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[0];
            var namespaceDeclration = (NamespaceDeclarationSyntax)firstMember;
            var designClassDeclaration = (ClassDeclarationSyntax)namespaceDeclration.Members[0];
            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("
".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。