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How to: Scroll Form Contents

With a Panel control, you can set its AutoScroll property to true and vertically scroll through its contents. However, to scroll both vertically and horizontally you need to add scroll bars to define their properties.

This example shows how to use horizontal and vertical scroll bar controls to scroll across and down an image on a form. When you click the scroll bars, the Left and Left properties of the panel change according to scroll bar values, thereby creating the scrolling experience.

This example creates a large image in the form, or a Rectangle with an X diagonally connecting the four corners.

The event-handling code for the ValueChanged event changes the Left or Left properties of the Panel by the changed value of the scroll bar. These properties decrease when you scroll right with the horizontal scroll bar and down with the vertical scroll bar. Conversely, they increase when you go in the opposite directions.

using System;
using System.Drawing;
using System.Collections;
using System.Windows.Forms;
using System.Data;
using System.Reflection;

namespace Scrolling
{

    public class Scrolling : System.Windows.Forms.Form
    {
        private System.Windows.Forms.HScrollBar hScrollBar1;
        private System.Windows.Forms.VScrollBar vScrollBar1;
        private System.Windows.Forms.Panel panel1;
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Label label2;
        private System.Windows.Forms.Label label3;
        private System.Windows.Forms.Label label4;
        private System.Windows.Forms.PictureBox pictureBox1;
        private System.Windows.Forms.MainMenu mainMenu1;

        public Scrolling()
        {

            InitializeComponent();

            Bitmap bmp = new Bitmap(pictureBox1.Width,pictureBox1.Height);
            Pen blackpen = new Pen(Color.Black);
            Graphics g = Graphics.FromImage(bmp);
            g.FillRectangle(new SolidBrush(Color.Gainsboro),0,0,bmp.Width,bmp.Height);
            g.DrawLine(blackpen,0,0, bmp.Width, bmp.Height);
            g.DrawLine(blackpen,0,bmp.Height,bmp.Width,0);
            g.Dispose();

            this.pictureBox1.Image = bmp;
            this.pictureBox1.Size = bmp.Size;
            this.vScrollBar1.Maximum = bmp.Height + this.ClientSize.Height;
            this.hScrollBar1.Maximum = bmp.Width + this.ClientSize.Width;
            this.hScrollBar1.Value = 0;

            this.Text = "x = 0, y = 0";
        }

        protected override void Dispose( bool disposing )
        {
            base.Dispose( disposing );
        }

        private void InitializeComponent()
        {
            this.mainMenu1 = new System.Windows.Forms.MainMenu();
            this.hScrollBar1 = new System.Windows.Forms.HScrollBar();
            this.vScrollBar1 = new System.Windows.Forms.VScrollBar();
            this.panel1 = new System.Windows.Forms.Panel();
            this.pictureBox1 = new System.Windows.Forms.PictureBox();
            this.label1 = new System.Windows.Forms.Label();
            this.label2 = new System.Windows.Forms.Label();
            this.label3 = new System.Windows.Forms.Label();
            this.label4 = new System.Windows.Forms.Label();
            // 
            // hScrollBar1 
            // 
            this.hScrollBar1.LargeChange = 240;
            this.hScrollBar1.Location = new System.Drawing.Point(0, 255);
            this.hScrollBar1.Maximum = 493;
            this.hScrollBar1.Size = new System.Drawing.Size(227, 13);
            this.hScrollBar1.ValueChanged += new System.EventHandler(this.hScrollBar1_ValueChanged);
            // 
            // vScrollBar1 
            // 
            this.vScrollBar1.LargeChange = 268;
            this.vScrollBar1.Location = new System.Drawing.Point(227, 0);
            this.vScrollBar1.Maximum = 549;
            this.vScrollBar1.Size = new System.Drawing.Size(13, 255);
            this.vScrollBar1.ValueChanged += new System.EventHandler(this.vScrollBar1_ValueChanged);
            // 
            // panel1 
            // 
            this.panel1.Controls.Add(this.pictureBox1);
            this.panel1.Controls.Add(this.label1);
            this.panel1.Controls.Add(this.label2);
            this.panel1.Controls.Add(this.label3);
            this.panel1.Controls.Add(this.label4);
            this.panel1.Size = new System.Drawing.Size(480, 536);
            // 
            // pictureBox1 
            // 
            this.pictureBox1.Location = new System.Drawing.Point(88, 36);
            this.pictureBox1.Size = new System.Drawing.Size(304, 464);
            // 
            // label1 
            // 
            this.label1.Location = new System.Drawing.Point(8, 8);
            this.label1.Size = new System.Drawing.Size(82, 20);
            this.label1.Text = "Top Left";
            // 
            // label2 
            // 
            this.label2.Location = new System.Drawing.Point(400, 8);
            this.label2.Size = new System.Drawing.Size(82, 20);
            this.label2.Text = "Top Right";
            // 
            // label3 
            // 
            this.label3.Location = new System.Drawing.Point(8, 508);
            this.label3.Size = new System.Drawing.Size(82, 20);
            this.label3.Text = "Bottom Left";
            // 
            // label4 
            // 
            this.label4.Location = new System.Drawing.Point(400, 508);
            this.label4.Size = new System.Drawing.Size(82, 20);
            this.label4.Text = "Bottom Right";
            // 
            // Scrolling 
            // 
            this.Controls.Add(this.vScrollBar1);
            this.Controls.Add(this.hScrollBar1);
            this.Controls.Add(this.panel1);
            this.Menu = this.mainMenu1;
            this.Text = "Scrolling";

        }

        static void Main()
        {
            Application.Run(new Scrolling());
        }

        private void hScrollBar1_ValueChanged(object sender, System.EventArgs e)
        {
            this.panel1.Left = -this.hScrollBar1.Value;

            // Display the current values in the title bar. 
            this.Text = "x = " + this.panel1.Location.X + ", y = " + this.panel1.Location.Y;
        }

        private void vScrollBar1_ValueChanged(object sender, System.EventArgs e)
        {
            this.panel1.Top = -this.vScrollBar1.Value;

            // Display the current values in the title bar. 
            this.Text = "x = " + this.panel1.Location.X + ", y = " + this.panel1.Location.Y;
        }
    }
}

This example requires references to the following namespaces:

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