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ListBox.ScrollAlwaysVisible Property

Gets or sets a value indicating whether the vertical scroll bar is shown at all times.

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

[LocalizableAttribute(true)] 
public bool ScrollAlwaysVisible { get; set; }
/** @property */
public boolean get_ScrollAlwaysVisible ()

/** @property */
public void set_ScrollAlwaysVisible (boolean value)

public function get ScrollAlwaysVisible () : boolean

public function set ScrollAlwaysVisible (value : boolean)

Not applicable.

Property Value

true if the vertical scroll bar should always be displayed; otherwise, false. The default is false.

The ScrollAlwaysVisible property indicates whether a vertical scroll bar is always displayed, even if the number of items in the ListBox does not require displaying the vertical scroll bar. By default, a ListBox only shows a vertical scroll bar when there are enough items to warrant displaying. For a multicolumn ListBox, the ScrollAlwaysVisible property indicates that a horizontal scroll bar is displayed. A vertical scroll bar is never displayed regardless of the value of this property for a multicolumn ListBox.

The following code example demonstrates an owner-drawn ListBox by setting the DrawMode property to the OwnerDrawVariable value and handling the DrawItem and MeasureItem events. It also demonstrates setting the BorderStyle and ScrollAlwaysVisible properties and using the AddRange method.

To run this example, paste it in an empty form that imports the System.Drawing namespace and the System.Windows.Forms namespace. Call InitializeOwnerDrawnListBox from the form's constructor or Load event-handling method.

internal System.Windows.Forms.ListBox ListBox1;

private void InitializeOwnerDrawnListBox()
{
    this.ListBox1 = new System.Windows.Forms.ListBox();

    // Set the location and size.
    ListBox1.Location = new Point(20, 20);
    ListBox1.Size = new Size(240, 240);

    // Populate the ListBox.ObjectCollection property 
    // with several strings, using the AddRange method.
    this.ListBox1.Items.AddRange(new object[]{"System.Windows.Forms", 
        "System.Drawing", "System.Xml", "System.Net", "System.Runtime.Remoting", 
        "System.Web"});

    // Turn off the scrollbar.
    ListBox1.ScrollAlwaysVisible = false;

    // Set the border style to a single, flat border.
    ListBox1.BorderStyle = BorderStyle.FixedSingle;

    // Set the DrawMode property to the OwnerDrawVariable value. 
    // This means the MeasureItem and DrawItem events must be 
    // handled.
    ListBox1.DrawMode = DrawMode.OwnerDrawVariable;
    ListBox1.MeasureItem += 
        new MeasureItemEventHandler(ListBox1_MeasureItem);
    ListBox1.DrawItem += new DrawItemEventHandler(ListBox1_DrawItem);
    this.Controls.Add(this.ListBox1);
    
}


// Handle the DrawItem event for an owner-drawn ListBox.
private void ListBox1_DrawItem(object sender, DrawItemEventArgs e)
{

    // If the item is the selected item, then draw the rectangle
    // filled in blue. The item is selected when a bitwise And  
    // of the State property and the DrawItemState.Selected 
    // property is true.
    if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
    {
        e.Graphics.FillRectangle(Brushes.CornflowerBlue, e.Bounds);
    }
    else
    {
        // Otherwise, draw the rectangle filled in beige.
        e.Graphics.FillRectangle(Brushes.Beige, e.Bounds);
    }

    // Draw a rectangle in blue around each item.
    e.Graphics.DrawRectangle(Pens.Blue, e.Bounds);

    // Draw the text in the item.
    e.Graphics.DrawString(ListBox1.Items[e.Index].ToString(),
        this.Font, Brushes.Black, e.Bounds.X, e.Bounds.Y);

    // Draw the focus rectangle around the selected item.
    e.DrawFocusRectangle();
}

// Handle the MeasureItem event for an owner-drawn ListBox.
private void ListBox1_MeasureItem(object sender, 
    MeasureItemEventArgs e)
{

    // Cast the sender object back to ListBox type.
    ListBox theListBox = (ListBox) sender;

    // Get the string contained in each item.
    string itemString = (string) theListBox.Items[e.Index];

    // Split the string at the " . "  character.
    string[] resultStrings = itemString.Split('.');

    // If the string contains more than one period, increase the 
    // height by ten pixels; otherwise, increase the height by 
    // five pixels.
    if (resultStrings.Length>2)
    {
        e.ItemHeight += 10;
    }
    else
    {
        e.ItemHeight += 5;
    }

}


private System.Windows.Forms.ListBox listBox1;

private void InitializeOwnerDrawnListBox()
{
    this.listBox1 = new System.Windows.Forms.ListBox();
    // Set the location and size.
    listBox1.set_Location(new Point(20, 20));
    listBox1.set_Size(new Size(240, 240));
    // Populate the ListBox.ObjectCollection property 
    // with several strings, using the AddRange method.
    this.listBox1.get_Items().AddRange(new Object[] { 
        "System.Windows.Forms", "System.Drawing", 
        "System.Xml", "System.Net", "System.Runtime.Remoting", 
        "System.Web" });
    // Turn off the scrollbar.
    listBox1.set_ScrollAlwaysVisible(false);
    // Set the border style to a single, flat border.
    listBox1.set_BorderStyle(BorderStyle.FixedSingle);
    // Set the DrawMode property to the OwnerDrawVariable value. 
    // This means the MeasureItem and DrawItem events must be 
    // handled.
    listBox1.set_DrawMode(DrawMode.OwnerDrawVariable);
    listBox1.add_MeasureItem(new MeasureItemEventHandler(
        listBox1_MeasureItem));
    listBox1.add_DrawItem(new DrawItemEventHandler(listBox1_DrawItem));
    this.get_Controls().Add(this.listBox1);
} //InitializeOwnerDrawnListBox

// Handle the DrawItem event for an owner-drawn ListBox.
private void listBox1_DrawItem(Object sender, DrawItemEventArgs e)
{
    // If the item is the selected item, then draw the rectangle
    // filled in blue. The item is selected when a bitwise And  
    // of the State property and the DrawItemState.Selected 
    // property is true.
    if ((e.get_State() & DrawItemState.Selected) 
        == DrawItemState.Selected) {
        e.get_Graphics().FillRectangle(Brushes.get_CornflowerBlue(), 
            e.get_Bounds());
    }
    else {
        // Otherwise, draw the rectangle filled in beige.
        e.get_Graphics().FillRectangle(Brushes.get_Beige(), 
            e.get_Bounds());
    }
    // Draw a rectangle in blue around each item.
    e.get_Graphics().DrawRectangle(Pens.get_Blue(), e.get_Bounds());
    // Draw the text in the item.
    e.get_Graphics().DrawString(listBox1.get_Items().get_Item(
        e.get_Index()).ToString(), this.get_Font(), 
        Brushes.get_Black(), e.get_Bounds().get_X(), 
        e.get_Bounds().get_Y());
    // Draw the focus rectangle around the selected item.
    e.DrawFocusRectangle();
} //listBox1_DrawItem

// Handle the MeasureItem event for an owner-drawn ListBox.
private void listBox1_MeasureItem(Object sender, MeasureItemEventArgs e)
{
    // Cast the sender object back to ListBox type.
    ListBox theListBox = (ListBox) sender;
    // Get the string contained in each item.
    String itemString = (String)(theListBox.get_Items().
           get_Item(e.get_Index()));
    // Split the string at the " . "  character.
    String resultStrings[] = itemString.Split(new char[] { '.' });
    // If the string contains more than one period, increase the 
    // height by ten pixels; otherwise, increase the height by 
    // five pixels.
    if (resultStrings.length > 2) {
        e.set_ItemHeight(e.get_ItemHeight() + 10);
    }
    else {
        e.set_ItemHeight(e.get_ItemHeight() + 5);
    }
} //listBox1_MeasureItem

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, 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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