ArcGIS Engine Developer Guide

C++ APPLICATION PROGRAMMING INTERFACE
• ISet—provides access to members that control a simple set of unique objects.
For example, the following code snippet cycles through a map’s layers and
attempts to add all of the unique feature class workspaces that aren’t being
edited to a set.
// ipMap is of type IMapPtr and was previously declared and instantiated.
ISetPtr ipSet(CLSID_Set);
ILayerPtr ipLayer;
IFeatureLayerPtr ipFeatLayer;
IFeatureClassPtr ipFeatClass;
IDatasetPtr ipDataset;
IWorkspacePtr ipWorkspace;
IWorkspaceEditPtr ipWorkspaceEdit;
long layerCount;
hr = ipMap->get_LayerCount(&layerCount);
for (long i=0; iget_Layer(i, &ipLayer);
ipFeatLayer = ipLayer;
// Layer might not be a feature layer.
if (ipFeatLayer == 0 || FAILED(hr)) continue;
hr = ipFeatLayer->get_FeatureClass(&ipFeatClass);
// Layer could reference bogus data.
if (ipFeatClass == 0 || FAILED(hr)) continue;
ipDataset = ipFeatClass;
hr = ipDataset->get_Workspace (&ipWorkspace);
ipWorkspaceEdit = ipWorkspace;
// Some data is not editable.
if (ipWorkspaceEdit == 0 || FAILED(hr)) continue;
VARIANT_BOOL beingEdited;
hr = ipWorkspaceEdit->IsBeingEdited(&beingEdited);
if (!beingEdited)
{
// Only adds unique workspaces
hr = ipSet->Add(ipWorkspace);
}
}
Copy objects
The IClone interface is helpful when comparing and copying objects, saving time,
and computing resources. Many coclasses support the IClone interface. See the
documentation for IClone in ArcGIS Developer Help for details. The following
code snippet clones a Point object:
// ipMouseClickPoint is of type IPointPtr and was previously declared
// and instantiated.
IClonePtr ipClone (ipMouseClickPoint);
IClonePtr ipCloned;
ipClone->Clone(&ipCloned);
230 • ArcGIS Engine Developer Guide