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DrawToolTipEventHandler Delegate

Represents the method that will handle the Draw event of a ToolTip.

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

'Declaration
Public Delegate Sub DrawToolTipEventHandler ( _
	sender As Object, _
	e As DrawToolTipEventArgs _
)

Parameters

sender
Type: System.Object

The source of the event.

e
Type: System.Windows.Forms.DrawToolTipEventArgs

A DrawToolTipEventArgs that contains the event data.

The ToolTip.Draw event is raised by the ToolTip class when the ToolTip is drawn and the ToolTip.OwnerDraw property value is true. The DrawToolTipEventArgs class contains all the information needed to paint the ToolTip, including the ToolTip text, the Rectangle, and the Graphics object on which the drawing should be done. To customize the look of the ToolTip, use the Rectangle to determine the bounds of the ToolTip, and the Graphics object to perform your customized drawing. You can increase the bounds of the ToolTip before it is shown by handling the Popup event.

When you create a DrawToolTipEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see Handling and Raising Events.

The following code example demonstrates how to custom draw the ToolTip. The example creates a ToolTip and associates it to three Button controls located on the Form. The example sets the OwnerDraw property to true and handles the Draw event. In the Draw event handler, the ToolTip is custom drawn differently depending upon what button the ToolTip is being displayed for as indicated by the DrawToolTipEventArgs.AssociatedControl property.

Imports System
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Windows.Forms.VisualStyles

Public Module ToolTipExampleApp
    ' The main entry point for the application.
    <STAThread()> _
    Sub Main()
        Application.Run(New ToolTipExampleForm)
    End Sub 
End Module 

' Form for the ToolTip example. 
Public Class ToolTipExampleForm
    Inherits System.Windows.Forms.Form

    Private WithEvents toolTip1 As System.Windows.Forms.ToolTip
    Private WithEvents button1 As System.Windows.Forms.Button
    Private WithEvents button2 As System.Windows.Forms.Button
    Private WithEvents button3 As System.Windows.Forms.Button

    Public Sub New()
        ' Create the ToolTip and set initial values. 
        Me.toolTip1 = New System.Windows.Forms.ToolTip
        Me.toolTip1.AutoPopDelay = 5000
        Me.toolTip1.InitialDelay = 500
        Me.toolTip1.OwnerDraw = True 
        Me.toolTip1.ReshowDelay = 10

        ' Create button1 and set initial values. 
        Me.button1 = New System.Windows.Forms.Button
        Me.button1.Location = New System.Drawing.Point(8, 8)
        Me.button1.Text = "Button 1" 
        Me.toolTip1.SetToolTip(Me.button1, "Button1 tip text")

        ' Create button2 and set initial values. 
        Me.button2 = New System.Windows.Forms.Button
        Me.button2.Location = New System.Drawing.Point(8, 32)
        Me.button2.Text = "Button 2" 
        Me.toolTip1.SetToolTip(Me.button2, "Button2 tip text")

        ' Create button3 and set initial values. 
        Me.button3 = New System.Windows.Forms.Button
        Me.button3.Location = New System.Drawing.Point(8, 56)
        Me.button3.Text = "Button 3" 
        Me.toolTip1.SetToolTip(Me.button3, "Button3 tip text")

        ' Set up the Form. 
        Me.Controls.AddRange(New Control() {Me.button1, _
                                            Me.button2, _
                                            Me.button3})
        Me.Text = "owner drawn ToolTip example" 
    End Sub 

    ' Clean up any resources being used.         
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If (disposing) Then
            toolTip1.Dispose()
        End If 

        MyBase.Dispose(disposing)
    End Sub 

    ' Determines the correct size for the button2 ToolTip. 
    Private Sub toolTip1_Popup(ByVal sender As System.Object, _
        ByVal e As PopupEventArgs) Handles toolTip1.Popup

        If e.AssociatedControl Is button2 Then 

            Dim f As New Font("Tahoma", 9)
            Try
                e.ToolTipSize = TextRenderer.MeasureText( _
                    toolTip1.GetToolTip(e.AssociatedControl), f)
            Finally
                f.Dispose()
            End Try 

        End If 
    End Sub 

    ' Handles drawing the ToolTip. 
    Private Sub toolTip1_Draw(ByVal sender As System.Object, _
        ByVal e As DrawToolTipEventArgs) Handles toolTip1.Draw
        ' Draw the ToolTip differently depending on which  
        ' control this ToolTip is for. 

        ' Draw a custom 3D border if the ToolTip is for button1. 
        If (e.AssociatedControl Is button1) Then 
            ' Draw the standard background.
            e.DrawBackground()

            ' Draw the custom border to appear 3-dimensional.
            e.Graphics.DrawLines( _
                SystemPens.ControlLightLight, New Point() { _
                New Point(0, e.Bounds.Height - 1), _
                New Point(0, 0), _
                New Point(e.Bounds.Width - 1, 0)})
            e.Graphics.DrawLines( _
                SystemPens.ControlDarkDark, New Point() { _
                New Point(0, e.Bounds.Height - 1), _
                New Point(e.Bounds.Width - 1, e.Bounds.Height - 1), _
                New Point(e.Bounds.Width - 1, 0)})

            ' Specify custom text formatting flags. 
            Dim sf As TextFormatFlags = TextFormatFlags.VerticalCenter Or _
                                 TextFormatFlags.HorizontalCenter Or _
                                 TextFormatFlags.NoFullWidthCharacterBreak

            ' Draw standard text with customized formatting options.
            e.DrawText(sf)
        ElseIf (e.AssociatedControl Is button2) Then 
            ' Draw a custom background and text if the ToolTip is for button2. 

            ' Draw the custom background.
            e.Graphics.FillRectangle(SystemBrushes.ActiveCaption, e.Bounds)

            ' Draw the standard border.
            e.DrawBorder()

            ' Draw the custom text. 
            Dim sf As StringFormat = New StringFormat
            Try
                sf.Alignment = StringAlignment.Center
                sf.LineAlignment = StringAlignment.Center
                sf.HotkeyPrefix = System.Drawing.Text.HotkeyPrefix.None
                sf.FormatFlags = StringFormatFlags.NoWrap

                Dim f As Font = New Font("Tahoma", 9)
                Try
                    e.Graphics.DrawString(e.ToolTipText, f, _
                        SystemBrushes.ActiveCaptionText, _
                        RectangleF.op_Implicit(e.Bounds), sf)
                Finally
                    f.Dispose()
                End Try 
            Finally
                sf.Dispose()
            End Try 
        ElseIf (e.AssociatedControl Is button3) Then 
            ' Draw the ToolTip using default values if the ToolTip is for button3.
            e.DrawBackground()
            e.DrawBorder()
            e.DrawText()
        End If 
    End Sub 
End Class

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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