自定义控件在 Visual Studio 设计器中不更新

Question

我正在创建一个布局单选按钮的自定义控件（不，它不一定是单选按钮。我只是想学习如何做到这一点，以便我可以在路上制作一些更复杂的东西可能包含多个控件列表）通过 Items 属性添加（类似于其他一些控件）。

我可以构建项目，将其从组件面板拖到表单上，并通过 Items 属性添加单选按钮。不幸的是，这在设计器中没有更新，除非您：

• 重建项目 2-3 次
• 在设计器中关闭并重新打开表单

起初我的逻辑是在 Initialize 之后将它们放在构造函数中包含的表单上，但这不起作用，所以我转到了 Form_Load。

我错过了什么？上述选项只是短期解决方法，而不是解决方案。

RBLTest.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WFCL_Library
{
    public partial class RBLTest : UserControl
    {
        private List<RadioButton> _items;

        private int leftSpacing = 100;
        private int topSpacing = 25;

        public RBLTest()
        {
            _items = new List<RadioButton>();
            InitializeComponent();
        }

        private void RadioButtonList_Load(object sender, EventArgs e)
        {
            int curLeftPos = 0;
            int curTopPos = 0;
            foreach (RadioButton rb in _items)
            {
                rb.Location = new Point(curLeftPos, curTopPos);
                rb.Size = new Size(85, 17);

                curLeftPos += leftSpacing;

                if (curLeftPos > this.Width)
                {
                    curLeftPos = 0;
                    curTopPos += topSpacing;
                }

                this.Controls.Add(rb);                
            }
        }

        [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
        public List<RadioButton> Items
        {
            get
            {
                return _items;
            }
            set
            {
                _items = value;
            }
        }
    }       
}

RBLTest.Designer.cs

namespace WFCL_Library
{
    partial class RBLTest
    {
        /// <summary> 
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary> 
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Component Designer generated code

        /// <summary> 
        /// Required method for Designer support - do not modify 
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.SuspendLayout();
            // 
            // RBLTest
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.Name = "RBLTest";
            this.Size = new System.Drawing.Size(407, 44);
            this.Load += new System.EventHandler(this.RadioButtonList_Load);
            this.ResumeLayout(false);

        }

        #endregion

    }
}

Answer 1

您不应使用Load 事件或构造函数，因为当您使用设计器工具添加控件时，会创建UserControl 的实例并触发Load 事件。在您发生这种情况时，_item 仍然是空的。另一个问题是序列化列表存在一些问题，所以我会使用数组：

public partial class RBLTest : UserControl {
    private RadioButton[] _items;

    private int leftSpacing = 100;
    private int topSpacing = 25;

    public RBLTest( ) {
        InitializeComponent( );
    }

    [DesignerSerializationVisibility( DesignerSerializationVisibility.Content )]
    public RadioButton[] Items {
        get {
            return _items;
        }
        set {
            _items = value;

            int curLeftPos = 0;
            int curTopPos = 0;
            foreach ( RadioButton rb in _items ) {
                rb.Location = new Point( curLeftPos, curTopPos );
                rb.Size = new Size( 85, 17 );

                curLeftPos += leftSpacing;

                if ( curLeftPos > this.Width ) {
                    curLeftPos = 0;
                    curTopPos += topSpacing;
                }

                this.Controls.Add( rb );
            }
        }
    }
}

表单设计器中的结果：

Answer 2

原因是您仅在 Load 事件中向 ControlsCollection 添加控件。这是我在 Google 上搜索的在 WinForms 中创建容器控件的教程： http://www.codeproject.com/Articles/9238/WinForms-Custom-Container-Control