ListBox.DrawItem Event
Definition
Important
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Occurs when a visual aspect of an owner-drawn ListBox changes.
public:
event System::Windows::Forms::DrawItemEventHandler ^ DrawItem;public event System.Windows.Forms.DrawItemEventHandler DrawItem;public event System.Windows.Forms.DrawItemEventHandler? DrawItem;member this.DrawItem : System.Windows.Forms.DrawItemEventHandler Public Custom Event DrawItem As DrawItemEventHandler Event Type
Examples
The following code example demonstrates how to create owner-drawn ListBox items. The code uses the DrawMode property to specify that the items drawn are fixed sized and the DrawItem event to perform the drawing of each item into the ListBox. The example code uses the properties and methods of the DrawItemEventArgs class passed as a parameter to the event handler to draw the items. This example requires that a ListBox control called listBox1 has been added to a form and that the DrawItem event is handled by the event handler defined in the example code. The example also requires that items have been added to the ListBox with the text of "Apple", "Orange", and "Plum" in that order.
private ListBox ListBox1 = new ListBox();
private void InitializeListBox()
{
ListBox1.Items.AddRange(new Object[]
{ "Red Item", "Orange Item", "Purple Item" });
ListBox1.Location = new System.Drawing.Point(81, 69);
ListBox1.Size = new System.Drawing.Size(120, 95);
ListBox1.DrawMode = DrawMode.OwnerDrawFixed;
ListBox1.DrawItem += new DrawItemEventHandler(ListBox1_DrawItem);
Controls.Add(ListBox1);
}
private void ListBox1_DrawItem(object sender,
System.Windows.Forms.DrawItemEventArgs e)
{
// Draw the background of the ListBox control for each item.
e.DrawBackground();
// Define the default color of the brush as black.
Brush myBrush = Brushes.Black;
// Determine the color of the brush to draw each item based
// on the index of the item to draw.
switch (e.Index)
{
case 0:
myBrush = Brushes.Red;
break;
case 1:
myBrush = Brushes.Orange;
break;
case 2:
myBrush = Brushes.Purple;
break;
}
// Draw the current item text based on the current Font
// and the custom brush settings.
e.Graphics.DrawString(ListBox1.Items[e.Index].ToString(),
e.Font, myBrush, e.Bounds, StringFormat.GenericDefault);
// If the ListBox has focus, draw a focus rectangle around the selected item.
e.DrawFocusRectangle();
}
Private WithEvents ListBox1 As New ListBox()
Private Sub InitializeListBox()
ListBox1.Items.AddRange(New Object() _
{"Red Item", "Orange Item", "Purple Item"})
ListBox1.Location = New System.Drawing.Point(81, 69)
ListBox1.Size = New System.Drawing.Size(120, 95)
ListBox1.DrawMode = DrawMode.OwnerDrawFixed
Controls.Add(ListBox1)
End Sub
Private Sub ListBox1_DrawItem(ByVal sender As Object, _
ByVal e As System.Windows.Forms.DrawItemEventArgs) _
Handles ListBox1.DrawItem
' Draw the background of the ListBox control for each item.
e.DrawBackground()
' Define the default color of the brush as black.
Dim myBrush As Brush = Brushes.Black
' Determine the color of the brush to draw each item based on
' the index of the item to draw.
Select Case e.Index
Case 0
myBrush = Brushes.Red
Case 1
myBrush = Brushes.Orange
Case 2
myBrush = Brushes.Purple
End Select
' Draw the current item text based on the current
' Font and the custom brush settings.
e.Graphics.DrawString(ListBox1.Items(e.Index).ToString(), _
e.Font, myBrush, e.Bounds, StringFormat.GenericDefault)
' If the ListBox has focus, draw a focus rectangle around _
' the selected item.
e.DrawFocusRectangle()
End Sub
Remarks
This event is used by an owner-drawn ListBox. The event is only raised when the DrawMode property is set to DrawMode.OwnerDrawFixed or DrawMode.OwnerDrawVariable. You can use this event to perform the tasks needed to draw items in the ListBox. If you have a variable-sized item (when the DrawMode property is set to DrawMode.OwnerDrawVariable), before drawing an item, the MeasureItem event is raised. You can create an event handler for the MeasureItem event to specify the size for the item that you are going to draw in your event handler for the DrawItem event.
For more information about handling events, see Handling and Raising Events.
