Question

This part of the IronPython Mono Winforms programming tutorial will be about basic controls.

Winforms controls are basic building blocks of an application. Winforms has a wide range of various controls. Buttons, check boxes, trackbars, labels etc. Everything a programmer needs for his job. In this section of the tutorial, we will describe several useful controls.

Label Control

Label is a simple control for displaying text or images. It does not receive focus.

label.py

#!/usr/bin/ipy

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

from System.Windows.Forms import Application, Form, Label
from System.Drawing import Size, Point, Font


text = """Meet you downstairs in the bar and heard
Your rolled up sleeves and your skull t-shirt
You say why did you do it with him today?
And sniffed me out like I was tanqueray

Cause you're my fella, my guy
Hand me your stella and fly
By the time I'm out the door
You tear me down like roger moore

I cheated myself
Like I knew I would
I told ya, I was trouble
You know that I'm no good

Upstairs in bed, with my ex boy
He's in a place, but I cant get joy
Thinking of you in the final throws, this is when my buzzer goes"""


class IForm(Form):

  def __init__(self):

    self.Text = "You know I'm No Good"

    font = Font("Serif", 10)

    lyrics = Label()
    lyrics.Parent = self
    lyrics.Text = text
    lyrics.Font = font
    lyrics.Location = Point(10, 10)
    lyrics.Size = Size(290, 290)

    self.CenterToScreen()


Application.Run(IForm())

In our example, we show some lyrics on the form.

lyrics = Label()

Label control is created.

text = """Meet you downstairs in the bar and heard 
    ... """

This is our text.

font = Font("Serif", 10)
...
lyrics.Font = font

The font of the text of the label is set to 10px Serif.

Figure: Label

CheckBox

CheckBox is a control that has two states: on and off. It is a box with a label or an image. If the CheckBox is checked, it is represented by a tick in a box. A CheckBox can be used to show or hide splashscreen at startup, toggle visibility of a toolbar etc.

checkbox.py

#!/usr/bin/ipy

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

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



class IForm(Form):

  def __init__(self):

    self.Text = "CheckBox"
    self.Size = Size(220, 170)

    cb = CheckBox()
    cb.Parent = self
    cb.Location = Point(30, 30)
    cb.Text = "Show Title"
    cb.Checked = True

    cb.CheckedChanged += self.OnChanged


    self.CenterToScreen()

  def OnChanged(self, sender, event):
    if sender.Checked:
      self.Text = "CheckBox"
    else:
      self.Text = ""
    
  
Application.Run(IForm())

Our code example shows or hides the title of the window depending on its state.

cb = CheckBox()

CheckBox control is created.

cb.Text = "Show Title"
cb.Checked = True

When the application starts, we show the title. And we set the CheckBox control to checked state.

cb.CheckedChanged += self.OnChanged

When we click on the CheckBox control, the CheckedChanged event is triggered.

if sender.Checked:
  self.Text = "CheckBox"
else:
  self.Text = ""

Here we toggle the title of the window.

Figure: CheckBox

TrackBar

TrackBar is a component that lets the user graphically select a value by sliding a knob within a bounded interval. Our example will show a volume control.

trackbar.py

#!/usr/bin/ipy

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

from System.Windows.Forms import Application, Form, PictureBox
from System.Windows.Forms import TrackBar, TickStyle
from System.Drawing import Size, Point, Bitmap


class IForm(Form):

  def __init__(self):
    self.Text = 'TrackBar'
    self.Size = Size(260, 190)
    

    tb = TrackBar()
    tb.Parent = self
    tb.Size = Size(150, 30)
    tb.Location = Point(30, 50)
    tb.TickStyle = TickStyle.None
    tb.SetRange(0, 100)

    tb.ValueChanged += self.OnChanged

    self.LoadImages()

    self.pb = PictureBox()
    self.pb.Parent = self
    self.pb.Location = Point(210, 50)
    self.pb.Image = self.mutep
    
    self.CenterToScreen()


  def LoadImages(self):
    try:
      self.mutep = Bitmap("mute.png")
      self.minp = Bitmap("min.png")
      self.medp = Bitmap("med.png")
      self.maxp = Bitmap("max.png")
    except Exception, e:
      print "Error reading images"
      print e.msg
      sys.exit(1)
  


  def OnChanged(self, sender, event): 
    val = sender.Value

    if val == 0: 
      self.pb.Image = self.mutep
    elif val > 0 and val <= 30:
      self.pb.Image = self.minp
    elif val > 30 and val < 80:
      self.pb.Image = self.medp
    else: self.pb.Image = self.maxp



Application.Run(IForm())

In the code example, we show a TrackBar and a PictureBox . By dragging the track bar, we change the image on the PictureBox control.

tb = TrackBar()

TrackBar control is created.

tb.TickStyle = TickStyle.None

We show no ticks for this TrackBar .

self.pb = PictureBox()
...
self.pb.Image = self.mutep

PictureBox control is created. It is used to display an image. At the start, it shows the mute image.

self.mutep = Bitmap("mute.png")
self.minp = Bitmap("min.png")
self.medp = Bitmap("med.png")
self.maxp = Bitmap("max.png")

Here we create four images that we will use.

val = sender.Value

if val == 0: 
  self.pb.Image = self.mutep
elif val > 0 and val <= 30:
  self.pb.Image = self.minp
elif val > 30 and val < 80:
  self.pb.Image = self.medp
else: self.pb.Image = self.maxp

We determine the value of the TrackBar . Depending on its value, we update the PictureBox control.

Figure: TrackBar

ComboBox

ComboBox is a control that combines a button or editable field and a drop-down list. The user can select a value from the drop-down list, which appears at the user's request. If you make the combo box editable, then the combo box includes an editable field into which the user can type a value.

combobox.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 ComboBox, Label
from System.Drawing import Size, Point


class IForm(Form):

  def __init__(self):

    self.Text = "ComboBox"
    self.Size = Size(240, 240)

    cb = ComboBox()
    cb.Parent = self
    cb.Location = Point(50, 30)

    cb.Items.AddRange(("Ubuntu",
      "Mandriva",
      "Red Hat",
      "Fedora",
      "Gentoo"))

    cb.SelectionChangeCommitted += self.OnChanged

    self.label = Label()
    self.label.Location = Point(50, 140)
    self.label.Parent = self
    self.label.Text = "..."


    self.CenterToScreen()

  def OnChanged(self, sender, event):
     self.label.Text = sender.Text
  
  
Application.Run(IForm())

Our code programming example shows a combobox with five items. The selected item is shown in a label control.

cb = ComboBox()

ComboBox control is created.

cb.Items.AddRange(("Ubuntu",
  "Mandriva",
  "Red Hat",
  "Fedora",
  "Gentoo"))

The ComboBox control is filled with items.

cb.SelectionChangeCommitted += self.OnChanged

If we select an item from the combobox, the SelectionChangeCommitted event is triggered.

def OnChanged(self, sender, event):
  self.label.Text = sender.Text

Here the selected text from the combobox is copied to the label.

Figure: ComboBox

We have finished chapter of the IronPython Mono Winforms tutorial, dedicated to basic controls.