[mapguide-users] Buffer Creation
tejaswi
tejaswi_a at rediffmail.com
Tue May 19 05:23:08 EDT 2009
hi
I have to do 2 things in my application
1. Select a point from a query function that i have called.Once the point is
selected I have to create a buffer of 1km above this selection point.
I able to select the point through my programming and create the buffer
also(I am creating the buffer function by building my own code not using the
default buffer function).
2. Now once the buffer is showing on the map.its initial state should be
selected , i should not select it manually on the map using the
pointer(mouse).
I am not able to do this.
I am putting in the code for creating buffer....
public void create_buffer()
{
siteConnection = new MgSiteConnection();
userInfo = new MgUserInformation(mgsessionid);
siteConnection.Open(userInfo);
featureService =
(MgFeatureService)siteConnection.CreateService(MgServiceType.FeatureService);
resourceService =
(MgResourceService)siteConnection.CreateService(MgServiceType.ResourceService);
mapDefinition = "Library://DELHI/Maps/DelhiMap.MapDefinition";
resId = new MgResourceIdentifier(mapDefinition);
mapName = resId.GetName();
map.Open(resourceService, mapName);
Lays = map.GetLayers();
//Response.Write(resourceService.GetResourceContent(resId));
//map.Save(resourceService);
/////////----------------------------------------------------------------------
if (ddl_buffer.Text == "1Km")
{
bufferRingSize = 0.003;//0.01;
}
if (ddl_buffer.Text == "3Km")
{
bufferRingSize = 0.007;//0.02;
}
if (ddl_buffer.Text == "5Km")
{
bufferRingSize = 0.015;//0.04;
}
//LayerName = ddl_layers.Text;
//Response.Write(bufferRingSize);
try
{
//btn_select_within.Visible = true;
//btn_buffer_report.Visible = true;
//lblERR.Visible = false;
MgSelection selection = new MgSelection(map);
//Response.Write(selection.GetLayers().GetCount());
selection.Open(resourceService, mapName);
LayerName = selection.GetLayers().GetItem(0).GetName();
layer = LayerByName(map, LayerName);
//Response.Write(layer.GetName());
string LayerClassName = layer.GetFeatureClassName();
string selectionString = "";
selectionString = selection.GenerateFilter(layer,
LayerClassName);
string LayerFeatureId = layer.GetFeatureSourceId();
MgResourceIdentifier LayerFeatureResource = new
MgResourceIdentifier(LayerFeatureId);
queryOptions = new MgFeatureQueryOptions();
queryOptions.SetFilter(selectionString);
featureReader =
featureService.SelectFeatures(LayerFeatureResource, LayerClassName,
queryOptions);
if (selectionString != "")
{
//Response.Write("Selected Feature-->" + selectionString);
bufferRingCount = 3.0;
string mapWktSrs = map.GetMapSRS();
MgAgfReaderWriter agfReaderWriter = new MgAgfReaderWriter();
MgWktReaderWriter wktReaderWriter = new MgWktReaderWriter();
MgCoordinateSystemFactory coordSysFactory = new
MgCoordinateSystemFactory();
MgCoordinateSystem srs = coordSysFactory.Create(mapWktSrs);
MgCoordinateSystemMeasure srsMeasure = srs.GetMeasure();
MgResourceIdentifier bufferFeatureResId;
MgLayerBase bufferLayer;
// Check for a buffer layer. If it exists, delete
// the current features.
// If it does not exist, create a feature source and
// a layer to hold the buffer.
MgLayerBase bufferLayer1 = LayerByName(map, "Buffer");
if (bufferLayer1 == null)//try
{
bufferFeatureResId = new MgResourceIdentifier("Session:"
+ mgsessionid + "//Buffer.FeatureSource");
CreateBufferFeatureSource(featureService, mapWktSrs,
bufferFeatureResId);
bufferLayer = CreateBufferLayer(resourceService,
bufferFeatureResId, mgsessionid);
map.GetLayers().Insert(0, bufferLayer);
bufferLayer.ForceRefresh();
//Response.Write("<script type=text/javascript>");
//Response.Write("parent.parent.mapFrame.Refresh();");
//Response.Write("</script>");
map.Save(resourceService);
//bufferLayer = map.GetLayers().GetItem("Buffer");
//bufferFeatureResId = new
MgResourceIdentifier(bufferLayer.GetFeatureSourceId());
//MgFeatureCommandCollection commands = new
MgFeatureCommandCollection();
//commands.Add(new MgDeleteFeatures("BufferClass", "ID
like '%'"));
//featureService.UpdateFeatures(bufferFeatureResId,
commands, false);
//map.Save(resourceService);
}
else//catch (MgObjectNotFoundException e)
{
RemoveLayer(map, "Buffer");
// When an MgObjectNotFoundException is thrown, the
layer
// does not exist and must be created.
bufferFeatureResId = new MgResourceIdentifier("Session:"
+ mgsessionid + "//Buffer.FeatureSource");
CreateBufferFeatureSource(featureService, mapWktSrs,
bufferFeatureResId);
bufferLayer = CreateBufferLayer(resourceService,
bufferFeatureResId, mgsessionid);
map.GetLayers().Insert(0, bufferLayer);
bufferLayer.ForceRefresh();
Response.Write("<script type=text/javascript>");
Response.Write("parent.parent.mapFrame.Refresh();");
Response.Write("</script>");
map.Save(resourceService);
}
Double srsDist =
srs.ConvertMetersToCoordinateSystemUnits(bufferRingSize);
//--------
///////////----------------------------------------------------------
MgGeometry featureGeometry;
MgLayerCollection selectedLayers = map.GetLayers();
for (int i = 0; i < selectedLayers.GetCount(); i++)
{
// Only check selected features in the Parcels layer.
layer = selectedLayers.GetItem(i);
//
if (layer.GetName() == LayerName)
{
//Response.Write(layer.GetName());
// Create a filter containing the IDs of the
selected features on this layer
String layerClassName = layer.GetFeatureClassName();
selectionString = selection.GenerateFilter(layer,
layerClassName);
// Get the feature resource for the selected layer
String layerFeatureId = layer.GetFeatureSourceId();
MgResourceIdentifier layerFeatureResource = new
MgResourceIdentifier(layerFeatureId);
// Apply the filter to the feature resource for the
selected layer. This returns
// an MgFeatureReader of all the selected features.
queryOptions.SetFilter(selectionString);
featureReader =
featureService.SelectFeatures(layerFeatureResource, layerClassName,
queryOptions);
// Process each item in the MgFeatureReader. Get the
// geometries from all the selected features and
// merge them into a single geometry.
MgGeometryCollection inputGeometries = new
MgGeometryCollection();
while (featureReader.ReadNext())
{
//SHPGEOM
MgByteReader featureGeometryData =
featureReader.GetGeometry("Geometry");
featureGeometry =
agfReaderWriter.Read(featureGeometryData);
inputGeometries.Add(featureGeometry);
}
MgGeometryFactory geometryFactory = new
MgGeometryFactory();
MgMultiGeometry mergedGeometries =
geometryFactory.CreateMultiGeometry(inputGeometries);
// Add buffer features to the temporary feature
source.
// Create multiple concentric buffers to show area.
// If the stylization for the layer draws the
features
// partially transparent, the concentric rings will
be
// progressively darker towards the center.
// The stylization is set in the layer template
file, which
// is used in function CreateBufferLayer().
MgFeatureCommandCollection commands = new
MgFeatureCommandCollection();
for (int bufferRing = 0; bufferRing <
bufferRingCount; bufferRing++)
{
//Double bufferDist =
srs.ConvertMetersToCoordinateSystemUnits(bufferRingSize * (bufferRing + 1));
Double bufferDist = bufferRingSize *(bufferRing
+ 1);
bufferGeometry =
mergedGeometries.Buffer(bufferDist, srsMeasure);
MgPropertyCollection properties = new
MgPropertyCollection();
properties.Add(new
MgGeometryProperty("BufferGeometry",
agfReaderWriter.Write(bufferGeometry)));
//--
//MgByteReader featureGeometryData =
featureReader.GetGeometry("Geometry");
//featureGeometry =
agfReaderWriter.Read(featureGeometryData);
//==
commands.Add(new MgInsertFeatures("BufferClass",
properties));
}
MgPropertyCollection results =
featureService.UpdateFeatures(bufferFeatureResId, commands, false);
bufferLayer.SetVisible(true);
bufferLayer.ForceRefresh();
bufferLayer.SetSelectable(true);
bufferLayer.SetDisplayInLegend(true);
Response.Write("<script type=text/javascript>");
Response.Write("parent.parent.mapFrame.Refresh();");
Response.Write("</script>");
map.Save(resourceService);
}
}
}
}
catch (NullReferenceException f)
{
Response.Write("No selection");
//btn_select_within.Visible = false;
//btn_buffer_report.Visible = false;
//lblERR.Visible = true;
//lblERR.Text = "Select Parcel On Map";
}
}
public void CreateBufferFeatureSource(MgFeatureService featureService,
String wkt, MgResourceIdentifier bufferFeatureResId)
{
MgClassDefinition bufferClass = new MgClassDefinition();
bufferClass.SetName("BufferClass");
MgPropertyDefinitionCollection properties =
bufferClass.GetProperties();
MgDataPropertyDefinition idProperty = new
MgDataPropertyDefinition("ID");
idProperty.SetDataType(MgPropertyType.Int32);
idProperty.SetReadOnly(true);
idProperty.SetNullable(false);
idProperty.SetAutoGeneration(true);
properties.Add(idProperty);
MgGeometricPropertyDefinition polygonProperty = new
MgGeometricPropertyDefinition("BufferGeometry");
polygonProperty.SetGeometryTypes(MgFeatureGeometricType.Surface);
polygonProperty.SetHasElevation(false);
polygonProperty.SetHasMeasure(false);
polygonProperty.SetReadOnly(false);
polygonProperty.SetSpatialContextAssociation("defaultSrs");
properties.Add(polygonProperty);
MgPropertyDefinitionCollection idProperties =
bufferClass.GetIdentityProperties();
idProperties.Add(idProperty);
bufferClass.SetDefaultGeometryPropertyName("BufferGeometry");
MgFeatureSchema bufferSchema = new
MgFeatureSchema("BufferLayerSchema", "temporary schema to hold a buffer");
bufferSchema.GetClasses().Add(bufferClass);
MgCreateSdfParams sdfParams = new MgCreateSdfParams("defaultSrs",
wkt, bufferSchema);
featureService.CreateFeatureSource(bufferFeatureResId, sdfParams);
}
public MgLayer CreateBufferLayer(MgResourceService resourceService,
MgResourceIdentifier bufferFeatureResId, String sessionId)
{
// Load the layer definition template into
// a DOM object, find the "ResourceId" element, and
// modify its content to reference the temporary
// feature source.
XmlDocument doc = new XmlDocument();
doc.PreserveWhitespace = false;
doc.Load(Request.ServerVariables["APPL_PHYSICAL_PATH"] +
"bufferlayerdefinition.xml");
XmlNode featureSourceNode =
doc.GetElementsByTagName("ResourceId").Item(0);
XmlNode resContent =
doc.CreateTextNode(bufferFeatureResId.ToString());
featureSourceNode.AppendChild(resContent);
//featureSourceNode.nodeValue = bufferFeatureResId.ToString();
// Get the updated layer definition from the DOM object
// and save it to the session repository using the
// ResourceService object.
MemoryStream xmlStream = new MemoryStream();
doc.Save(xmlStream);//saveXML();
byte[] layerDefinition = xmlStream.ToArray();
Encoding utf8 = Encoding.UTF8;
String layerDefStr = new String(utf8.GetChars(layerDefinition));
layerDefinition = new byte[layerDefStr.Length - 1];
int byteCount = utf8.GetBytes(layerDefStr, 1, layerDefStr.Length -
1, layerDefinition, 0);
MgByteSource byteSource = new MgByteSource(layerDefinition,
layerDefinition.Length);
byteSource.SetMimeType(MgMimeType.Xml);
MgResourceIdentifier tempLayerResId = new
MgResourceIdentifier("Session:" + sessionId + "//Buffer.LayerDefinition");
//Response.Write(resourceService.ResourceExists(tempLayerResId));//--Error
"NOT IMPLEMENTED"
resourceService.SetResource(tempLayerResId, byteSource.GetReader(),
null);
// Create an MgLayer object based on the new layer definition
// and return it to the caller.
MgLayer bufferLayer = new MgLayer(tempLayerResId, resourceService);
bufferLayer.SetName("Buffer");
bufferLayer.SetLegendLabel("Buffer");
bufferLayer.SetDisplayInLegend(true);
bufferLayer.SetSelectable(false);
bufferLayer.SetVisible(true);
Response.Write("<script type=text/javascript>");
Response.Write("parent.parent.mapFrame.Refresh();");
Response.Write("</script>");
return bufferLayer;
}
Kindly suggest me wat to do..
Thanking you,
Regards
Tejaswi.
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