Question

The IronPython 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 layout.

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 combination of these values using the | operator.

Basic Anchor example

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

anchor.py

#!/usr/bin/ipy

import clr
clr.AddReference("System.Windows.Forms")
clr.AddReference("System.Drawing")

from System.Windows.Forms import Application, Form
from System.Windows.Forms import Button, AnchorStyles
from System.Drawing import Size, Point


class IForm(Form):

  def __init__(self):
    self.Text = 'Anchor'    
    self.Size = Size(210, 210)
        
    btn1 = Button()
    btn1.Text = "Button"
    btn1.Parent = self
    btn1.Location = Point(30, 30)

    btn2 = Button()
    btn2.Text = "Button"
    btn2.Parent = self
    btn2.Location = Point(30, 80)
    btn2.Anchor = AnchorStyles.Right
    
    self.CenterToScreen()
  

Application.Run(IForm())

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.

editor.py

#!/usr/bin/ipy

import clr
clr.AddReference("System.Windows.Forms")
clr.AddReference("System.Drawing")


from System.Windows.Forms import Application, Form, MainMenu, StatusBar
from System.Windows.Forms import Shortcut, MenuItem, TextBox, DockStyle
from System.Drawing import Size, Point


class IForm(Form):

  def __init__(self):

    self.Text = 'Editor'
    self.Size = Size(210, 180)

    mainMenu = MainMenu()
    filem = mainMenu.MenuItems.Add('&File')
    filem.MenuItems.Add(MenuItem('E&xit',
         self.OnExit, Shortcut.CtrlX))

    self.Menu = mainMenu

    tb = TextBox()
    tb.Parent = self
    tb.Dock = DockStyle.Fill
    tb.Multiline = True

    sb = StatusBar()
    sb.Parent = self
    sb.Text = 'Ready'

    self.CenterToScreen()
  

  def OnExit(self, sender, event): 
    self.Close()
  

Application.Run(IForm())

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

tb = TextBox()
tb.Parent = self

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.

anchoredbuttons.py

#!/usr/bin/ipy

import clr
clr.AddReference("System.Windows.Forms")
clr.AddReference("System.Drawing")
clr.AddReference("System")

from System.Windows.Forms import Application, Form, Button, Panel
from System.Windows.Forms import DockStyle, AnchorStyles
from System.Drawing import Size, Point


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


class IForm(Form):

  def __init__(self):
    self.Text = 'Buttons'
    
    self.Size = Size(WIDTH, HEIGHT)

    ok = Button()

    PANEL_HEIGHT = ok.Height + PANEL_SPACE

    panel = Panel()
    panel.Height = PANEL_HEIGHT
    panel.Dock = DockStyle.Bottom
    panel.Parent = self

    x = ok.Width * 2 + BUTTONS_SPACE
    y = (PANEL_HEIGHT - ok.Height) / 2

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

    close = Button()
  
    x = close.Width

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


    self.CenterToScreen()  

Application.Run(IForm())

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

WIDTH = 250
HEIGHT = 150

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

BUTTONS_SPACE = 15
PANEL_SPACE = 8
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.

PANEL_HEIGHT = 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.

panel = Panel()
panel.Height = PANEL_HEIGHT
panel.Dock = DockStyle.Bottom
panel.Parent = self

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 = Point(WIDTH-x, y)
ok.Anchor = AnchorStyles.Right

The OK button's parent is set to the panel widget. 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 IronPython Mono Winforms tutorial shows a more complex example. It is a skeleton of a music player.

player.py

#!/usr/bin/ipy

import clr
clr.AddReference("System.Windows.Forms")
clr.AddReference("System.Drawing")


from System.Windows.Forms import Application, Form, Button, Panel
from System.Windows.Forms import DockStyle, AnchorStyles, StatusBar
from System.Windows.Forms import TrackBar, MainMenu, MenuItem
from System.Windows.Forms import FlatStyle, TickStyle, Shortcut
from System.Drawing import Size, Point, Bitmap, Color


class IForm(Form):

  def __init__(self):

    self.Text = 'Player'    
    self.Size = Size(350, 280)

    mainMenu = MainMenu()
    filem = mainMenu.MenuItems.Add("&File")
    playm = mainMenu.MenuItems.Add("&Play")
    view = mainMenu.MenuItems.Add("&View")

    tools = mainMenu.MenuItems.Add("&Tools")
    favourites = mainMenu.MenuItems.Add("&Favourites")
    help = mainMenu.MenuItems.Add("&Help")
    filem.MenuItems.Add(MenuItem("E&xit",
         self.OnExit, Shortcut.CtrlX))

    self.Menu = mainMenu

    panel = Panel()
    panel.Parent = self
    panel.BackColor = Color.Black
    panel.Dock = DockStyle.Fill
     
    buttonPanel = Panel()
    buttonPanel.Parent = self
    buttonPanel.Height = 40
    buttonPanel.Dock = DockStyle.Bottom

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

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

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

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

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

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

    sb = StatusBar()
    sb.Parent = self
    sb.Text = "Ready"

    self.CenterToScreen()
  
  def OnExit(self, sender, event):
    self.Close()


Application.Run(IForm())

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

mainMenu = MainMenu()
filem = mainMenu.MenuItems.Add("&File")
...
self.Menu = mainMenu

Here we create the menubar.

panel = Panel()
panel.Parent = self
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.

buttonPanel = Panel()
buttonPanel.Parent = self
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.

pause = Button()
pause.FlatStyle = FlatStyle.Popup
pause.Parent = buttonPanel
pause.Location = Point(5, 10)
pause.Size = Size(25, 25)
pause.Image = 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 IronPython Mono Winforms tutorial was about the layout management of controls. We practised various possibilities that the Winforms library offers.