Introduction to the Width and Height of a Control

The combination of the width and the height of a control is referred to as its size. If you add a control to a form, it assumes a default size.

To specify the size of a control during design, access its Properties window:

• Click the Size field and enter two numbers separated by a comma
• Alternatively, expand the Size field, click Width and type a value; click Height and type a value

To support the size of an object, the System.Drawing namespace defines the Size structure. There are four characteristics that define a Size value: its location and its dimensions. A Size value must have a starting point (X, Y) just as the Point object was illustrated earlier. The width is the distance from the left to the right borders of a Size object. The height represents the distance from the top to the bottom borders of a Size value:

To assist you with sizes, the Size structure provides the following constructor:

Public Sub New(width As Integer, height As Integer)

Using this constructor, to programmatically specify the size of a control, assign a Size value to its Size property. Here is an example:

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Module Exercise

    Public Class WinControls
        Inherits Form

        Private btnSubmit As Button

        Dim components As System.ComponentModel.Container

        Public Sub New()
            InitializeComponent()
        End Sub

        Public Sub InitializeComponent()
            Dim pt As Point

            btnSubmit = New Button()
            btnSubmit.Text = "Submit"
            btnSubmit.Location = New Point(100, 40)

            btnSubmit.Size = New Size(80, 32)

            Controls.Add(btnSubmit)
        End Sub

        Public Shared Function Main() As Integer

            Application.Run(New WinControls())
            Return 0

        End Function

    End Class

End Module

You can also define a Size object using a Point value. To support this, the Size structure is equipped with the following constructor:

Public Sub New(pt As Point)

After declaring a variable with this constructor, you can access its Width and Height properties to complete the definition of the Size object. If you already have the size of an object, you may only want to specify the dimensions of the variable. To do this, you can use the 

Besides the Size, the System.Drawing namespace also provides the SizeF structure. It uses the same properties as Size except that its members float types.

To retrieve the dimensions of a control, you can get its Size property and assign it to a Size object.

The combination of the location and size of an object is represented as a rectangle: a geometric figure with four sides. To support this figure, the System.Drawing namespace provides the Rectangle and the RectangleF structures. A rectangle can be represented as follows:

Like every geometric representation in your program, a rectangular figure is based on a coordinate system whose origin is located on a top-left corner. The object that "owns" or defines the rectangle also owns this origin. For example, if the rectangle belongs to a control that is positioned on a form, then the origin is on the top-left corner just under the title bar of the form, provided the form has a title bar.

To completely represent it, a rectangle is defined by its location and its dimensions. The location is defined by a point on the top-left corner of the rectangle. The distance from the left border of the object that owns the rectangle to the left border of the rectangle is represented by a property called Left. The distance from the top border of the object that owns the rectangle to the top border of the rectangle is represented by a property called Top. The distance from the left to the right borders of the rectangle is represented by a property called Width. The distance from the left to the right borders of the rectangle is represented by a property called Height. The distance from the left border of the object that owns the rectangle to the right border of the rectangle is represented by a property called Right. The distance from the top border of the object that owns the rectangle to the bottom border of the rectangle is represented by a property called Bottom. Based on this, a rectangle can be illustrated as follows:

To create a rectangle, you must provide at least its location and dimensions. The location can be represented by a Point value and the dimensions can be represented with a Size value. Based on this, you can use the following constructor to declare a Rectangle variable:

Public Sub New(location As Point, size As Size)

This constructor requires that you define a Point and a Size in order to use it. If instead you know the integer values of the location and dimensions, you can use the following constructor to declare a Rectangle object:

Public Sub New(x As Integer, y As Integer, width As Integer, height As Integer)

At any time, you can access or retrieve the characteristics of a Rectangle object as illustrated in the above picture from its properties. You use the same names we used in the picture.

Besides the Rectangle structure, the System.Drawing namespace provides the RectangleF structure that uses the same definition as Rectangle, except that it is defined with float values instead of integers.

The be able to recognize the location and the size of a control, the Control class is equipped with a property named Bounds. This property is of type Rectangle represented by the property. Therefore, at any time, to get the location and the size of a control, you can call its Bounds property, which produces a Rectangle value.