Relocating panels gets mixed up WinForms

Question

I am creating an application using C# and WinForms. I have three panels. Two of them are fairly large and are currently positioned side by side. I am trying to implement a feature for users who have smaller screens or wish to have the form as a smaller size. I am relocating the right panel underneath the middle one and re-centering them in the form. The issue that I have though is when the user scrolls down and re-sizes the form again the two middle panels (the big ones) move lower in the form leaving a chunk of blank space at the top.

My code is fairly simple

namespace ResizeCheck
{
    public partial class Form1 : Form
    {
        Point originalLeft, originalRight;
        bool flag = false;
        public Form1()
        {
            InitializeComponent();
            originalLeft = leftInnerPanel.Location;
            originalRight = rightInnerPanel.Location;
        }
        private void vertical()//move the right panel under the left one
        {
            leftInnerPanel.Location = new Point(this.Width / 2 - leftInnerPanel.Width / 2, 5);
            if (leftInnerPanel.Location.X <= buttonPanel.Location.X + buttonPanel.Width)
            {
                leftInnerPanel.Location = new Point(buttonPanel.Location.X + buttonPanel.Width, leftInnerPanel.Location.Y);
            }
            rightInnerPanel.Location = new Point(leftInnerPanel.Location.X, leftInnerPanel.Height + 10);
            MessageBox.Show("inside vertical " + leftInnerPanel.Location.Y);
        }

        private void horizontal()//relocate to their original horizontal position
        {
            leftInnerPanel.Location = new Point(buttonPanel.Location.X + buttonPanel.Width + 10, 5);
            if (leftInnerPanel.Location.X <= buttonPanel.Location.X + buttonPanel.Width)
            {
                leftInnerPanel.Location = new Point(buttonPanel.Location.X + buttonPanel.Width, leftInnerPanel.Location.Y);
            }
            rightInnerPanel.Location = new Point(leftInnerPanel.Location.X + leftInnerPanel.Width + 20, 5);
            MessageBox.Show("inside horizontal " + leftInnerPanel.Location.Y);
        }

        private void Form1_SizeChanged(object sender, EventArgs e)//handler for when the form is resized by the user
        {
            if ((leftInnerPanel.Width + rightInnerPanel.Width + buttonPanel.Width) >= this.Width)
            {
                vertical();
                //flag = true;
            }
            else if ((leftInnerPanel.Width + rightInnerPanel.Width + buttonPanel.Width) + 50 < this.Width)
            {
                horizontal();
                //flag = false;
            }
        }
    }
}

My designer code is also fairly simple.

namespace ResizeCheck
{
    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.rightInnerPanel = new System.Windows.Forms.Panel();
            this.leftInnerPanel = new System.Windows.Forms.Panel();
            this.buttonPanel = new System.Windows.Forms.Panel();
            this.SuspendLayout();
            // 
            // rightInnerPanel
            // 
            this.rightInnerPanel.BackColor = System.Drawing.Color.Yellow;
            this.rightInnerPanel.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
            this.rightInnerPanel.Location = new System.Drawing.Point(887, 13);
            this.rightInnerPanel.Name = "rightInnerPanel";
            this.rightInnerPanel.Size = new System.Drawing.Size(662, 936);
            this.rightInnerPanel.TabIndex = 1;
            // 
            // leftInnerPanel
            // 
            this.leftInnerPanel.BackColor = System.Drawing.Color.Yellow;
            this.leftInnerPanel.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
            this.leftInnerPanel.Location = new System.Drawing.Point(219, 13);
            this.leftInnerPanel.Name = "leftInnerPanel";
            this.leftInnerPanel.Size = new System.Drawing.Size(662, 936);
            this.leftInnerPanel.TabIndex = 0;
            // 
            // buttonPanel
            // 
            this.buttonPanel.BackColor = System.Drawing.SystemColors.ActiveCaptionText;
            this.buttonPanel.Location = new System.Drawing.Point(13, 13);
            this.buttonPanel.Name = "buttonPanel";
            this.buttonPanel.Size = new System.Drawing.Size(200, 258);
            this.buttonPanel.TabIndex = 1;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.AutoScroll = true;
            this.ClientSize = new System.Drawing.Size(1008, 601);
            this.Controls.Add(this.rightInnerPanel);
            this.Controls.Add(this.buttonPanel);
            this.Controls.Add(this.leftInnerPanel);
            this.Name = "Form1";
            this.Text = "Form1";
            this.WindowState = System.Windows.Forms.FormWindowState.Maximized;
            this.SizeChanged += new System.EventHandler(this.Form1_SizeChanged);
            this.ResumeLayout(false);

        }

        #endregion

        private System.Windows.Forms.Panel rightInnerPanel;
        private System.Windows.Forms.Panel leftInnerPanel;
        private System.Windows.Forms.Panel buttonPanel;
    }
}

Answer 1

In vertical() since you are not adjusting the Y of leftInnerPanel, we can straightaway use the buttonPanel.Top

leftInnerPanel.Location = new Point(this.Width / 2 - leftInnerPanel.Width / 2, buttonPanel.Top);

Secondly,

//rightInnerPanel.Location = new Point(leftInnerPanel.Location.X, leftInnerPanel.Height + 10);
rightInnerPanel.Location = new Point(leftInnerPanel.Location.X, leftInnerPanel.Bottom + 10);

Answer 2

You are not accounting for how much the form has scrolled, you are simply plopping the panel at the top of the visible client area.

Change your Vertical() method thusly:

    private void vertical()
    {
        leftInnerPanel.Location = new Point(this.Width / 2 - leftInnerPanel.Width / 2, 5 - VerticalScroll.Value);
        if (leftInnerPanel.Location.X <= buttonPanel.Location.X + buttonPanel.Width)
            leftInnerPanel.Location = new Point(buttonPanel.Location.X + buttonPanel.Width, leftInnerPanel.Location.Y);
        rightInnerPanel.Location = new Point(leftInnerPanel.Location.X, leftInnerPanel.Bottom + 10);
    }

Two points to note:

1) use of the VerticalScroll member.

2) use of Bottom instead of Height (and Right instead of Width in the Horizontal() method).