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The SelectionAPI provides functions to select areas on a map and display them graphically.
It is based on an IWMap, which represents the basic map and provides the basic functionalities such as pan, zoom. The areas to be selected (for example, zip code areas) are represented by the base layer. The selected areas are displayed in an overlying layer. There is also the possibility of additional layers. Base layer, selection layer and additional layers can be filtered geographical and/or by their attribute values with their own rendering options.
When selecting a new base layer all selections and associated layers are reset.
To use the SelectionAPI, the integration of the MapAPI-1.1 is necessary. The following code snippet shows how such integration can be performed on an HTML page:
<script type="text/javascript" src=http://iw.mapandroute.de/MapAPI-1.1/js/core.js"></script>
This provides the basic functionalities of MapAPI. The requiered functions for the SelectionAPI, are located in the module
'selection'
. These can be loaded with the following code snippet:
IWLoader.loadModules(['selection']);
The following steps should only be performed when the modules are fully loaded. For this purpose the MapAPI provides an event
'onmoduleload'
, which is called when the requested modules have been loaded.
IWEventManager.addListener(IWLoader, 'onmoduleload', function(event) {
if (event.name == 'selection') {
//now you can use the SelectionAPI
}
});
Please remember to declare the listener before loading the modules!
For the SelectionAPI there are special layers, which can be accessed via the IWSelectionManager
. When initializing the
IWSelectionManager
these layers are loaded and are available after initialization. For this purpose, the
IWSelectionManager
trigger the event
'oninitialize'
, in which the existing layers are included. Each layer in turn contains a 'layerName' and a 'layerId'. The name is used to display. The ID is used to identify the layer and is an input parameter in
many functions of the SelectionAPI. Here is a code snippet:
//initialize selectionManager
selectionManager = new IWSelectionManager();
IWEventManager.addListener(selectionManager, 'oninitialize', function(event)
{
var layers = event.layers;
for(var i=0; i<layers.length; i++) {
// Zugriff auf layers[i].layerId
// und layers[i].layerName
}
});
Alternatively to the attribute 'layers' in the event object, the available layers can be retrieved with the method
selectionManager.getLayers()
and can be displayed in a list.
The basis of a selection is a
IWMap
, that can be initialized using the standard methods of the MapAPI-1.1
map = new IWMap(mapContainer);
map.setCenter(coord, zoomLevel, maptype);
The central object of SelectionAPI is the
IWSelectableMap
. This provides a container for underlying
IWMap
, the baselayer, the selectionlayer and the additional layers. By alteration of rendering options the appearance of the layers can be customized. Here is an example how a
IWSelectableMap
can be initialized:
selectableMap = new IWSelectableMap(map);
If IWSelectableMap
is initialized you can set the layer which you want to use for selecting.
selectableMap.setLayer(layerId, area, filters, baseLayerRenderOptions, highlightRenderOptions, selectionRenderOptions);
Name | Description |
---|---|
layerId | Id of the layer to select |
area | Limiting the shown geometries to the given area.
|
filters | Limiting the shown geometries with the given filter.
|
baseLayerRenderOptions | RenderOptions for baselayer |
highlightRenderOptions | RenderOptions for highlighting (mouseover) |
selectionRenderOptions | RenderOptions for selectionlayer |
If the layer is set, the event 'onlayerchanged' is thrown. To respond to changes in the selection, another listener must be defined in the listener of this event which respond to the event 'onselectionchange'. Here is the list of the selected elements are accessed
IWEventManager.addListener(selectableMap, 'onlayerchanged', function(event)
{
selectionchangeListener = IWEventManager.addListener(selectableMap,
'onselectionchange', function(event)
{
showSelectedItems(event.selectedItems);
});
});
Starting the selection means that the map is initialized, a base layer was selected and now the elements of this base layer can be selected on the map. How a selection is performed depends on the one hand by the "tool" (point, circle, polygon, ID) and on the other hand by the "mode".
The mode determines how the selected elements should be included in the current selection. The different modes are defined as constants in the
IWSelectionMode
class.
Name | Description |
---|---|
NONE | no selection possible |
ADD | adds the selected items to the current selection |
REMOVE | deletes the selected items from the current selection |
TOGGLE | changes the selection state of the selected elements |
EXCLUSIV | moves the selection exclusively on selected items |
UNSELECTALL | deletes all selected items from the current selection |
Allows the selection by clicking on elements of the base layer. The element which includes the corresponding coordinate is now added or removed from the current selection.
selectableMap.selectByCoordinate(selectionMode);
By clicking and dragging on the map a circle is spanned that selects all the elements that intersect this circle.
selectableMap.selectByCircle(selectionMode);
With several clicks on the map a polygon is spanned that selects all the elements that intersect this polygon.
selectableMap.selectByPolygon(selectionMode);
The elements of a selection layer consist of at least an ID and a name. The ID can be used to add or remove elements in/from the selection, without the graphical support at the map. For this, the following method can be used:
selectableMap.selectById(id, selectionMode);
The parameter id can be a comma-separated list of ids to select more than one ID.
If the selection should be stopped, the method
disableSelect()
can be called, whereby the standard functions of the map (move, zoom, ..) are restored.
selectableMap.disableSelect();
var filters = [{type:'value',key:'ID',value:'53175'}];
selectableMap.drawLayer('PLZ', null, filters, {"fill": "red", "fillOpacity":0, "stroke": "blue", "strokeWidth": 8}, null);
Essentially the selectableMap consists of layers which can be customized in its presentation with the following rendering options:
Property | Description | Value |
---|---|---|
fill | the fill or text color | CSS color description, e.g. #ff0000 or blue or rgb, such as rgb(0,0,0,0) |
fillOpacity | the opacity of the fill color | value between 0 (transparent) 1 (opaque) |
stroke | the stroke color | CSS color description, e.g. #ff0000 or blue |
strokeWidth | the width of the stroke in pixels | number |
The following methods can set new rendering options for base layer, the selection and the highlighting (mouseOver), which are passed as JSON objects:
var renderOptions = JSON.parse('{"fill": "red", "fillOpacity":0.5, "stroke": "0/0/0", "strokeWidth": 10}');
selectableMap.setRenderOptions(renderOptions);
selectableMap.setBaseLayerRenderOptions(baseLayerRenderOptions);
selectableMap.setHighlightingRenderOptions(highlightingRenderOptions);
Events are thrown by the API to notify the client that initializations or changes are completed. These events must be intercepted by appropriate Listener. For this purpose, the method
addListener
of
IWEventManager
can be used (more on this in the documentation of MapAPI).
Certain functionalities are only available when the corresponding event was received. For example, the available layer will only be requested if the SelectionManager has been initialized.
'graphics'
and
'selection'
are required:
IWLoader.loadModules(['graphics','selection']);
The listener can be defined as follows:
IWEventManager.addListener(IWLoader, 'onmoduleload', function(event) {
if(event.name == 'selection') {
...
}
});
Informs the client that the manager was initialized after
new IWSelectionManager()
is called. After that, the layers are available.
IWEventManager.addListener(selectionManager, 'oninitialize', function (event) {
var layers = event.layers; //weitere Verarbeitung
});
In the attribute 'layers' this event provides an array with the existing base layers. Each object in this array has the following attributes:
Name | Description |
---|---|
layerId | Id of the layer |
layerName | Name of the layer to display |
Is thrown if a new layer is selected. This can be done via the method
selectableMap.setLayers()
:
IWEventManager.addListener(selectableMap, 'onlayerchanged', function(event){ //selection can be started });
selectableMap.setLayer(layerId, area, filters, baseLayerRenderOptions, highlightingRenderOptions, selectionRenderOptions);
The baselayer is now fully initialized and the selection can be started.
is thrown when the selection has changed.
IWEventManager.addListener(selectableMap, 'onselectionchange', function(event) {
showSelectedItems(event.selectedItems); });
The event includes the attribute selectedItems
, which contains a list of all selected elements. Each item has the following attributes:
Name | Description |
---|---|
itemId | Id of the element |
itemName | Name of the element to display |
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