Form.AutoSize Property


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Resize the form according to the setting of AutoSizeMode.

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

Public Overrides Property AutoSize As Boolean

Property Value

Type: System.Boolean

true if the form will automatically resize; false if it must be manually resized.

Use AutoSize to force a form to resize to fit its contents.

A form does not automatically resize in the Visual Studio forms designer, regardless of the values of the AutoSize and AutoSizeMode properties. The form correctly resizes itself at run time according to the values of these two properties. By contrast, a custom UserControl automatically resizes itself both at design time and at run time.

When using AutoSize, the MinimumSize and MaximumSize properties are respected, but the current value of the Size property is ignored. Using AutoSize and AutoSizeMode also renders the AutoScroll property superfluous, as there is no way to shrink the form to hide its contained controls from view.

See the AutoSizeMode enumeration for information on how a form behaves when AutoSize is true.

The following code example shows a form created using code that automatically resizes to fit its contents. When run, the form displays a Label, a TextBox for entering a URL, and a Button for displaying that URL inside of the user's default Web browser. The code example uses a FlowLayoutPanel to lay out the contained controls one after the other. It also sets the AutoSize and AutoSizeMode to grow and shrink to fit the contents of its form.

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Me.AutoSize = True
    Me.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink
    Me.Text = "URL Opener"

    flowPanel = New FlowLayoutPanel()
    flowPanel.AutoSize = True
    flowPanel.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink

    urlLabel = New Label()
    urlLabel.Name = "urlLabel"
    urlLabel.Text = "URL:"
    urlLabel.Width = 50
    urlLabel.TextAlign = ContentAlignment.MiddleCenter

    urlTextBox = New TextBox()
    urlTextBox.Name = "urlTextBox"
    urlTextBox.Width = 250

    urlButton = New Button()
    urlButton.Name = "urlButton"
    urlButton.Text = "Open URL in Browser"
End Sub

Private Sub urlButton_Click(ByVal sender As Object, ByVal e As EventArgs) Handles urlButton.Click
        Dim newUri As New Uri(urlTextBox.Text)
    Catch uriEx As UriFormatException
        MessageBox.Show(("Sorry, your URL is malformed. Try again. Error: " + uriEx.Message))
        urlTextBox.ForeColor = Color.Red
    End Try

    ' Valid URI. Reset any previous error color, and launch the URL in the 
    ' default browser.
    ' NOTE: Depending on the user's settings, this method of starting the
    ' browser may use an existing window in an existing Web browser process.
    ' To get around this, start up a specific browser instance instead using one of
    ' the overloads for Process.Start. You can examine the registry to find the
    ' current default browser and launch that, or hard-code a specific browser.
    urlTextBox.ForeColor = Color.Black
End Sub

.NET Framework
Available since 2.0
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