AO+C++实现唯一值渲染

                                        //对行政略图中的面图层进行唯一值渲染
					ipFeaClass = ipTmpFeaCls;
					ipGeoFeaLayer = ipTmpGeoFeaLayer;

					IQueryFilterPtr ipQueryFilter(__uuidof(QueryFilter));
					IFeatureCursorPtr ipcursor;
					ipFeaClass->Search(ipQueryFilter, false, &ipcursor);


					
					ISimpleFillSymbolPtr ipsymbol(CLSID_SimpleFillSymbol);

					
					//随机颜色
					IRandomColorRampPtr iprx(CLSID_RandomColorRamp);
					iprx->put_MinSaturation(20);
					iprx->put_MaxSaturation(40);
					iprx->put_MinValue(76);
					iprx->put_MaxValue(188);
					iprx->put_StartHue(0);
					iprx->put_EndHue(360);
					iprx->put_Size(100);

					VARIANT_BOOL btrue = true;
					iprx->CreateRamp(&btrue);

					IEnumColorsPtr ipnumcolors;
					iprx->get_Colors(&ipnumcolors);
					if(ipnumcolors == NULL)
						return;
					ipnumcolors->Reset();

					IUniqueValueRendererPtr ipuniqueRnd;
					IFeatureRendererPtr ipRnd;
					if((ipuniqueRnd = ipRnd) == NULL)
					{
						hr = ipuniqueRnd.CreateInstance(CLSID_UniqueValueRenderer);
						if(FAILED(hr))
							return;
						ipRnd = ipuniqueRnd;
					}
					CString fname = _T("FNAME");
					BSTR fieldname = fname.AllocSysString();

					ipuniqueRnd->put_FieldCount(1);
					ipuniqueRnd->put_Field(0, fieldname);


					//遍历
					IFeaturePtr ipfeat;
					ipcursor->NextFeature(&ipfeat);
					IFieldsPtr ifields;
					long index;
					ipfeat->get_Fields(&ifields);
					ifields->FindField(fieldname, &index);

					ISimpleLineSymbolPtr ipline(CLSID_SimpleLineSymbol);
					ipline->put_Width(0.01);

					
					while(ipfeat != NULL)
					{
						ISimpleFillSymbolPtr ipsymbol(CLSID_SimpleFillSymbol);
						
						IColorPtr ipcolor2;
						ipnumcolors->Next(&ipcolor2);
						ipsymbol->put_Color(ipcolor2);
						ipsymbol->put_Outline(ipline);

						VARIANT valuevar;
						ipfeat->get_Value(index, &valuevar);
						CString valuestr(valuevar);
						BSTR valuebstr = valuestr.AllocSysString();
						ipuniqueRnd->AddValue(valuebstr, valuebstr, (ISymbolPtr)ipsymbol);

						ipcursor->NextFeature(&ipfeat);
					}
					ipRnd = (IFeatureRendererPtr)ipuniqueRnd;
					ipGeoFeaLayer->putref_Renderer(ipRnd);