Help setting combobox dropdown list width

Hi,


How do you adjust the width of the dropdown list of a combobox based on the size of the text?

Thanks,

Victor
vcharlesAsked:
Who is Participating?
 
it_saigeConnect With a Mentor DeveloperCommented:
Sure, you could do something like:
Public Class Form1
	ReadOnly items As New List(Of String)({"TEXT", "LONGTEXT", "LONGERTEXT", "LONGESTTEXT", "LONGTEXTTHATISLONGERTHANTHELONGEST"})
	Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
		ComboBox1.DataSource = items
		ComboBox2.DataSource = items
		ComboBox3.DataSource = items
		AutoSizeComboBox(ComboBox3, 20)
	End Sub

	Private Sub AutoSizeComboBox(cb As ComboBox, Optional minWidth As Integer = 50)
		Using g As Graphics = cb.CreateGraphics()
			Dim maxWidth = 0.0F
			For Each item In cb.Items
				maxWidth = Math.Max(maxWidth, g.MeasureString(item.ToString(), cb.Font).Width)
			Next
			cb.Width = CType(Math.Min(maxWidth, minWidth) + 20, Integer)
		End Using
	End Sub
End Class

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Which now produces the following output (I explicitly chose an extremely small width):Capture.JPG-saige-
0
 
it_saigeDeveloperCommented:
At it's simplest -

Form1.vb -
Public Class Form1
	ReadOnly items As New List(Of String)({"TEXT", "LONGTEXT", "LONGERTEXT", "LONGESTTEXT", "LONGTEXTTHATISLONGERTHANTHELONGEST"})
	Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
		ComboBox1.DataSource = items
		ComboBox2.DataSource = items
		ComboBox3.DataSource = items
		AutoSizeComboBox(ComboBox3)
	End Sub

	Private Sub AutoSizeComboBox(cb As ComboBox)
		Using g As Graphics = cb.CreateGraphics()
			Dim maxWidth = 0.0F
			For Each item In cb.Items
				maxWidth = Math.Max(maxWidth, g.MeasureString(item.ToString(), cb.Font).Width)
			Next
			cb.Width = CType(maxWidth + 20, Integer)
		End Using
	End Sub
End Class

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Form1.Designer.vb -
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class Form1
    Inherits System.Windows.Forms.Form

    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        Try
            If disposing AndAlso components IsNot Nothing Then
                components.Dispose()
            End If
        Finally
            MyBase.Dispose(disposing)
        End Try
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
		Me.ComboBox1 = New System.Windows.Forms.ComboBox()
		Me.ComboBox2 = New System.Windows.Forms.ComboBox()
		Me.ComboBox3 = New System.Windows.Forms.ComboBox()
		Me.SuspendLayout()
		'
		'ComboBox1
		'
		Me.ComboBox1.FormattingEnabled = True
		Me.ComboBox1.Location = New System.Drawing.Point(13, 13)
		Me.ComboBox1.Name = "ComboBox1"
		Me.ComboBox1.Size = New System.Drawing.Size(121, 21)
		Me.ComboBox1.TabIndex = 0
		'
		'ComboBox2
		'
		Me.ComboBox2.FormattingEnabled = True
		Me.ComboBox2.Location = New System.Drawing.Point(13, 41)
		Me.ComboBox2.Name = "ComboBox2"
		Me.ComboBox2.Size = New System.Drawing.Size(329, 21)
		Me.ComboBox2.TabIndex = 1
		'
		'ComboBox3
		'
		Me.ComboBox3.FormattingEnabled = True
		Me.ComboBox3.Location = New System.Drawing.Point(13, 69)
		Me.ComboBox3.Name = "ComboBox3"
		Me.ComboBox3.Size = New System.Drawing.Size(121, 21)
		Me.ComboBox3.TabIndex = 2
		'
		'Form1
		'
		Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
		Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
		Me.ClientSize = New System.Drawing.Size(354, 261)
		Me.Controls.Add(Me.ComboBox3)
		Me.Controls.Add(Me.ComboBox2)
		Me.Controls.Add(Me.ComboBox1)
		Me.Name = "Form1"
		Me.Text = "Form1"
		Me.ResumeLayout(False)

	End Sub
	Friend WithEvents ComboBox1 As System.Windows.Forms.ComboBox
	Friend WithEvents ComboBox2 As System.Windows.Forms.ComboBox
	Friend WithEvents ComboBox3 As System.Windows.Forms.ComboBox

End Class

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Produces the following output -Capture.JPGThe first and second combobox's are hard set to initial size and full form size whereas the third combo box uses the autosize method to resize according to it's items.
Capture.JPG-saige-
1
 
vcharlesAuthor Commented:
Hi,

Thank you for the code, is there a  way to also set a naximum width when you use autosize?

Victor
0
 
vcharlesAuthor Commented:
Thank You.
0
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