实现类似“添加扩展程序…”的设计时支持

• 2019 年 10 月 5 日
• 筆記

Ajax Control Toolkit这个控件库内包含一些扩展控件，利用这些扩展控件，可以非常方便的为普通的控件添加Ajax效果，例如，利用AutoCompleteExtender控件，可以为文本框添加自动完成的ajax效果。当然，这并不是本文想讨论的内容。

将Ajax Control Toolkit加入到Visual Studio 2008的工具箱中，并打开一个新的aspx文件，向里面拖入一个TextBox。这时，有趣的事情发生了，在TextBox的SmartTasks面板里，竟然出现了一个“添加扩展程序…”的链接！我又试着拖入一个Button，一个Panel，无一例外的，每个控件的SmartTasks面板的底部都出现了“添加扩展程序…”的链接。

最近我正打算把保存、删除、关闭页面等功能抽象成动作，每一种动作对应一个自定义的Web控件，将某个动作控件附加到目标控件（例如Button）上面之后，目标控件就拥有了诸如保存、删除、关闭页面的功能。如何在WebForm设计器里为一个Button控件方便地附加动作？我想要的正是类似“添加扩展程序…”这样的效果。

开发过自定义服务器控件的朋友应该知道，如果想给控件添加SmartTasks，需要重写ControlDesigner的ActionLists属性，并实现自己的DesignerActionList。显然，一个TextBox并不知道AjaxControlToolkit的存在，所以“添加扩展程序…”这么一个DesignerActionMethodItem并不是它加进来的。那么，.net framework是否提供了某种接口，可以让我们为别的控件“动态的注入”DesignerActionItem呢？

通过对AjaxControlToolKit.dll的研究，我发现这些扩展控件的Designer并不负责提供“添加扩展程序”这个Action，他们只负责提供相应扩展程序对应的扩展内容，所以只能从Visual studio的webform designer作为入口来研究。用reflector打开Microsoft Visual Studio 9.0Common7IDEMicrosoft.Web.Design.Client.dll，找到了IWebSmartTasksProvider接口，该接口有一个GetDesignerActionLists的方法，这个方法的返回值应该就是SmartTasks面板里显示的内容了。这个接口有3个实现类，DataFormDesigner、DataFormXslValueOfDesigner、ElementDesigner。从这三个类的命名上可以推断，ElementDesigner应该是用的最多的实现类了。ElementDesigner的GetDesignerActionLists的方法实现如下：

1: DesignerActionListCollection IWebSmartTasksProvider.GetDesignerActionLists()   2: {   3:     DesignerActionListCollection componentActions = null;   4:     if (this.Designer != null)   5:     {   6:         DesignerActionService service = (DesignerActionService) base.DesignerHost.GetService(typeof(DesignerActionService));   7:         if (service != null)   8:         {   9:             componentActions = service.GetComponentActions(this.Designer.Component);  10:         }  11:     }  12:     if (componentActions == null)  13:     {  14:         componentActions = new DesignerActionListCollection();  15:     }  16:     return componentActions;  17: }  18:    19:    20:    21:

从上面代码里可以看到最终的DesignerActionListCollection是由System.Design程序集下的System.ComponentModel.Design.DesignerActionService类的GetComponentActions决定的，Microsoft.Web.Design.Client.dll下的Microsoft.Web.Design.WebFormDesigner+WebDesignerActionService继承了该类，他的实现如下：

1: protected override void GetComponentDesignerActions(IComponent component, DesignerActionListCollection actionLists)   2: {   3:     Control control = component as Control;   4:     ElementDesigner parent = null;   5:     if (control != null)   6:     {   7:         parent = ElementDesigner.GetElementDesigner(control);   8:     }   9:     if ((parent == null) || !parent.InTemplateMode)  10:     {  11:         base.GetComponentDesignerActions(component, actionLists);  12:         if ((parent != null) && (parent.Designer != null))  13:         {  14:             ControlDesigner designer = parent.Designer as ControlDesigner;  15:             if ((designer != null) && (designer.AutoFormats.Count > 0))  16:             {  17:                 actionLists.Insert(0, new AutoFormatActionList(parent));  18:             }  19:         }  20:         if ((parent != null) && (parent.Element != null))  21:         {  22:             IWebDataFormElementCallback dataFormElementCallback = parent.Element.GetDataFormElementCallback();  23:             if (dataFormElementCallback != null)  24:             {  25:                 DataFormElementActionList list = new DataFormElementActionList(parent, parent.Control, dataFormElementCallback);  26:                 actionLists.Add(list);  27:                 DataFormElementActionList.ModifyActionListsForListControl(actionLists, list);  28:             }  29:         }  30:         if (((parent != null) && (parent.Designer != null)) && parent.DocumentDesigner.ExtenderControlHelper.ProvidesActionLists)  31:         {  32:             parent.DocumentDesigner.ExtenderControlHelper.AddActionLists(parent, actionLists);  33:         }  34:     }  35:     if ((parent != null) && (parent.TemplateEditingUI != null))  36:     {  37:         actionLists.Add(new TemplateEditingActionList(parent.TemplateEditingUI, parent.Element));  38:     }  39: }  40:    41:    42:    43:

这个方法里，有这么一段：

1: if (((parent != null) && (parent.Designer != null)) && parent.DocumentDesigner.ExtenderControlHelper.ProvidesActionLists)   2:        {   3:            parent.DocumentDesigner.ExtenderControlHelper.AddActionLists(parent, actionLists);   4:        }

看来“添加扩展程序”这个action就是在这里加进去的了。继续查看ExtenderControlHelper.AddActionLists的实现：

1: public void AddActionLists(ElementDesigner element, DesignerActionListCollection lists)   2: {   3:     lists.Add(new ControlExtenderActionList(element));   4:     ExtenderControl component = element.Designer.Component as ExtenderControl;   5:     Control control = element.Designer.Component as Control;   6:     if ((component == null) && (control != null))   7:     {   8:         IExtenderInformationService service = (IExtenderInformationService) control.Site.GetService(typeof(IExtenderInformationService));   9:         if (service != null)  10:         {  11:             foreach (Control control3 in service.GetAppliedExtenders(control))  12:             {  13:                 lists.Add(new HoistedExtenderActionList(element.Designer, control3));  14:             }  15:         }  16:     }  17: }  18:    19:    20:    21:

这个方法里的第一句是lists.Add(new ControlExtenderActionList(element))，ControlExtenderActionList继承了System.ComponentModel.Design.DesignerActionList，他的GetSortedActionItems方法定义如下：

1: public override DesignerActionItemCollection GetSortedActionItems()   2: {   3:     Control component = (Control) this._htmlDesigner.Component;   4:     DesignerActionItemCollection items = new DesignerActionItemCollection();   5:     IExtenderInformationService service = (IExtenderInformationService) component.Site.GetService(typeof(IExtenderInformationService));   6:     string category = SR.GetString(SR.Ids.SmartTasksLabelExtenderSection, CultureInfo.CurrentUICulture);   7:     if (service.IsControlExtendible(component))   8:     {   9:         string displayName = SR.GetString(SR.Ids.SmartTasksAddExtender, CultureInfo.CurrentUICulture);  10:         items.Add(new DesignerActionMethodItem(this, "AddExtender", displayName, category, true));  11:     }  12:     if (service.IsControlExtended(component))  13:     {  14:         string str3 = SR.GetString(SR.Ids.SmartTasksRemoveExtender, CultureInfo.CurrentUICulture);  15:         items.Add(new DesignerActionMethodItem(this, "RemoveExtender", str3, category, true));  16:     }  17:     return items;  18: }  19:

这下清楚了，“添加扩展程序”这个action，是在Visual studio的web form设计器里，写死进去的，.net framework并没有提供相应接口来供我们添加类似的action。但是我想要的效果是增加一个“添加动作”的action，所以我不能参考AjaxControlToolkit的方法去实现，应该要寻找别的方法。

回过头来，重新查看Microsoft.Web.Design.WebFormDesigner+WebDesignerActionService类的GetComponentActions方法，找到基类System.Web.UI.Design.WebFormsDesignerActionService（在System.Design程序集下）的定义，如下：

1: protected override void GetComponentDesignerActions(IComponent component, DesignerActionListCollection actionLists)   2: {   3:     if (component == null)   4:     {   5:         throw new ArgumentNullException("component");   6:     }   7:     if (actionLists == null)   8:     {   9:         throw new ArgumentNullException("actionLists");  10:     }  11:     IServiceContainer site = component.Site as IServiceContainer;  12:     if (site != null)  13:     {  14:         DesignerCommandSet service = (DesignerCommandSet) site.GetService(typeof(DesignerCommandSet));  15:         if (service != null)  16:         {  17:             DesignerActionListCollection lists = service.ActionLists;  18:             if (lists != null)  19:             {  20:                 actionLists.AddRange(lists);  21:             }  22:         }  23:         if ((actionLists.Count == 0) || ((actionLists.Count == 1) && (actionLists[0] is ControlDesigner.ControlDesignerActionList)))  24:         {  25:             DesignerVerbCollection verbs = service.Verbs;  26:             if ((verbs != null) && (verbs.Count != 0))  27:             {  28:                 DesignerVerb[] array = new DesignerVerb[verbs.Count];  29:                 verbs.CopyTo(array, 0);  30:                 actionLists.Add(new DesignerActionVerbList(array));  31:             }  32:         }  33:     }  34: }  35:    36:    37:    38:

通过研究上述代码，可以看到DesignerActionListCollection是由DesignerCommandSet这个service的ActionLists属性负责返回的，而这个service是从component的Site里面取得的，只要我另外写一个DesignerCommandSet，并且保证从Site里面取出的DesignerCommandSet是我写的这个service就可以了。终于找到了切入点，下面是具体做法。

首先，创建一个类继承DesignerCommandSet，如下：

1: public class MyDesignerCommandSet : DesignerCommandSet   2:     {   3:         private ComponentDesigner _componentDesigner;   4:     5:         public MyDesignerCommandSet(ComponentDesigner componentDesigner)   6:         {   7:             _componentDesigner = componentDesigner;   8:         }   9:    10:         public override ICollection GetCommands(string name)  11:         {  12:             if (name.Equals("ActionLists"))  13:             {  14:                 return GetActionLists();  15:             }  16:             return base.GetCommands(name);  17:         }  18:    19:         private DesignerActionListCollection GetActionLists()  20:         {  21:             //先取得控件原有的DesignerActionLists  22:             DesignerActionListCollection lists = _componentDesigner.ActionLists;  23:               24:             //增加“添加动作”这个DesignerActionList  25:             lists.Add(new ActionList(_componentDesigner));  26:             return lists;  27:         }  28:    29:         internal class ActionList : DesignerActionList  30:         {  31:             private DesignerActionItemCollection _actions;  32:    33:             public ActionList(IDesigner designer)  34:                 : base(designer.Component)  35:             {  36:             }  37:             public override DesignerActionItemCollection GetSortedActionItems()  38:             {  39:                 if (_actions == null)  40:                 {  41:                     const string actionCategory = "Actions";  42:                     _actions = new DesignerActionItemCollection();  43:                     _actions.Add(new DesignerActionMethodItem(this, "AddAction", "添加动作...", actionCategory, true));  44:                 }  45:                 return _actions;  46:             }  47:    48:             public void AddAction()  49:             {  50:                 //添加动作的逻辑，略  51:             }  52:         }  53:     }

下一步就是如何使component的Site这个ServiceProvider返回自己的这个service。方法是自己写一个Site，并使Component的Site变成自己写的SIte类的对象。

自己写的Site类的定义如下：

1: public class SiteProxy : ISite, IServiceContainer   2:     {   3:         private ISite _site;   4:         private ComponentDesigner _designer;   5:     6:         public SiteProxy(ISite site, ComponentDesigner designer)   7:         {   8:             _site = site;   9:             _designer = designer;  10:    11:         }  12:    13:         #region ISite 成员  14:    15:         public IComponent Component  16:         {  17:             get { return _site.Component; }  18:         }  19:    20:         public System.ComponentModel.IContainer Container  21:         {  22:             get { return _site.Container; }  23:         }  24:    25:         public bool DesignMode  26:         {  27:             get { return _site.DesignMode; }  28:         }  29:    30:         public string Name  31:         {  32:             get { return _site.Name; }  33:             set { _site.Name = value; }  34:         }  35:    36:         #endregion  37:    38:         #region IServiceProvider 成员  39:    40:         public object GetService(Type serviceType)  41:         {  42:             object service = _site.GetService(serviceType);  43:    44:             if (serviceType == typeof(DesignerCommandSet) && !(_designer.Component is ExtenderControl))  45:             {  46:                 if (service == null || !(service is MyDesignerCommandSet))  47:                 {  48:                     if (service != null)  49:                     {  50:                         RemoveService(typeof(DesignerCommandSet));  51:                     }  52:                     //返回自己写的DesignerCommandSet  53:                     service = new MyDesignerCommandSet(_designer);  54:                     AddService(typeof(DesignerCommandSet), service);  55:                 }  56:             }  57:             return service;  58:         }  59:    60:         #endregion  61:    62:         #region IServiceContainer 成员  63:    64:         public void AddService(Type serviceType, ServiceCreatorCallback callback, bool promote)  65:         {  66:             (_site as IServiceContainer).AddService(serviceType, callback, promote);  67:         }  68:    69:         public void AddService(Type serviceType, ServiceCreatorCallback callback)  70:         {  71:             (_site as IServiceContainer).AddService(serviceType, callback);  72:         }  73:    74:         public void AddService(Type serviceType, object serviceInstance, bool promote)  75:         {  76:             (_site as IServiceContainer).AddService(serviceType, serviceInstance, promote);  77:         }  78:    79:         public void AddService(Type serviceType, object serviceInstance)  80:         {  81:             (_site as IServiceContainer).AddService(serviceType, serviceInstance);  82:         }  83:    84:         public void RemoveService(Type serviceType, bool promote)  85:         {  86:             (_site as IServiceContainer).RemoveService(serviceType, promote);  87:         }  88:    89:         public void RemoveService(Type serviceType)  90:         {  91:             (_site as IServiceContainer).RemoveService(serviceType);  92:         }  93:    94:         #endregion  95:     }

在这个Site的GetService方法中，判断要get的service类型，如果是DesignerCommandSet，就返回自己创建的MyDesignerCommandSet。

下一步是如何使component的Site变成自己写的SiteProxy。一种方法是新增一种自定义控件，在该控件的ControlDesigner的Initialize方法中改变Container中其他控件的Site，只需要向WebForm中拖入该控件，就可以改变其他控件的Site；另外一种方法是写一个vs package，在package中捕获web form designer的相应事件。下面介绍第一种做法：

新增一个继承自Control的控件，叫做ActionManager，这个控件不用添加任何功能，只需要为它制作ControlDesigner。它的ControlDesigner类主要代码如下：

1: public class ActionManagerDesigner : ControlDesigner   2:     {   3:         private IDesignerHost _host;   4:         private IDictionary<IComponent, ISite> _components;   5:     6:         public override void Initialize(IComponent component)   7:         {   8:             base.Initialize(component);   9:    10:             _components = new Dictionary<IComponent, ISite>();  11:    12:             _host = GetService(typeof(IDesignerHost)) as IDesignerHost;  13:             if (_host != null)  14:             {  15:                 //替换已有控件的Site  16:                 ProcessComponent();  17:    18:                 IComponentChangeService service =  19:                     _host.GetService(typeof(IComponentChangeService)) as IComponentChangeService;  20:                 if (service != null)  21:                 {  22:                     service.ComponentAdded += ComponentAdded;  23:                     service.ComponentRemoving += ComponentRemoving;  24:                 }  25:             }  26:         }  27:    28:         #region ProcessComponent  29:    30:         private void ProcessComponent()  31:         {  32:             ComponentCollection components = _host.Container.Components;  33:             foreach (IComponent component in components)  34:             {  35:                 if (component is ActionControl)  36:                     continue;  37:                 ProcessComponentSite(component);  38:             }  39:         }  40:    41:         #endregion  42:    43:         #region 替换Site  44:    45:         /// <summary>  46:         /// 替换Component原来的Site，换成SiteProxy  47:         /// </summary>  48:         private void ProcessComponentSite(IComponent component)  49:         {  50:             ComponentDesigner designer = _host.GetDesigner(component) as ComponentDesigner;  51:             _components[component] = component.Site;  52:             component.Site = new SiteProxy(component.Site, designer);  53:         }  54:    55:         /// <summary>  56:         /// 恢复Component原来的site  57:         /// </summary>  58:         /// <param name="component"></param>  59:         private void RestoreComponentSite(IComponent component)  60:         {  61:             if (_components.ContainsKey(component))  62:             {  63:                 ISite site = _components[component];  64:                 component.Site = site;  65:                 _components.Remove(component);  66:             }  67:         }  68:    69:         #endregion  70:    71:         #region on Component Add, remove, change  72:           73:         private void ComponentRemoving(object sender, ComponentEventArgs e)  74:         {  75:             if (e.Component is ActionControl)  76:             {  77:                 return;  78:             }  79:             //在删除Component的时候，要把他的Site属性还原回去，否则DesignerHost中还会保留原来的Site,  80:             //这样再添加同名的Component的时候，会报“重复的组件名称”错误  81:             RestoreComponentSite(e.Component);  82:         }  83:          84:    85:         private void ComponentAdded(object sender, ComponentEventArgs e)  86:         {  87:             if (e.Component is ActionControl)  88:             {  89:                 return;  90:             }  91:             ProcessComponentSite(e.Component);  92:         }  93:    94:         #endregion  95:    96:         #region dispose  97:    98:         protected override void Dispose(bool disposing)  99:         { 100:             if (_host != null) 101:             { 102:                 IComponentChangeService service = 103:                     _host.GetService(typeof(IComponentChangeService)) as IComponentChangeService; 104:                 if (service != null) 105:                 { 106:                     service.ComponentAdded -= ComponentAdded; 107:                     service.ComponentRemoving -= ComponentRemoving; 108:                 } 109:             } 110:             base.Dispose(disposing); 111:         } 112:   113:         #endregion 114:     }

至此，只要把一个ActionManager控件拖入到web form designer中，就可以在其他控件的smart task面板上看到“添加动作…”这个链接了。但是这种方式需要在webform designer中放入额外的一个控件，该控件只在设计时有用，在运行时则无用，看起来比较奇怪，所以最好的做法是第二种做法，即开发一个vs package，在package的Initialize方法中，注册IDesignerEventService的DesignerCreated事件，进而通过IDesignerHost和IComponentChangeService达到更改控件Site的目的，具体实现和上面差不多，就不再写了。