We all like the cool icons that adorn a modern application's menu items. You would have thought that .NET would have directly supported it out of the box. Well it does, sort of.
When a menu is constructed with the VS IDE menu editor, it's very easy to add menu items and set up the hierarchy of the menu structure. Using just a few mouse clicks and a few keystrokes, your whole menu structure can created in just a few minutes. "So", you may ask, "how do we get these cool icons like you promised?"
To use the supplied code, you will need to know how to create menu items with the VS IDE menu editor
When you use the menu editor, you are creating individual MenuItems. As you can guess, MenuItems contains various properties, methods, and events. The primary property we are concerned with is the OwnerDraw Property. The default setting for a MenuItem for OwnerDraw is False. This causes the CLR to draw the text and checks on the item without any intervention, giving you the standard menu look and feel.
Setting the OwnerDraw property to True, however, puts all the control into your hands. When this property is true, the CLR cause two events to be fired - MeasureItem and DrawItem. The help documentation defines these properties as follows:
MeasureItem |
Occurs when the menu needs to know the size of a menu item before drawing it |
DrawItem |
Occurs when the OwnerDraw property of a menu item is set to true and a request is made to draw the menu item |
When the MeasureItem event is fired, you tell the CLR how big your MenuItem should be as follows:
e.ItemWidth = 80
e.ItemHeight = 24
This would tell the CLR that the menu item is 80 pixels wide and 24 pixels high. This is important, because these are the dimensions used to construct a graphics area for you to draw into in the DrawItem event, demonstrated below:
e.DrawBackground()
Dim TextPoint As PointF = New PointF(18, 0)
e.Graphics.DrawIcon(New Icon(New Icon("c:\icons\myicon.ico"), 16, 16), _
New Rectangle(0, 0, 16, 16))
e.Graphics.DrawString(sender.Text, MyFont, New SolidBrush(Black), TextPoint)
The above code will draw the icon on the menu item and print the text defined in your menu. This is a very simple example, but it demonstrates the power of owner draw menus.
The below class takes this example and goes a bit further. Not only does the class draw the menu item, but it also sets the OwnerDraw property and handles the MeasureItem and DrawItem events for you, so that all you have to do is add a menu item to the class and it does all the work. The class creates an ArrayList and populates it with items of the LocalMenuItem structure type. This makes it easier to identify and work with the menu items.
Several Add Method constructors are provided which construct and add the individual LocalMenuItem items to the ArrayList. Some things are vitally important when adding items to the class:
MenuItems should be added - the total menu will not be drawn correctly if items are skipped
MenuItemNumber parameter determines the position of the item in the menu, starting at 0 - these must be sequential as this is used to determine the position and graphics area of the MenuItem
IsSeparator parameter flags the menu item as a separator
Nothing as the icon if the item is a separator or you don't want an icon drawn for the item
The class only handles vertical (sub menu) items and does not handle the MainMenu items, although it could be modified to draw these also. It also handles separators properly.
Imports System.Drawing
Imports System.Windows.Forms
Public Class OwnerDrawMenu
'holds menu items
Private _MenuItems As New ArrayList()
'default font
Private _Font As Font = SystemInformation.MenuFont
'default text color
Private _TextColor As Color = System.Drawing.SystemColors.MenuText
'constants
Private Const NORMALITEMHEIGHT As Integer = 20
Private Const SEPITEMHEIGHT As Integer = 12
Private Const EXTRAWIDTH As Integer = 30
Private Const ICONSIZE16 As Integer = 16
'structure to hold menu items
Private Structure LocalMenuItem
Dim MenuItemNumber As Integer
Dim MenuItem As Windows.Forms.MenuItem
Dim Icon As System.Drawing.Icon
Dim IconRectangle As System.Drawing.Rectangle
Dim TextLeft As Integer
Dim TextTopPosition As Integer
Dim Font As System.Drawing.Font
Dim TextColor As System.Drawing.Color
Dim Height As Integer
Dim Width As Integer
Dim IsSeperator As Boolean
End Structure
Public Sub New()
'
End Sub
'various constructors for the class
Public Sub New(ByVal Font As System.Drawing.Font)
_Font = Font
If _Font.Size > 12 Then
_Font = New Font(_Font.Name, 12, _Font.Style)
End If
End Sub
Public Sub New(ByVal TextColor As System.Drawing.Color)
_TextColor = TextColor
End Sub
Public Sub New(ByVal Font As System.Drawing.Font, _
ByVal TextColor As System.Drawing.Color)
_TextColor = TextColor
_Font = Font
If _Font.Size > 12 Then
_Font = New Font(_Font.Name, 12, _Font.Style)
End If
End Sub
'various constructors for the add method
Public Sub Add(ByVal MenuItem As Windows.Forms.MenuItem, _
ByVal Icon As System.Drawing.Icon, _
ByVal MenuItemNumber As Integer, _
ByVal IsSeperator As Boolean)
Me.Add(MenuItem, Icon, MenuItemNumber, IsSeperator, _Font, _TextColor)
End Sub
Public Sub Add(ByVal MenuItem As Windows.Forms.MenuItem, _
ByVal Icon As System.Drawing.Icon, _
ByVal MenuItemNumber As Integer, _
ByVal IsSeperator As Boolean, _
ByVal Font As System.Drawing.Font)
Me.Add(MenuItem, Icon, MenuItemNumber, IsSeperator, Font, _TextColor)
End Sub
Public Sub Add(ByVal MenuItem As Windows.Forms.MenuItem, _
ByVal Icon As System.Drawing.Icon, _
ByVal MenuItemNumber As Integer, _
ByVal IsSeperator As Boolean, _
ByVal Font As System.Drawing.Font, _
ByVal TextColor As System.Drawing.Color)
'hold and save the last top and left position
Static LastTopPosition As Integer
Static LastLeftPosition As Integer
Dim li As New LocalMenuItem()
If MenuItemNumber = 0 Then
LastLeftPosition = 2
LastTopPosition = 0
Else
'calculate the new top position
LastTopPosition = LastTopPosition + IIf(IsSeperator, _
SEPITEMHEIGHT, NORMALITEMHEIGHT)
LastLeftPosition = 2
End If
Const ICONWIDTH As Integer = ICONSIZE16
Const ICONHEIGHT As Integer = ICONSIZE16
Dim IconRect As Rectangle
'calculate new drawing rectangle for icon
If IsSeperator Then
IconRect = New Rectangle(LastLeftPosition, LastTopPosition, _
ICONWIDTH, ICONHEIGHT)
Else
IconRect = New Rectangle(LastLeftPosition, LastTopPosition + 2, _
ICONWIDTH, ICONHEIGHT)
End If
'you don't need to set ownerdraw - the class does it for you
MenuItem.OwnerDraw = True
With li
.MenuItemNumber = MenuItemNumber
.Font = Font
.MenuItem = MenuItem
.Icon = Icon
.TextLeft = LastLeftPosition + ICONWIDTH
.TextTopPosition = LastTopPosition
.IconRectangle = IconRect
.TextColor = TextColor
.IsSeperator = IsSeperator
End With
_MenuItems.Add(li)
'set the handlers for the menuitems
AddHandler MenuItem.DrawItem, AddressOf Me.DrawItemHandler
AddHandler MenuItem.MeasureItem, AddressOf Me.MesaureItemHandler
End Sub
Private Sub DoDraw(ByVal LI As LocalMenuItem, _
ByRef e As System.Windows.Forms.DrawItemEventArgs)
e.DrawBackground()
Const LastLeftPosition As Integer = 2
Const ICONWIDTH As Integer = ICONSIZE16
Dim ThisMenuItem As MenuItem = LI.MenuItem
Dim MenuItemGraphics As Graphics = e.Graphics
Dim bBypassString As Boolean
'set size and textpoint for our text
Dim SizeF As SizeF = e.Graphics.MeasureString(LI.MenuItem.Text, _Font)
Dim TextPoint As PointF = New PointF(LI.TextLeft, _
LI.TextTopPosition + ((NORMALITEMHEIGHT - SizeF.Height) / 2))
Dim RectHeight As Integer = SizeF.Height
If Not LI.Icon Is Nothing Then
'draw the icon
MenuItemGraphics.DrawIcon(New Icon(LI.Icon, _
ICONSIZE16, ICONSIZE16), LI.IconRectangle)
ElseIf LI.IsSeperator Then
'draw the separator
MenuItemGraphics.DrawLine(New Pen(LI.TextColor, 1), _
TextPoint.X, TextPoint.Y + 11, _
TextPoint.X + LI.Width + EXTRAWIDTH, TextPoint.Y + 11)
bBypassString = True
End If
If Not bBypassString Then
'bypass string if separator
'draw differently if enabled/dsabled
If LI.MenuItem.Enabled Then
MenuItemGraphics.DrawString(Replace(LI.MenuItem.Text, "&", ""), _
LI.Font, New SolidBrush(LI.TextColor), TextPoint)
Else
MenuItemGraphics.DrawString(Replace(LI.MenuItem.Text, "&", ""), _
LI.Font, New SolidBrush(Drawing.SystemColors.GrayText), TextPoint)
End If
End If
End Sub
Private Sub DoMeasure(ByVal LI As LocalMenuItem, _
ByRef e As System.Windows.Forms.MeasureItemEventArgs)
'calculate the size of the drawing area
Dim ThisMenuItem_Strings As String() = LI.MenuItem.Text.Split(",")
Dim TextSize As SizeF = e.Graphics.MeasureString( _
ThisMenuItem_Strings(0).Replace("&", ""), LI.Font)
e.ItemWidth = TextSize.Width + EXTRAWIDTH
If LI.MenuItem.Text = "-" Then
e.ItemHeight = SEPITEMHEIGHT
Else
e.ItemHeight = NORMALITEMHEIGHT
End If
LI.Height = e.ItemHeight
LI.Width = e.ItemWidth
End Sub
Public Sub DrawItemHandler(ByVal sender As Object, _
ByVal e As System.Windows.Forms.DrawItemEventArgs)
'look through the items and find out which one we are drawing
Dim li As LocalMenuItem
For Each li In _MenuItems
If li.MenuItem Is sender Then
DoDraw(li, e)
Exit For
End If
Next
End Sub
Public Sub MesaureItemHandler(ByVal sender As Object, _
ByVal e As System.Windows.Forms.MeasureItemEventArgs)
'look through the items and find out which one we are measuring
Dim li As LocalMenuItem
For Each li In _MenuItems
If li.MenuItem Is sender Then
DoMeasure(li, e)
Exit For
End If
Next
End Sub
End Class
After adding a MainMenu control, add a few menu items. Remember, the class handles setting the OwnerDraw Property for you and also handles the MeasureItem and DrawItem events so you need do nothing else but add it to the class. To do this, in the Form_Load event, add the following code:
Dim odm As New ODM.OwnerDrawMenu(New Font("Tahoma", 8), System.Drawing.Color.Red)
odm.Add(Me.MenuItem3, New Icon("new.ico"), 0, False)
odm.Add(Me.MenuItem2, New Icon("open.ico"), 1, False)
odm.Add(Me.MenuItem4, Nothing, 2, False)
odm.Add(Me.MenuItem5, Nothing, 3, True)
odm.Add(Me.MenuItem6, Nothing, 4, False)
That's all there is to it! You now have those "cool" icons.
| You must Sign In to use this message board. | |||||
|
|||||
|
|||||
. If you created the menuitems using the menu editor, your menuitem will show up as a control in the left dropdown in the code pane as it would had you not used the class. then all you should have to do is put your code into the menuitem_click event. If you are dynamically creating menuitems, you would need to use the AddHandler method to create a delegate to a method used as the Click event for the menuitem. The class is not designed to handle the click events. If you wanted to do this you could add the following in the class to handle the event: