Figures

GraphicMenu类

Public Class GraphicMenu : Inherits Component

  ' Appearance Properties
  ' TODO:: List properties

  ' Behavior Properties
  ' TODO:: List properties

  Public Sub Init(ByVal menu As Menu)

     ' Return if the menu is null
     If menu Is Nothing Then
          Return
     End If

     ' Initialize the font object used to render the menu items
     ItemFont = New Font(FontName, FontSize)

     ' Initialize the hashtable used to hold bitmap/item bindings
     If menuItemIconCollection Is Nothing Then
         menuItemIconCollection = New Hashtable
     End If

     ' Context menu requires a different treatment
     If TypeOf menu Is ContextMenu Then
         HandleChildMenuItems(menu)
         Return
     End If

     ' Iterate on all top-level menus and handle their items
     For Each popup As MenuItem In menu.MenuItems
         HandleChildMenuItems(popup)
     Next

  End Sub

End Class

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MeasureItemEventArgs

Property	Description
Graphics	获得用以计算尺寸所需的Graphics对象
Index	读取或设置需要改变的高宽度的项索引
ItemHeight	读取或设置项的高度值
ItemWidth	读取或设置项的宽度值

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定义对象们的大小

' ****************************************************************
' HELPER: StdMeasureItem
' INPUT : menu item, data used for measurement
' NOTES : Event handler for the MeasureItem event typical of 
' owner-drawn objects
       Private Sub StdMeasureItem(ByVal sender As Object, _
           ByVal e As MeasureItemEventArgs)

    ' Grab a reference to the menu item being measured
    Dim item As MenuItem = CType(sender, MenuItem)

    ' If it is a separator, handle differently
    If (item.Text = "-") Then
        e.ItemHeight = SeparatorHeight
        Return
    End If

    ' Measure the item text with the current font. The text to 
    ' measure includes keyboard shortcuts
    Dim stringSize As SizeF
    stringSize = e.Graphics.MeasureString(GetEffectiveText(item), ItemFont)

    ' Set the height and width of the item
    e.ItemHeight = MenuItemHeight
    e.ItemWidth = BitmapWidth + HorizontalTextOffset + _ 
        CInt(stringSize.Width) + RightOffset
End Sub

' ****************************************************************
' HELPER: StdDrawItem
' INPUT : menu item, ad hoc structure for custom drawing
' NOTES : Event handler for the DrawItem event typical of 
' owner-drawn objects
Private Sub StdDrawItem(ByVal sender As Object, ByVal e As _
    DrawItemEventArgs)

    ' Grab a reference to the item being drawn
    Dim item As MenuItem = CType(sender, MenuItem)

    ' Saves helper objects for easier reference
    Dim g As Graphics = e.Graphics
    Dim bounds As RectangleF = MakeRectangleF(e.Bounds)
    Dim itemText As String = item.Text
    Dim itemState As DrawItemState = e.State

    ' Define bounding rectangles to use later
    CreateLayout(bounds)

    ' Draw the menu item background and text
    DrawBackground(g, itemState)

    ' Draw the bitmap leftmost area
    DrawBitmap(g, item, itemState)

    ' Draw the text
    DrawText(g, item)
End Sub

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DrawItemEventArgs

Property	Description
BackColor	获取项的背景
Bounds	获取项将要占据的矩形
Font	获取项所使用的字体
ForeColor	获取项的前景色
Graphics	获取用以绘制该项的Graphics对象
Index	获取将要绘制的项的索引
State	获取该项的状态

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灰化图像

If (disabled) Then
   Dim imageAttr As New ImageAttributes
   imageAttr.SetGamma(0.2F)
   Dim tmpRect = New Rectangle( BitmapBounds.X + 2, _
        BitmapBounds.Y + 2, BitmapBounds.Width - 2, _
        BitmapBounds.Right - 2)
   g.DrawImage(bmp, tmpRect, 0, 0, _
        bmp.Width, bmp.Height, GraphicsUnit.Pixel, imageAttr)
   ImageAttr.ClearGamma()
Else
   g.DrawImage(bmp, BitmapBounds.X + 2, BitmapBounds.Y + 2)
End If

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