Question

The Mono Winforms tutorial continues with the layout management of controls. After we have placed controls on their parent containers, we have to ensure their proper layuot.

Anchor

The Anchor property of a control determines how it is resized with its parent. Anchor is a term from the marine world. When an anchor is dropped into the water, the ship is fixed in certain place. Same applies for the Winforms controls.

Each control in Winforms can have one of these AnchorStyles values:

• Top
• Left
• Right
• Bottom

Notice that controls are not restricted to one value. They can take any combinatino of these values using the | operator.

Basic Anchor example

The following example shows a very basic example, demonstrating the Anchor property.

' ZetCode Mono Visual Basic Winforms tutorial
'
' This program demonstrates the Anchor property
'
' author jan bodnar
' last modified May 2009
' website www.zetcode.com

Imports System.Windows.Forms
Imports System.Drawing


Public Class WinVBApp
  Inherits Form

  Public Sub New

     Me.Text = "Check menu item"
     Me.Size = New Size(380, 220)
     
     Me.InitUI
     
     Me.CenterToScreen

  End Sub
  
  Private Sub InitUI
  
    Me.Text = "Anchor"
    Size = New Size(210, 210)

    Dim btn1 As New Button
    btn1.Text = "Button"
    btn1.Parent = Me
    btn1.Location = New Point(30, 30)

    Dim btn2 As New Button
    btn2.Text = "Button"
    btn2.Parent = Me
    btn2.Location = New Point(30, 80)
    btn2.Anchor = AnchorStyles.Right

    Me.CenterToScreen
    
  End Sub


  Public Shared Sub Main
    Application.Run(New WinVBApp)
  End Sub
   
End Class

This is a very basic code example that clearly shows what the Anchor property is all about. We have two buttons on the form. The first button has the default AnchorStyles values, which are AnchorStyles.Top | AnchorStyles.Left. The second button has explicitly set the AnchorStyles.Right.

btn2.Anchor = AnchorStyles.Right

We explicitly set the Anchor property of the second button to AnchorStyles. Right value.

Now have a look at the following two images. The left one shows the application at the beginning. The right one shows the same application after resizement. The first button keeps its distance from the left and top borders of the form. The second button keeps its distance from the right border of the form. But it does not keep any distance in the vertical direction.

Figure: Before and after resizing

Dock

The Dock property allows us to stick a control to a certain edge of the parent form or control.

The following are possible DockStyle values.

• Top
• Left
• Right
• Bottom
• Fill
• None

Editor skeleton

The following code example shows the Dock property in action.

' ZetCode Mono Visual Basic Winforms tutorial
'
' This program demonstrates the Dock property
'
' author jan bodnar
' last modified May 2009
' website www.zetcode.com

Imports System.Windows.Forms
Imports System.Drawing


Public Class WinVBApp
  Inherits Form

  Public Sub New

     Me.Text = "Editor"
     Me.Size = New Size(220, 170)
     
     Me.InitUI
     
     Me.CenterToScreen

  End Sub
  
  Private Sub InitUI
  
    Dim mainMenu As New MainMenu
    Dim file As MenuItem = mainMenu.MenuItems.Add("&File")
    file.MenuItems.Add(New MenuItem("E&xit", _
         New EventHandler(AddressOf Me.OnExit), Shortcut.CtrlX))

    Menu = mainMenu

    Dim tb As New TextBox
    tb.Parent = Me
    tb.Dock = DockStyle.Fill
    tb.Multiline = True

    Dim sb As New StatusBar
    sb.Parent = Me
    sb.Text = "Ready"
    
  End Sub

  Private Sub OnExit(ByVal sender As Object, ByVal e As EventArgs)
    Me.Close
  End Sub


  Public Shared Sub Main
    Application.Run(New WinVBApp)
  End Sub
   
End Class

We show a menubar and a statusbar. And the remaining area is taken by the TextBox control.

Dim tb As New TextBox
tb.Parent = Me

Here we create the TextBox control. Form container is set to be the parent for the text box.

tb.Dock = DockStyle.Fill

This code line makes the TextBox control take up the remaining space inside the form container.

Figure: Editor skeleton

Anchored buttons

The next example shows two buttons placed in the bottom right corner of the form.

' ZetCode Mono Visual Basic Winforms tutorial
'
' This program positions two buttons
' in the bottom right corner of
' the window
'
' author jan bodnar
' last modified May 2009
' website www.zetcode.com

Imports System.Windows.Forms
Imports System.Drawing


Public Class WinVBApp
  Inherits Form

  Private Const WIDTH = 250
  Private Const HEIGHT = 150
  Private Const BUTTONS_SPACE = 15
  Private Const PANEL_SPACE = 8
  Private Const CLOSE_SPACE = 10


  Public Sub New

     Me.Text = "Buttons"
     Me.Size = New Size(WIDTH, HEIGHT)
     
     Me.InitUI
     
     Me.CenterToScreen

  End Sub
  
  Private Sub InitUI

    Dim ok As New Button

    Dim panelHeight As New Integer = ok.Height + PANEL_SPACE

    Dim panel As New Panel
    panel.Height = panelHeight
    panel.Dock = DockStyle.Bottom
    panel.Parent = Me

    Dim x As Integer = ok.Width * 2 + BUTTONS_SPACE
    Dim y As Integer = (panelHeight - ok.Height) / 2

    ok.Text = "Ok"
    ok.Parent = panel
    ok.Location = New Point(WIDTH-x, y)
    ok.Anchor = AnchorStyles.Right

    Dim close As New Button
  
    x = close.Width

    close.Text = "Close"
    close.Parent = panel
    close.Location = New Point(WIDTH-x-CLOSE_SPACE, y)
    close.Anchor = AnchorStyles.Right

    
  End Sub

  Private Sub OnExit(ByVal sender As Object, ByVal e As EventArgs)
    Me.Close
  End Sub


  Public Shared Sub Main
    Application.Run(New WinVBApp)
  End Sub
   
End Class

The example displayes OK, Close buttons in the bottom right corner of the window, as it is common in dialog windows.

Private Const WIDTH = 250
Private Const HEIGHT = 150

The WIDTH and HEIGHT variables determine the width and height of the application window.

Private Const BUTTONS_SPACE = 15
Private Const PANEL_SPACE = 8
Private Const CLOSE_SPACE = 10

The BUTTONS_SPACE is the space between the OK and the Close button. The PANEL_SPACE is the space between the panel and the bottom of the form. Finally, the CLOSE_SPACE variable sets the space between the Close button and the right border of the form.

Dim panelHeight As New Integer = ok.Height + PANEL_SPACE

Here we compute the height of the panel. The height of the panel is based on the height of the OK button. And we add some additional space, so that the buttons are not too close to the border.

Dim panel As New Panel
panel.Height = panelHeight
panel.Dock = DockStyle.Bottom
panel.Parent = Me

Here we create and manage the Panel control. In this example, it is used as a container for our buttons. It is glued to the bottom border of the form. And the buttons are placed within the panel.

ok.Text = "Ok"
ok.Parent = panel
ok.Location = New Point(WIDTH-x, y)
ok.Anchor = AnchorStyles.Right

The OK button's parent is set to the panel control. The location is computed. And the Anchor property is set to the right. The other button is created similarly.

Figure: Anchored buttons

Player skeleton

The last example of this part of the tutorial shows a more complex example. It is a skeleton of a music player.

' ZetCode Mono Visual Basic Winforms tutorial
'
' This program creates a skeleton of 
' a music player.
'
' author jan bodnar
' last modified June 2009
' website www.zetcode.com


Imports System.Windows.Forms
Imports System.Drawing

Public Class WinVBApp
  Inherits Form

  Public Sub New

     Me.Text = "Player"
     Me.Size = New Size(350, 280)
     
     Me.InitUI
     
     Me.CenterToScreen

  End Sub
  
  Private Sub InitUI

    Dim mainMenu As New MainMenu
    Dim file As MenuItem = mainMenu.MenuItems.Add("&File")
    Dim playm As MenuItem = mainMenu.MenuItems.Add("&Play")
    Dim view As MenuItem = mainMenu.MenuItems.Add("&View")

    Dim tools As MenuItem = mainMenu.MenuItems.Add("&Tools")
    Dim favourites As MenuItem = mainMenu.MenuItems.Add("&Favourites")
    Dim help As MenuItem = mainMenu.MenuItems.Add("&Help")
    file.MenuItems.Add(New MenuItem("E&xit", _
         New EventHandler(AddressOf Me.OnExit), Shortcut.CtrlX))

    Menu = mainMenu

    Dim panel As New Panel
    panel.Parent = Me
    panel.BackColor = Color.Black
    panel.Dock = DockStyle.Fill
    
    Dim buttonPanel As New Panel
    buttonPanel.Parent = Me
    buttonPanel.Height = 40
    buttonPanel.Dock = DockStyle.Bottom

    Dim pause As New Button
    pause.FlatStyle = FlatStyle.Popup
    pause.Parent = buttonPanel
    pause.Location = New Point(5, 10)
    pause.Size = New Size(25, 25)
    pause.Image = New Bitmap("pause.png")

    Dim play As New Button
    play.FlatStyle = FlatStyle.Popup
    play.Parent = buttonPanel
    play.Location = New Point(35, 10)
    play.Size = New Size(25, 25)
    play.Image = New Bitmap("play.png")

    Dim forward As New Button
    forward.FlatStyle = FlatStyle.Popup
    forward.Parent = buttonPanel
    forward.Location = New Point(80, 10)
    forward.Size = New Size(25, 25)
    forward.Image = New Bitmap("forward.png")

    Dim backward As New Button
    backward.FlatStyle = FlatStyle.Popup
    backward.Parent = buttonPanel
    backward.Location = New Point(110, 10)
    backward.Size = New Size(25, 25)
    backward.Image = New Bitmap("backward.png")

    Dim tb As = New TrackBar
    tb.Parent = buttonPanel
    tb.TickStyle = TickStyle.None
    tb.Size = New Size(150, 25)
    tb.Location = New Point(200, 10)
    tb.Anchor = AnchorStyles.Right

    Dim audio As New Button
    audio.FlatStyle = FlatStyle.Popup
    audio.Parent = buttonPanel
    audio.Size = New Size(25, 25)
    audio.Image = New Bitmap("audio.png")
    audio.Location = New Point(170, 10)
    audio.Anchor = AnchorStyles.Right

    Dim sb As New StatusBar
    sb.Parent = Me
    sb.Text = "Ready"

    Me.CenterToScreen
  
  End Sub
  

  Private Sub OnExit(ByVal sender As Object, ByVal e As EventArgs)
    Me.Close  
  End Sub


  Public Shared Sub Main
    Application.Run(New WinVBApp)
  End Sub
   
End Class

This is a more complex example showing both Dock and Anchor properties in action.

Dim mainMenu As New MainMenu
Dim file As MenuItem = mainMenu.MenuItems.Add("&File")
...
Menu = mainMenu

Here we create the menubar.

Dim panel As New Panel
panel.Parent = Me
panel.BackColor = Color.Black
panel.Dock = DockStyle.Fill

This is the black panel, which takes all the remaining space, left by the menubar, statusbar and the control panel.

Dim buttonPanel As New Panel
buttonPanel.Parent = Me
buttonPanel.Height = 40
buttonPanel.Dock = DockStyle.Bottom

This is the control panel. Its parent is the form container. It is glued to the bottom of the form. Its height is 40px. Inside this control panel, we place all the buttons and the trackar.

Dim pause As New Button
pause.FlatStyle = FlatStyle.Popup
pause.Parent = buttonPanel
pause.Location = New Point(5, 10)
pause.Size = New Size(25, 25)
pause.Image = New Bitmap("pause.png")

The pause button is one of the four buttons that has the default Anchor property value. The style of the button is set to flat, because it looks better. We put a bitmap on the button.

tb.Anchor = AnchorStyles.Right
...
audio.Anchor = AnchorStyles.Right

The last two controls are anchored to the right.

Figure: Player skeleton

This part of the Mono Visual Basic Winforms tutorial was about the layout management of controls. We practised various possibilities that the Winforms library offers.