MSDN: 访问设计时服务
下面的代码示例向您演示如何获取访问大量的 .NET Framework 服务的权限，以便您可以将您的组件和控件集成到设计环境中。
http://msdn.microsoft.com/zh-cn/library/ms171822(v=vs.100).aspx
此代码示例演示如何在您的自定义设计器中访问服务。在此示例中，一个名为 DemoControlDesigner 的设计器类附加到了 DemoControl 类，它执行以下操作：
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使用 CreateComponent 方法创建 Timer 组件。
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使用 DestroyComponent 方法从设计环境中移除 Timer 组件。
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使用 GetExtenderProviders 枚举所有扩展程序提供程序并将它们显示在 MessageBox 中。
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使用 GetReferences 方法枚举设计图面上的 DemoControl 的所有实例。
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使用 GetPathOfAssembly 方法显示执行程序集的路径。
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使用 GetComponentTypes 方法查找从 ScrollableControl 派生的所有类型。
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使用 CategoryNames 方法枚举“工具箱”中出现的所有类别。
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在设计器上设置一个被影化的 BackColor 属性，该属性是由设计环境序列化的，而不是由 DemoControl 的 BackColor 值序列化的。
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使用 PreFilterProperties 和 PostFilterProperties 方法添加和移除属性。
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using System; using System.Collections; using System.ComponentModel; using System.ComponentModel.Design; using System.Diagnostics; using System.Drawing; using System.Drawing.Design; using System.Data; using System.Reflection; using System.Runtime.Serialization; using System.Text; using System.Windows.Forms; using System.Windows.Forms.Design; using System.Windows.Forms.Design.Behavior; public class Form1 : Form { private DemoControl demoControl1; private System.ComponentModel.IContainer components = null; public Form1() { InitializeComponent(); } protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } [STAThread] static void Main() { Application.EnableVisualStyles(); Application.Run(new Form1()); } #region Windows Form Designer generated code private void InitializeComponent() { this.demoControl1 = new DemoControl(); this.SuspendLayout(); // // demoControl1 // this.demoControl1.AutoSize = true; this.demoControl1.BackColor = System.Drawing.Color.Chartreuse; this.demoControl1.Location = new System.Drawing.Point(0, 0); this.demoControl1.Name = "demoControl1"; this.demoControl1.Size = new System.Drawing.Size(232, 14); this.demoControl1.TabIndex = 0; this.demoControl1.Text = "This text was set by CreateComponentsCore."; // // Form1 // this.ClientSize = new System.Drawing.Size(492, 482); this.Controls.Add(this.demoControl1); this.Name = "Form1"; this.Text = "r"; this.ResumeLayout(false); this.PerformLayout(); } #endregion } // This control is derived from UserControl, with only a little // added logic for the Toolbox interaction. // // All of the custom designer code is implemented in the // DemoControlDesigner class. [DesignerAttribute(typeof(DemoControlDesigner))] [ToolboxItem(typeof(DemoToolboxItem))] public class DemoControl : Label { private System.ComponentModel.IContainer components = null; public DemoControl() { InitializeComponent(); MessageBox.Show("DemoControl", "Constructor"); } protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } private void InitializeComponent() { // // DemoControl // this.Name = "DemoControl"; } // Toolbox items must be serializable. [Serializable] [System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.InheritanceDemand, Name="FullTrust")] [System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.LinkDemand, Name="FullTrust")] class DemoToolboxItem : ToolboxItem { // The add components dialog in VS looks for a public // ctor that takes a type. public DemoToolboxItem(Type toolType) : base(toolType) { } // And you must provide this special constructor for serialization. // If you add additional data to MyToolboxItem that you // want to serialize, you may override Deserialize and // Serialize methods to add that data. DemoToolboxItem(SerializationInfo info, StreamingContext context) { Deserialize(info, context); } // This implementation sets the new control's Text and // AutoSize properties. protected override IComponent[] CreateComponentsCore( IDesignerHost host, IDictionary defaultValues) { IComponent[] comps = base.CreateComponentsCore(host, defaultValues); // The returned IComponent array contains a single // component, which is an instance of DemoControl. ((DemoControl)comps[0]).Text = "This text was set by CreateComponentsCore."; ((DemoControl)comps[0]).AutoSize = true; return comps; } } } // This class demonstrates a designer that attaches to various // services and changes the properties exposed by the control // being designed. [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] public class DemoControlDesigner : ControlDesigner { // This member backs the Locked property. private bool lockedValue = false; // This is the collection of DesignerActionLists that // defines the smart tags offered on the control. private DesignerActionListCollection actionLists = null; // This Timer is created when you select the Create Timer // smart tag item. private Timer createdTimer = null; // These are the services which DemoControlDesigner will use. private DesignerActionService actionService = null; private DesignerActionUIService actionUiService = null; private IComponentChangeService changeService = null; private IDesignerEventService eventService = null; private IDesignerHost host = null; private IDesignerOptionService optionService = null; private IEventBindingService eventBindingService = null; private IExtenderListService listService = null; private IReferenceService referenceService = null; private ISelectionService selectionService = null; private ITypeResolutionService typeResService = null; private IComponentDiscoveryService componentDiscoveryService = null; private IToolboxService toolboxService = null; private UndoEngine undoEng = null; public DemoControlDesigner() { MessageBox.Show("DemoControlDesigner", "Constructor"); } // The Dispose method override is implemented so event handlers // can be removed. This prevents objects from lingering in // memory beyond the desired lifespan. protected override void Dispose(bool disposing) { if (disposing) { if (this.changeService != null) { // Unhook event handlers. this.changeService.ComponentChanged -= new ComponentChangedEventHandler( ChangeService_ComponentChanged); this.changeService.ComponentAdded -= new ComponentEventHandler( ChangeService_ComponentAdded); this.changeService.ComponentRemoved -= new ComponentEventHandler( changeService_ComponentRemoved); } if (this.eventService != null) { this.eventService.ActiveDesignerChanged -= new ActiveDesignerEventHandler( eventService_ActiveDesignerChanged); } if (this.selectionService != null) { this.selectionService.SelectionChanged -= new EventHandler( selectionService_SelectionChanged); } } base.Dispose(disposing); } // This method initializes the designer. public override void Initialize(IComponent component) { base.Initialize(component); // Connect to various designer services. InitializeServices(); // Set up the BackColor value that will be serialized. // This is the shadowed property on the designer. this.BackColor = Color.Chartreuse; // Set up the BackColor value that will be displayed. this.Control.BackColor = Color.AliceBlue; } // This method creates the DesignerActionList on demand, causing // smart tags to appear on the control being designed. public override DesignerActionListCollection ActionLists { get { if (null == actionLists) { actionLists = new DesignerActionListCollection(); actionLists.Add( new DemoActionList(this.Component)); } return actionLists; } } // This utility method connects the designer to various // services it will use. private void InitializeServices() { // Acquire a reference to DesignerActionService. this.actionService = GetService(typeof(DesignerActionService)) as DesignerActionService; // Acquire a reference to DesignerActionUIService. this.actionUiService = GetService(typeof(DesignerActionUIService)) as DesignerActionUIService; // Acquire a reference to IComponentChangeService. this.changeService = GetService(typeof(IComponentChangeService)) as IComponentChangeService; // Hook the IComponentChangeService events. if (this.changeService != null) { this.changeService.ComponentChanged += new ComponentChangedEventHandler( ChangeService_ComponentChanged); this.changeService.ComponentAdded += new ComponentEventHandler( ChangeService_ComponentAdded); this.changeService.ComponentRemoved += new ComponentEventHandler( changeService_ComponentRemoved); } // Acquire a reference to ISelectionService. this.selectionService = GetService(typeof(ISelectionService)) as ISelectionService; // Hook the SelectionChanged event. if (this.selectionService != null) { this.selectionService.SelectionChanged += new EventHandler(selectionService_SelectionChanged); } // Acquire a reference to IDesignerEventService. this.eventService = GetService(typeof(IDesignerEventService)) as IDesignerEventService; if (this.eventService != null) { this.eventService.ActiveDesignerChanged += new ActiveDesignerEventHandler( eventService_ActiveDesignerChanged); } // Acquire a reference to IDesignerHost. this.host = GetService(typeof(IDesignerHost)) as IDesignerHost; // Acquire a reference to IDesignerOptionService. this.optionService = GetService(typeof(IDesignerOptionService)) as IDesignerOptionService; // Acquire a reference to IEventBindingService. this.eventBindingService = GetService(typeof(IEventBindingService)) as IEventBindingService; // Acquire a reference to IExtenderListService. this.listService = GetService(typeof(IExtenderListService)) as IExtenderListService; // Acquire a reference to IReferenceService. this.referenceService = GetService(typeof(IReferenceService)) as IReferenceService; // Acquire a reference to ITypeResolutionService. this.typeResService = GetService(typeof(ITypeResolutionService)) as ITypeResolutionService; // Acquire a reference to IComponentDiscoveryService. this.componentDiscoveryService = GetService(typeof(IComponentDiscoveryService)) as IComponentDiscoveryService; // Acquire a reference to IToolboxService. this.toolboxService = GetService(typeof(IToolboxService)) as IToolboxService; // Acquire a reference to UndoEngine. this.undoEng = GetService(typeof(UndoEngine)) as UndoEngine; if (this.undoEng != null) { MessageBox.Show("UndoEngine"); } } // This is the shadowed property on the designer. // This value will be serialized instead of the // value of the control's property. public Color BackColor { get { return (Color)ShadowProperties["BackColor"]; } set { if (this.changeService != null) { PropertyDescriptor backColorDesc = TypeDescriptor.GetProperties(this.Control)["BackColor"]; this.changeService.OnComponentChanging( this.Control, backColorDesc); this.ShadowProperties["BackColor"] = value; this.changeService.OnComponentChanged( this.Control, backColorDesc, null, null); } } } // This is the property added by the designer in the // PreFilterProperties method. private bool Locked { get { return lockedValue; } set { lockedValue = value; } } // The PreFilterProperties method is where you can add or remove // properties from the component being designed. // // In this implementation, the Visible property is removed, // the BackColor property is shadowed by the designer, and // the a new property, called Locked, is added. protected override void PreFilterProperties(IDictionary properties) { // Always call the base PreFilterProperties implementation // before you modify the properties collection. base.PreFilterProperties(properties); // Remove the visible property. properties.Remove("Visible"); // Shadow the BackColor property. PropertyDescriptor propertyDesc = TypeDescriptor.CreateProperty( typeof(DemoControlDesigner), (PropertyDescriptor)properties["BackColor"], new Attribute[0]); properties["BackColor"] = propertyDesc; // Create the Locked property. properties["Locked"] = TypeDescriptor.CreateProperty( typeof(DemoControlDesigner), "Locked", typeof(bool), CategoryAttribute.Design, DesignOnlyAttribute.Yes); } // The PostFilterProperties method is where you modify existing // properties. You must only use this method to modify existing // items. Do not add or remove items here. Also, be sure to // call base.PostFilterProperties(properties) after your filtering // logic. // // In this implementation, the Enabled property is hidden from // any PropertyGrid or Properties window. This is done by // creating a copy of the existing PropertyDescriptor and // attaching two new Attributes: Browsable and EditorBrowsable. protected override void PostFilterProperties(IDictionary properties) { PropertyDescriptor pd = properties["Enabled"] as PropertyDescriptor; pd = TypeDescriptor.CreateProperty( pd.ComponentType, pd, new Attribute[2] { new BrowsableAttribute(false), new EditorBrowsableAttribute(EditorBrowsableState.Never)}); properties[pd.Name] = pd; // Always call the base PostFilterProperties implementation // after you modify the properties collection. base.PostFilterProperties(properties); } #region Event Handlers void eventService_ActiveDesignerChanged( object sender, ActiveDesignerEventArgs e) { if (e.NewDesigner != null) { MessageBox.Show( e.NewDesigner.ToString(), "ActiveDesignerChanged"); } } void ChangeService_ComponentChanged( object sender, ComponentChangedEventArgs e) { string msg = String.Format( "{0}, {1}", e.Component, e.Member); MessageBox.Show(msg, "ComponentChanged"); } void ChangeService_ComponentAdded( object sender, ComponentEventArgs e) { MessageBox.Show( e.Component.ToString(), "ComponentAdded"); } void changeService_ComponentRemoved( object sender, ComponentEventArgs e) { MessageBox.Show( e.Component.ToString(), "ComponentRemoved"); } void selectionService_SelectionChanged( object sender, EventArgs e) { if (this.selectionService != null) { if (this.selectionService.PrimarySelection == this.Control) { MessageBox.Show( this.Control.ToString(), "SelectionChanged"); } } } #endregion // This class defines the smart tags that appear on the control // that is being designed. internal class DemoActionList : System.ComponentModel.Design.DesignerActionList { // Cache a reference to the designer host. private IDesignerHost host = null; // Cache a reference to the control. private DemoControl relatedControl = null; // Cache a reference to the designer. private DemoControlDesigner relatedDesigner = null; //The constructor associates the control //with the smart tag list. public DemoActionList(IComponent component) : base(component) { this.relatedControl = component as DemoControl; this.host = this.Component.Site.GetService(typeof(IDesignerHost)) as IDesignerHost; IDesigner dcd = host.GetDesigner(this.Component); this.relatedDesigner = dcd as DemoControlDesigner; } // This method creates and populates the // DesignerActionItemCollection which is used to // display smart tag items. public override DesignerActionItemCollection GetSortedActionItems() { DesignerActionItemCollection items = new DesignerActionItemCollection(); // If the Timer component has not been created, show the // "Create Timer" DesignerAction item. // // If the Timer component exists, show the timer-related // options. if (this.relatedDesigner.createdTimer == null) { items.Add(new DesignerActionMethodItem( this, "CreateTimer", "Create Timer", true)); } else { items.Add(new DesignerActionMethodItem( this, "ShowEventHandlerCode", "Show Event Handler Code", true)); items.Add(new DesignerActionMethodItem( this, "RemoveTimer", "Remove Timer", true)); } items.Add(new DesignerActionMethodItem( this, "GetExtenderProviders", "Get Extender Providers", true)); items.Add(new DesignerActionMethodItem( this, "GetDemoControlReferences", "Get DemoControl References", true)); items.Add(new DesignerActionMethodItem( this, "GetPathOfAssembly", "Get Path of Executing Assembly", true)); items.Add(new DesignerActionMethodItem( this, "GetComponentTypes", "Get ScrollableControl Types", true)); items.Add(new DesignerActionMethodItem( this, "GetToolboxCategories", "Get Toolbox Categories", true)); items.Add(new DesignerActionMethodItem( this, "SetBackColor", "Set Back Color", true)); return items; } // This method creates a Timer component using the // IDesignerHost.CreateComponent method. It also // creates an event handler for the Timer component's // tick event. private void CreateTimer() { if (this.host != null) { if (this.relatedDesigner.createdTimer == null) { // Create and configure the Timer object. this.relatedDesigner.createdTimer = this.host.CreateComponent(typeof(Timer)) as Timer; Timer t = this.relatedDesigner.createdTimer; t.Interval = 1000; t.Enabled = true; EventDescriptorCollection eventColl = TypeDescriptor.GetEvents(t, new Attribute[0]); if (eventColl != null) { EventDescriptor ed = eventColl["Tick"] as EventDescriptor; if (ed != null) { PropertyDescriptor epd = this.relatedDesigner.eventBindingService.GetEventProperty(ed); epd.SetValue(t, "timer_Tick"); } } this.relatedDesigner.actionUiService.Refresh(this.relatedControl); } } } // This method uses the IEventBindingService.ShowCode // method to start the Code Editor. It places the caret // in the timer_tick method created by the CreateTimer method. private void ShowEventHandlerCode() { Timer t = this.relatedDesigner.createdTimer; if (t != null) { EventDescriptorCollection eventColl = TypeDescriptor.GetEvents(t, new Attribute[0]); if (eventColl != null) { EventDescriptor ed = eventColl["Tick"] as EventDescriptor; if (ed != null) { this.relatedDesigner.eventBindingService.ShowCode(t, ed); } } } } // This method uses the IDesignerHost.DestroyComponent method // to remove the Timer component from the design environment. private void RemoveTimer() { if (this.host != null) { if (this.relatedDesigner.createdTimer != null) { this.host.DestroyComponent( this.relatedDesigner.createdTimer); this.relatedDesigner.createdTimer = null; this.relatedDesigner.actionUiService.Refresh( this.relatedControl); } } } // This method uses IExtenderListService.GetExtenderProviders // to enumerate all the extender providers and display them // in a MessageBox. private void GetExtenderProviders() { if (this.relatedDesigner.listService != null) { StringBuilder sb = new StringBuilder(); IExtenderProvider[] providers = this.relatedDesigner.listService.GetExtenderProviders(); for (int i = 0; i < providers.Length; i++) { sb.Append(providers[i].ToString()); sb.Append("\r\n"); } MessageBox.Show( sb.ToString(), "Extender Providers"); } } // This method uses the IReferenceService.GetReferences method // to enumerate all the instances of DemoControl on the // design surface. private void GetDemoControlReferences() { if (this.relatedDesigner.referenceService != null) { StringBuilder sb = new StringBuilder(); object[] refs = this.relatedDesigner.referenceService.GetReferences(typeof(DemoControl)); for (int i = 0; i < refs.Length; i++) { sb.Append(refs[i].ToString()); sb.Append("\r\n"); } MessageBox.Show( sb.ToString(), "DemoControl References"); } } // This method uses the ITypeResolutionService.GetPathOfAssembly // method to display the path of the executing assembly. private void GetPathOfAssembly() { if (this.relatedDesigner.typeResService != null) { System.Reflection.AssemblyName name = System.Reflection.Assembly.GetExecutingAssembly().GetName(); MessageBox.Show( this.relatedDesigner.typeResService.GetPathOfAssembly(name), "Path of executing assembly"); } } // This method uses the IComponentDiscoveryService.GetComponentTypes // method to find all the types that derive from // ScrollableControl. private void GetComponentTypes() { if (this.relatedDesigner.componentDiscoveryService != null) { ICollection components = this.relatedDesigner.componentDiscoveryService.GetComponentTypes(host, typeof(ScrollableControl)); if (components != null) { if (components.Count > 0) { StringBuilder sb = new StringBuilder(); IEnumerator e = components.GetEnumerator(); while (e.MoveNext()) { sb.Append(e.Current.ToString()); sb.Append("\r\n"); } MessageBox.Show( sb.ToString(), "Controls derived from ScrollableControl"); } } } } // This method uses the IToolboxService.CategoryNames // method to enumerate all the categories that appear // in the Toolbox. private void GetToolboxCategories() { if (this.relatedDesigner.toolboxService != null) { StringBuilder sb = new StringBuilder(); CategoryNameCollection names = this.relatedDesigner.toolboxService.CategoryNames; foreach (string name in names) { sb.Append(name.ToString()); sb.Append("\r\n"); } MessageBox.Show(sb.ToString(), "Toolbox Categories"); } } // This method sets the shadowed BackColor property on the // designer. This is the value that is serialized by the // design environment. private void SetBackColor() { ColorDialog d = new ColorDialog(); if (d.ShowDialog() == DialogResult.OK) { this.relatedDesigner.BackColor = d.Color; } } } }
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DemoControl 类是从 UserControl 类派生的，但它不需要特别的逻辑来扩展其设计时 UI。设计时 UI 是由 DemoControlDesigner 类实现的。
连接到服务
DemoControl 类在其 InitializeServices 方法中获取对各种服务的引用。
// These are the services which DemoControlDesigner will use. private DesignerActionService actionService = null; private DesignerActionUIService actionUiService = null; private IComponentChangeService changeService = null; private IDesignerEventService eventService = null; private IDesignerHost host = null; private IDesignerOptionService optionService = null; private IEventBindingService eventBindingService = null; private IExtenderListService listService = null; private IReferenceService referenceService = null; private ISelectionService selectionService = null; private ITypeResolutionService typeResService = null; private IComponentDiscoveryService componentDiscoveryService = null; private IToolboxService toolboxService = null; private UndoEngine undoEng = null;
// This utility method connects the designer to various // services it will use. private void InitializeServices() { // Acquire a reference to DesignerActionService. this.actionService = GetService(typeof(DesignerActionService)) as DesignerActionService; // Acquire a reference to DesignerActionUIService. this.actionUiService = GetService(typeof(DesignerActionUIService)) as DesignerActionUIService; // Acquire a reference to IComponentChangeService. this.changeService = GetService(typeof(IComponentChangeService)) as IComponentChangeService; // Hook the IComponentChangeService events. if (this.changeService != null) { this.changeService.ComponentChanged += new ComponentChangedEventHandler( ChangeService_ComponentChanged); this.changeService.ComponentAdded += new ComponentEventHandler( ChangeService_ComponentAdded); this.changeService.ComponentRemoved += new ComponentEventHandler( changeService_ComponentRemoved); } // Acquire a reference to ISelectionService. this.selectionService = GetService(typeof(ISelectionService)) as ISelectionService; // Hook the SelectionChanged event. if (this.selectionService != null) { this.selectionService.SelectionChanged += new EventHandler(selectionService_SelectionChanged); } // Acquire a reference to IDesignerEventService. this.eventService = GetService(typeof(IDesignerEventService)) as IDesignerEventService; if (this.eventService != null) { this.eventService.ActiveDesignerChanged += new ActiveDesignerEventHandler( eventService_ActiveDesignerChanged); } // Acquire a reference to IDesignerHost. this.host = GetService(typeof(IDesignerHost)) as IDesignerHost; // Acquire a reference to IDesignerOptionService. this.optionService = GetService(typeof(IDesignerOptionService)) as IDesignerOptionService; // Acquire a reference to IEventBindingService. this.eventBindingService = GetService(typeof(IEventBindingService)) as IEventBindingService; // Acquire a reference to IExtenderListService. this.listService = GetService(typeof(IExtenderListService)) as IExtenderListService; // Acquire a reference to IReferenceService. this.referenceService = GetService(typeof(IReferenceService)) as IReferenceService; // Acquire a reference to ITypeResolutionService. this.typeResService = GetService(typeof(ITypeResolutionService)) as ITypeResolutionService; // Acquire a reference to IComponentDiscoveryService. this.componentDiscoveryService = GetService(typeof(IComponentDiscoveryService)) as IComponentDiscoveryService; // Acquire a reference to IToolboxService. this.toolboxService = GetService(typeof(IToolboxService)) as IToolboxService; // Acquire a reference to UndoEngine. this.undoEng = GetService(typeof(UndoEngine)) as UndoEngine; if (this.undoEng != null) { MessageBox.Show("UndoEngine"); } }
服务事件
一些服务提供您的设计器可以附加到的事件。例如，DemoControlDesigner 类将事件处理程序附加到 ComponentChanged、ComponentAdded 和ComponentRemoved 事件。
void ChangeService_ComponentChanged( object sender, ComponentChangedEventArgs e) { string msg = String.Format( "{0}, {1}", e.Component, e.Member); MessageBox.Show(msg, "ComponentChanged"); } void ChangeService_ComponentAdded( object sender, ComponentEventArgs e) { MessageBox.Show( e.Component.ToString(), "ComponentAdded"); } void changeService_ComponentRemoved( object sender, ComponentEventArgs e) { MessageBox.Show( e.Component.ToString(), "ComponentRemoved"); }
在设计器中实现 Dispose 方法
在设计器的 Dispose 方法中分离您的事件处理程序时要小心。这可避免在您的设计器超出范围时发生意外的情况。
// The Dispose method override is implemented so event handlers // can be removed. This prevents objects from lingering in // memory beyond the desired lifespan. protected override void Dispose(bool disposing) { if (disposing) { if (this.changeService != null) { // Unhook event handlers. this.changeService.ComponentChanged -= new ComponentChangedEventHandler( ChangeService_ComponentChanged); this.changeService.ComponentAdded -= new ComponentEventHandler( ChangeService_ComponentAdded); this.changeService.ComponentRemoved -= new ComponentEventHandler( changeService_ComponentRemoved); } if (this.eventService != null) { this.eventService.ActiveDesignerChanged -= new ActiveDesignerEventHandler( eventService_ActiveDesignerChanged); } if (this.selectionService != null) { this.selectionService.SelectionChanged -= new EventHandler( selectionService_SelectionChanged); } } base.Dispose(disposing); }
使用服务
DemoControl 类在其智能标记面板中使用了多项服务。从 DesignerActionList 类派生了一个名为 DemoActionList 的内部类。此类有一些方法可供您用来创建、删除和枚举设计环境中提供的各种对象。它将这些方法公开为智能标记。例如，下面的代码示例使用 GetExtenderProviders 方法枚举设计环境中存在的所有扩展程序提供程序。
// This method uses IExtenderListService.GetExtenderProviders // to enumerate all the extender providers and display them // in a MessageBox. private void GetExtenderProviders() { if (this.relatedDesigner.listService != null) { StringBuilder sb = new StringBuilder(); IExtenderProvider[] providers = this.relatedDesigner.listService.GetExtenderProviders(); for (int i = 0; i < providers.Length; i++) { sb.Append(providers[i].ToString()); sb.Append("\r\n"); } MessageBox.Show( sb.ToString(), "Extender Providers"); } }
