[mapserver-commits] r11111 - in trunk/docs/en: input/vector mapfile

[svn at osgeo.org]

Author: tamas
Date: 2011-03-08 07:28:31 -0800 (Tue, 08 Mar 2011)
New Revision: 11111

Added:
   trunk/docs/en/input/vector/union.txt
Modified:
   trunk/docs/en/mapfile/layer.txt
Log:
Adding documentation for the union layer provider (#3674)

Added: trunk/docs/en/input/vector/union.txt
===================================================================
--- trunk/docs/en/input/vector/union.txt	                        (rev 0)
+++ trunk/docs/en/input/vector/union.txt	2011-03-08 15:28:31 UTC (rev 11111)
@@ -0,0 +1,93 @@
+.. _union:
+
+*****************************************************************************
+ Union Layer
+*****************************************************************************
+
+:Author: Tamas Szekeres
+:Contact: szekerest at gmail.com
+:Last Updated: 2011-03-08
+
+The union layer provides the option to represent features from multiple 
+layers (called as 'source layers') in a single layer. This functionality
+has been added according to :ref:`rfc68`.
+
+Map File Example
+-----------------
+
+* The CONNECTIONTYPE parameter must be set to UNION.
+* The CONNECTION parameter must contain the comma separated list of the source layers.
+* All of the source layers and the union layer must have the same TYPE.
+* At your convenience you may disable the visibility of the source layers to avoid to display the features twice.
+
+::
+
+	LAYER
+        CONNECTIONTYPE UNION
+        CONNECTION "layer1,layer2,layer3" # reference to the source layers
+        TYPE POINT
+        NAME "union-layer"
+        PROCESSING "ITEMS=itemname1,itemname2,itemname3"
+        STATUS default
+        ...
+    END
+    LAYER
+      CONNECTIONTYPE OGR
+      CONNECTION ...
+      TYPE POINT
+      NAME layer1
+      STATUS off
+      ...
+    END
+    LAYER
+      CONNECTIONTYPE SHAPE
+      CONNECTION ...
+      TYPE POINT
+      NAME layer2
+      STATUS off
+      ...
+    END
+    LAYER
+      CONNECTIONTYPE SHAPE
+      CONNECTION ...
+      TYPE POINT
+      NAME layer3
+      STATUS off
+      ...
+    END
+
+    
+Data Access / Connection Method
+-------------------------------
+
+This is a native MapServer option that doesn't use any external libraries to support it. The CONNECTION
+parameter must contain the name of the source layers from which the features are actually retrieved.
+    
+Feature attributes
+------------------
+
+In the LAYER definition you may refer to any attributes supported by each of the source layers.
+In addition to the source layer attributes the union layer provides the following additional attributes:
+
+1) Combine:SourceLayerName - The name of the source layer the feature belongs to
+2) Combine:SourceLayerGroup - The group of the source layer the feature belongs to
+
+During the selection / feature query operations only the 'Combine:SourceLayerName' and 'Combine:SourceLayerGroup'
+attributes are provided by default. The set of the provided attributes can manually be overridden 
+(and further attributes can be exposed) by using the ITEMS processing option (refer to the example above).
+
+Classes and Styles
+------------------
+
+We can define the symbology and labelling for the union layers in the same way as for
+any other layer by specifying the classes and styles. In addition the STYLEITEM AUTO 
+option is also supported for the union layer, which provides to display 
+the features as specified at the source layers. The source layers 
+may also use the STYLEITEM AUTO setting if the underlying data source provides that.
+
+Projections
+-----------
+
+It is suggested to use the same projection of the union layer and the source layers. The layer provider
+however supports transforming the feature positions between the source layers and the union layer.
+

Modified: trunk/docs/en/mapfile/layer.txt
===================================================================
--- trunk/docs/en/mapfile/layer.txt	2011-03-07 18:19:50 UTC (rev 11110)
+++ trunk/docs/en/mapfile/layer.txt	2011-03-08 15:28:31 UTC (rev 11111)
@@ -42,7 +42,7 @@
         See :ref:`vector` for specific connection information for various
         data sources.
 
-CONNECTIONTYPE [local|sde|ogr|postgis|oraclespatial|wms|wfs|plugin]
+CONNECTIONTYPE [local|sde|ogr|postgis|oraclespatial|wms|wfs|plugin|union]
     Type of connection. Default is local. See additional documentation for 
     any other type.