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Updated OGR (markdown)

tmcw 2011-12-21 09:44:21 -08:00
parent 3992db33e8
commit 8478a12123
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OGR.md

@ -1,9 +1,3 @@
<!-- Name: OGR -->
<!-- Version: 10 -->
<!-- Last-Modified: 2011/08/03 13:16:21 -->
<!-- Author: tmcw -->
Mapnik's PluginArchitecture supports the use of different input formats.
This plugin supports the [OGR](http://www.gdal.org/ogr/index.html) library in order to read multiple spatial vector formats.
@ -37,7 +31,7 @@ To check if the ogr plugin built and was installed correctly, try the usual Pyth
*Note*: The layer names of OGR datasources are returned by Mapnik in the error message when you do not provide the `layer` parameter.
#!python
```python
>>> import mapnik
>>> mapnik.Ogr(file='test_point_line.gpx')
Traceback (most recent call last):
@ -47,11 +41,12 @@ To check if the ogr plugin built and was installed correctly, try the usual Pyth
RuntimeError: missing <layer> parameter, available layers are: 'waypoints' 'routes' 'tracks' 'route_points' 'track_points'
>>> mapnik.Ogr(file='test_point_line.gpx',layer='waypoints')
<mapnik.Datasource object at 0x23f6b0> # works!
```
However the best way to discover the layer names is to use the OGR provided utility called `ogrinfo`. For example running `ogrinfo` on a test GPX files provided with the OGR source code reveals the layer names and geometry types:
#!sh
```sh
$ ogrinfo test_point_line.gpx
Had to open data source read-only.
INFO: Open of `test_point_line.gpx'
@ -61,12 +56,12 @@ However the best way to discover the layer names is to use the OGR provided util
3: tracks (Multi Line String)
4: route_points (Point)
5: track_points (Point)
```
## XML
#!xml
```xml
<Layer name="gps_waypoints">
<StyleName>waypoint_styles</StyleName>
<Datasource>
@ -75,9 +70,9 @@ However the best way to discover the layer names is to use the OGR provided util
<Parameter name="layer">waypoints</Parameter>
</Datasource>
</Layer>
```
#!xml
```xml
<Layer name="states">
<StyleName>states_shp_styles</StyleName>
<Datasource>
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<Parameter name="layer">us_states</Parameter>
</Datasource>
</Layer>
```
## C++
@ -97,7 +93,7 @@ Plugin datasource initialization example code can be found on PluginArchitecture
A OGR datasource may be created as follows:
#!C
```cpp
{
parameters p;
p["type"]="ogr";
@ -111,6 +107,6 @@ A OGR datasource may be created as follows:
lyr.add_style("bridges");
m.addLayer(lyr);
}
```
## Further References