/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/data.py
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revision 1515 by bh, Tue Jul 29 14:59:11 2003 UTC revision 1551 by bh, Wed Aug 6 17:21:07 2003 UTC
# Line 13  __version__ = "$Revision$" Line 13  __version__ = "$Revision$"
13    
14  import os  import os
15  import weakref  import weakref
16    from math import ceil, log
17    
18  import shapelib  import shapelib
19    import shptree
20  import table  import table
21  import transientdb  import transientdb
22    
23  from Thuban import _  from Thuban import _
24    
25    # Shape type constants
26    SHAPETYPE_POLYGON = "polygon"
27    SHAPETYPE_ARC = "arc"
28    SHAPETYPE_POINT = "point"
29    
30    # mapping from shapelib shapetype constants to our constants
31    shapelib_shapetypes = {shapelib.SHPT_POLYGON: SHAPETYPE_POLYGON,
32                           shapelib.SHPT_ARC: SHAPETYPE_ARC,
33                           shapelib.SHPT_POINT: SHAPETYPE_POINT}
34    
35    
36    class Shape:
37    
38        """Represent one shape"""
39    
40        def __init__(self, points):
41            self.points = points
42            #self.compute_bbox()
43            self.bbox = None
44    
45        def compute_bbox(self):
46            if self.bbox is not None:
47                return self.bbox
48    
49            xs = []
50            ys = []
51            for part in self.points:
52                for x, y in part:
53                    xs.append(x)
54                    ys.append(y)
55            self.llx = min(xs)
56            self.lly = min(ys)
57            self.urx = max(xs)
58            self.ury = max(ys)
59    
60            self.bbox = (self.llx, self.lly, self.urx, self.ury)
61    
62            return self.bbox
63    
64        def Points(self):
65            return self.points
66    
67    
68    
69  class ShapeTable(transientdb.AutoTransientTable):  class ShapeTable(transientdb.AutoTransientTable):
70    
# Line 60  class ShapefileStore: Line 105  class ShapefileStore:
105          self.dbftable = table.DBFTable(filename)          self.dbftable = table.DBFTable(filename)
106          self.table = ShapeTable(self, session.TransientDB(), self.dbftable)          self.table = ShapeTable(self, session.TransientDB(), self.dbftable)
107    
108            self.numshapes, shapetype, mins, maxs = self.shapefile.info()
109            if self.numshapes:
110                self.bbox = mins[:2] + maxs[:2]
111            else:
112                self.bbox = None
113            self.shapetype = shapelib_shapetypes[shapetype]
114    
115            # estimate a good depth for the quad tree. Each depth multiplies
116            # the number of nodes by four, therefore we basically take the
117            # base 4 logarithm of the number of shapes.
118            if self.numshapes < 4:
119                maxdepth = 1
120            else:
121                maxdepth = int(ceil(log(self.numshapes / 4.0) / log(4)))
122    
123            self.shapetree = shptree.SHPTree(self.shapefile.cobject(), 2,
124                                             maxdepth)
125    
126      def Table(self):      def Table(self):
127          """Return the table containing the attribute data"""          """Return the table containing the attribute data"""
128          return self.table          return self.table
# Line 76  class ShapefileStore: Line 139  class ShapefileStore:
139          """Return the filetype. This is always the string 'shapefile'"""          """Return the filetype. This is always the string 'shapefile'"""
140          return "shapefile"          return "shapefile"
141    
142        def ShapeType(self):
143            """Return the type of the shapes in the shapestore.
144    
145            This is either SHAPETYPE_POINT, SHAPETYPE_ARC or SHAPETYPE_POLYGON.
146            """
147            return self.shapetype
148    
149        def NumShapes(self):
150            """Return the number of shapes in the shape store"""
151            return self.numshapes
152    
153      def Dependencies(self):      def Dependencies(self):
154          """Return the empty tuple.          """Return the empty tuple.
155    
# Line 90  class ShapefileStore: Line 164  class ShapefileStore:
164          """          """
165          return None          return None
166    
167        def BoundingBox(self):
168            """Return the bounding box of the shapes in the shapestore.
169    
170            The coordinate system used is whatever was used in the shapefile.
171            If the shapefile is empty, return None.
172            """
173            return self.bbox
174    
175        def ShapesInRegion(self, box):
176            """Return the ids of the shapes that overlap the box.
177    
178            Box is a tuple (left, bottom, right, top) in the coordinate
179            system used used in the shapefile.
180            """
181            left, bottom, right, top = box
182            return self.shapetree.find_shapes((left, bottom), (right, top))
183    
184        def Shape(self, index):
185            """Return the shape with index index"""
186            shape = self.shapefile.read_object(index)
187    
188            if self.ShapeType() == SHAPETYPE_POINT:
189                points = [shape.vertices()]
190            else:
191                points = []
192                for poly in shape.vertices():
193                    part = []
194                    for x, y in poly:
195                        part.append((x, y))
196                    points.append(part)
197    
198            return Shape(points)
199    
200    
201    
202  class DerivedShapeStore:  class DerivedShapeStore:
203    
# Line 129  class DerivedShapeStore: Line 237  class DerivedShapeStore:
237          Return the original shapestore the derived store was instantiated with          Return the original shapestore the derived store was instantiated with
238          """          """
239          return self.shapestore          return self.shapestore
240    
241        def Shape(self, index):
242            """Return the shape with index index"""
243            return self.shapestore.Shape(index)
244    
245        def ShapesInRegion(self, bbox):
246            """Return the ids of the shapes that overlap the box.
247    
248            This method is simply delegated to the shapestore the
249            DerivedShapeStore was instantiated with.
250            """
251            return self.shapestore.ShapesInRegion(bbox)
252    
253        def ShapeType(self):
254            """Return the type of the shapes in the layer.
255    
256            This method is simply delegated to the shapestore the
257            DerivedShapeStore was instantiated with.
258            """
259            return self.shapestore.ShapeType()
260    
261        def NumShapes(self):
262            """Return the number of shapes in the shapestore."""
263            return self.shapestore.NumShapes()
264    
265        def BoundingBox(self):
266            """Return the bounding box of the shapes in the shapestore.
267    
268            This method is simply delegated to the shapestore the
269            DerivedShapeStore was instantiated with.
270            """
271            return self.shapestore.BoundingBox()
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