滚动条可见性

Question

我只写代码：

namespace Test01
{
    partial class Form1
    {
        /// <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.panel1 = new System.Windows.Forms.Panel();
            this.button1 = new System.Windows.Forms.Button();
            this.button2 = new System.Windows.Forms.Button();
            this.button3 = new System.Windows.Forms.Button();
            this.button4 = new System.Windows.Forms.Button();
            this.panel1.SuspendLayout();
            this.SuspendLayout();
            // 
            // panel1
            // 
            this.panel1.AutoScroll = true;
            this.panel1.Controls.Add(this.button4);
            this.panel1.Controls.Add(this.button3);
            this.panel1.Controls.Add(this.button2);
            this.panel1.Location = new System.Drawing.Point(24, 13);
            this.panel1.Name = "panel1";
            this.panel1.Size = new System.Drawing.Size(206, 43);
            this.panel1.TabIndex = 0;
            // 
            // button1
            // 
            this.button1.Location = new System.Drawing.Point(89, 62);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(75, 23);
            this.button1.TabIndex = 1;
            this.button1.Text = "button1";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // 
            // button2
            // 
            this.button2.Location = new System.Drawing.Point(3, 3);
            this.button2.Name = "button2";
            this.button2.Size = new System.Drawing.Size(75, 23);
            this.button2.TabIndex = 2;
            this.button2.Text = "button2";
            this.button2.UseVisualStyleBackColor = true;
            // 
            // button3
            // 
            this.button3.Location = new System.Drawing.Point(84, 3);
            this.button3.Name = "button3";
            this.button3.Size = new System.Drawing.Size(75, 23);
            this.button3.TabIndex = 3;
            this.button3.Text = "button3";
            this.button3.UseVisualStyleBackColor = true;
            // 
            // button4
            // 
            this.button4.Location = new System.Drawing.Point(165, 3);
            this.button4.Name = "button4";
            this.button4.Size = new System.Drawing.Size(75, 23);
            this.button4.TabIndex = 4;
            this.button4.Text = "button4";
            this.button4.UseVisualStyleBackColor = true;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(251, 98);
            this.Controls.Add(this.button1);
            this.Controls.Add(this.panel1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.panel1.ResumeLayout(false);
            this.ResumeLayout(false);

        }

        #endregion

        private System.Windows.Forms.Panel panel1;
        private System.Windows.Forms.Button button4;
        private System.Windows.Forms.Button button3;
        private System.Windows.Forms.Button button2;
        private System.Windows.Forms.Button button1;
    }
}

还有：

namespace Test01
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            panel1.Controls.Remove(button4);
        }
    }
}

我运行它并得到以下结果：

在第一列我只需按下按钮 1 - 它按预期工作。

在第二列，我移动滚动条并按下按钮 1 - 按钮 4 消失了，但滚动条仍然存在。当我折叠和展开窗口滚动条消失了。

在第三列，我打开经典主题，然后按 button1 - 一切正常。

我已阅读 stackoverflow1 stackoverflow2 stackoverflow3 并尝试使用验证、无效、更新、刷新 - 但它没有帮助。那么，我该如何解决这个问题呢？

Answer 1

在移除按钮之前将滚动条的位置重置为零：

    private void button1_Click(object sender, EventArgs e)
    {
        panel1.HorizontalScroll.Value = 0;
        panel1.Controls.Remove(button4);
    }

编辑

我发现当滚动条的值为零时，这种方法并不总是有效。我尝试了各种方法来强制它始终清除滚动条，但唯一可靠的方法是在移除按钮之前将其值设置为 1 然后 0：

        panel1.HorizontalScroll.Value = 1;
        panel1.HorizontalScroll.Value = 0;
        panel1.Controls.Remove(button4);

它很丑，但它似乎工作。我个人认为这是框架中的一个错误。

Answer 2

尝试用 FlowLayoutPanel 替换您的面板。使用与您要更换的面板相同的尺寸。在 FlowLayoutPanel 控件上，设置AutoScroll = True 和FlowDirection = TopDown。

面板应该会为您移动控件，您也不必担心滚动条。

Answer 3

尝试通过BeginInvoke调用刷新方法，使其重新进入窗口循环：

this.BeginInvoke((Action)scrollBar.PerformLayout);

从当前方法调用它（不调用）有时可以避免重新渲染。