MouseWheelScrollLines Property
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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 Shared ReadOnly Property MouseWheelScrollLines As Integer

Property Value

Type: System.Int32

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.

System_CAPS_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.

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Reflection
Imports System.Windows.Forms

Public Class SystemInfoBrowserForm
    Inherits System.Windows.Forms.Form

    Private listBox1 As System.Windows.Forms.ListBox
    Private textBox1 As System.Windows.Forms.TextBox  

    Public Sub New()
        Me.SuspendLayout()
        InitForm()

        ' Add each property of the SystemInformation class to the list box.
        Dim t As Type = GetType(System.Windows.Forms.SystemInformation)
        Dim pi As PropertyInfo() = t.GetProperties()
        Dim i As Integer
        For i = 0 To pi.Length - 1
            listBox1.Items.Add(pi(i).Name)
        Next i
        textBox1.Text = "The SystemInformation class has " + pi.Length.ToString() + " properties." + ControlChars.CrLf

        ' Configure the list item selected handler for the list box to invoke a 
        ' method that displays the value of each property.
        AddHandler listBox1.SelectedIndexChanged, AddressOf listBox1_SelectedIndexChanged

        Me.ResumeLayout(False)
    End Sub    

    Private Sub listBox1_SelectedIndexChanged(sender As Object, e As EventArgs)
        ' Return if no list item is selected.
        If listBox1.SelectedIndex = - 1 Then
            Return
        End If         
        ' Get the property name from the list item.
        Dim propname As String = listBox1.Text

        If propname = "PowerStatus" Then
            ' Cycle and display the values of each property of the PowerStatus property.
            textBox1.Text += ControlChars.CrLf + "The value of the PowerStatus property is:"
            Dim t As Type = GetType(System.Windows.Forms.PowerStatus)
            Dim pi As PropertyInfo() = t.GetProperties()
            Dim i As Integer
            For i = 0 To pi.Length - 1
                Dim propval As Object = pi(i).GetValue(SystemInformation.PowerStatus, Nothing)
                textBox1.Text += ControlChars.CrLf + "    PowerStatus." + pi(i).Name + " is: " + propval.ToString()
            Next i
        Else
            ' Display the value of the selected property of the SystemInformation type.
            Dim t As Type = GetType(System.Windows.Forms.SystemInformation)
            Dim pi As PropertyInfo() = t.GetProperties()
            Dim prop As PropertyInfo = Nothing
            Dim i As Integer
            For i = 0 To pi.Length - 1
                If pi(i).Name = propname Then
                    prop = pi(i)
                    Exit For
                End If
            Next i
            Dim propval As Object = prop.GetValue(Nothing, Nothing)
            textBox1.Text += ControlChars.CrLf + "The value of the " + propname + " property is: " + propval.ToString()
        End If
    End Sub    

    Private Sub InitForm()
        ' Initialize the form settings
        Me.listBox1 = New System.Windows.Forms.ListBox()
        Me.textBox1 = New System.Windows.Forms.TextBox()
        Me.listBox1.Anchor = CType(System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left Or System.Windows.Forms.AnchorStyles.Right, System.Windows.Forms.AnchorStyles)
        Me.listBox1.Location = New System.Drawing.Point(8, 16)
        Me.listBox1.Size = New System.Drawing.Size(172, 496)
        Me.listBox1.TabIndex = 0
        Me.textBox1.Anchor = CType(System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Right, System.Windows.Forms.AnchorStyles)
        Me.textBox1.Location = New System.Drawing.Point(188, 16)
        Me.textBox1.Multiline = True
        Me.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical
        Me.textBox1.Size = New System.Drawing.Size(420, 496)
        Me.textBox1.TabIndex = 1
        Me.ClientSize = New System.Drawing.Size(616, 525)
        Me.Controls.Add(Me.textBox1)
        Me.Controls.Add(Me.listBox1)
        Me.Text = "Select a SystemInformation property to get the value of"
    End Sub

    <STAThread()>  _
    Shared Sub Main()
        Application.Run(New SystemInfoBrowserForm())
    End Sub

End Class

.NET Framework
Available since 1.1
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