/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/resource.py
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revision 718 by jonathan, Wed Apr 23 10:39:46 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 XMLReader  from Thuban import _
21  from Thuban.Model.save import XMLWriter  
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      Raises IOError if the file cannot be opened.      # wasn't even compiled, we obviously don't have gdal support.
39      Raises OSError if the file cannot be read.      import gdalwarp
40      Raises SAXParseException if the file is not valid XML.  
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    projfile_cache = weakref.WeakValueDictionary()
51    
52    def clear_proj_file_cache():
53        """Clear the cache of ProjFile objects maintained by read_proj_file.
54    
55        This function is probably only useful for the test suite.
56      """      """
57        projfile_cache.clear()
58    
59      handler = ProjFileReader()  def read_proj_file(filename):
60      handler.read(filename)      """Read a .proj file and return a ProjFile object and warnings
     return handler.GetProjFile()  
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 GetProjFiles(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    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        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          dirlist = os.listdir(dir)          return read_proj_file(filename)
110      except OSError:      except (OSError, IOError, SAXParseException), val:
111          pass # if we can't get a directory listing just return []          msg = _('Could not read "%s": %s') % (filename, str(val))
112      else:          return ProjFile(filename), [msg]
113          for file in filter(lambda s: s.endswith(PROJ_EXT), dirlist):  
114              try:  def get_user_proj_file():
115                  filename = os.path.join(dir, file)      """Return the user's projections and a list with warnings
116                  list.append(ReadProjFile(filename))  
117              except (OSError, IOError, SAXParseException):      The projections read from the user's thuban projection file (usually
118                  pass # just move onto the next file      in ~/.thuban/user.proj). The return value is a tuple with the
119        projections in a ProjFile object and a list of strings with warning
120      return list      messages. The warnings list is usually empty but may contain
121        messages about ignored errors.
122  def GetSystemProjFiles():  
123      """Return a list of ProjFile objects from files that are      If the file could could not be opened return an empty projection
124      supplied by Thuban.      file object set to store data in the default file.
125      """      """
126      return GetProjFiles(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    
 def GetUserProjFiles():  
     """Return a list of ProjFile objects from files that are user-defined."""  
     return GetProjFiles(usrdir)  
134    
135  class ProjFileReader(XMLReader):  class ProjFileReader(XMLReader):
136    
137      def __init__(self):      def __init__(self):
138          XMLReader.__init__(self)          XMLReader.__init__(self)
139          self.__pf = ProjFile("")          self.projfile = ProjFile("")
140            self.warnings = []
141    
142          XMLReader.AddDispatchers(self,          XMLReader.AddDispatchers(self,
143              {'projection': ("start_projection", "end_projection"),              {'projection': ("start_projection", "end_projection"),
144               'parameter':  ("start_parameter", None)})               'parameter':  ("start_parameter", None)})
145                
146      def read(self, file_or_filename):      def read(self, file_or_filename):
147          XMLReader.read(self, file_or_filename)          XMLReader.read(self, file_or_filename)
148    
149          self.__pf.SetFileName(XMLReader.GetFileName(self))          self.projfile.SetFilename(XMLReader.GetFilename(self))
150            
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            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                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'))
# Line 92  class ProjFileReader(XMLReader): Line 171  class ProjFileReader(XMLReader):
171          self.params.append(s)          self.params.append(s)
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(XMLWriter):  class ProjFileSaver(XMLWriter):
# Line 104  class ProjFileSaver(XMLWriter): Line 187  class ProjFileSaver(XMLWriter):
187      def write(self, file_or_filename):      def write(self, file_or_filename):
188          XMLWriter.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    
# Line 113  class ProjFileSaver(XMLWriter): Line 196  class ProjFileSaver(XMLWriter):
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.GetAllParameters():              for param in p.GetAllParameters():
205                  self.write_element("parameter", {"value": param})                  self.write_element("parameter", {"value": param})
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