Having a nice interface is a must for professional software, it’s why the Custom Controls market is growing so fast. Programmers can have a nice interface without writing a single line of code, all that they have to do is to buy a Control Library. If you’re planning to save money and write your own custom controls i hope that this small sample could show you something interesting. In this sample i created an extended listbox control that shows:
- An icon for each item
- A title for each listbox item
- A subtitle for each listbox item
The main things to do are:
- Add a New() method and setup the listbox to be drawn in ownermodevariable
- Create a new class to handle single items (in our case ItemEX)
- Create the functions to add custom items (ItemEX) to listbox
- Create the DrawItemHandler function to draw the items as you like
- Handle the Resize,DrawItem and MeasureItem event for the new control
When you decide that a control will be drawn by code you have to handle all these events and mainly the DrawItem event. To make a control ownerdrawn use Me.DrawMode = DrawMode.OwnerDrawVariable in the constructor of your control ( New() )I think that giving a look at the code will be easier to understend.
Public Class ListBoxEX
Inherits System.Windows.Forms.ListBox
Public Shadows Event Resize(ByVal sender As Object,_
ByVal e As EventArgs, ByVal i As Integer)
Public Shadows Event DrawItem(ByVal sender As Object,_
ByVal e As DrawItemEventArgs)
Public Shadows Event MeasureItem(ByVal sender As Object,_
ByVal e As MeasureItemEventArgs)
Private WithEvents mListBox As System.Windows.Forms.ListBox
Private IcoFolder As String = Application.StartupPath() + "\Ico\"
Private Icons As New ArrayList
Public Shadows Function Items(ByVal idx As Integer) As ItemEX
Return mListBox.Items(idx)
End Function
Public Class ItemEX
Public IconIndex As Integer
Public Text As String
Public UserID As Integer
Public User As String
Public Sub New(ByVal _User As String, ByVal _Text As String,_
ByVal _IconIndex As Integer, ByVal _UserID As String)
User = _User
Text = _Text
IconIndex = _IconIndex
UserID = _UserID
End Sub
End Class
Public Property IconsFolder()
Get
Return IcoFolder
End Get
Set(ByVal Value)
IcoFolder = Value
End Set
End Property
Public Sub AddIcon(ByVal filename As String)
Dim icona As Icon
Dim fname As String
fname = IconsFolder.ToString + filename
icona = New Icon(fname)
Icons.Add(icona)
End Sub
Public Sub New()
MyBase.New()
Me.DrawMode = DrawMode.OwnerDrawVariable
mListBox = Me
End Sub
Public Sub Add(ByVal _User As String, ByVal _Text As String,_
Optional ByVal _iconindex As Integer = -1,_
Optional ByVal _UserID As Integer = -1)
mListBox.Items.Add(New ItemEX(_User, _Text, _iconindex, _UserID))
End Sub
Private Sub mListBox_Resize(ByVal sender As Object,_
ByVal e As System.EventArgs) _
Handles mListBox.Resize
RaiseEvent Resize(sender, e, 1)
End Sub
Private Sub DrawItemHandler(ByVal sender As Object,_
ByVal e As DrawItemEventArgs) Handles mListBox.DrawItem
e.DrawBackground()
e.DrawFocusRectangle()
Dim titFont As New Font("Tahoma", 12, FontStyle.Bold,_
GraphicsUnit.Pixel)
Dim subTitFont As New Font("Tahoma", 11, FontStyle.Regular,_
GraphicsUnit.Pixel)
Dim titBrush As New SolidBrush(Color.DimGray)
Dim subTitBrush As New SolidBrush(Color.Gray)
Dim idx As Integer = e.Index
e.Graphics.DrawString(DirectCast(mListBox.Items(idx),_
ItemEX).Text, titFont, titBrush, e.Bounds.Left + 30,_
e.Bounds.Top)
e.Graphics.DrawString("Utente: " + DirectCast(mListBox.Items(idx),_
ItemEX).User, subTitFont, subTitBrush, e.Bounds.Left + 30,_
e.Bounds.Top + titFont.Height + 2)
e.Graphics.DrawLine(New Pen(Color.LightGray), 0, _
e.Bounds.Bottom - 1, e.Bounds.Right, e.Bounds.Bottom - 1)
If Items(idx).IconIndex > -1 Then
e.Graphics.DrawIcon(DirectCast(Icons(Items(idx).IconIndex),_
Icon), e.Bounds.Left + 1, e.Bounds.Top + 2)
End If
End Sub
Private Sub MeasureItemHandler(ByVal sender As Object,_
ByVal e As MeasureItemEventArgs) Handles mListBox.MeasureItem
e.ItemHeight = 40
RaiseEvent MeasureItem(sender, e)
End Sub
End Class
Download this code: ListBoxEx.vb.txt
Download the Demo project Simple Extended ListBox
TAGS: Asp.net, dotnet, code snippet, seo, search engine optimization, visual studio.net, sample code, c#, vb.net
