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SystemInformation.MouseWheelScrollLines Property

Gets the number of lines to scroll when the mouse wheel is rotated.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

public static int MouseWheelScrollLines { get; }
/** @property */
public static int get_MouseWheelScrollLines ()

public static function get MouseWheelScrollLines () : int

Not applicable.

Property Value

The number of lines to scroll on a mouse wheel rotation, or -1 if the "One screen at a time" mouse option is selected.

The MouseWheelScrollLines property indicates how many lines to scroll, by default, in a multi-line control that has a scroll bar. The corresponding Platform SDK system-wide parameters are SPI_GETWHEELSCROLLLINES and SPI_SETWHEELSCROLLLINES. For more information about system-wide parameters, see "SystemParametersInfo" in the Platform SDK documentation at http://msdn.microsoft.com.

NoteNote:

Be sure to handle the special case that occurs if the "One screen at a time" mouse option is selected. In this case, the MouseWheelScrollLines property has a value of -1.

The following code example lists all properties of the SystemInformation class in a ListBox and displays the current value of the property in a TextBox when a list item selected.

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

namespace SystemInfoBrowser
{
    public class SystemInfoBrowserForm : System.Windows.Forms.Form
    {
        private System.Windows.Forms.ListBox listBox1;
        private System.Windows.Forms.TextBox textBox1;        
        
        public SystemInfoBrowserForm()
	    {
            this.SuspendLayout();
            InitForm();
            
            // Add each property of the SystemInformation class to the list box.
            Type t = typeof(System.Windows.Forms.SystemInformation);            
            PropertyInfo[] pi = t.GetProperties();            
            for( int i=0; i<pi.Length; i++ )
                listBox1.Items.Add( pi[i].Name );            
            textBox1.Text = "The SystemInformation class has "+pi.Length.ToString()+" properties.\r\n";

            // Configure the list item selected handler for the list box to invoke a 
            // method that displays the value of each property.
            listBox1.SelectedIndexChanged += new EventHandler(listBox1_SelectedIndexChanged);
            this.ResumeLayout(false);
	    }
		
        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            // Return if no list item is selected.
            if( listBox1.SelectedIndex == -1 ) return;
            // Get the property name from the list item.
            string propname = listBox1.Text;
            
            if( propname == "PowerStatus" )
            {
                // Cycle and display the values of each property of the PowerStatus property.
                textBox1.Text += "\r\nThe value of the PowerStatus property is:";                                
                Type t = typeof(System.Windows.Forms.PowerStatus);
                PropertyInfo[] pi = t.GetProperties();            
                for( int i=0; i<pi.Length; i++ )
                {
                    object propval = pi[i].GetValue(SystemInformation.PowerStatus, null);            
                    textBox1.Text += "\r\n    PowerStatus."+pi[i].Name+" is: "+propval.ToString();
                }
            }
            else
            {
                // Display the value of the selected property of the SystemInformation type.
                Type t = typeof(System.Windows.Forms.SystemInformation);
                PropertyInfo[] pi = t.GetProperties();            
                PropertyInfo prop = null;
                for( int i=0; i<pi.Length; i++ )
                    if( pi[i].Name == propname )
                    {
                        prop = pi[i];
                        break;           
                    }
                object propval = prop.GetValue(null, null);            
                textBox1.Text += "\r\nThe value of the "+propname+" property is: "+propval.ToString();
            }
        }

        private void InitForm()
        {
            // Initialize the form settings
            this.listBox1 = new System.Windows.Forms.ListBox();
            this.textBox1 = new System.Windows.Forms.TextBox();            
            this.listBox1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
                | System.Windows.Forms.AnchorStyles.Left) | System.Windows.Forms.AnchorStyles.Right)));
            this.listBox1.Location = new System.Drawing.Point(8, 16);
            this.listBox1.Size = new System.Drawing.Size(172, 496);
            this.listBox1.TabIndex = 0;            
            this.textBox1.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
                | System.Windows.Forms.AnchorStyles.Right)));
            this.textBox1.Location = new System.Drawing.Point(188, 16);
            this.textBox1.Multiline = true;
            this.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;           
            this.textBox1.Size = new System.Drawing.Size(420, 496);
            this.textBox1.TabIndex = 1;            
            this.ClientSize = new System.Drawing.Size(616, 525);            
            this.Controls.Add(this.textBox1);
            this.Controls.Add(this.listBox1);            
            this.Text = "Select a SystemInformation property to get the value of";                   
        }

        [STAThread]
        static void Main() 
        {
            Application.Run(new SystemInfoBrowserForm());
        }
    }
}

package SystemInfoBrowser;

import System.*;
import System.Collections.*;
import System.ComponentModel.*;
import System.Drawing.*;
import System.Reflection.*;
import System.Windows.Forms.*;

public class SystemInfoBrowserForm extends System.Windows.Forms.Form
{
    private System.Windows.Forms.ListBox listBox1;
    private System.Windows.Forms.TextBox textBox1;

    public SystemInfoBrowserForm()
    {
        this.SuspendLayout();
        InitForm();
        // Add each property of the SystemInformation class to the list box.
        Type t = System.Windows.Forms.SystemInformation.class.ToType();
        PropertyInfo pi[] = t.GetProperties();
        for (int i = 0; i < pi.length; i++) {
            listBox1.get_Items().Add(pi[i].get_Name());
        }
        textBox1.set_Text("The SystemInformation class has "
            + ((Int32)pi.length).ToString() + " properties.\r\n");
        // Configure the list item selected handler for the list box to invoke
        // a method that displays the value of each property.
        listBox1.add_SelectedIndexChanged(
            new EventHandler(listBox1_SelectedIndexChanged));
        this.ResumeLayout(false);
    } //SystemInfoBrowserForm

    private void listBox1_SelectedIndexChanged(Object sender, EventArgs e)
    {
        // Return if no list item is selected.
        if (listBox1.get_SelectedIndex() == -1) {
            return;
        }
        // Get the property name from the list item.
        String propname = listBox1.get_Text();

        if (propname.Equals("PowerStatus")) {
            // Cycle and display the values of each property of the
            // PowerStatus property.
            textBox1.set_Text(textBox1.get_Text()
                + "\r\nThe value of the PowerStatus property is:");
            Type t = System.Windows.Forms.PowerStatus.class.ToType();
            PropertyInfo pi[] = t.GetProperties();
            for (int i = 0; i < pi.length; i++) {
                Object propval = pi[i].GetValue(
                    SystemInformation.get_PowerStatus(), null);
                textBox1.set_Text(textBox1.get_Text()
                    + "\r\n    PowerStatus." + pi[i].get_Name()
                    + " is: " + propval.ToString());
            }
        }
        else {
            // Display the value of the selected property of the
            // SystemInformation type.
            Type t = System.Windows.Forms.SystemInformation.class.ToType();
            PropertyInfo pi[] = t.GetProperties();
            PropertyInfo prop = null;
            for (int i = 0; i < pi.length; i++) {
                if (pi[i].get_Name().Equals(propname)) {
                    prop = pi[i];
                    break;
                }
            }
            Object propval = prop.GetValue(null, null);
            textBox1.set_Text(textBox1.get_Text() + "\r\nThe value of the "
                + propname + " property is: " + propval.ToString());
        }
    } //listBox1_SelectedIndexChanged

    private void InitForm()
    {
        // Initialize the form settings
        this.listBox1 = new System.Windows.Forms.ListBox();
        this.textBox1 = new System.Windows.Forms.TextBox();
        this.listBox1.set_Anchor((System.Windows.Forms.AnchorStyles)
            (System.Windows.Forms.AnchorStyles.Top
            | System.Windows.Forms.AnchorStyles.Bottom
            | System.Windows.Forms.AnchorStyles.Left
            | System.Windows.Forms.AnchorStyles.Right));
        this.listBox1.set_Location(new System.Drawing.Point(8, 16));
        this.listBox1.set_Size(new System.Drawing.Size(172, 496));
        this.listBox1.set_TabIndex(0);
        this.textBox1.set_Anchor((System.Windows.Forms.AnchorStyles)
            (System.Windows.Forms.AnchorStyles.Top
            | System.Windows.Forms.AnchorStyles.Bottom
            | System.Windows.Forms.AnchorStyles.Right));
        this.textBox1.set_Location(new System.Drawing.Point(188, 16));
        this.textBox1.set_Multiline(true);
        this.textBox1.set_ScrollBars(System.Windows.Forms.ScrollBars.Vertical);
        this.textBox1.set_Size(new System.Drawing.Size(420, 496));
        this.textBox1.set_TabIndex(1);
        this.set_ClientSize(new System.Drawing.Size(616, 525));
        this.get_Controls().Add(this.textBox1);
        this.get_Controls().Add(this.listBox1);
        this.set_Text("Select a SystemInformation property to get the value of");
    } //InitForm

    /** @attribute STAThread()
     */
    public static void main(String[] args)
    {
        Application.Run(new SystemInfoBrowserForm());
    } //main
} //SystemInfoBrowserForm

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0
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