public static IEnumerable <T> GetUniqueColumnValues <T>(ICursor cursor, string columnName)
{
IDataStatistics dataStatistics = null;
try
{
//获取null值
T nullValue = default(T);
dataStatistics = new DataStatisticsClass();
dataStatistics.Cursor = cursor;
dataStatistics.Field = columnName;
IEnumerator enumerator = dataStatistics.UniqueValues;
enumerator.Reset();
while (enumerator.MoveNext())
{
object currValue = enumerator.Current;
if (currValue == DBNull.Value || currValue == null)
{
yield return(nullValue);
}
else
{
yield return((T)Convert.ChangeType(currValue, typeof(T)));
}
}
}
finally
{
AOUtil.ReleaseComObjectAllRefs(dataStatistics);
}
}
public override void OnClick()
{
ILayer pLayer = (ILayer)_mapControl.CustomProperty;
if (pLayer is IGroupLayer)
{
//获取GroupLayer中的图层
var subLayers = LayerUtil.GetFeatureLayersFromGroupLayer(pLayer as IGroupLayer);
foreach (var subLayer in subLayers)
{
_mapControl.Map.DeleteLayer(subLayer);
AOUtil.ReleaseComObjectAllRefs(subLayer);
}
}
_mapControl.Map.DeleteLayer(pLayer);
_mapControl.ActiveView.Refresh();
AOUtil.ReleaseComObjectAllRefs(pLayer);
}
public override void OnClick()
{
_mapControl.Map.ClearLayers();
AOUtil.ReleaseComObjectAllRefs(_mapControl.Map.Layers);
_mapControl.ActiveView.Refresh();
}