c# - 我可以在 Windows 窗体窗体中创建和显示多少个控件？

实际上，有一个限制，虽然不是硬编码和可配置的 - 它的默认值为 10,000（为什么？）。

每个控件都在操作系统中创建一个用户对象，Windows 中每个进程的默认最大活动用户对象数为 10,000 - 因此，一旦您尝试将 10,001 控件添加到表单中，您应该会得到类型异常 System.ComponentModel.Win32Exception并显示以下消息：

创建窗口句柄时出错。

当然，没有用户会希望看到一个包含 10,000 个控件的表单，所以除非你在某处有泄漏，否则这永远不会发生。（当然，我知道它的唯一原因只是因为我过去曾发生过这种泄漏 - 我有用户控件监听来自静态类的事件并且没有在Dispose方法中解开它们，所以即使在他们从屏幕上清除后，他们还活着......）

当您收到此异常时，请查看任务管理器的进程选项卡。单击View菜单，在内部单击Select Columns，标记USER Objects的复选框（默认情况下不可见；在尝试了解我的泄漏时，这一事实可能花费了我几个小时）-然后按该列排序。如果您在顶部看到您的应用程序，有 10,000 个用户对象 - 那么您知道您的应用程序已达到最大控件数 - 这意味着您需要修复泄漏。

请注意，即使您从表单中删除控件，如果它们有其他引用，它们也不会被释放，并且如果您的应用程序运行足够的时间，您最终会收到此错误。

如果有人感兴趣，这是我用来重新创建错误的代码（包括设计器代码）

using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace UserObjectsLeak
{
    public partial class FrmUserObjectsLeak : Form
    {
        // This is used to keep references of the labels being added dynamically.
        static readonly List<Label> Labels = new List<Label>();

        public FrmUserObjectsLeak()
        {
            InitializeComponent();
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            for (var i = 0; i < 11000; i++)
            {
                var label = new Label()
                {
                    Text = i.ToString(),
                    Width = 50
                };
                Labels.Add(label);
                try
                {
                    panel1.Controls.Add(label);
                }
                catch (System.ComponentModel.Win32Exception ex)
                {
                    lblException.Text = ex.ToString();
                    return;
                }

                lblControlsCount.Text = (i).ToString();

                // Quick and dirty just to show the progress...
                Application.DoEvents();

                if (i % 500 == 0)
                {
                    // Remove all labels from the panel,
                    // keep only the reference in the list.
                    panel1.Controls.Clear();
                }
            }
        }

        private void btnClear_Click(object sender, EventArgs e)
        {
            panel1.Controls.Clear();
            Labels.Clear();
            lblControlsCount.Text = "";
            lblException.Text = "";
        }

        #region Designer code

        /// <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 Windows Form 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.label1 = new System.Windows.Forms.Label();
            this.label2 = new System.Windows.Forms.Label();
            this.btnStart = new System.Windows.Forms.Button();
            this.lblControlsCount = new System.Windows.Forms.Label();
            this.btnClear = new System.Windows.Forms.Button();
            this.panel1 = new System.Windows.Forms.FlowLayoutPanel();
            this.lblException = new System.Windows.Forms.Label();
            this.SuspendLayout();
            // 
            // label1
            // 
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(15, 17);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(191, 13);
            this.label1.TabIndex = 0;
            this.label1.Text = "Click the button to start adding controls";
            // 
            // label2
            // 
            this.label2.AutoSize = true;
            this.label2.Location = new System.Drawing.Point(12, 95);
            this.label2.Name = "label2";
            this.label2.Size = new System.Drawing.Size(77, 13);
            this.label2.TabIndex = 1;
            this.label2.Text = "controls count:";
            // 
            // btnStart
            // 
            this.btnStart.Location = new System.Drawing.Point(12, 49);
            this.btnStart.Name = "btnStart";
            this.btnStart.Size = new System.Drawing.Size(75, 23);
            this.btnStart.TabIndex = 2;
            this.btnStart.Text = "Start";
            this.btnStart.UseVisualStyleBackColor = true;
            this.btnStart.Click += new System.EventHandler(this.btnStart_Click);
            // 
            // lblControlsCount
            // 
            this.lblControlsCount.AutoSize = true;
            this.lblControlsCount.Location = new System.Drawing.Point(95, 95);
            this.lblControlsCount.Name = "lblControlsCount";
            this.lblControlsCount.Size = new System.Drawing.Size(0, 13);
            this.lblControlsCount.TabIndex = 3;
            // 
            // btnClear
            // 
            this.btnClear.Location = new System.Drawing.Point(98, 49);
            this.btnClear.Name = "btnClear";
            this.btnClear.Size = new System.Drawing.Size(75, 23);
            this.btnClear.TabIndex = 5;
            this.btnClear.Text = "Clear";
            this.btnClear.UseVisualStyleBackColor = true;
            this.btnClear.Click += new System.EventHandler(this.btnClear_Click);
            // 
            // panel1
            // 
            this.panel1.FlowDirection = System.Windows.Forms.FlowDirection.TopDown;
            this.panel1.Location = new System.Drawing.Point(226, 17);
            this.panel1.Name = "panel1";
            this.panel1.Size = new System.Drawing.Size(200, 148);
            this.panel1.TabIndex = 6;
            // 
            // lblException
            // 
            this.lblException.AutoSize = true;
            this.lblException.Location = new System.Drawing.Point(15, 179);
            this.lblException.Name = "lblException";
            this.lblException.Size = new System.Drawing.Size(0, 13);
            this.lblException.TabIndex = 7;
            // 
            // frmUserObjectsLeak
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(452, 308);
            this.Controls.Add(this.lblException);
            this.Controls.Add(this.panel1);
            this.Controls.Add(this.btnClear);
            this.Controls.Add(this.lblControlsCount);
            this.Controls.Add(this.btnStart);
            this.Controls.Add(this.label2);
            this.Controls.Add(this.label1);
            this.Name = "FrmUserObjectsLeak";
            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
            this.Text = "User Objects Leak Demo";
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Label label2;
        private System.Windows.Forms.Button btnStart;
        private System.Windows.Forms.Label lblControlsCount;
        private System.Windows.Forms.Button btnClear;
        private System.Windows.Forms.FlowLayoutPanel panel1;
        private System.Windows.Forms.Label lblException;

        #endregion Designer code
    }
}

c# - 我可以在 Windows 窗体窗体中创建和显示多少个控件？

问题描述

解决方案

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