Basic Controls in Mono Winforms

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 Serif, 10px.

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/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 it's 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.

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.

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.

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

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