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3.1 The Control Properties
Before writing an event procedure for the control to response
to a user's input, you have to set certain properties for the
control to determine its appearance and how it will work with the
event procedure. You can set the properties of the controls in the
properties window at design time or at runtime. Figure 3.2 on the
right is a typical properties window for a form. It refers
particularly to interface of the first program you have learned in
the previous lesson, as shown
in Figure 3.1
:
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Figure 3.1 |
Figure 3.2: The Properties
Window |
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The title of the form is defined by the Text property
and its default name is Form 1. To change the form's title to
any name that you like, simple click in the box on the right
of the Text property and type in the new name, in this
example, the title is Addition Calculator. Notice that this
title will appear on top of the windows. In the
properties window, the item appears at the top part is the
object currently selected (in Figure 3.1, the object selected
is Form1). At the bottom part, the items listed in the left
column represent the names of various properties associated
with the selected object while the items listed in the right
column represent the states of the properties. Properties can
be set by highlighting the items in the right column then
change them by typing or selecting the options available. You
may also alter other properties of the form such as
font, location, size, foreground color, background color
,MaximizeBox, MinimizeBox and etc.
| You can also change the properties of the object at runtime
to give special effects such as change of color, shape,
animation effect and so on. For example the following code will
change the form color to yellow every time the form is loaded.
VB2010 uses RGB(Red, Green, Blue) to determine the colors. The RGB
code for yellow is 255,255,0. Me in the code refer to the
current form and Backcolor is the property of the form's background
color. The formula to assign the RGB color to the form is
Color.FormArbg(RGB codes).
Public Class
Form1
Private Sub Form1_Load(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles
MyBase.Load
Me.BackColor =
Color.FromArgb(255, 0, 255)
End Sub
End
Class
You may also use the follow procedure to assign the color at
run time.
Private Sub Form1_Load(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles
MyBase.Load
Me.BackColor =
Color.Magenta
End Sub
Both procedures above will load the form with a magenta
background as follows:
Here are some of the common colors and the
corresponding RGB codes. You can always experiment with other
combinations, but remember the maximum number for each color is 255
and the minimum number is 0.
| Color |
RGB code |
Color |
RGB code |
Color |
RGB Code |
|
255,0,0 |
|
255, 255, 0 |
|
255, 165, 0 |
|
0,255,0 |
|
0, 255, 255 |
|
0, 0, 0 |
|
0, 0, 255 |
|
255, 0, 255 |
|
255, 255, 255 |
The following is another program that allows
the user to enter the RGB codes into three different textboxes and
when he/she clicks the display color button, the background
color of the form will change according to the RGB codes. So, this
program allows users to change the color properties of the form at
run time.
The code
Private Sub Button1_Click(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles
Button1.Click
Dim rgb1, rgb2, rgb3 As Integer
rgb1 =
TextBox1.Text
rgb2 = TextBox2.Text
rgb3 =
TextBox3.Text
Me.BackColor = Color.FromArgb(rgb1, rgb2,
rgb3)
End
Sub
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