ae开发基础功能

放大、缩小、pan、框选要素（新建命令，建立命令HOOK，赋给当前地图控件）：

ICommand cmd = new ControlsSelectFeaturesTool();
cmd.OnCreate(axMapControl1.Object);
axMapControl1.CurrentTool = cmd as ITool;

取消要素选择（层——要素选择——清空）：

IFeatureSelection pfs = axMapControl1.get_Layer(0) as IFeatureSelection;
pfs.Clear();
axMapControl1.Refresh();
axMapControl1.CurrentTool = null;