VB .Net Programming
Unit-III:
Working with Forms:
Loading, showing and hiding forms, controlling One form within another. GUI Programming with Windows Form:
Textbox Properties, Methods and Events,
Label Properties, Methods and Events,
Button, Listbox Properties, Methods and Events,
Combobox Properties, Methods and Events,
Checkbox Properties, Methods and Events,
PictureBox Properties, Methods and Events,
Radio Button Properties, Methods and Events,
Panel, Scroll bar, Timer, List View, Tree View, Toolbar, Status Bar OpenFileDialog,
SaveFileDialog,
FontDialog,
ColorDialog,
Print Dialog.
LinkLabel.
Designing menus:
Context Menu, access & shortcut keys.
Working with Forms:
A Form is used in VB.NET to create a form-based or window-based application. Using the form, we can build a attractive user interface. It is like a container for holding different control that allows the user to interact with an application. The controls are an object in a form such as buttons, Textboxes, Textarea, labels, etc.
A Form uses a System.Windows.Form namespace, and it has a wide family of controls that add both forms and functions in a Window-based user interface.
For creating a Windows Forms application
GoTo File Menu.
Click on New Project.
Click on Windows Forms App or Application
LOADING FORM.
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load Dim button1 As New Button()
Dim button2 As New Button()
button1.Text = "OK"
button1.Location = New Point(10, 10)
button2.Text = "Cancel"
button2.Location = _
New Point(button1.Left, button1.Height + button1.Top + 10)
Me.Text = "Wel-Come To VB .Net"
Me.HelpButton = True
Me.FormBorderStyle = FormBorderStyle.FixedDialog
Me.MaximizeBox = False
Me.MinimizeBox = False
Me.AcceptButton = button1
Me.CancelButton = button2
Me.StartPosition = FormStartPosition.CenterScreen
Me.Height = 300
Me.Width = 560
Me.Controls.Add(button1)
Me.Controls.Add(button2)
End Sub
End Class
Showing and Hiding Forms
Visual Basic.NET, everything is an object, and objects are based on classes. Because the definition of a form is a class, you have to create a new Form object using the class as a template.
The process of creating an object from a class (or template) is called instantiation. The syntax you'll use most often to instantiate a form is the following:
Dim {objectvariable} As New {formclassname()}
The three parts of this declaration are
∙ The Dim statement A reserved word that tells the compiler that you're creating a variable. ∙ The name of the variable This will be the name for the form that you will use in code. ∙ The keyword New Indicates that you want to instantiate a new object for the variable.
∙ frmLoginDialog.Show
∙ or
∙ frmLoginDialog.Visible = True
HIDING FORM.
First, you can make a form disappear without closing it or freeing its resources (this is called hiding).
Set its visible property to False. This hides the visual part of the form, but the form still resides in memory and can still be manipulated by code.
All the variables and controls of the form retain their values when a form is hidden, so that if the form is displayed again, the form looks the same as it did when its visible property was set to False.
Second, you can completely close a form and release the resources it consumes. You should close a form when it's no longer needed, so Windows can reclaim all resources used by the form. To do so, you invoke the Close method of the form like this:
Me.Close()
Because Me represents the current Form object, you can manipulate properties and call methods of the current form using Me. (Me.Visible = False).
The Close method tells Visual Basic to not simply hide the form, but to destroy it completely. If variables in other forms are holding a reference to the form you close, their references will be set to nothing and will no longer point to a valid Form object.
Controlling One Form from within Another
Controlling the form means accessing its controls, and setting or reading values from within another form’s code.
When you are dealing with Windows Forms it's quite likely that sooner or later you are going to want to pass the data held in a control on one form over to another form.
the text a user has entered in a text box, a selection from a combobox, a checkbox's Checked property, etc. You may also want to insert data into a control on another form.
Public Class Form1
Inherits System.Windows.Forms.Form
Private Sub UserLabel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles UserLabel.Click
End Sub
Private Sub ShowButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ShowButton.Click
Dim F2 As New Form2()
Me.UserLabel.Text = " "
F2.ShowDialog(Me)
Me.UserLabel.Text = "Current User : " & Form2.NuNameTB.Text
End Sub
End Class
Public Class Form2
Public Shared NuNameTB As TextBox
Private Sub CloseButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CloseButton.Click
NuNameTB = UsersName
' Now close the form
Me.Close()
End Sub
End Class
GUI Programming with Windows Form:
Textbox Properties, Methods and Events
A TextBox control is used to display, accept the text from the user as an input, or a single line of text on a VB.NET Windows form at runtime. Furthermore, we can add multiple text and scroll bars in textbox control. However, we can set the text on the textbox that displays on the form.
Properties
AutoCompleteMode- Gets or sets an option that controls how automatic completion works for the TextBox.
Font - Gets or sets the font of the text displayed by the control.
Lines- Gets or sets the lines of text in a text box control.
TextAlign
Gets or sets how text is aligned in a TextBox control. This property has values −
∙ Left, Right, Center .
Multiline - Gets or sets a value indicating whether this is a multiline TextBox control.
AcceptsReturn - Gets or sets a value indicating whether pressing ENTER in a multiline TextBox control creates a new line of text in the control or activates the default button for the form.
PasswordChar - Gets or sets the character used to mask characters of a password in a single-line TextBox control.
TextLength
Gets the length of text in the control.
ScrollBars
Gets or sets which scroll bars should appear in a multiline TextBox control. This property has values
∙ None, Horizontal, Vertical, Both
Text - Gets or sets the current text in the TextBox.
Visible - The Visible property sets a value that indicates whether the textbox should be displayed on a Windows Form.
WordWrap- Indicates whether a multiline text box control automatically wraps words to the beginning of the next line when necessary.
Methods
AppendText- Appends text to the current text of a text box.
Clear - Clears all text from the text box control.
Copy - Copies the current selection in the text box to the Clipboard.
Cut - Moves the current selection in the text box to the Clipboard.
Paste - Replaces the current selection in the text box with the contents of the Clipboard. ResetText- Resets the Text property to its default value.
ToString- Returns a string that represents the TextBoxBase control.
Focus - Method to set focus to a TextBox Control.
Events
Click- When a textbox is clicked, a click event is called in the textbox control.
BackColorChanged- It is found in the TextBox Control when the property value of the BackColoris changed.
BorderStyleChanged- It is found in the TextBox Control when the value of the BorderStyle is changed.
CursorChanged- It is found in TextBox, when the textbox control is removed from the Control.ControlCollection.
FontChanged- It occurs when the property of the Font is changed.
GetFocus- It is found in TextBox control to get the focus.
MultilineChanged- It is found in a textbox control when the value of multiline changes.
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) _
Handles MyBase.Load
' Set the caption bar text of the form.
Me.Text = "Example of MessageBox"
End Sub
Private Sub btnMessage_Click(sender As Object, e As EventArgs) _
Handles btnMessage.Click
MessageBox.Show("Thank you " + txtName.Text + " from " + txtOrg.Text)
End Sub
End Class
Lable Properties, Methods and Events
A label control is used to display descriptive text for the form in control.
It does not participate in user input or keyboard or mouse events.
We cannot rename labels at runtime.
The labels are defined in the class System.Windows.Forms namespace.
Properties
AutoSize- an AutoSize property of label control is used to set or get a value if it is automatically resized to display all its contents.
Border Style- It is used to set the style of the border in the Windows form.
TextAlign- It is used to set the alignment of text such as centre, bottom, top, left, or right. ForeColor- It is used to set the color of the text.
Image- It is used to set the image to a label in Windows Form.
ImageIndex- It is used to set the index value to a label control displayed on the Windows form.
Methods
GetPreferredSize- Retrieves the size of a rectangular area into which a control can be fitted. Refresh- Forces the control to invalidate its client area and immediately redraw itself and any child controls.
Select- Activates the control.
Show- Displays the control to the user.
ToString- Returns a String that contains the name of the control.
Events
Click- Click event is occurring in the Label Control to perform a click.
DoubleClick- When a user performs a double-clicked in the Label control, the DoubleClick event occurs.
GotFocus- Occurs when the control receives focus.
TextChanged- Occurs when the Text property value changes.
BackColorChanged- A BackColorChanged event occurs in the Label control when the value of the BackColor property is changed.
DragDrop- A DragDrop event occurs in the Label control when a drag and drop operation is completed.
Button Properties, Methods and Events
Button control is used to perform a click event in Windows Forms, and it can be clicked by a mouse or by pressing Enter keys.
It is used to submit all queries of the form by clicking the submit button or transfer control to the next form.
Properties
BackColor- It is used to set the background color of the Button in the Windows form. BackgroundImage- It is used to set the background image of the button control. ForeColor- It is used to set or get the foreground color of the button control.
Image- It is used to set or gets the image on the button control that is displayed.
Location- It is used to set the upper-left of the button control's coordinates relative to the upper-left corner in the windows form.
Text- It is used to set the name of the button control in the windows form.
TabIndex- It is used to set or get the tab order of the button control within the form. Methods
GetPreferredSize- Retrieves the size of a rectangular area into which a control can be fitted.
NotifyDefault- Notifies the Button whether it is the default button so that it can adjust its appearance accordingly.
Select- Activates the control.
ToString- Returns a String containing the name of the Component, if any. This method should not be overridden.
Events
Click- A Click event is found in the button control when the control is clicked.
DoubleClick- When the user makes a double click on the button, a double click event is found in the button control.
GotFocus- Occurs when the control receives focus.
BackColorChanged- A BackColorChaged event is found in button control when the Background property is changed.
BackgroundImageChanged- A BackgoundImageChanged event is found in button control when the value of the BackgoundImage property is changed.
TextChanged- It is found in the button control when the value of the text property is changed.
DragDrop- The DragDrop event is found in the button control when the drag and drop operation is completed in the Form.
ListBox Properties, Methods and Events
The ListBox represents a Windows control to display a list of items to a user. A user can select an item from the list. It allows the programmer to add items at design time by using the properties window or at the runtime.
You can populate the list box items either from the properties window or at runtime. To add items to a ListBox, select the ListBox control and get to the properties window, for the properties of this control. Click the ellipses (...) button next to the Items property. This opens the String Collection Editor dialog box, where you can enter the values one at a line.
Properties –
AllowSelection-Gets a value indicating whether the ListBox currently enables selection of list items. BorderStyle-Gets or sets the type of border drawn around the list box.
ColumnWidth-Gets of sets the width of columns in a multicolumn list box.
HorizontalScrollBar- Gets or sets the value indicating whether a horizontal scrollbar is displayed in the list box.
MultiColumn-Gets or sets a value indicating whether the list box supports multiple columns. SelectedIndex-Gets or sets the zero-based index of the currently selected item in a list box. SelectedItem-Gets or sets the currently selected item in the list box.
SelectedItems-Gets a collection containing the currently selected items in the list box.
SelectionMode - Gets or sets the method in which items are selected in the list box. This property has values −
∙ None, One, MultiSimple, MultiExtended.
Methods
BeginUpdate-Prevents the control from drawing until the EndUpdate method is called, while items are added to the ListBox one at a time.
ClearSelected-Unselects all items in the ListBox.
Sort-As the name suggests, a Sort() method is used to arrange or sort the elements in the ListBox.
Remove-It is used to remove an item from an item collection. However, we can remove items using the item name.
FindStringExact-Finds the first item in the ListBox that exactly matches the specified string. OnSelectedIndexChanged-Raises the SelectedIndexChanged event.
OnSelectedValueChanged-Raises the SelectedValueChanged event.
Events
Public Class Listbx
Private Sub Listbx_Load(sender As Object, e As EventArgs) Handles MyBase.Load Me.Text = "Example of ListBox"
ListBox1.Items.Add("Earth")
ListBox1.Items.Add("Mercury")
ListBox1.Items.Add("Mars")
ListBox1.Items.Add("Jupiter")
ListBox1.Items.Add("Venus")
ListBox1.Items.Add("Neptune")
ListBox1.Items.Add("Uranus")
Button1.Text = "Show"
Button2.Text = "Exit"
Label2.Text = "Select the solar system from the ListBox"
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click Dim lt As String
lt = ListBox1.Text
MsgBox(" Selected Solar System is " & lt)
End Sub
Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles List Box1.SelectedIndexChanged
Label1.Text = ListBox1.SelectedItem.ToString()
End Sub
Private Sub Button2_Click (sender As Object, e As EventArgs) Handles Button2.Click End
End Sub
End Class
Combobox Properties, Methods and Events
The ComboBox control is used to display more than one item in a drop-down list. It is a combination of Listbox and Textbox in which the user can input only one item. it also allows a user to select an item from a drop-down list.
Properties
DataBinding- It is used to bind the data with a ComboBox Control.
DataSource- It is used to get or set the data source for a ComboBox Control. MaxLength- It is used by the user to enter maximum characters in the editable area of the combo box.
SelectedItem- It is used to set or get the selected item in the ComboBox Control. Sorted- The Sorted property is used to sort all the items in the ComboBox by setting the value.
Methods
BeginUpdate- Prevents the control from drawing until the EndUpdate method is called, while items are added to the combo box one at a time.
EndUpdate- Resumes drawing of a combo box, after it was turned off by the BeginUpdate method.
FindString
Finds the first item in the combo box that starts with the string specified as an argument. FindStringExact
Finds the first item in the combo box that exactly matches the specified string.
SelectAll
Selects all the text in the editable area of the combo box.
Events
DropDown
Occurs when the drop-down portion of a combo box is displayed.
DropDownClosed
Occurs when the drop-down portion of a combo box is no longer visible.
DropDownStyleChanged
Occurs when the DropDownStyle property of the ComboBox has changed.
SelectedIndexChanged
Occurs when the SelectedIndex property of a ComboBox control has changed. SelectionChangeCommitted
Occurs when the selected item has changed and the change appears in the combo box.
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Me.Text = "Example Of Combobox"
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If ComboBox1.SelectedIndex > -1 Then
Dim sindex As Integer
sindex = ComboBox1.SelectedIndex
Dim sitem As Object
sitem = ComboBox1.SelectedItem
ListBox1.Items.Add(sitem)
End If
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
ComboBox1.Items.Clear()
ComboBox1.Items.Add("Safety")
ComboBox1.Items.Add("Security")
ComboBox1.Items.Add("Governance")
ComboBox1.Items.Add("Education")
ComboBox1.Items.Add("Roads")
ComboBox1.Items.Add("Health")
ComboBox1.Items.Add("Food for all")
ComboBox1.Text = "Select from..."
End Sub
Private Sub Button3_Click(sender As Object, e As EventArgs) ComboBox1.Sorted = True
End Sub
Private Sub Button4_Click(sender As Object, e As EventArgs) ComboBox1.Items.Clear()
End Sub
Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) _
Handles ListBox1.SelectedIndexChanged
Label1.Text = ComboBox1.SelectedItem.ToString()
End Sub
End Class
CheckBox Properties, Methods and Events
The CheckBox control allows the user to set true/false or yes/no type options. The user can select or deselect it. When a check box is selected it has the value True, and when it is cleared, it holds the value False.
Properties
Appearance
Gets or sets a value determining the appearance of the check box.
AutoCheck
Gets or sets a value indicating whether the Checked or CheckedState value and the appearance of the control automatically change when the check box is selected.
CheckAlign
Gets or sets the horizontal and vertical alignment of the check mark on the check box. Checked
Gets or sets a value indicating whether the check box is selected.
CheckState
Gets or sets the state of a check box.
Text
Gets or sets the caption of a check box.
Methods
OnCheckedChanged
Raises the CheckedChanged event.
OnCheckStateChanged
Raises the CheckStateChanged event.
OnClick
Raises the OnClick event.
Events
CheckedChanged- The CheckedChanged event is found when the value of the checked property is changed to CheckBox.
DoubleClick- It occurs when the user performs a double click on the CheckBox control.
CheckStateChanged- It occurs when the value of the CheckState property changes to the CheckBox control.
AppearanceChanged- It occurs when the property of the Appearance is changed to the CheckBox control.
Public Class Checkbxvb
Private Sub Checkbxvb_Load(sender As Object, e As EventArgs) Handles MyBase.Load Me.Text = "CheckBox Example"
Label1.Text = "Select the fruits name"
CheckBox1.Text = "Apple" CheckBox2.Text = "Mango" CheckBox3.Text = "Banana" CheckBox4.Text = "Orange"CheckBox5.Text = "Potato" CheckBox6.Text = "Tomato"Button1.Text = " Submit" Button2.Text = "Close"
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click Dim fruit As Stri ng fruit = " "
If CheckBox1.Checked = True Then fruit = "Apple" End If
If CheckBox2.Checked = True Then fruit = fruit & " Mango" End If
If CheckBox3.Checked = True Then fruit = fruit & " Banana" End If
If CheckBox4.Checked = True Then fruit = fruit & " Orange" End If
If CheckBox5.Checked = True Then
fruit = fruit & " Potato"
End If
If CheckBox6.Checked = True Then
fruit = fruit & " Tomato"
End If
If fruit.Length <> 0 Then
MsgBox(" Selected items " & fruit)
End If
CheckBox1.ThreeState = True
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click End 'terminate the program
End Sub
End Class
PictureBox Properties, Methods and Events
PictureBox control is used to display the images on Windows Form. The PictureBox control has an image property that allows the user to set the image at runtime or design time.
Properties
AllowDrop
Specifies whether the picture box accepts data that a user drags on it.
ErrorImage
Gets or specifies an image to be displayed when an error occurs during the image-loading process or if the image load is cancelled.
Image
Gets or sets the image that is displayed in the control.
ImageLocation
Gets or sets the path or the URL for the image displayed in the control.
SizeMode
Determines the size of the image to be displayed in the control. This property takes its value from the PictureBoxSizeMode enumeration, which has values −
∙ Normal − the upper left corner of the image is placed at upper left part of the picture box ∙ StrechImage − allows stretching of the image
∙ AutoSize − allows resizing the picture box to the size of the image
∙ CenterImage − allows centering the image in the picture box
∙ Zoom − allows increasing or decreasing the image size to maintain the size ratio. TabIndex
Gets or sets the tab index value.
Text
Gets or sets the text for the picture box.
Methods
CancelAsync
Cancels an asynchronous image load.
Load
Displays an image in the picture box
LoadAsync
Loads image asynchronously.
ToString
Returns the string that represents the current picture box.
Events
Click
Occurs when the control is clicked.
KeyUp
Occurs when a key is released when the control has focus.
KeyDown
Occurs when a key is pressed when the control has focus.
KeyPress
Occurs when a key is pressed when the control has focus.
Resize
Occurs when the control is resized.
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
' Set the caption bar text of the form.
Me.Text = "PictureBoc Example"
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
PictureBox1.ClientSize = New Size(300, 300)
PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage End Sub
End Class
Radio Button Properties, Methods and Events
The RadioButton is used to select one option from the number of choices. If we want to select only one item from a related or group of items in the windows forms, we can use the radio button. The RadioButton is mutually exclusive that represents only one item is active and the remains unchecked in the form.
Properties
Appearance
Gets or sets a value determining the appearance of the radio button.
AutoCheck
Gets or sets a value indicating whether the Checked value and the appearance of the control automatically change when the control is clicked.
CheckAlign
Gets or sets the location of the check box portion of the radio button.
Checked
Gets or sets a value indicating whether the control is checked.
Text
Gets or sets the caption for a radio button.
Methods
Contains(Control)- The Contains() method is used to check if the defined control is available in the RadioButton control.
DefWndProc(Message)- It is used to send the specified message to the Window procedure. Focus()-The Focus() method is used to set the input focus to the window form's RadioButton control. GetAutoSizeMode()-It is used to return a value that represents how the control will operate when the AutoSize property is enabled in the RadioButton control of the Window form.
ResetText()-As the name suggests, a ResetText() method is used to reset the property of text to its default value or empty.
Update()-It is used to reroute an invalid field, which causes control in the client region. Events
AppearanceChanged
Occurs when the value of the Appearance property of the RadioButton control is changed. CheckedChanged
Occurs when the value of the Checked property of the RadioButton control is changed.
Public Class RadioBtn
Private Sub RadioBtn_Load(sender As Object, e As EventArgs) Handles MyBase.Load Me.Text = "javaTpoint.com" ' Set the title of the form
Label1.Text = "Select the Gender"
RadioButton1.Text = "Male" ' Set the radiobutton1 and radiobutton2
RadioButton2.Text = "Female"
RadioButton3.Text = "Transgender"
Button1.Text = "Submit" ' Set the button name
Button2.Text = "Exit"
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click Dim gen As String
If RadioButton1.Checked = True Then
gen = "Male"
MsgBox(" Your gender is : " & gen)
ElseIf RadioButton2.Checked = True Then
gen = "Female"
MsgBox(" Your gender is : " & gen)
Else
gen = "Transgender"
MsgBox(" You have Selected the gender : " & gen)
End If
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click End 'Terminate the program
End Sub
End Class
Panel
The Panel control is a container control that is used to host a group of similar child controls.
Panel control when you have to show and hide a group of controls. Instead of show and hide individual controls, you can simply hide and show a single Panel and all child controls.
Creating a Panel
We can create a Panel control using the Forms designer at design-time or using the Panel class in code at run- time.
Design-time
To create a Panel control at design-time, you simply drag and drop a Panel control from Toolbox to a Form in Visual Studio. After you drag and drop a Panel on a Form, the Panel looks like Figure 1. Once a Panel is on the Form, you can move it around and resize it using mouse and set its properties and events.
Run-time
Creating a Panel control at run-time is merely a work of creating an instance of Panel class, set its properties and adds Panel class to the Form controls.
First step to create a dynamic Panel is to create an instance of Panel class. The following code snippet creates a Panel control object.
Dim dynamicPanel As New Panel()
In the next step, you may set properties of a Panel control. The following code snippet sets location, size and Name properties of a Panel.
dynamicPanel.Location = New
System.Drawing.Point(26, 12) dynamicPanel.Name =
"Panel1"
dynamicPanel.Size = New
System.Drawing.Size(228, 200)
dynamicPanel.BackColor = Color.LightBlue
Once the Panel control is ready with its properties, the next step is to add the Panel to a Form. To do so, we use Form.Controls.Add method that adds Panel control to the Form controls and displays on the Form based on the location and size of the control. The following code snippet adds a Panel control to the current Form.
Controls.Add(dynamicPanel)
Setting Panel Properties
After you place a Panel control on a Form, the next step is to set its properties.
The easiest way to set properties is from the Properties Window. You can open Properties window by pressing F4 or right click on a control and select Properties menu item.
The Panel control is a container control that is used to host a group of similar child controls. One of the major uses I found for a Panel control when you have to show and hide a group of controls. Instead of show and hide individual controls, you can simply hide and show a single Panel and all child controls.
In this article, we will demonstrate how to create and use a Panel control in a Windows Forms application. Creating a Panel
We can create a Panel control using the Forms designer at design-time or using the Panel class in code at run- time.
Design-time
To create a Panel control at design-time, you simply drag and drop a Panel control from Toolbox to a Form in Visual Studio. After you drag and drop a Panel on a Form, the Panel looks like Figure 1. Once a Panel is on the Form, you can move it around and resize it using mouse and set its properties and events.
Figure 1
Run-time
Creating a Panel control at run-time is merely a work of creating an instance of Panel class, set its properties and adds Panel class to the Form controls.
First step to create a dynamic Panel is to create an instance of Panel class. The following code snippet creates a Panel control object.
Dim dynamicPanel As New Panel()
In the next step, you may set properties of a Panel control. The following code snippet sets location, size and Name properties of a Panel.
dynamicPanel.Location = New
System.Drawing.Point(26, 12) dynamicPanel.Name =
"Panel1"
dynamicPanel.Size = New
System.Drawing.Size(228, 200)
dynamicPanel.BackColor = Color.LightBlue
Once the Panel control is ready with its properties, the next step is to add the Panel to a Form. To do so, we use Form.Controls.Add method that adds Panel control to the Form controls and displays on the Form based on the location and size of the control. The following code snippet adds a Panel control to the current Form.
Controls.Add(dynamicPanel)
Setting Panel Properties
After you place a Panel control on a Form, the next step is to set its properties.
The easiest way to set properties is from the Properties Window. You can open Properties window by pressing F4 or right click on a control and select Properties menu item. The Properties window looks like Figure 2.
Figure 2
Panel has most of the common control properties. Here I am going to discuss the main purpose of a Panel. Adding Controls to a Panel
You can add controls to a Panel by dragging and dropping control to the Panel. We can add controls to a Panel at run-time by using its Add method. The following code snippet creates a Panel, creates a TextBox and a CheckBox and adds these two controls to a Panel.
Private Sub CreateButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handl es CreateButton.Click
Dim dynamicPanel As New Panel()
dynamicPanel.Location = New
System.Drawing.Point(26, 12) dynamicPanel.Name =
"Panel1"
dynamicPanel.Size = New
System.Drawing.Size(228, 200)
dynamicPanel.BackColor = Color.LightBlue
Dim textBox1 As New TextBox()
textBox1.Location = New Point(10,
10)
textBox1.Text = "I am a
TextBox5" textBox1.Size =
New Size(200, 30)
Dim checkBox1 As New CheckBox()
checkBox1.Location = New Point(10,
50) checkBox1.Text = "Check Me"
checkBox1.Size = New Size(200,
30)
dynamicPanel.Controls.Add(textBox
1)
dynamicPanel.Controls.Add(checkB
ox1)
Controls.Add(dynamicPan
el) End Sub
Show and Hide a Panel
I have seen in many applications when you want to show and hide a group of controls on a Form based on some condition. That is where a Panel is useful. Instead of show and hide individual controls, we can group controls that we want to show and hide and place them on two different Panels and show and hide the Panels. To show and hide a Panel, we use Visible property.
dynamicPanel.Visible = False
Scroll Bar
The ScrollBar controls display vertical and horizontal scroll bars on the form. This is used for navigating through large amount of information. There are two types of scroll bar controls: HScrollBar for horizontal scroll bars and VScrollBar for vertical scroll bars. These are used independently from each other.
Properties
AutoSize
Gets or sets a value indicating whether the ScrollBar is automatically resized to fit its contents. BackColor
Gets or sets the background color for the control.
ForeColor
Gets or sets the foreground color of the scroll bar control.
ImeMode
Gets or sets the Input Method Editor (IME) mode supported by this control.
Maximum
Gets or sets the upper limit of values of the scrollable range.
Minimum
Gets or sets the lower limit of values of the scrollable range.
Value
Gets or sets a numeric value that represents the current position of the scroll box on the scroll bar control.
Methods
UpdateScrollInfo- It is used to update the ScrollBar control using the Minimum, maximum, and the value of LargeChange properties.
OnScroll(ScrollEventArgs)- It is used to raise the Scroll event in the ScrollBar Control. OnEnabledChanged- It is used to raise the EnabledChanged event in the ScrollBar control. Select- It is used to activate or start the ScrollBar control.
Events
Click
Occurs when the control is clicked.
DoubleClick
Occurs when the user double-clicks the control.
Scroll
Occurs when the control is moved.
ValueChanged
Occurs when the Value property changes, either by handling the Scroll event or programmatically.
Public Class ScrollBar
Private Sub ScrollBar_Load(sender As Object, e As EventArgs) Handles MyBase.Load Me.Text = "Example of Scroll Bar" 'Set the title for a Windows Form
Label1.Text = "Use of ScrollBar in Windows Form"
Label1.ForeColor = Color.Blue
Me.AutoScroll = True
Me.VScrollBar1.Minimum = 0
Me.VScrollBar1.Maximum = 100
Me.VScrollBar1.Value = 0
Me.VScrollBar1.BackColor = Color.Blue
Me.HScrollBar1.Minimum = 0
Me.HScrollBar1.Maximum = 100
Me.HScrollBar1.Value = 35
End Sub
End Class
Timer
Timer Control plays an important role in the Client side programming and Server side programming, also used in Windows Services. By using this Timer Control, windows allow you to control when actions take place without the interaction of another thread.
We can use Timer Control in many situations in our development environment.
If you want to run some code after a certain interval of time continuously, you can use the Timer control.
As well as to start a process at a fixed time schedule, to increase or decrease the speed in an animation graphics with time schedule etc.you can use the Timer Control.
At runtime it does not have a visual representation and works as a component in the background. we can control programs in millisecond, seconds, minutes and even in hours. The Timer Control allows us to set Interval property in milliseconds
(1 second is equal to 1000 milliseconds).
For example, if we want to set an interval of two minute we set the value at Interval property as 120000, means 120x1000 .
The Timer Control starts its functioning only after its Enabled property is set to True, by default Enabled property is False.
Public Class Form1
Dim second As Integer
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Interval = 1000
Timer1.Start() 'Timer starts functioning
End Sub
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Label1.Text = DateTime.Now.ToString
second = second + 1
If second >= 10 Then
Timer1.Stop() 'Timer stops functioning
MsgBox("Timer Stopped ...")
End If
End Sub
End Class
List View
The ListView Controls are used to display a collection of items in the Windows Forms. It uses one of the view lists, such as LargeIcon, SmallIcon, Details, List, and Tile. Furthermore, the ListViewallows the user to add or remove icons from the ListView Control.
Properties
Alignment
Gets or sets the alignment of items in the control.
BackColor
Gets or sets the background color.
CheckBoxes
Gets or sets a value indicating whether a check box appears next to each item in the control. CheckedItems
Gets the currently checked items in the control.
Items
Gets a collection containing all items in the control.
Scrollable
Gets or sets a value indicating whether a scroll bar is added to the control when there is not enough room to display all items.
View
Gets or sets how items are displayed in the control. This property has the following values:
∙ LargeIcon − displays large items with a large 32 x 32 pixels icon.
∙ SmallIcon − displays items with a small 16 x 16 pixels icon
∙ List − displays small icons always in one column
∙ Details − displays items in multiple columns with column headers and fields ∙ Tile − displays items as full-size icons with item labels and sub-item information.
Methods
ArrangeIcons()-The ArrangeIcons method is used to arrange all the items displayed as icons in the ListView control.
FindItemWithText()-It is used to search the first ListViewItem that started with the given text value. GetItemAt()-The GetItemAt method is used to get an item at the specified location of the ListView control.
Clear()- The Clear method is used to clear all the items and columns from the ListView control. Sort() - The Sort method is used to sort items of the ListView.
Events
ItemActivate- the Item Activate event occurred when an item activated in the List View control. ItemChecked- the Item Checked event is found in the List View control when the checked state of an item changes.
TextChanged- Occurs when the Text property is changed.
ItemCheck
Occurs when an item in the control is checked or unchecked.
AfterLabelEditEvent- It occurs when the user in the ListView control edits the label for an item.
Public Class List_View
Private Sub List_View_Load(sender As Object, e As EventArgs) Handles MyBase.Load Me.Text = "Example Of ListVIew" 'Set the title for the Windows form
ListView1.View = View.Details ' Display the List in details
ListView1.GridLines = True ' Set the Grid lines
Label1.Text = "Enter the Roll No." ' Set the name of Labels
Label2.Text = "Enter Your Name"
Label3.Text = "Enter Your Email"
Label4.Text = "Enter the Course"
Label5.Text = "Student details"
ListView1.Columns.Add("Roll No", 70, HorizontalAlignment.Left) ' set the name of column ListView1.Columns.Add("Name", 100, HorizontalAlignment.Left) ' set the name of column ListView1.Columns.Add("Email", 150, HorizontalAlignment.Left) ' set the name of column ListView1.Columns.Add("Course", 100, HorizontalAlignment.Left) ' set the name of column
ListView1.BackColor = Color.LightSkyBlue
Button1.Text = "Add New Entry"
Button1.ForeColor = Color.White
Button1.BackColor = Color.Green
Label5.ForeColor = Color.Red
Button2.Text = "Exit"
Button2.BackColor = Color.Red
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click Dim str(4) As String
Dim itm As ListViewItem
str(0) = TextBox1.Text 'Accept value from the user.
str(1) = TextBox2.Text
str(2) = TextBox3.Text
str(3) = TextBox4.Text
itm = New ListViewItem(str)
ListView1.Items.Add(itm) 'Add the items into the ListView
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
End 'Exit from the program
End Sub
End Class
Tree View
The TreeView control is used to display a hierarchical representation of the same data in a tree structure. The top-level in the tree view is the root node with one or more child nodes. In addition, the root node can be contracted or expanded by clicking on the plus sign (+) button. It is also useful to provide the full path of the root node to the child node.
Properties
BackColor
Gets or sets the background color for the control.
BackgroundImage
Gets or set the background image for the TreeView control.
BackgroundImageLayout
Gets or sets the layout of the background image for the TreeView control.
BorderStyle
Gets or sets the border style of the tree view control.
VisibleCount
Gets the number of tree nodes that can be fully visible in the tree view control.
Method
CollapseAll
Collapses all the nodes including all child nodes in the tree view control.
ExpandAll
Expands all the nodes.
GetNodeAt
Gets the node at the specified location.
GetNodeCount
Gets the number of tree nodes.
Sort
Sorts all the items in the tree view control.
Events
AfterCheck
Occurs after the tree node check box is checked.
AfterCollapse
Occurs after the tree node is collapsed.
AfterExpand
Occurs after the tree node is expanded.
AfterSelect
Occurs after the tree node is selected.
Paint
Occurs when the TreeView is drawn.
The TreeNode Class
The TreeNode class represents a node of a TreeView. Each node in a TreeView control is an object of the TreeNode class. To be able to use a TreeView control we need to have a look at some commonly used properties and methods of the TreeNode class.
Properties
Name
Gets or sets the name of the tree node.
Text
Gets or sets the text displayed in the label of the tree node.
ToolTipText
Gets or sets the text that appears when the mouse pointer hovers over a TreeNode.
Methods
Collapse
Collapses the tree node.
Expand
Expands the tree node.
ExpandAll
Expands all the child tree nodes.
Remove
Removes the current tree node from the tree view control.
ToolBar
The Windows Forms ToolBar control is used on forms as a control bar that displays a row of drop down menus and bitmapped buttons that activate commands.
a toolbar contains buttons and menus that correspond to items in an application's menu structure, providing quick access to an application's most frequently used functions and commands.
A ToolBar control is usually "docked" along the top of its parent window, but it can also be docked to any side of the window. A toolbar can display tooltips when the user points the mouse pointer at a toolbar button. A ToolTip is a small pop-up window that briefly describes the button or menu's purpose. To display ToolTips
The ToolBar control allows you to create toolbars by adding Button objects to a Buttons collection. You can use the Collection Editor to add buttons to a ToolBar control; each Button object should have text or an image assigned, although you can assign both. The image is supplied by an associated ImageList component.
Status Bar
A status bar is commonly used to provide hints for the selected item or information about an action currently being performed on a dialog. Normally, the StatusBar is placed at the bottom of the screen, as it is in MS Office applications and Paint, but it can be located anywhere you like.
Properties
BackgroundImage- It is possible to assign an image to the status bar that will be drawn in the background.
Panels- This is the collection of panels in the status bar. Use this collection to add and remove panels.
ShowPanels- If you want to display panels, this property must be set to true.
Text-set text on status bar.
Open File Dialog
The OpenFileDialog control prompts the user to open a file and allows the user to select a file to open. The user can check if the file exists and then open it. The OpenFileDialog control class inherits from the abstract class FileDialog.
If the ShowReadOnly property is set to True, then a read-only check box appears in the dialog box. You can also set the ReadOnlyChecked property to True, so that the read-only check box appears checked.
Public Class OpenFIleDialog
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
OpenFileDialog1.InitialDirectory = "C:\"
OpenFileDialog1.Title = "Open Image File"
OpenFileDialog1.Filter = "Image|*jpg"
PictureBox1.Image = Image.FromFile(OpenFileDialog1.FileName)
Label2.Text = OpenFileDialog1.FileName
End If
End Sub
End Class
Save File Dialog
The SaveFileDialog control prompts the user to select a location for saving a file and allows the user to specify the name of the file to save data. The SaveFileDialog control class inherits from the abstract class FileDialog.
Public Class SaveFileDialog
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
SaveFileDialog1.Filter = "TXT Files(*txt*)|*.txt"
If SaveFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then My.Computer.FileSystem.WriteAllText(SaveFileDialog1.FileName,
RichTextBox1.Text, True)
RichTextBox1.Clear()
End If
End Sub
End Class
Font Dialog
The Font Dialog Box allows the user to select the font family, style, and size for the text in an application. However, a user can also select the font color and apply the current setting to the selected text of the control by clicking the Apply button.
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
FontDialog1.ShowColor = True
If FontDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
RichTextBox1.Font = FontDialog1.Font 'Change the font of the selected string
RichTextBox1.ForeColor = FontDialog1.Color 'Change the color of selected string End If
End Sub
Color Dialog
The Color Dialog box is used to display the Color dialog box and the selection of colors on the Microsoft Windows Application. It allows users to set or change the color of an object, such as the background color of a control or the color used to paint an object. Furthermore, the control dialog box also allows the facility to the user to create a new color by mixing all other colors of the Color Dialog Box.
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
ColorDialog1.FullOpen = False
If ColorDialog1.ShowDialog <> Windows.Forms.DialogResult.Cancel Then
RichTextBox1.ForeColor = ColorDialog1.Color
End If
'Me.BackColor = ColorDialog1.Color 'Change Background color of the form
End Sub
Print Dialog
The PrintDialog control lets the user to print documents by selecting a printer and choosing which sections of the document to print from a Windows Forms application.
There are various other controls related to printing of documents. Let us have a brief look at these controls and their purpose. These other controls are −
∙ The PrintDocument control − it provides support for actual events and operations of printing in Visual Basic and sets the properties for printing.
∙ The PrinterSettings control − it is used to configure how a document is printed by specifying the printer.
∙ The PageSetUpDialog control − it allows the user to specify page-related print settings including page orientation, paper size and margin size.
∙ The PrintPreviewControl control − it represents the raw preview part of print previewing from a Windows Forms application, without any dialog boxes or buttons.
∙ The PrintPreviewDialog control − it represents a dialog box form that contains a PrintPreviewControl for printing from a Windows Forms application.
Private Sub printpriview_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
If RichTextBox1.Text = "" Then
MsgBox("Please write some text...")
Else
PrintPreviewDialog1.ShowDialog()
End If
End Sub
Private Sub print_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
If PrintDialog1.ShowDialog = DialogResult.OK Then 'Open the print dialog box PrintDocument1.PrinterSettings = PrintDialog1.PrinterSettings
PrintDocument1.Print() 'print a document
End If
End Sub
Private Sub PrintDocument1_PrintPage(ByVal sender As System.Object, ByVal e As System.Drawing.Printing.PrintPageEventArgs) Handles PrintDocument1.PrintPage Dim font As New Font("Times New Roman", 10, FontStyle.Bold) 'set the font to display e.Graphics.DrawString(RichTextBox1.Text, font, Brushes.Red, 100, 100)
End Sub
Private Sub Form_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
PrintPreviewDialog1.Document = PrintDocument1
End Sub
Link Lable
A LinkLabel control is a label control that can display a hyperlink. A LinkLabel control is inherited from the Label class so it has all the functionality provided by the Windows Forms Label control. LinkLabel control does not participate in user input or capture mouse or keyboard events.
Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
System.Diagnostics.Process.Start("www.google.com")
End Sub
Designing menus:
A menu is used as a menu bar in the Windows form that contains a list of related commands, and it is implemented through MenuStrip Control. The Menu control is also known as the VB.NET MenuStrip Control. The menu items are created with ToolStripMenuItem Objects. Furthermore, the ToolStripDropDownMenu and ToolStripMenuItem objects enable full control over the structure, appearance, functionalities to create menu items, submenus, and drop-down menus
Private Sub ExitToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExitToolStripMenuItem.Click
Me.Dispose()
End Sub
Private Sub NewToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NewToolStripMenuItem.Click
Dim f1 As New ChkBoxForm()
f1.Visible = True
End Sub
Context menu:
The ContextMenuStrip control represents a shortcut menu that pops up over controls, usually when you right click them. They appear in context of some specific controls, so are called context menus. For example, Cut, Copy or Paste options.
This control associates the context menu with other menu items by setting that menu item's ContextMenuStrip property to the ContextMenuStrip control you designed.
Context menu items can also be disabled, hidden or deleted. You can also show a context menu with the help of the Show method of the ContextMenuStrip control.
Private Sub CutToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CutToolStripMenuItem.Click
RichTextBox1.Cut()
End Sub
Private Sub CopyToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CopyToolStripMenuItem.Click
RichTextBox1.Copy()
End Sub
Private Sub PasteToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PasteToolStripMenuItem.Click
RichTextBox1.Paste()
End Sub
Access & shortcut keys
The ToolStripMenuItem class supports the menus and menu items in a menu system. You handle these menu items through the click events in a menu system.
Set Access Keys for Menu Items
Setting access keys for a menu allows a user to select it from the keyboard by using the ALT key.
For example, if you want to set an access key ALT + F for the file menu, change its Text with an added & (ampersand) preceding the access key letter. In other words, you change the text property of the file menu to &File.
Set Shortcut Keys for Menu Items
When you set a shortcut key for a menu item, user can press the shortcut from the keyboard and it would result in occurrence of the Click event of the menu.
A shortcut key is set for a menu item using the ShortcutKeys property. For example, to set a shortcut key CTRL + E, for the Edit menu −
∙ Select the Edit menu item and select its ShortcutKeys property in the properties window. ∙ Click the drop down button next to it.
∙ Select Ctrl as Modifier and E as the key.
The End
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