在Designer支持下将表单作为属性添加到用户控件

本文介绍了在Designer支持下将表单作为属性添加到用户控件的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 我已经创建了一个自定义标签.它具有 Form 类型的属性，用户可以在设计器中选择该表单，然后单击标签时将加载该表单.它可以正常工作，但属性下拉列表中的唯一形式是标签所在的形式.是否可以显示所有可能的表单，或者让用户将表单作为字符串传递，然后将其转换为表单?这是我标签的代码: 公共类BMLabel私有t作为字符串私有ID作为字符串私人frm作为新形式<类别("BM")>公共属性类型为字符串得到返回t结束获取设置(值作为字符串)t =值端套最终财产公共属性标识符为字符串得到返回编号结束获取设置(值作为字符串)id =值端套最终财产公共财产表格得到返回frm结束获取设置(值形式)frm =值端套最终财产私有Sub BMLabel_Click(作为对象发送，作为EventArgs发送)处理我.昏暗t = frm.GetType()昏暗的形式为Form = DirectCast(Activator.CreateInstance(t)，Form)form.ShowDialog()结束子末级 解决方案问题是，当您声明类型为 Form 的属性时，它允许您选择 form实例，而不是继承自 Form 的类型/类.您需要做的是声明一个类型为 Type 的属性，并准备编辑器，该编辑器将允许您选择所需的类型(将选项限制为从 Form ).So, here we go. The custom label class would look something like this:Public Class BMLabel Inherits Label ' Don't forget to change the namespace. ' ↓↓↓↓↓↓↓↓↓↓↓ <Editor("WindowsApp1.TypeSelector, System.Design", GetType(UITypeEditor)), Localizable(True)> Public Property FormType As Type Private Sub BMLabel_Click(sender As Object, e As EventArgs) Handles Me.Click Using frm As Form = DirectCast(Activator.CreateInstance(FormType), Form) frm.ShowDialog(Me) End Using End SubEnd ClassNow, we need to create the TypeSelector class:Public Class TypeSelector Inherits UITypeEditor Public Overrides Function GetEditStyle(context As ITypeDescriptorContext) As UITypeEditorEditStyle If context Is Nothing OrElse context.Instance Is Nothing Then Return MyBase.GetEditStyle(context) End If Return UITypeEditorEditStyle.Modal End Function Public Overrides Function EditValue(context As ITypeDescriptorContext, provider As IServiceProvider, value As Object) As Object Dim editorService As IWindowsFormsEditorService If context Is Nothing OrElse context.Instance Is Nothing OrElse provider Is Nothing Then Return value End If editorService = DirectCast(provider.GetService(GetType(IWindowsFormsEditorService)), IWindowsFormsEditorService) Dim dlg As New FormTypeSelector() dlg.Value = DirectCast(value, Type) dlg.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen If editorService.ShowDialog(dlg) = System.Windows.Forms.DialogResult.OK Then Return dlg.Value End If Return value End FunctionEnd ClassThen, we create a form called FormTypeSelector with a ComboBox or a ListBox to list the available options:Public Class FormTypeSelector Friend Property Value As Type Private Sub FormTypeSelector_Load(sender As Object, e As EventArgs) Handles MyBase.Load Dim availableFormTypes = System.Reflection.Assembly.GetExecutingAssembly(). GetTypes(). Where(Function(t) t.BaseType = GetType(Form) AndAlso t <> Me.GetType()).ToList() cboFormTypes.DisplayMember = "Name" cboFormTypes.DataSource = availableFormTypes cboFormTypes.SelectedItem = Value End Sub Private Sub BtnOK_Click(sender As Object, e As EventArgs) Handles btnOK.Click Value = DirectCast(cboFormTypes.SelectedItem, Type) DialogResult = DialogResult.OK Close() End Sub Private Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.Click DialogResult = DialogResult.Cancel Close() End SubEnd ClassAnd that's it; it should be ready to go:Note: You'll probably need to add an option in FormTypeSelector to allow clearing the selected value of the FormType property which should be easy enough to do. 这篇关于在Designer支持下将表单作为属性添加到用户控件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！