C#用DesignSurface实现一个简单的窗体设计器

　　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。

         private void Form1_Load(object sender, EventArgs e)
         {
            //引用System.Deisgn.dll
            DesignSurface ds = new DesignSurface();
             //开始加载窗体
             ds.BeginLoad(typeof(Form));
             Control designerContorl = (Control)ds.View;
             designerContorl.Dock = DockStyle.Fill;
             this.Controls.Add(designerContorl);
         }

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：

         protected override CodeCompileUnit Parse()
         {
 
             #region 源文件读取
             var sw = new StreamReader(@"E:\FrmUser.cs");
             var sw_designer = new StreamReader(@"E:\FrmUser.Designer.cs");
 
             string formCodeCS = sw.ReadToEnd();
             string formCodeDesigner = sw_designer.ReadToEnd();
 
             List<string> source = new List<string>();
             source.Add(formCodeCS);
             source.Add(formCodeDesigner);
 
             #endregion
             //Rolsyn解析C#
             var rootDesigner = Source2CodeDom.Parse(formCodeDesigner);
             codeDesingerCompileUnit = Source2CodeDom.GetDesignerCodeComplieUnit(rootDesigner);
             var rootCS = Source2CodeDom.Parse(formCodeCS);
             codeCSCompileUnit = Source2CodeDom.GetCodeComplieUnit(rootCS);
             //MergeFormSource
             string mergeS = Source2CodeDom.MergeFormSource(formCodeDesigner, formCodeCS);
             codeMergeCompileUnit = Source2CodeDom.GetMergeDesignerCodeComplieUnit(mergeS);
             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：

        public static CodeCompileUnit GetDesignerCodeComplieUnit2(CompilationUnitSyntax root)
         {
             CodeCompileUnit ccu = new CodeCompileUnit();
             var firstMember = root.Members[];
             var namespaceDeclration = (NamespaceDeclarationSyntax)firstMember;
             var designClassDeclaration = (ClassDeclarationSyntax)namespaceDeclration.Members[];
             var myDesignerClass = new CodeTypeDeclaration(designClassDeclaration.Identifier.ToString());
             var initializeComponent = new CodeMemberMethod();
             var ns = new CodeNamespace(namespaceDeclration.Name.ToString());
 
             foreach (var m in designClassDeclaration.Members)
             {
 
                 if (m is ConstructorDeclarationSyntax)
                 {
                     var ctor = ((ConstructorDeclarationSyntax)m);
                     var codeBody = ctor.Body.ToString();
                     codeBody = codeBody.Trim().TrimStart('{').TrimEnd('}').Trim().TrimEnd(';');
                     CodeSnippetExpression csbody = new CodeSnippetExpression(codeBody);
                     CodeExpressionStatement stmt = new CodeExpressionStatement(csbody);
                     //Add the expression statements to the method.
                     // InitializeComponent
                     var cctor = new CodeConstructor();
                     cctor.Name = ctor.Identifier.ToString();
                     //var cmm = new CodeMemberMethod();
                     //cmm.Name = ctor.Identifier.ToString();
                     //cmm.Attributes = GetCtoRAttrMapping(ctor);
                     //cmm.ReturnType = new CodeTypeReference(typeof(void));
                     cctor.Statements.Add(stmt);
 
                     myDesignerClass.Members.Add(cctor);
                 }
                 if (m is FieldDeclarationSyntax)
                 {
                     var F = ((FieldDeclarationSyntax)m);
                     var type = F.Declaration.Type;
                     foreach (var variable in F.Declaration.Variables)
                     {
                         var field = new CodeMemberField();
                         field.Name = variable.Identifier.ToString();
                         field.Type = new CodeTypeReference(type.ToString());
                         field.Attributes = GetFieldAttrMapping(F);
                         //field.InitExpression = new CodePrimitiveExpression(null);
                         myDesignerClass.Members.Add(field);
                     }
                 }
                 if (m is MethodDeclarationSyntax)
                 {
                     var node = m as MethodDeclarationSyntax;
                     #region xml comments
                     var xmlTrivia = node.GetLeadingTrivia()
                         .Select(i => i.GetStructure())
                         .OfType<DocumentationCommentTriviaSyntax>()
                         .FirstOrDefault();
 
                     #endregion
 
                     var method = (MethodDeclarationSyntax)m;
 
                     var cmm = new CodeMemberMethod();
                     cmm.Name = method.Identifier.ToString();
 
                     ///XML注释
                     string[] comments = xmlTrivia.ToString().Split("\r\n".ToCharArray());
                     foreach (string text in comments)
                     {
                         if (text.Trim() != "")
                         {
                             cmm.Comments.Add(new CodeCommentStatement(text.Trim().TrimStart("///".ToCharArray()).Trim(), true));
                         }
                     }
 
                     if (cmm.Name == "InitializeComponent")
                     {
                         //region
                         CodeRegionDirective codeRegion = new CodeRegionDirective(CodeRegionMode.Start, "Windows 窗体设计器生成的代码");
                         CodeRegionDirective codeEndRegion = new CodeRegionDirective(CodeRegionMode.End, "");
 
                         cmm.StartDirectives.Add(codeRegion);
                         cmm.EndDirectives.Add(codeEndRegion);
                     }
 
                     //MemberAttributes.Family is protected
                     //cmm.Attributes = MemberAttributes.Override | MemberAttributes.Family;
                     cmm.Attributes = GetMethodAttrMapping(method);
                     cmm.ReturnType = new CodeTypeReference(method.ReturnType.ToString());
 
                     foreach (var p in method.ParameterList.Parameters)
                     {
                         CodeParameterDeclarationExpression cpd = new CodeParameterDeclarationExpression();
                         cpd.Name = p.Identifier.ToString();
 
                         cpd.Type = new CodeTypeReference(p.Type.ToString());
 
                         cmm.Parameters.Add(cpd);
                     }
                     //包含方法{};，会重复生成{};
                     string codeBody = method.Body.ToString();
                     codeBody = codeBody.Trim().TrimStart('{').TrimEnd('}').Trim().TrimEnd(';');
                     if (codeBody != "")
                     {
                         CodeSnippetExpression csbody = new CodeSnippetExpression(codeBody);
                         CodeExpressionStatement stmt = new CodeExpressionStatement(csbody);
                         //Add the expression statements to the method.
                         cmm.Statements.Add(stmt);
                     }
                     myDesignerClass.Members.Add(cmm);
 
                 }
                 if (m is MemberDeclarationSyntax)
                 {
 
                 }
             }
 
             ccu.Namespaces.Add(ns);
 
             //Partial Class
             myDesignerClass.IsPartial = true;
 
             ns.Types.Add(myDesignerClass);
 
             return ccu;
         }

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。

 //直接返回代码，最简单
  public string GetTextCSCode()
  {
        Flush();
        return __CSTextCode;
 }

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。