LayoutEventArgs Class

 

Provides data for the Layout event. This class cannot be inherited.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

System.Object
  System.EventArgs
    System.Windows.Forms.LayoutEventArgs

Public NotInheritable Class LayoutEventArgs
	Inherits EventArgs

NameDescription
System_CAPS_pubmethodLayoutEventArgs(Control, String)

Initializes a new instance of the LayoutEventArgs class with the specified control and property affected.

System_CAPS_pubmethodLayoutEventArgs(IComponent, String)

Initializes a new instance of the LayoutEventArgs class with the specified component and property affected.

NameDescription
System_CAPS_pubpropertyAffectedComponent

Gets the Component affected by the layout change.

System_CAPS_pubpropertyAffectedControl

Gets the child control affected by the change.

System_CAPS_pubpropertyAffectedProperty

Gets the property affected by the change.

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

Changes to a control such as resizing, showing or hiding child controls, and adding or removing child controls make it necessary for a control to layout its child controls. A LayoutEventArgs specifies the child control that has been changed and its affected property. For example, if a control has been made visible since the last layout operation, the Visible property is affected.

The AffectedControl and AffectedProperty properties are set to null if no values were provided when the PerformLayout method was called.

For more information about handling events, see Handling and Raising Events.

The following code example uses the AffectedProperty and AffectedControl properties as LayoutEventHandler arguments to coordinate the size of a Windows form and its controls with various property changes to both the Windows form and the controls.

Public Class Form1
    Inherits System.Windows.Forms.Form
    Private WithEvents textBox1 As System.Windows.Forms.TextBox
    Private label1 As System.Windows.Forms.Label
    Private layoutButton As System.Windows.Forms.Button
    Private components As System.ComponentModel.Container = Nothing


    Public Sub New()
        InitializeComponent()
    End Sub

    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If (components IsNot Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    Private Sub InitializeComponent()
        Me.layoutButton = New System.Windows.Forms.Button()
        Me.textBox1 = New System.Windows.Forms.TextBox()
        Me.label1 = New System.Windows.Forms.Label()
        Me.SuspendLayout()
        ' 
        ' layoutButton
        ' 
        Me.layoutButton.Anchor = System.Windows.Forms.AnchorStyles.Bottom
        Me.layoutButton.Location = New System.Drawing.Point(72, 88)
        Me.layoutButton.Name = "layoutButton"
        Me.layoutButton.Size = New System.Drawing.Size(150, 23)
        Me.layoutButton.TabIndex = 0
        Me.layoutButton.Text = "Hello"
        ' 
        ' textBox1
        ' 
        Me.textBox1.Anchor = System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Left Or System.Windows.Forms.AnchorStyles.Right
        Me.textBox1.Location = New System.Drawing.Point(24, 40)
        Me.textBox1.Name = "textBox1"
        Me.textBox1.Size = New System.Drawing.Size(248, 20)
        Me.textBox1.TabIndex = 1
        Me.textBox1.Text = "Hello"
        ' 
        ' label1
        ' 
        Me.label1.Location = New System.Drawing.Point(24, 16)
        Me.label1.Name = "label1"
        Me.label1.TabIndex = 2
        Me.label1.Text = "Button's Text:"
        ' 
        ' Form1
        ' 
        Me.ClientSize = New System.Drawing.Size(292, 129)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.label1, Me.textBox1, Me.layoutButton})
        Me.Name = "Form1"
        Me.Text = "Layout Sample"
        Me.ResumeLayout(False)
    End Sub

   ' This method ensures that the form's width is the preferred size of 300 pixels
   ' or the size of the button plus 50 pixels, whichever amount is less.
    Private Sub Form1_Layout(ByVal sender As Object, ByVal e As System.Windows.Forms.LayoutEventArgs) Handles MyBase.Layout
      ' This event is raised once at startup with the AffectedControl
      ' and AffectedProperty properties on the LayoutEventArgs as null. 
      ' The event provides size preferences for that case.
        If (e.AffectedControl IsNot Nothing) And (e.AffectedProperty IsNot Nothing) Then
            ' Ensure that the affected property is the Bounds property
            ' of the form.
            If e.AffectedProperty.ToString() = "Bounds" Then
             ' If layoutButton's width plus a padding of 50 pixels is greater than the preferred 
             ' size of 300 pixels, increase the form's width.
                If Me.layoutButton.Width + 50 > 300 Then
                    Me.Width = Me.layoutButton.Width + 50
                    ' If not, keep the form's width at 300 pixels.
                Else
                    Me.Width = 300
                End If

                ' Center layoutButton on the form.
                Me.layoutButton.Left = (Me.ClientSize.Width - Me.layoutButton.Width) / 2
            End If
        End If
    End Sub

    ' This method sets the Text property of layoutButton to the Text property
    ' of textBox1.  If the new text plus a padding of 20 pixels is larger than 
    ' the preferred size of 150 pixels, increase layoutButton's Width property.
    Private Sub textBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles textBox1.TextChanged
        ' Set the Text property of layoutButton.
        Me.layoutButton.Text = Me.textBox1.Text
        ' Get the width of the text using the proper font.
        Dim textWidth As Integer = CInt(Me.CreateGraphics().MeasureString(layoutButton.Text, layoutButton.Font).Width)

        ' If the width of the text plus a padding of 20 pixels is greater than the preferred size of
        ' 150 pixels, increase layoutButton's width.
        If textWidth + 20 > 150 Then
            ' Setting the size property on any control raises 
            ' the Layout event for its container.
            Me.layoutButton.Width = textWidth + 20
            ' If not, keep layoutButton's width at 150 pixels.
        Else
            Me.layoutButton.Width = 150
        End If
    End Sub
End Class

.NET Framework
Available since 1.1

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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