warnings
116    
117  def GetSuppliedProjections():      The projections read from the user's thuban projection file (usually
118      """Return a list of ProjFile objects from files that are      in ~/.thuban/user.proj). The return value is a tuple with the
119      supplied by Thuban.      projections in a ProjFile object and a list of strings with warning
120        messages. The warnings list is usually empty but may contain
121        messages about ignored errors.
122    
123        If the file could could not be opened return an empty projection
124        file object set to store data in the default file.
125      """      """
126      return GetProjections(projdir)      usrdir  = get_application_dir()
127        filename = os.path.join(usrdir, "user.proj")
128        try:
129            return read_proj_file(filename)
130        except (OSError, IOError, SAXParseException), val:
131            msg = _('Could not read "%s": %s') % (filename, str(val))
132            return ProjFile(filename), [msg]
133    
134    
135    class ProjFileReader(XMLReader):
136    
137        def __init__(self):
138            XMLReader.__init__(self)
139            self.projfile = ProjFile("")
140            self.warnings = []
141    
142            XMLReader.AddDispatchers(self,
143                {'projection': ("start_projection", "end_projection"),
144                 'parameter':  ("start_parameter", None)})
145    
146        def read(self, file_or_filename):
147            XMLReader.read(self, file_or_filename)
148    
149            self.projfile.SetFilename(XMLReader.GetFilename(self))
150    
 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)  
           
151      def start_projection(self, name, qname, attrs):      def start_projection(self, name, qname, attrs):
152          self.params = []          self.params = []
153          self.name = attrs.get((None, 'name'), "Unknown")          name = self.encode(attrs.get((None, 'name')))
154      XMLProcessor.start_dispatcher['projection'] = "start_projection"          if name is None:
155                name = _("Unknown")
156            self.name = name
157            self.epsg = self.encode(attrs.get((None, 'epsg')))
158    
159      def end_projection(self, name, qname):      def end_projection(self, name, qname):
160          self.pf.Add(Projection(self.params, self.name))          try:
161      XMLProcessor.end_dispatcher['projection'] = "end_projection"              proj = Projection(self.params, self.name, epsg = self.epsg)
162            except IOError, val:
163                self.warnings.append(_('Error in projection "%s": %s')
164                                     % (self.name, str(val)))
165            else:
166                self.projfile.Add(proj)
167    
168      def start_parameter(self, name, qname, attrs):      def start_parameter(self, name, qname, attrs):
169          s = attrs.get((None, 'value'))          s = attrs.get((None, 'value'))
170          s = str(s) # we can't handle unicode in proj          s = str(s) # we can't handle unicode in proj
171          self.params.append(s)          self.params.append(s)
     XMLProcessor.start_dispatcher['parameter'] = "start_parameter"  
172    
173      def GetProjFile(self):      def GetProjFile(self):
174          return self.pf          return self.projfile
175    
176        def GetWarnings(self):
177            """Return the list of warning messages that may have been produced"""
178            return self.warnings
179    
180    
181  class ProjFileSaver(XMLSaver):  class ProjFileSaver(XMLWriter):
182    
183      def __init__(self, pf):      def __init__(self, pf):
184          XMLSaver.__init__(self)          XMLWriter.__init__(self)
185          self.pf = pf          self.__pf = pf
186    
187      def write(self, file_or_filename):      def write(self, file_or_filename):
188          XMLSaver.write(self, file_or_filename)          XMLWriter.write(self, file_or_filename)
189    
190          self.write_header("projfile", "thuban.dtd")          self.write_header("projectionlist", "projfile.dtd")
191          self.write_projfile(self.pf)          self.write_projfile(self.__pf)
192          self.close()          self.close()
193    
194      def write_projfile(self, pf):      def write_projfile(self, pf):
# Line 105  class ProjFileSaver(XMLSaver): Line 196  class ProjFileSaver(XMLSaver):
196          self.open_element("projectionlist")          self.open_element("projectionlist")
197    
198          for p in pf.GetProjections():          for p in pf.GetProjections():
199              self.open_element("projection", {"name": p.GetName()})              attrs = {"name": p.GetName()}
200                if p.EPSGCode():
201                    attrs["epsg"] = p.EPSGCode()
202                self.open_element("projection", attrs)
203    
204              for param in p.GetParameters():              for param in p.GetAllParameters():
205                  self.write_element("parameter", {"value": param})                  self.write_element("parameter", {"value": param})
206    
207              self.close_element("projection")              self.close_element("projection")
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