1 | /* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for |
---|
2 | * full list of contributors). Published under the Clear BSD license. |
---|
3 | * See http://svn.openlayers.org/trunk/openlayers/license.txt for the |
---|
4 | * full text of the license. */ |
---|
5 | |
---|
6 | /** |
---|
7 | * @requires OpenLayers/Util.js |
---|
8 | */ |
---|
9 | |
---|
10 | /** |
---|
11 | * Class: OpenLayers.Projection |
---|
12 | * Class for coordinate transforms between coordinate systems. |
---|
13 | * Depends on the proj4js library. If proj4js is not available, |
---|
14 | * then this is just an empty stub. |
---|
15 | */ |
---|
16 | OpenLayers.Projection = OpenLayers.Class({ |
---|
17 | |
---|
18 | /** |
---|
19 | * Property: proj |
---|
20 | * {Object} Proj4js.Proj instance. |
---|
21 | */ |
---|
22 | proj: null, |
---|
23 | |
---|
24 | /** |
---|
25 | * Property: projCode |
---|
26 | * {String} |
---|
27 | */ |
---|
28 | projCode: null, |
---|
29 | |
---|
30 | /** |
---|
31 | * Constructor: OpenLayers.Projection |
---|
32 | * This class offers several methods for interacting with a wrapped |
---|
33 | * pro4js projection object. |
---|
34 | * |
---|
35 | * Parameters: |
---|
36 | * projCode - {String} A string identifying the Well Known Identifier for |
---|
37 | * the projection. |
---|
38 | * options - {Object} An optional object to set additional properties |
---|
39 | * on the layer. |
---|
40 | * |
---|
41 | * Returns: |
---|
42 | * {<OpenLayers.Projection>} A projection object. |
---|
43 | */ |
---|
44 | initialize: function(projCode, options) { |
---|
45 | OpenLayers.Util.extend(this, options); |
---|
46 | this.projCode = projCode; |
---|
47 | if (window.Proj4js) { |
---|
48 | this.proj = new Proj4js.Proj(projCode); |
---|
49 | } |
---|
50 | }, |
---|
51 | |
---|
52 | /** |
---|
53 | * APIMethod: getCode |
---|
54 | * Get the string SRS code. |
---|
55 | * |
---|
56 | * Returns: |
---|
57 | * {String} The SRS code. |
---|
58 | */ |
---|
59 | getCode: function() { |
---|
60 | return this.proj ? this.proj.srsCode : this.projCode; |
---|
61 | }, |
---|
62 | |
---|
63 | /** |
---|
64 | * APIMethod: getUnits |
---|
65 | * Get the units string for the projection -- returns null if |
---|
66 | * proj4js is not available. |
---|
67 | * |
---|
68 | * Returns: |
---|
69 | * {String} The units abbreviation. |
---|
70 | */ |
---|
71 | getUnits: function() { |
---|
72 | return this.proj ? this.proj.units : null; |
---|
73 | }, |
---|
74 | |
---|
75 | /** |
---|
76 | * Method: toString |
---|
77 | * Convert projection to string (getCode wrapper). |
---|
78 | * |
---|
79 | * Returns: |
---|
80 | * {String} The projection code. |
---|
81 | */ |
---|
82 | toString: function() { |
---|
83 | return this.getCode(); |
---|
84 | }, |
---|
85 | |
---|
86 | /** |
---|
87 | * Method: equals |
---|
88 | * Test equality of two projection instances. Determines equality based |
---|
89 | * soley on the projection code. |
---|
90 | * |
---|
91 | * Returns: |
---|
92 | * {Boolean} The two projections are equivalent. |
---|
93 | */ |
---|
94 | equals: function(projection) { |
---|
95 | if (projection && projection.getCode) { |
---|
96 | return this.getCode() == projection.getCode(); |
---|
97 | } else { |
---|
98 | return false; |
---|
99 | } |
---|
100 | }, |
---|
101 | |
---|
102 | /* Method: destroy |
---|
103 | * Destroy projection object. |
---|
104 | */ |
---|
105 | destroy: function() { |
---|
106 | delete this.proj; |
---|
107 | delete this.projCode; |
---|
108 | }, |
---|
109 | |
---|
110 | CLASS_NAME: "OpenLayers.Projection" |
---|
111 | }); |
---|
112 | |
---|
113 | /** |
---|
114 | * Property: transforms |
---|
115 | * Transforms is an object, with from properties, each of which may |
---|
116 | * have a to property. This allows you to define projections without |
---|
117 | * requiring support for proj4js to be included. |
---|
118 | * |
---|
119 | * This object has keys which correspond to a 'source' projection object. The |
---|
120 | * keys should be strings, corresponding to the projection.getCode() value. |
---|
121 | * Each source projection object should have a set of destination projection |
---|
122 | * keys included in the object. |
---|
123 | * |
---|
124 | * Each value in the destination object should be a transformation function, |
---|
125 | * where the function is expected to be passed an object with a .x and a .y |
---|
126 | * property. The function should return the object, with the .x and .y |
---|
127 | * transformed according to the transformation function. |
---|
128 | * |
---|
129 | * Note - Properties on this object should not be set directly. To add a |
---|
130 | * transform method to this object, use the <addTransform> method. For an |
---|
131 | * example of usage, see the OpenLayers.Layer.SphericalMercator file. |
---|
132 | */ |
---|
133 | OpenLayers.Projection.transforms = {}; |
---|
134 | |
---|
135 | /** |
---|
136 | * APIMethod: addTransform |
---|
137 | * Set a custom transform method between two projections. Use this method in |
---|
138 | * cases where the proj4js lib is not available or where custom projections |
---|
139 | * need to be handled. |
---|
140 | * |
---|
141 | * Parameters: |
---|
142 | * from - {String} The code for the source projection |
---|
143 | * to - {String} the code for the destination projection |
---|
144 | * method - {Function} A function that takes a point as an argument and |
---|
145 | * transforms that point from the source to the destination projection |
---|
146 | * in place. The original point should be modified. |
---|
147 | */ |
---|
148 | OpenLayers.Projection.addTransform = function(from, to, method) { |
---|
149 | if(!OpenLayers.Projection.transforms[from]) { |
---|
150 | OpenLayers.Projection.transforms[from] = {}; |
---|
151 | } |
---|
152 | OpenLayers.Projection.transforms[from][to] = method; |
---|
153 | }; |
---|
154 | |
---|
155 | /** |
---|
156 | * APIMethod: transform |
---|
157 | * Transform a point coordinate from one projection to another. Note that |
---|
158 | * the input point is transformed in place. |
---|
159 | * |
---|
160 | * Parameters: |
---|
161 | * point - {{OpenLayers.Geometry.Point> | Object} An object with x and y |
---|
162 | * properties representing coordinates in those dimensions. |
---|
163 | * sourceProj - {OpenLayers.Projection} Source map coordinate system |
---|
164 | * destProj - {OpenLayers.Projection} Destination map coordinate system |
---|
165 | * |
---|
166 | * Returns: |
---|
167 | * point - {object} A transformed coordinate. The original point is modified. |
---|
168 | */ |
---|
169 | OpenLayers.Projection.transform = function(point, source, dest) { |
---|
170 | if (source.proj && dest.proj) { |
---|
171 | point = Proj4js.transform(source.proj, dest.proj, point); |
---|
172 | } else if (source && dest && |
---|
173 | OpenLayers.Projection.transforms[source.getCode()] && |
---|
174 | OpenLayers.Projection.transforms[source.getCode()][dest.getCode()]) { |
---|
175 | OpenLayers.Projection.transforms[source.getCode()][dest.getCode()](point); |
---|
176 | } |
---|
177 | return point; |
---|
178 | }; |
---|