AutoCAD.NET文档事件：DocumentActivationChanged

关于DocumentCollection 的 DocumentActivationChanged 事件，查阅资料找到的解释是：活动文档窗口失活或销毁时触发。作为文档级别的事件，我理解的是要切换或者打开关闭文档才会触发该事件，所以在做层表事件响应的时候订阅了该事件，用以刷新图层列表。

后来发现：在进行一些图元编辑操作（比如移动多段线节点啥）的时候，鼠标会异常卡顿。最开始很纳闷，以为是订阅了 Object 相关事件造成的，专门控制变量做了好一阵测试，最后发现上述事件才是罪魁祸首，以下测试代码：

        [CommandMethod("TTT")]public void Test(){
    Application.DocumentManager.DocumentActivationChanged +=DocumentManager_DocumentActivationChanged;}private int count = 0;private void DocumentManager_DocumentActivationChanged(object sender, DocumentActivationChangedEventArgs e){
    count++;Application.DocumentManager.MdiActiveDocument.Editor.WriteMessage("DocumentActivationChanged，Count: " + count + Environment.NewLine);}

然后结果是这样：

我他喵的，随便拖一个节点触发几百次，不卡才怪了。所以这个事件并不仅仅是文档级别，应该是某些窗口刷新都会触发，慎用。
然后，顺便测试了下文档级别全部事件（13个）的触发顺序：

		public void Test(){
    Application.DocumentManager.DocumentCreated += DocumentManager_DocumentCreated;Application.DocumentManager.DocumentActivated += DocumentManager_DocumentActivated;Application.DocumentManager.DocumentBecameCurrent += DocumentManager_DocumentBecameCurrent;Application.DocumentManager.DocumentCreateStarted += DocumentManager_DocumentCreateStarted;Application.DocumentManager.DocumentCreationCanceled += DocumentManager_DocumentCreationCanceled;Application.DocumentManager.DocumentDestroyed += DocumentManager_DocumentDestroyed;Application.DocumentManager.DocumentLockModeChangeVetoed += DocumentManager_DocumentLockModeChangeVetoed;Application.DocumentManager.DocumentLockModeChanged += DocumentManager_DocumentLockModeChanged;Application.DocumentManager.DocumentLockModeWillChange += DocumentManager_DocumentLockModeWillChange;Application.DocumentManager.DocumentToBeActivated += DocumentManager_DocumentToBeActivated;Application.DocumentManager.DocumentToBeDeactivated += DocumentManager_DocumentToBeDeactivated;Application.DocumentManager.DocumentToBeDestroyed += DocumentManager_DocumentToBeDestroyed;Application.DocumentManager.DocumentActivationChanged +=DocumentManager_DocumentActivationChanged;}private int step = 0;private string fileName=@"d:test.txt";private void DocumentManager_DocumentToBeDestroyed(object sender, DocumentCollectionEventArgs e){
    step++;HtFileHelper.AppendText("step " + step + " :DocumentToBeDestroyed", fileName);}//后面就不一一列出....

文档从打开到关闭，大致顺序如下：

省略号是Step1+Step2组合的重复，意义不大，就删掉了，测试并不严谨，仅供参考。

最后，想起之前一个前辈的告诫：慎用事件，在你不确定的时候。