System.ComponentModel.Design.DesignSurface是为设计组件提供一个用户界面，通过它可以实现一个简单的窗体设计器。
在构建之前，我们需要引入System.Design.dll，否则会出现找不到DesignSurface的错误。
1 private void Form1_Load(object sender, EventArgs e) 2 { 3 //引用System.Deisgn.dll 4 DesignSurface ds = new DesignSurface(); 5 //开始加载窗体 6 ds.BeginLoad(typeof(Form)); 7 Control designerContorl = (Control)ds.View; 8 designerContorl.Dock = DockStyle.Fill; 9 this.Controls.Add(designerContorl);10 } 运行后出现简单的一个UI设计器
但是该设计器并不能实现控件拖放和UI设计器，以及控件的属性配置。
为了支持从源代码加载初始化窗体，需要对源码中的相关方法进行解析，这里我们 CodeDomDesignerLoader来实现定制化业务，CodeDomDesignerLoader是提供用于实现基于 CodeDOM 的设计器加载程序的基类。
继承它的类需要重写CodeCompileUnit Parse()方法，来实现加载窗体：
1 protected override CodeCompileUnit Parse() 2 { 3 4 #region 源文件读取 5 var sw = new StreamReader(@"E:\FrmUser.cs"); 6 var sw_designer = new StreamReader(@"E:\FrmUser.Designer.cs"); 7 8 string formCodeCS = sw.ReadToEnd(); 9 string formCodeDesigner = sw_designer.ReadToEnd();10 11 List source = new List ();12 source.Add(formCodeCS);13 source.Add(formCodeDesigner);14 15 #endregion16 //Rolsyn解析C#17 var rootDesigner = Source2CodeDom.Parse(formCodeDesigner);18 codeDesingerCompileUnit = Source2CodeDom.GetDesignerCodeComplieUnit(rootDesigner);19 var rootCS = Source2CodeDom.Parse(formCodeCS);20 codeCSCompileUnit = Source2CodeDom.GetCodeComplieUnit(rootCS);21 //MergeFormSource22 string mergeS = Source2CodeDom.MergeFormSource(formCodeDesigner, formCodeCS);23 codeMergeCompileUnit = Source2CodeDom.GetMergeDesignerCodeComplieUnit(mergeS);24 return codeMergeCompileUnit; 解析的方法如下，但是此解析只是用于代码的生成，并不能用户UI界面的显示：
1 public static CodeCompileUnit GetDesignerCodeComplieUnit2(CompilationUnitSyntax root) 2 { 3 CodeCompileUnit ccu = new CodeCompileUnit(); 4 var firstMember = root.Members[0]; 5 var namespaceDeclration = (NamespaceDeclarationSyntax)firstMember; 6 var designClassDeclaration = (ClassDeclarationSyntax)namespaceDeclration.Members[0]; 7 var myDesignerClass = new CodeTypeDeclaration(designClassDeclaration.Identifier.ToString()); 8 var initializeComponent = new CodeMemberMethod(); 9 var ns = new CodeNamespace(namespaceDeclration.Name.ToString()); 10 11 foreach (var m in designClassDeclaration.Members) 12 { 13 14 if (m is ConstructorDeclarationSyntax) 15 { 16 var ctor = ((ConstructorDeclarationSyntax)m); 17 var codeBody = ctor.Body.ToString(); 18 codeBody = codeBody.Trim().TrimStart('{ ').TrimEnd('}').Trim().TrimEnd(';'); 19 CodeSnippetExpression csbody = new CodeSnippetExpression(codeBody); 20 CodeExpressionStatement stmt = new CodeExpressionStatement(csbody); 21 //Add the expression statements to the method. 22 // InitializeComponent 23 var cctor = new CodeConstructor(); 24 cctor.Name = ctor.Identifier.ToString(); 25 //var cmm = new CodeMemberMethod(); 26 //cmm.Name = ctor.Identifier.ToString(); 27 //cmm.Attributes = GetCtoRAttrMapping(ctor); 28 //cmm.ReturnType = new CodeTypeReference(typeof(void)); 29 cctor.Statements.Add(stmt); 30 31 myDesignerClass.Members.Add(cctor); 32 } 33 if (m is FieldDeclarationSyntax) 34 { 35 var F = ((FieldDeclarationSyntax)m); 36 var type = F.Declaration.Type; 37 foreach (var variable in F.Declaration.Variables) 38 { 39 var field = new CodeMemberField(); 40 field.Name = variable.Identifier.ToString(); 41 field.Type = new CodeTypeReference(type.ToString()); 42 field.Attributes = GetFieldAttrMapping(F); 43 //field.InitExpression = new CodePrimitiveExpression(null); 44 myDesignerClass.Members.Add(field); 45 } 46 } 47 if (m is MethodDeclarationSyntax) 48 { 49 var node = m as MethodDeclarationSyntax; 50 #region xml comments 51 var xmlTrivia = node.GetLeadingTrivia() 52 .Select(i => i.GetStructure()) 53 .OfType () 54 .FirstOrDefault(); 55 56 57 58 #endregion 59 60 61 62 var method = (MethodDeclarationSyntax)m; 63 64 var cmm = new CodeMemberMethod(); 65 cmm.Name = method.Identifier.ToString(); 66 67 68 69 ///XML注释 70 string[] comments = xmlTrivia.ToString().Split("\r\n".ToCharArray()); 71 foreach (string text in comments) 72 { 73 if (text.Trim() != "") 74 { 75 cmm.Comments.Add(new CodeCommentStatement(text.Trim().TrimStart("///".ToCharArray()).Trim(), true)); 76 } 77 } 78 79 80 81 if (cmm.Name == "InitializeComponent") 82 { 83 //region 84 CodeRegionDirective codeRegion = new CodeRegionDirective(CodeRegionMode.Start, "Windows 窗体设计器生成的代码"); 85 CodeRegionDirective codeEndRegion = new CodeRegionDirective(CodeRegionMode.End, ""); 86 87 cmm.StartDirectives.Add(codeRegion); 88 cmm.EndDirectives.Add(codeEndRegion); 89 } 90 91 //MemberAttributes.Family is protected 92 //cmm.Attributes = MemberAttributes.Override | MemberAttributes.Family; 93 cmm.Attributes = GetMethodAttrMapping(method); 94 cmm.ReturnType = new CodeTypeReference(method.ReturnType.ToString()); 95 96 foreach (var p in method.ParameterList.Parameters) 97 { 98 CodeParameterDeclarationExpression cpd = new CodeParameterDeclarationExpression(); 99 cpd.Name = p.Identifier.ToString();100 101 cpd.Type = new CodeTypeReference(p.Type.ToString());102 103 cmm.Parameters.Add(cpd);104 }105 //包含方法{};，会重复生成{};106 string codeBody = method.Body.ToString();107 codeBody = codeBody.Trim().TrimStart('{ ').TrimEnd('}').Trim().TrimEnd(';');108 if (codeBody != "")109 {110 CodeSnippetExpression csbody = new CodeSnippetExpression(codeBody);111 CodeExpressionStatement stmt = new CodeExpressionStatement(csbody);112 //Add the expression statements to the method.113 cmm.Statements.Add(stmt);114 }115 myDesignerClass.Members.Add(cmm);116 117 }118 if (m is MemberDeclarationSyntax)119 {120 121 }122 }123 124 ccu.Namespaces.Add(ns);125 126 //Partial Class127 myDesignerClass.IsPartial = true;128 129 130 ns.Types.Add(myDesignerClass);131 132 133 134 return ccu;135 } 窗体的显示，需要逐句进行C#解析，特别是InitializeComponent()方法。
.CS Code其实最简单的就是读取源代码，然后返回就可以了。当设计器添加控件或者绑定事件时，可以通过文本操作进行代码完善。
1 //直接返回代码，最简单2 public string GetTextCSCode()3 {4 Flush();5 return __CSTextCode;6 } CodeDomHostLoader类中有OnComponentRename，在设计器重命名组件时候响应，这里可以修复后台.cs中的控件引用
但此设计器还有很多不完善的地方，后期有时间再完善吧。